IM 314Computer Aided Designing/ComputerAided Manufacturing (CAD/CAM)

Credit Hours: 3-1/2

Text Book/Reference Book(s):1. CAD/CAM Principles and Applications by PN Rao2. Principles of CAD/CAM/CAE Systems by Kunwoo Lee3. CADCAM: From Principles to Practice by Chris McMahon and

Jimmie Browne

Instructor: Ali HassanLecturer, IMEM, PNEC, NUST.

Marks Distribution Scheme- Assignment/Project (5% - 10%) 10%- Quiz (10% 15%) 15%- One Hour Test (30% - 40%) 35%- Final Exam (40% - 50%) 40%

- Tentative dates for One Hour Test- 04-March, 19-March, 30-April, 7-May, 13-May

- Assignment/Project (5% - 10%) 10%- Quiz (10% 15%) 15%- One Hour Test (30% - 40%) 35%- Final Exam (40% - 50%) 40%

- Tentative dates for One Hour Test- 04-March, 19-March, 30-April, 7-May, 13-May

Class Rules No drinks or eatables in the class No discussion/debate on politics/religion No mobile texting during class Please keep your mobile phone silent; if youhave to attend a call take it outside the class

Good is of discipline of utmost importance No collective bunking, or else.

No drinks or eatables in the class No discussion/debate on politics/religion No mobile texting during class Please keep your mobile phone silent; if youhave to attend a call take it outside the class

Good is of discipline of utmost importance No collective bunking, or else.

BibliographyThe lecture material has been compiled from the followingsources; CAD/ CAM Principles and Applications by PN Rao Principles of CAD/CAM/CAE Systems by Kunwoo Lee CADCAM: From Principles to Practice by Chris

McMahon and Jimmie Browne Notes from IM 314 CAD/CAM by Dr. Usama Umer,

PNEC, NUST Notes from IE 433 CADCAM by Dr. Saeed M Hassan

Darwaish, KSU,SA Notes from CAD/CAM by Zambri Harun, JKMB, UKM World Wide Web (Internet)

CAD/ CAM Principles and Applications by PN Rao Principles of CAD/CAM/CAE Systems by Kunwoo Lee CADCAM: From Principles to Practice by Chris

McMahon and Jimmie Browne Notes from IM 314 CAD/CAM by Dr. Usama Umer,

PNEC, NUST Notes from IE 433 CADCAM by Dr. Saeed M Hassan

Darwaish, KSU,SA Notes from CAD/CAM by Zambri Harun, JKMB, UKM World Wide Web (Internet)

CAM & its ApplicationsCAM & its Applications

Implementation of a Typical CAM Process on aCAD/CAM system

Geometric model

Interfacealgorithms

Inspection

AssemblyInterface

algorithms

Process planning

Assembly

Packaging

To shipping and marketingNC programs

Manufacturing phase Required CAM toolsProcess planning CAPP techniques; cost

analysis; material andtooling specification.

Part programming NC programming

CAM Tools Required to Support the Design Process

Part programming NC programmingInspection CAQ; and Inspection

softwareAssembly Robotics simulation and

programming

Definitions of CAM Tools Based on TheirConstituents

Networkingconcepts

Mfg tools CAD

CAMtools

Definition of CAM Tools Based on Their Implementationin a Manufacturing Environment

Hardware(control unit; displayterminals;I/O devices

Mfg tools + Computer Software (CAD; NC;MRP; CAPP)

= CAM tools

Networking

Why CAM Greater design freedom changed incorporatedduring design stage Increased productivity totally organized bycomputer Greater operating activity flexible manufacturingmethod Shorter lead time Reduced maintenance Reduce scrap and reworks Better management control

Greater design freedom changed incorporatedduring design stage Increased productivity totally organized bycomputer Greater operating activity flexible manufacturingmethod Shorter lead time Reduced maintenance Reduce scrap and reworks Better management control

CAM in Manufacturing Planning

Computer aided process planning (CAPP)Computer assisted NC part programmingComputerized machinability data systemDevelopment of work standardsCost estimatingProduction and Inventory planning

Computer aided process planning (CAPP)Computer assisted NC part programmingComputerized machinability data systemDevelopment of work standardsCost estimatingProduction and Inventory planning

CAM in Manufacturing Control

Process monitoring and controlQuality controlShop floor controlInventory controlJust in time production systems

Process monitoring and controlQuality controlShop floor controlInventory controlJust in time production systems

From CAM definition, the application of CAMfalls into two broad categories:

1. Computer monitoring and control .

Control signalsComputerMfg

operationsProcess data

2.Manufacturing support application.E.g. conveyers, AGVs, ASRS,

Types of Manufacturing Systems

1. Continuous-flow processes. Continuous dedicated production oflarge amount of bulk product. Continuous manufacturing isrepresented by chemicals, plastics, petroleum, and food industries.

2. Mass production of discrete products. Dedicated production oflarge quantities of one product (with perhaps limited modelvariations). Examples include automobiles, appliances and engineblocks.

3. Batch production. Production of medium lot sizes of the sameproduct. The lot may be produced once or repeated periodically.Examples: books, clothing and certain industrial machinery.

4. Job-shop production. Production of low quantities, often one of akind, of specialized products. The products are often customizedand technologically complex. Examples: prototypes, aircraft,machine tools and other equipment.

1. Continuous-flow processes. Continuous dedicated production oflarge amount of bulk product. Continuous manufacturing isrepresented by chemicals, plastics, petroleum, and food industries.

2. Mass production of discrete products. Dedicated production oflarge quantities of one product (with perhaps limited modelvariations). Examples include automobiles, appliances and engineblocks.

3. Batch production. Production of medium lot sizes of the sameproduct. The lot may be produced once or repeated periodically.Examples: books, clothing and certain industrial machinery.

4. Job-shop production. Production of low quantities, often one of akind, of specialized products. The products are often customizedand technologically complex. Examples: prototypes, aircraft,machine tools and other equipment.

Productionquantity

Continuous-flow

production Massproduction

Batchproduction

Productionquantity

Batchproduction

Job shopproduction

Product variety

Category Automation achievementsContinuous-flow process Flow process from beginning to end

Sensors technology available to measureimportant process variablesUse of sophisticated control and optimizationstrategiesFully computer automated lines

Mass production of discrete products Automated transfer machinesDial indexing machinesPartially and fully automated assembly linesIndustrial robots for spot welding, part handling,machine loading, spray painting, etc.Automated material handling systemsComputer production monitoring

Automated transfer machinesDial indexing machinesPartially and fully automated assembly linesIndustrial robots for spot welding, part handling,machine loading, spray painting, etc.Automated material handling systemsComputer production monitoring

Batch production Numerical control (NC), direct numerical control(DNC), computer numerical control (CNC).Adaptive control machiningRobots for arc welding, parts handling, etc.CIM systems.

Job shop production Numerical control, computer numerical control

321 TBTBQTTTlc

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Automation technology is concerned with reducingthe with emphasis on the unit production

time

CAD/CAM concerned with reducing all threeterms, but is perhaps focused on terms.The emphasis in CAD/CAM includes the designand planning function of the product life cycle.

1T

32 & TT

The most important term in mass productionand batch production

become very important in job shopmanufacturing.

1T21 & TT

Automation technology is concerned with reducingthe with emphasis on the unit production

time

CAD/CAM concerned with reducing all threeterms, but is perhaps focused on terms.The emphasis in CAD/CAM includes the designand planning function of the product life cycle.

1T

32 & TT

Advantages of CAD/CAM systems Greater flexibility. Reduced lead times. Reduced inventories. Increased Productivity. Improved customer

service. Improved quality. Improved communications

with suppliers.

Better product design. Greater manufacturing

control. Supported integration. Reduced costs. Increased utilization. Reduction of machine

tools. Less floor space.

Greater flexibility. Reduced lead times. Reduced inventories. Increased Productivity. Improved customer

service. Improved quality. Improved communications

with suppliers.

Better product design. Greater manufacturing

control. Supported integration. Reduced costs. Increased utilization. Reduction of machine

tools. Less floor space.

Rapid PrototypingRapid Prototyping

RAPID PROTOTYPING1. Fundamentals of Rapid Prototyping2. Rapid Prototyping Technologies3. Applications and Benefits of Rapid

Prototyping

1. Fundamentals of Rapid Prototyping2. Rapid Prototyping Technologies3. Applications and Benefits of Rapid

Prototyping

Rapid Prototyping (RP)A family of fabrication processes developed tomake engineering prototypes in minimumlead time based on a CAD model of the item

Traditional method is machining Can require significant lead-times several weeks,depending on part complexity and difficulty in orderingmaterials

RP allows a part to be made in hours or days,given that a computer model of the part hasbeen generated on a CAD system

A family of fabrication processes developed tomake engineering prototypes in minimumlead time based on a CAD model of the item

Traditional method is machining Can require significant lead-times several weeks,depending on part complexity and difficulty in orderingmaterials

RP allows a part to be made in hours or days,given that a computer model of the part hasbeen generated on a CAD system

Why is Rapid PrototypingImportant?

Product designers want to have a physicalmodel of a new part or product design ratherthan just a computer model or line drawing Creating a prototype is an integral step in design A virtual prototype (a CAD model of the part) may not besufficient for the designer to visualize the part adequately

Using RP to make the prototype, the designer can see andfeel the part and assess its merits and shortcomings

Product designers want to have a physicalmodel of a new part or product design ratherthan just a computer model or line drawing Creating a prototype is an integral step in design A virtual prototype (a CAD model of the part) may not besufficient for the designer to visualize the part adequately

Using RP to make the prototype, the designer can see andfeel the part and assess its merits and shortcomings

RP Two Basic Categories:1. Material removal RP - machining, using a

dedicated CNC machine that is available tothe design department on short notice Starting material is often wax

Easy to machine Can be melted and resolidified

The CNC machines are often small - called desktopmachining

2. Material addition RP - adds layers of materialone at a time to build the solid part frombottom to top

1. Material removal RP - machining, using adedicated CNC machine that is available tothe design department on short notice Starting material is often wax

Easy to machine Can be melted and resolidified

The CNC machines are often small - called desktopmachining

2. Material addition RP - adds layers of materialone at a time to build the solid part frombottom to top

Starting Materials in MaterialAddition RP

1. Liquid monomers that are cured layer by layer into solidpolymers

2. Powders that are aggregated and bonded layer by layer

3. Solid sheets that are laminated to create the solid part

Additional Methods In addition to starting material, the variousmaterial addition RP technologies usedifferent methods of building and addinglayers to create the solid part There is a correlation between starting material and

part building techniques

1. Liquid monomers that are cured layer by layer into solidpolymers

2. Powders that are aggregated and bonded layer by layer

3. Solid sheets that are laminated to create the solid part

Additional Methods In addition to starting material, the variousmaterial addition RP technologies usedifferent methods of building and addinglayers to create the solid part There is a correlation between starting material and

part building techniques

Steps to Prepare ControlInstructions

1. Geometric modeling - model the componenton a CAD system to define its enclosedvolume

2. Tessellation of the geometric model - the CADmodel is converted into a computerizedformat that approximates its surfaces byfacets (triangles or polygons)

3. Slicing of the model into layers - computerizedmodel is sliced into closely-spaced parallelhorizontal layers

1. Geometric modeling - model the componenton a CAD system to define its enclosedvolume

2. Tessellation of the geometric model - the CADmodel is converted into a computerizedformat that approximates its surfaces byfacets (triangles or polygons)

3. Slicing of the model into layers - computerizedmodel is sliced into closely-spaced parallelhorizontal layers

Tessellation is the process of creating a two-dimensional plane using the repetition of ageometric shape with no overlaps and nogaps.

A tessellation of a disk used tosolve a finite element problem

Solid Model to Layers

Figure 34.1 Conversion of a solid model of an object into layers(only one layer is shown).

Classification of RP Technologies There are various ways to classify the RP

techniques that have currently beendeveloped

The RP classification used here is based onthe form of the starting material:1. Liquid-based2. Solid-based3. Powder-based

There are various ways to classify the RPtechniques that have currently beendeveloped

The RP classification used here is based onthe form of the starting material:1. Liquid-based2. Solid-based3. Powder-based

Liquid-Based Rapid PrototypingSystems

Starting material is a liquid About a dozen RP technologies are in thiscategory

Includes the following processes: Stereolithography Solid ground curing Droplet deposition manufacturing

http://www.wimp.com/functionaltools/

Starting material is a liquid About a dozen RP technologies are in thiscategory

Includes the following processes: Stereolithography Solid ground curing Droplet deposition manufacturing

http://www.wimp.com/functionaltools/

Stereolithography (STL)RP process for fabricating a solid plastic part outof a photosensitive liquid polymer using adirected laser beam to solidify the polymer

Part fabrication is accomplished as a series oflayers - each layer is added onto the previouslayer to gradually build the 3-D geometry

The first addition RP technology - introduced1988 by 3D Systems Inc. based on the work ofCharles Hull

More installations than any other RP method

RP process for fabricating a solid plastic part outof a photosensitive liquid polymer using adirected laser beam to solidify the polymer

Part fabrication is accomplished as a series oflayers - each layer is added onto the previouslayer to gradually build the 3-D geometry

The first addition RP technology - introduced1988 by 3D Systems Inc. based on the work ofCharles Hull

More installations than any other RP method

Stereolithography

Figure 34.2 Stereolithography: (1) at the start of the process, in which theinitial layer is added to the platform; and (2) after several layers have beenadded so that the part geometry gradually takes form.

Rapid Prototyping Process (Damvig)A computer-controlled laser beam isscanned across the surface of a vat ofliquid photopolymer, instantlysolidifying the liquid at each point ofcontact. Using data generated from aCAD file, individual cross-sections ofthe three-dimensional geometry aresolidified in turn to build up a solidpart layer by layer. In this way evenhighly complex geometries can bebuilt in a few hours without requiringany tools.

A computer-controlled laser beam isscanned across the surface of a vat ofliquid photopolymer, instantlysolidifying the liquid at each point ofcontact. Using data generated from aCAD file, individual cross-sections ofthe three-dimensional geometry aresolidified in turn to build up a solidpart layer by layer. In this way evenhighly complex geometries can bebuilt in a few hours without requiringany tools.

Facts about STL Each layer is 0.076 mm to 0.50 mm (0.003 into 0.020 in.) thick Thinner layers provide better resolution and more intricateshapes; but processing time is longer

Starting materials are liquid monomers Polymerization occurs on exposure to UV lightproduced by laser scanning beam Scanning speeds ~ 500 to 2500 mm/s

Each layer is 0.076 mm to 0.50 mm (0.003 into 0.020 in.) thick Thinner layers provide better resolution and more intricateshapes; but processing time is longer

Starting materials are liquid monomers Polymerization occurs on exposure to UV lightproduced by laser scanning beam Scanning speeds ~ 500 to 2500 mm/s

Solid Ground Curing (SGC)Like stereolithography, SGC works by curing aphotosensitive polymer layer by layer tocreate a solid model based on CAD geometricdata

Instead of using a scanning laser beam to curea given layer, the entire layer is exposed to aUV source through a mask above the liquidpolymer

Hardening takes 2 to 3 s for each layer

Like stereolithography, SGC works by curing aphotosensitive polymer layer by layer tocreate a solid model based on CAD geometricdata

Instead of using a scanning laser beam to curea given layer, the entire layer is exposed to aUV source through a mask above the liquidpolymer

Hardening takes 2 to 3 s for each layer

Figure 34.4 SGC steps for eachlayer: (1) mask preparation,(2) applying liquidphotopolymer layer,(3) maskpositioning and exposure oflayer, (4) uncured polymerremoved from surface, (5)wax filling, (6) milling forflatness and thickness.

Solid Ground Curing

Figure 34.4 SGC steps for eachlayer: (1) mask preparation,(2) applying liquidphotopolymer layer,(3) maskpositioning and exposure oflayer, (4) uncured polymerremoved from surface, (5)wax filling, (6) milling forflatness and thickness.

Facts about SGC Sequence for each layer takes about 90seconds

Time to produce a part by SGC is claimed tobe about eight times faster than other RPsystems

The solid cubic form created in SGC consists ofsolid polymer and wax

The wax provides support for fragile andoverhanging features of the part duringfabrication, but can be melted away later toleave the free-standing part

Sequence for each layer takes about 90seconds

Time to produce a part by SGC is claimed tobe about eight times faster than other RPsystems

The solid cubic form created in SGC consists ofsolid polymer and wax

The wax provides support for fragile andoverhanging features of the part duringfabrication, but can be melted away later toleave the free-standing part

Droplet Deposition Manufacturing(DDM)

Starting material is melted and small droplets areshot by a nozzle onto previously formed layer

Droplets cold weld to surface to form a new layer Deposition for each layer controlled by a movingx-y nozzle whose path is based on a cross sectionof a CAD geometric model that is sliced intolayers

Work materials include wax and thermoplastics

Starting material is melted and small droplets areshot by a nozzle onto previously formed layer

Droplets cold weld to surface to form a new layer Deposition for each layer controlled by a movingx-y nozzle whose path is based on a cross sectionof a CAD geometric model that is sliced intolayers

Work materials include wax and thermoplastics

Droplet Deposition Manufacturing(DDM)

Solid-Based Rapid PrototypingSystems

Starting material is a solid Solid-based RP systems include the following

processes: Laminated object manufacturing Fused deposition modeling

Starting material is a solid Solid-based RP systems include the following

processes: Laminated object manufacturing Fused deposition modeling

Laminated Object Manufacturing(LOM)

Solid physical model made by stacking layers ofsheet stock, each an outline of the cross-sectionalshape of a CAD model that is sliced into layers

Starting sheet stock includes paper, plastic,cellulose, metals, or fiber-reinforced materials

The sheet is usually supplied with adhesivebacking as rolls that are spooled between tworeels

After cutting, excess material in the layer remainsin place to support the part during building

Solid physical model made by stacking layers ofsheet stock, each an outline of the cross-sectionalshape of a CAD model that is sliced into layers

Starting sheet stock includes paper, plastic,cellulose, metals, or fiber-reinforced materials

The sheet is usually supplied with adhesivebacking as rolls that are spooled between tworeels

After cutting, excess material in the layer remainsin place to support the part during building

Laminated Object Manufacturing

Figure 34.5 Laminated object manufacturing.

LOM Example

Fused Deposition Modeling (FDM)RP process in which a long filament of wax orpolymer is extruded onto existing part surfacefrom a workhead to complete each new layer

Workhead is controlled in the x-y plane duringeach layer and then moves up by a distanceequal to one layer in the z-direction

Extrudate is solidified and cold welded to thecooler part surface in about 0.1 s

Part is fabricated from the base up, using alayer-by-layer procedure

RP process in which a long filament of wax orpolymer is extruded onto existing part surfacefrom a workhead to complete each new layer

Workhead is controlled in the x-y plane duringeach layer and then moves up by a distanceequal to one layer in the z-direction

Extrudate is solidified and cold welded to thecooler part surface in about 0.1 s

Part is fabricated from the base up, using alayer-by-layer procedure

FDM Layer FormationFilament

Supply

HeatedFDM HeadMoltenFilament

FDM generatedcross section

Filament

Supply

HeatedFDM HeadMoltenFilament

Notice that the FDM filament cannotcross itself, as this would cause a highspot in the given layer

Fused Deposition Machine

Stratasys FDM 2000http://www.stratasys.com/

Powder-Based RP Systems Starting material is a powder Powder-based RP systems include the

following: Selective laser sintering Three dimensional printing

Starting material is a powder Powder-based RP systems include the

following: Selective laser sintering Three dimensional printing

Selective Laser Sintering (SLS)Moving laser beam sinters heat fusible powdersin areas corresponding to the CAD geometrymodel one layer at a time to build the solidpart

After each layer is completed, a new layer ofloose powders is spread across the surface

Layer by layer, the powders are graduallybonded by the laser beam into a solid massthat forms the 3-D part geometry

In areas not sintered, the powders are looseand can be poured out of completed part

Moving laser beam sinters heat fusible powdersin areas corresponding to the CAD geometrymodel one layer at a time to build the solidpart

After each layer is completed, a new layer ofloose powders is spread across the surface

Layer by layer, the powders are graduallybonded by the laser beam into a solid massthat forms the 3-D part geometry

In areas not sintered, the powders are looseand can be poured out of completed part

SLS ProcessPowder Bed

Piston

LaserOpticsMirror Powder Bed

LevelingRoller

Powder Feeding System

Powder Bed

Piston

LaserOpticsMirror Powder Bed

LevelingRoller

Powder Feeding System

Three Dimensional Printing (3DP)Part is built layer-by-layer using an ink-jet printer toeject adhesive bonding material onto successivelayers of powders

Binder is deposited in areas corresponding to thecross sections of part, as determined by slicingthe CAD geometric model into layers

The binder holds the powders together to formthe solid part, while the unbonded powdersremain loose to be removed later

To further strengthen the part, a sintering stepcan be applied to bond the individual powders

Part is built layer-by-layer using an ink-jet printer toeject adhesive bonding material onto successivelayers of powders

Binder is deposited in areas corresponding to thecross sections of part, as determined by slicingthe CAD geometric model into layers

The binder holds the powders together to formthe solid part, while the unbonded powdersremain loose to be removed later

To further strengthen the part, a sintering stepcan be applied to bond the individual powders

Three Dimensional Printing

Figure 34.6 Three dimensional printing: (1) powder layer is deposited,(2) ink-jet printing of areas that will become the part, and (3) pistonis lowered for next layer (key: v = motion).

3-D Printing Process

"Slow" Axis

"Fast" Axis

Print-head

Powder Bed

Print-head Powder

Bed

Piston

Binder

"Slow" Axis

"Fast" Axis

Print-head

Powder Bed

Print-head Powder

Bed

Piston

Binder

Ballistic Particle Manufacturing(BPM)

Employs a technology called Digital Microsynthesis1) Molten plastic is fed to a piezoelectric jetting mechanism,

similar to those on inkjet printers.2) A multi-axis controlled NC system shoots tiny droplets of

material onto the target, using the jetting mechanism.3) Small droplets freeze upon contact with the surface, forming

the surface particle by particle.Process allows use of virtually any thermoplastic (no health

hazard) & offers the possibility of using material other thanplastic.

Employs a technology called Digital Microsynthesis1) Molten plastic is fed to a piezoelectric jetting mechanism,

similar to those on inkjet printers.2) A multi-axis controlled NC system shoots tiny droplets of

material onto the target, using the jetting mechanism.3) Small droplets freeze upon contact with the surface, forming

the surface particle by particle.Process allows use of virtually any thermoplastic (no health

hazard) & offers the possibility of using material other thanplastic.

BPM ProcessEjector Head Has multi-axis control

to "aim" droplet stream

BuildPlatform

Dropletsof MoltenMaterial

Ejector Head Has multi-axis controlto "aim" droplet stream

BuildPlatform

Dropletsof MoltenMaterial

SFM Layer Formation MethodsSolid

Powder Bulk LiquidPolymerization

Melting &Solidification

1 ComponentSelective Laser

Sintering

Gluing SheetsLaminatedObjectManufacturing

Liquid

Shape Melting

Fused DepositionModeling

Ballistic ParticleManufacturing

Light HeatThermalPolymer-ization

1 ComponentSelective Laser

Sintering

Component& Binder

3D Printing &Gluing

Gluing SheetsLaminatedObjectManufacturing

PolymerizationFoilPolymerization

Shape Melting

Fused DepositionModeling

Ballistic ParticleManufacturing

ThermalPolymer-izationTwofrequencies

Beam Inter-ferencesolid

Onefrequency

Lamps

Lasers

Solid Base CuringPhotosolid. Layer at a Time

Stereolithography

RP Applications Applications of rapid prototyping can be

classified into three categories:1. Design2. Engineering analysis and planning3. Tooling and manufacturing

Applications of rapid prototyping can beclassified into three categories:1. Design2. Engineering analysis and planning3. Tooling and manufacturing

Design Applications Designers are able to confirm their design bybuilding a real physical model in minimumtime using RP

Design benefits of RP: Reduced lead times to produce prototypes Improved ability to visualize part geometry Early detection of design errors Increased capability to compute mass properties

Designers are able to confirm their design bybuilding a real physical model in minimumtime using RP

Design benefits of RP: Reduced lead times to produce prototypes Improved ability to visualize part geometry Early detection of design errors Increased capability to compute mass properties

Engineering Analysis and Planning Existence of part allows certain engineeringanalysis and planning activities to beaccomplished that would be more difficultwithout the physical entity Comparison of different shapes and styles to determineaesthetic appeal

Wind tunnel testing of streamline shapes Stress analysis of physical model Fabrication of pre-production parts for process planningand tool design

Existence of part allows certain engineeringanalysis and planning activities to beaccomplished that would be more difficultwithout the physical entity Comparison of different shapes and styles to determineaesthetic appeal

Wind tunnel testing of streamline shapes Stress analysis of physical model Fabrication of pre-production parts for process planningand tool design

Tooling Applications Called rapid tool making (RTM) when RP isused to fabricate production tooling

Two approaches for tool-making:1. Indirect RTM method2. Direct RTM method

Called rapid tool making (RTM) when RP isused to fabricate production tooling

Two approaches for tool-making:1. Indirect RTM method2. Direct RTM method

Indirect RTM MethodPattern is created by RP and the pattern is used

to fabricate the tool Examples:

Patterns for sand casting and investment casting Electrodes for EDM

Pattern is created by RP and the pattern is usedto fabricate the tool

Examples: Patterns for sand casting and investment casting Electrodes for EDM

Direct RTM MethodRP is used to make the tool itself Example:

3DP to create a die of metal powders followed bysintering and infiltration to complete the die

RP is used to make the tool itself Example:

3DP to create a die of metal powders followed bysintering and infiltration to complete the die

Manufacturing Applications Small batches of plastic parts that could notbe economically molded by injection moldingbecause of the high mold cost

Parts with intricate internal geometries thatcould not be made using conventionaltechnologies without assembly

One-of-a-kind parts such as bonereplacements that must be made to correctsize for each user

Small batches of plastic parts that could notbe economically molded by injection moldingbecause of the high mold cost

Parts with intricate internal geometries thatcould not be made using conventionaltechnologies without assembly

One-of-a-kind parts such as bonereplacements that must be made to correctsize for each user

Problems with Rapid Prototyping Part accuracy:

Staircase appearance for a sloping part surface due tolayering

Shrinkage and distortion of RP parts Limited variety of materials in RP

Mechanical performance of the fabricated parts is limitedby the materials that must be used in the RP process

Part accuracy: Staircase appearance for a sloping part surface due tolayering

Shrinkage and distortion of RP parts Limited variety of materials in RP

Mechanical performance of the fabricated parts is limitedby the materials that must be used in the RP process

Rapid Prototyping Layer by layer fabrication of

three-dimensional physicalmodels from CAD

Fast and inexpensive alternativefor producing prototypes andfunctional models

Build parts in thin layers Minimum operation time;

typically runs unattended

Layer by layer fabrication ofthree-dimensional physicalmodels from CAD

Fast and inexpensive alternativefor producing prototypes andfunctional models

Build parts in thin layers Minimum operation time;

typically runs unattendedRapid Prototyping hassurgical applications

Medical Modeling - Zcorp

For more information on RP

efunda.com http://www.efunda.com/processes/rapid_prototyping/

Numerical Control MachinesNumerical Control Machines

Introduction to Numerical ControlWhat is numerical control (NC)?NC has been defined by the Electronic Industries Association (EIA) as asystem in which actions are controlled by the direct insertion of numericaldata at some points. The system must automatically interpret at least someportion of this dataThe term NC is used to describe the control of the various functions of amachine using numeric data. In the early age of NC, machines were fedwith information by means of the punched tape. An Electro-mechanicaltape reader was used to load a machine tape into the controller.

What is numerical control (NC)?NC has been defined by the Electronic Industries Association (EIA) as asystem in which actions are controlled by the direct insertion of numericaldata at some points. The system must automatically interpret at least someportion of this dataThe term NC is used to describe the control of the various functions of amachine using numeric data. In the early age of NC, machines were fedwith information by means of the punched tape. An Electro-mechanicaltape reader was used to load a machine tape into the controller.

In general there are three basic components of anoperational NC (as illustrated in Figure 1):1. Programme of instruction.2. A machine control unit.3. Machine tool.

Program ofinstruction

Control unitMachine tool

Punch Card for storing NC program

The program of instruction is a numerical or symboliccode that is detailed step-by-step to tell the machinetool what to do.The controller unit is the unit that reads theprogramme of instructions and converts it to realmovement of a machine tool. Two basic types ofcontrol unit are used with NC machines: open-loopcontrol and closed-loop control.The machine tool performs the mechanical work anddeals directly with the part being machined.

The program of instruction is a numerical or symboliccode that is detailed step-by-step to tell the machinetool what to do.The controller unit is the unit that reads theprogramme of instructions and converts it to realmovement of a machine tool. Two basic types ofcontrol unit are used with NC machines: open-loopcontrol and closed-loop control.The machine tool performs the mechanical work anddeals directly with the part being machined.

Computer Numerical Control (CNC)CNC refers to a computer that is joined to the NC machine tomake the machine versatile. Information can be stored in amemory bank. The programme is read from a storage mediumsuch as the punched tape and retrieved to the memory of theCNC computer. Some CNC machines have a magnetic medium(tape or disk) for storing programs. This gives more flexibility forediting or saving CNC programs.

CNC refers to a computer that is joined to the NC machine tomake the machine versatile. Information can be stored in amemory bank. The programme is read from a storage mediumsuch as the punched tape and retrieved to the memory of theCNC computer. Some CNC machines have a magnetic medium(tape or disk) for storing programs. This gives more flexibility forediting or saving CNC programs.

Machine tool

Miscellaneous control-e.g. limit switches,coolant, spindle, etc.

NC controllerwith keypadand display

Magnetic tapeor disk orpaper tapereader

Machine tool

Axis drive andcontrol (x,y,z,a,b,w)spindle speed

Papertape punch

Multi-machinecontroller

Direct Numerical control (DNC) can be defined as a set of NCmachines that is connected to a main computer system toestablish a direct interface between the DNC computer memoryand the machine tools. The tape is not used in the DNC system;hence a central time-sharing computer is used.

Multi-machinecontrollerDirect axis andservice control

Distributed Numerical ControlDistributed NC is more advanced than DNC and is widelyused in many current applications. The distributed NC uses alocal area network but not like that in DNC. It has beenindicated that the main difference between DNC anddistributed NC is that because modern NC machines haveCNC capability, they have memory and therefore computerprograms can be downloaded into the memory of a CNClocal computer, rather than one block at a time as in DNCsystems.

Distributed Numerical ControlDistributed NC is more advanced than DNC and is widelyused in many current applications. The distributed NC uses alocal area network but not like that in DNC. It has beenindicated that the main difference between DNC anddistributed NC is that because modern NC machines haveCNC capability, they have memory and therefore computerprograms can be downloaded into the memory of a CNClocal computer, rather than one block at a time as in DNCsystems.

CIM host database ofprocesses partprogramscontroller

Local area network

CNCcontroller

CNCcontroller

CNCcontroller

CNCcontroller

CNCcontroller

CNCcontroller

CNCcontroller

CNCcontroller

CNCcontroller

CNCcontroller

Voice Numerical Control (VNC)Voice Numerical Control (VNC) is similar to DNCmachines but the programmer conveys theinformation needed to operate the machine by meansof computer system. The programmer talks into thecomputer, and the memory receives the informationusing a wire. This information can be taken and usedto run the machines.

Voice Numerical Control (VNC)Voice Numerical Control (VNC) is similar to DNCmachines but the programmer conveys theinformation needed to operate the machine by meansof computer system. The programmer talks into thecomputer, and the memory receives the informationusing a wire. This information can be taken and usedto run the machines.

Advantages of CNC1. Increased productivity.2. High accuracy and repeatability.3. Reduced production costs.4. Reduced indirect operating costs.5. Facilitation of complex machining operations.6. Grater flexibility.7. Improved production planning and control.8. Lower operator skill requirement.9. Facilitation of flexible automation.

Advantages of CNC1. Increased productivity.2. High accuracy and repeatability.3. Reduced production costs.4. Reduced indirect operating costs.5. Facilitation of complex machining operations.6. Grater flexibility.7. Improved production planning and control.8. Lower operator skill requirement.9. Facilitation of flexible automation.Limitations of CNC:1. High initial investment.2. High maintenance requirement.3. Not cost-effective for low production cost.

Applications of NCMachine tool applications:1. Milling machines.2. Drilling machines.3. Boring machines.4. Turning machines.5. Grinding machines.6. Sawing machines.

Applications of NCMachine tool applications:1. Milling machines.2. Drilling machines.3. Boring machines.4. Turning machines.5. Grinding machines.6. Sawing machines.Non- machine tool applications:1. Welding machines- flame cutting machines.2. Press-working machines- assembly machines.3. Inspection machines- automatic drafting machines

Computer-Assisted Part ProgrammingComputer-Assisted Part Programming

Stages of Computer-Assisted Part Programming Identify the part geometry, cutter motions, feeds, speeds and

cutter parameters Code geometry, cutter motions and machine instructions by

part programming language source file. Automatically Programmed Tools (APT) COMPACT II

Compile the source file to machine-independent cutterlocation data file (CLDATA)

Post-process the CLDATA to machine control data (MCD) fortarget machine

Transmit MCD to machine

Identify the part geometry, cutter motions, feeds, speeds andcutter parameters

Code geometry, cutter motions and machine instructions bypart programming language source file. Automatically Programmed Tools (APT) COMPACT II

Compile the source file to machine-independent cutterlocation data file (CLDATA)

Post-process the CLDATA to machine control data (MCD) fortarget machine

Transmit MCD to machine

APT (programming language) APT or Automatically Programmed Tool is a high-level computer

programming language used to generate instructionsfor numerically controlled machine tools. Douglas T. Ross isconsidered by many to be the father of APT. APT is a language andsystem that makes numerically controlled manufacturing possible.

It is used to calculate a path that a tool must follow to generate adesired form. APT is a special-purpose language and thepredecessor to modern CAM systems. It was created and refinedduring the late 1950s and early 1960s to simplify the task ofcalculating geometry points that a tool must traverse in space to cutthe complex parts required in the aerospace industry.

APT was created before graphical interfaces were available, and soit relies on text to specify the geometry and toolpaths needed tomachine a part. The original version was created before evenFORTRAN was available and was the very first ANSI standard. Laterversions were rewritten in FORTRAN.

APT or Automatically Programmed Tool is a high-level computerprogramming language used to generate instructionsfor numerically controlled machine tools. Douglas T. Ross isconsidered by many to be the father of APT. APT is a language andsystem that makes numerically controlled manufacturing possible.

It is used to calculate a path that a tool must follow to generate adesired form. APT is a special-purpose language and thepredecessor to modern CAM systems. It was created and refinedduring the late 1950s and early 1960s to simplify the task ofcalculating geometry points that a tool must traverse in space to cutthe complex parts required in the aerospace industry.

APT was created before graphical interfaces were available, and soit relies on text to specify the geometry and toolpaths needed tomachine a part. The original version was created before evenFORTRAN was available and was the very first ANSI standard. Laterversions were rewritten in FORTRAN.

Language Statements of APT Geometry statements

Definition of part geometry Motion statements

Define the motion of cutting tool Post-processor statements

Machine instructions passed unchanged intoCLDATA file

Auxiliary statements Additional information of part name, tolerancesetc.

Geometry statements Definition of part geometry

Motion statements Define the motion of cutting tool

Post-processor statements Machine instructions passed unchanged intoCLDATA file

Auxiliary statements Additional information of part name, tolerancesetc.

Geometry Statements Format:

symbol = geometry_word / descriptive datasymbol : name of geometric elementgeometry_word : major word name of geometry typedescriptive data : numeric data for the geometry entity,

reference to other entities, or qualifying minor words Examples:

CIR = CIRCLE/CENTER, PT, TANTO,LNP1 = POINT/X, Y, ZL1 = LINE/P1, P2

Format:symbol = geometry_word / descriptive data

symbol : name of geometric elementgeometry_word : major word name of geometry typedescriptive data : numeric data for the geometry entity,

reference to other entities, or qualifying minor words Examples:

CIR = CIRCLE/CENTER, PT, TANTO,LNP1 = POINT/X, Y, ZL1 = LINE/P1, P2

Points Definition in APT

P1 = POINT/X, Y, ZP2 = POINT/L1, L2P3 = POINT/CENTER, C1P4 = POINT/YLARGE, INTOF, L1, C1P5 = POINT/XLARGE, INTOF, L1, C1P6 = POINT/YLARGE, INTOF, C1, C2P7 = POINT/XLARGE, INTOF, C1, C2

Lines Definition in APTL1 = LINE/X1,Y1,Z1,X2,Y2,Z2L2 = LINE/P1, P2L3 = LINE/P1, PARLEL, L0L4 = LINE/P1, PERPTO, L0L5 = LINE/P1, TANTO, C1L6 = LINE/P1, RIGHT, TANTO, C1L7 = LINE/LEFT, TANTO, C1, LEFT, TANTO, C2L8 = LINE/LEFT, TANTO, C1,RIGHT, TANTO, C2L9 = LINE/RIGHT, TANTO, C1, LEFT, TANTO, C2L10 = LINE/RIGHT, TANTO, C1, RIGHT, TANTO, C2L11 = LINE/P1, ATANGL, Degree, L0

L1 = LINE/X1,Y1,Z1,X2,Y2,Z2L2 = LINE/P1, P2L3 = LINE/P1, PARLEL, L0L4 = LINE/P1, PERPTO, L0L5 = LINE/P1, TANTO, C1L6 = LINE/P1, RIGHT, TANTO, C1L7 = LINE/LEFT, TANTO, C1, LEFT, TANTO, C2L8 = LINE/LEFT, TANTO, C1,RIGHT, TANTO, C2L9 = LINE/RIGHT, TANTO, C1, LEFT, TANTO, C2L10 = LINE/RIGHT, TANTO, C1, RIGHT, TANTO, C2L11 = LINE/P1, ATANGL, Degree, L0

Circles Definition in APT

C1 = CIRCLE/X, Y, Z, RC2 = CIRCLE/CENTER, P1, RADIUS, RC3 = CIRCLE/CENTER, P1, TANTO, L0C4 = CIRCLE/P1, P2, P3C5 = CIRCLE/XSMALL, L1, XSMALL, L2, RADIUS, R

Motion Statements Point-to-point operation

FROM/point_locationGOTO/point_locationGODLTA/x, y, z

Point-to-point operationFROM/point_locationGOTO/point_locationGODLTA/x, y, z

ExamplesP0 = POINT/0.0, 3.0, 0.1P1 = POINT/1.0, 1.0, 0.1P2 = POINT/2.0, 1.0, 0.1FROM/P0GOTO/P1GODLTA/0, 0, -0.7GODLTA/0, 0, 0.7GOTO/P2GODLTA/0, 0, -0.7GODLTA/0, 0, 0.7GOTO/P0

P0 = POINT/0.0, 3.0, 0.1P1 = POINT/1.0, 1.0, 0.1P2 = POINT/2.0, 1.0, 0.1FROM/P0GOTO/P1GODLTA/0, 0, -0.7GODLTA/0, 0, 0.7GOTO/P2GODLTA/0, 0, -0.7GODLTA/0, 0, 0.7GOTO/P0

Motion Statements Contouring operation

Control surface Part surface Drive surface Check surface

Contouring operation Control surface

Part surface Drive surface Check surface

Motion Statements Contouring operation

GO commandGO/ {TO}, Drive surface, { TO }, part surface, { TO }, Checksurface

Constraint modifiers TO PAST ON TANTO used only with check surface

Contouring operation GO command

GO/ {TO}, Drive surface, { TO }, part surface, { TO }, Checksurface

Constraint modifiers TO PAST ON TANTO used only with check surface

Motion Statements

A: GO/TO, L1, TO, PS, TANTO, C1B: GO/PAST, L1, TO, PS, TANTO, C1

Motion Statements Contouring operation

Tool moving commandGOLFT/GORGT/GOUP/GODOWN/GOFWD/GOBACK/

Contouring operation Tool moving command

GOLFT/GORGT/GOUP/GODOWN/GOFWD/GOBACK/

ExampleFROM/SPGO/TO, L1, TO, PS, ON, L4GORGT/L1, PAST, L2GOLFT/L2, PAST, L3GOLFT/L3, PAST, C1GOLFT/C1, PAST, L3GOLFT/L3, PAST, L4GOLFT/L4, PAST, L1GOTO/SP

FROM/SPGO/TO, L1, TO, PS, ON, L4GORGT/L1, PAST, L2GOLFT/L2, PAST, L3GOLFT/L3, PAST, C1GOLFT/C1, PAST, L3GOLFT/L3, PAST, L4GOLFT/L4, PAST, L1GOTO/SP

ExampleFROM/SPGO/TO, L1, TO, PS, TO, L6GORGT/L1, TO, L2GORGT/L2, TANTO, C1GOFWD/C1, TANTO, L3GOFWD/L3, PAST, L4GOLFT/L4, PAST, L5GOLFT/L5, PAST, L6GOLFT/L6, PAST, L1GOTO/SP

FROM/SPGO/TO, L1, TO, PS, TO, L6GORGT/L1, TO, L2GORGT/L2, TANTO, C1GOFWD/C1, TANTO, L3GOFWD/L3, PAST, L4GOLFT/L4, PAST, L5GOLFT/L5, PAST, L6GOLFT/L6, PAST, L1GOTO/SP

Post-Processor Statements MACHIN/

MACHINE/DRILL, 2 COOLNT/

COOLNT/MIST COOLNT/FLOOD COOLNT/OFF COOLNT/ON

FEDRAT/ FEDRAT/4.5

SPINDL/ SPINDL/ON SPINDL/1250, CCLW

TOOLNO/ TOOLNO/3572, 6

TURRET END

MACHIN/ MACHINE/DRILL, 2

COOLNT/ COOLNT/MIST COOLNT/FLOOD COOLNT/OFF COOLNT/ON

FEDRAT/ FEDRAT/4.5

SPINDL/ SPINDL/ON SPINDL/1250, CCLW

TOOLNO/ TOOLNO/3572, 6

TURRET END

Tolerance and Cutter Statements OUTTOL/, INTOL/

INTOL/0.005 OUTTOL/0.003

CUTTTER/ CUTTER/0.6

OUTTOL/, INTOL/ INTOL/0.005 OUTTOL/0.003

CUTTTER/ CUTTER/0.6

Other Capabilities of APT Arithmetic manipulation and looping Subprogram asmacro facility

P0 = POINT/0.0, 3.0, 0.1FROM/P0CALL/DRILL, X = 1.0, Y = 1.0, Z = 0.1, DEPTH = 0.7CALL/DRILL, X = 2.0, Y = 1.0, Z = 0.1, DEPTH = 0.7

DRILL = MACRO/X, Y, Z, DEPTHGOTO/X, Y, ZGODLTA/0.0, -DEPTHGODLTA/0.0, DEPTHTARMAC

Arithmetic manipulation and looping Subprogram asmacro facility

P0 = POINT/0.0, 3.0, 0.1FROM/P0CALL/DRILL, X = 1.0, Y = 1.0, Z = 0.1, DEPTH = 0.7CALL/DRILL, X = 2.0, Y = 1.0, Z = 0.1, DEPTH = 0.7

DRILL = MACRO/X, Y, Z, DEPTHGOTO/X, Y, ZGODLTA/0.0, -DEPTHGODLTA/0.0, DEPTHTARMAC

Post-Processing

Post-Processing Compile APT program to Cutter Location Datafile (CLDATA)

Processing CLDATA file to MCD (G- and M-code)

GeneralizedPost-Processors (G-Post)

Post-processor output

Compile APT program to Cutter Location Datafile (CLDATA)

Processing CLDATA file to MCD (G- and M-code)

GeneralizedPost-Processors (G-Post)

Post-processor output

APT Language Example

CNC FundamentalsCNC Fundamentals

All CNC machine tools follow the same standard formotion nomenclature and the same coordinatesystem. This is defined as the EIA 267-C standard. Thestandard defines a machine coordinate system andmachine movements so that a programmer candescribe machining operations without worrying aboutwhether a tool approaches a workpiece or a workpieceapproaches a tool.

All CNC machine tools follow the same standard formotion nomenclature and the same coordinatesystem. This is defined as the EIA 267-C standard. Thestandard defines a machine coordinate system andmachine movements so that a programmer candescribe machining operations without worrying aboutwhether a tool approaches a workpiece or a workpieceapproaches a tool.

Machine coordinate systemThe direction of each fingerrepresents the positive directionof motion.The axis of the main spindle isalways Z, and the positivedirection is into the spindle.On a mill the longest travel slideis designated the X axis and isalways perpendicular to the Z axis.If you rotate your hand lookinginto your middle finger, theforefinger represents the Y axis.The base of your fingers is thestart point or (X0, Y0, Z0).

The direction of each fingerrepresents the positive directionof motion.The axis of the main spindle isalways Z, and the positivedirection is into the spindle.On a mill the longest travel slideis designated the X axis and isalways perpendicular to the Z axis.If you rotate your hand lookinginto your middle finger, theforefinger represents the Y axis.The base of your fingers is thestart point or (X0, Y0, Z0).

Axis and motion nomenclature Rotary motiondesignationThe right-hand rule for determining the correct axis ona CNC machine may also be used to determine theclockwise rotary motion about X, Y, and Z.To determine the positive, or clockwise, directionabout an axis, close your hand with the thumb pointingout.

The thumb may represent the X, Y, or Z direction and thecurl of the fingers may represent the clockwise, or positive,rotation about each axis.These are known as A, B, and C and represent the rotarymotions about X, Y, and Z, respectively.

To determine the positive, or clockwise, directionabout an axis, close your hand with the thumb pointingout.

The thumb may represent the X, Y, or Z direction and thecurl of the fingers may represent the clockwise, or positive,rotation about each axis.These are known as A, B, and C and represent the rotarymotions about X, Y, and Z, respectively.

Axis and motion nomenclature CNC mill

On this gantry mill the spindle travels along the X Axis. Thetravel direction of the table designates the Y Axis. The Z Axis isdesignated by the stationary vertical column.

Axis and motion nomenclature CNC lathe

On most CNC lathes the Z Axis is parallel to the spindle and longer than the X Axis.

Axis and motion nomenclature 5-axis CNC contour mill

On this five-axis horizontal contour milling machine, note theorientation of the X and Y axes in relation to the Z Axis. The rotaryaxes for both the X and Y axes are designated by the A and Brotary tables.

Axis and motion nomenclature vertical CNC knee mill

On a common vertical knee CNC mill the spindle isstationary while the rest of the components moveaccording to their axis designations (X, Y, and Z).

Axis and motion nomenclature CNC punch machine

On a CNC punch press the part is moved in the Xand Y directions while the punch is stationary.

CNC milling fundamentals The three Cartesian planes

The three planes in the Cartesian coordinate system are XY, XZ,and YZ. These are referred to as G17, G18, and G19,respectively, on the mill.

CNC milling fundamentals The part reference zero

There are two reference points on a CNC Machine:Machine Reference Zero (MRZ) and the PartReference Zero (PRZ). All coordinates are based onthese two points.

All CNC machine tools require a reference pointfrom which to base coordinates.It is generally easier to use a point on theworkpiece itself for reference, because thecoordinates apply to the part anyway thus thePRZ designation.The PRZ is defined as the lower left-hand cornerand the top of the stock of each part.

There are two reference points on a CNC Machine:Machine Reference Zero (MRZ) and the PartReference Zero (PRZ). All coordinates are based onthese two points.

All CNC machine tools require a reference pointfrom which to base coordinates.It is generally easier to use a point on theworkpiece itself for reference, because thecoordinates apply to the part anyway thus thePRZ designation.The PRZ is defined as the lower left-hand cornerand the top of the stock of each part.

The advantages of having the PRZ at the lower left topcorner are:

1.Geometry creation is in the positive XY plane forCAD/CAM systems.2.The corner of the workpiece is easy to find.3.All negative Z depths are below the surface of theworkpiece.

The advantages of having the PRZ at the lower left topcorner are:

1.Geometry creation is in the positive XY plane forCAD/CAM systems.2.The corner of the workpiece is easy to find.3.All negative Z depths are below the surface of theworkpiece.

The Cartesian graphCartesian coordinates wereinvented by Ren Descartes,who is famous for the phrase"I think, therefore I am."Most Cartesian graphs formilling and turning use athree-axis coordinate system,denoted by the X, Y, and Zaxes. These coordinates areused to instruct the machinetool where to move on theworkpiece.

Cartesian coordinates wereinvented by Ren Descartes,who is famous for the phrase"I think, therefore I am."Most Cartesian graphs formilling and turning use athree-axis coordinate system,denoted by the X, Y, and Zaxes. These coordinates areused to instruct the machinetool where to move on theworkpiece.

CNC milling fundamentals Absolute coordinates

Absolute coordinates use theorigin as the reference point.This means that any point onthe Cartesian graph can beplotted accurately bymeasuring the distance fromthe origin to the point, firstin the X direction, then in theY direction, and then, ifapplicable, in the Z direction.

Absolute coordinates use theorigin as the reference point.This means that any point onthe Cartesian graph can beplotted accurately bymeasuring the distance fromthe origin to the point, firstin the X direction, then in theY direction, and then, ifapplicable, in the Z direction.

Incremental coordinates usethe present position as thereference point for the nextmovement. This means thatany point in the Cartesiangraph can be plottedaccurately by measuring thedistance between points,generally starting at theorigin.

CNC milling fundamentals Incremental coordinates

Incremental coordinates usethe present position as thereference point for the nextmovement. This means thatany point in the Cartesiangraph can be plottedaccurately by measuring thedistance between points,generally starting at theorigin.

EXERCISE 1: Absolute CoordinatesFill in the X and Y blanks with the appropriate absolute coordinatesfor points A through H.A: X_____, Y_____ B: X_____, Y_____C: X_____, Y_____ D: X_____, Y_____E: X_____, Y_____ F: X_____, Y_____G: X_____, Y_____ H: X_____, Y_____

EXERCISE 2: Incremental CoordinatesFill in the X and Y blanks with the appropriate incrementalcoordinates for points A through H.A: X_____, Y_____ B: X_____, Y_____C: X_____, Y_____ D: X_____, Y_____E: X_____, Y_____ F: X_____, Y_____G: X_____, Y_____ H: X_____, Y_____

CNC lathes share the same two-axis coordinate system.This allows for the transfer of CNC programs amongdifferent machines, as all measurements are derivedfrom the same reference points.In CNC turning there is a primary, or horizontal, axis anda secondary, or vertical, axis. Because the major axisalways runs through the spindle (horizontally), the Z axisis usually the longer one. The X axis is perpendicular tothe Z axis (or vertical).It is important to remember that on most CNC lathesthe tool post is on the top, or backside, of the machine,unlike on a conventional lathe. This is why the tool isshown above the part in the simulation examples.

CNC turning fundamentalsCNC lathes share the same two-axis coordinate system.This allows for the transfer of CNC programs amongdifferent machines, as all measurements are derivedfrom the same reference points.In CNC turning there is a primary, or horizontal, axis anda secondary, or vertical, axis. Because the major axisalways runs through the spindle (horizontally), the Z axisis usually the longer one. The X axis is perpendicular tothe Z axis (or vertical).It is important to remember that on most CNC lathesthe tool post is on the top, or backside, of the machine,unlike on a conventional lathe. This is why the tool isshown above the part in the simulation examples.

CNC turning fundamentals Cartesian graph for turning

When measuring X and Z coordinates, use a central referencepoint. Start all measurements at this reference point, the originpoint (X0, Z0). For all our examples the origin is located at thecenter right-hand endpoint of the workpiece. Keep in mind thatat times the center left-hand endpoint of the workpiece may beused

Diameter (or diametrical)programming relates theX axis to the diameter ofthe workpiece. Forexample, if the workpiecehas a 5-in. outsidediameter and you want tocommand an absolutemove to the outside, youwould program X5.0.

CNC turning fundamentals Diameter programming

Diameter (or diametrical)programming relates theX axis to the diameter ofthe workpiece. Forexample, if the workpiecehas a 5-in. outsidediameter and you want tocommand an absolutemove to the outside, youwould program X5.0.

CNC turning fundamentals Radial programming

Radius (or radial)programming relates theX axis to the radius of theworkpiece. For example,for the same 5-in. outsidediameter workpiece, youwould program X2.5 tomove the tool to theoutside.

Radius (or radial)programming relates theX axis to the radius of theworkpiece. For example,for the same 5-in. outsidediameter workpiece, youwould program X2.5 tomove the tool to theoutside.

CNC turning fundamentals Absolute coordinatesWhen plotting points usingabsolute coordinates,always start at the origin(X0, Z0). Then travel alongthe Z axis until you reach apoint directly below thepoint that you are trying toplot. Write down the Z valueand then go up until youreach your point. Writedown the X value. You nowhave the XZ (or ZX)coordinate for that point.

When plotting points usingabsolute coordinates,always start at the origin(X0, Z0). Then travel alongthe Z axis until you reach apoint directly below thepoint that you are trying toplot. Write down the Z valueand then go up until youreach your point. Writedown the X value. You nowhave the XZ (or ZX)coordinate for that point.

CNC turning fundamentals Incremental coordinatesThe second method forfinding points in aCartesian coordinatesystem is by usingincremental coordinates.Incremental, or relative,coordinates use eachsuccessive point tomeasure the nextcoordinate. Instead ofconstantly referring backto the origin, theincremental methodrefers to the previouspoint

The second method forfinding points in aCartesian coordinatesystem is by usingincremental coordinates.Incremental, or relative,coordinates use eachsuccessive point tomeasure the nextcoordinate. Instead ofconstantly referring backto the origin, theincremental methodrefers to the previouspoint

EXERCISE 1: Using Incremental Coordinates.Find the diametrical X and Z coordinates for points Athrough E.A: X_____, Z_____ B: X_____, Z_____C: X_____, Z_____ D: X_____, Z_____E: X_____, Z_____

EXERCISE 2: Using Absolute CoordinatesFind the X and Z coordinates for points A through E.A: X_____, Z_____ B: X_____, Z_____C: X_____, Z_____ D: X_____, Z_____E: X_____, Z_____

CNC MachiningCNC Machining

Before you can fully understand CNC, you must firstunderstand how a manufacturing company processes ajob that will be produced on a CNC machine. Thefollowing is an example of how a company may breakdown the CNC process .

Before you can fully understand CNC, you must firstunderstand how a manufacturing company processes ajob that will be produced on a CNC machine. Thefollowing is an example of how a company may breakdown the CNC process .

FLOW OF CNC PROCESSING1. Obtain or develop the part drawing.2. Decide what machine will produce the part.3. Decide on the machining sequence.4. Choose the tooling required.5. Do the required math calculations for the programcoordinates.6. Calculate the speeds and feeds required for thetooling and part material.7. Write the NC program.8. Prepare setup sheets and tool lists.9. Send the program to machine.10. Verify the program.11. Run the program if no changes are required

FLOW OF CNC PROCESSING1. Obtain or develop the part drawing.2. Decide what machine will produce the part.3. Decide on the machining sequence.4. Choose the tooling required.5. Do the required math calculations for the programcoordinates.6. Calculate the speeds and feeds required for thetooling and part material.7. Write the NC program.8. Prepare setup sheets and tool lists.9. Send the program to machine.10. Verify the program.11. Run the program if no changes are required

A program is a sequential list of machininginstructions for the CNC machine to execute.These instructions are CNC code that consists ofblocks (also called lines). Each block contains anindividual command for a movement or specificaction. As with conventional machines, onemovement is made before the next one. This iswhy CNC codes are listed sequentially innumbered blocks.

PREPARING A PROGRAMA program is a sequential list of machininginstructions for the CNC machine to execute.These instructions are CNC code that consists ofblocks (also called lines). Each block contains anindividual command for a movement or specificaction. As with conventional machines, onemovement is made before the next one. This iswhy CNC codes are listed sequentially innumbered blocks.

The following is a sample CNC milling program. Note how eachblock is numbered and usually contains only one specificcommand. The blocks are numbered in increments of 5 (this isthe software default on startup). Each block contains specificinformation for the machine to execute in sequence.Workpiece Size: X4, Y3, Z1Tool: Tool #3, 3/8" Slot DrillTool Start position: X0, Y0, Z1.0% (Program Start Flag):1002 (Program #1002)N5 G90 G20 G40 G17 (Block #5, Absolute in Inches)N10 M06 T3 (Tool Change to Tool #3)N15 M03 S1250 (Spindle on CW at 1250 RPM)N20 G00 X1.0 Y1.0 (Rapid over to X1.0, Y1.0)N25 Z0.1 (Rapid down to Z0.1)N30 G01 Z-0.125 F5 (Feed down to Z-0.125 at 5ipm)N35 X3.0 Y2.0 F10.0 (Feed diagonally to X3.0, Y2.0 at 10ipm)N40 G00 Z1.0 (Rapid up to Z1.0)N45 X0 Y0 (Rapid over to X0, Y0)N50 M05 (Spindle Off)N55 M30 (Program End)

Workpiece Size: X4, Y3, Z1Tool: Tool #3, 3/8" Slot DrillTool Start position: X0, Y0, Z1.0% (Program Start Flag):1002 (Program #1002)N5 G90 G20 G40 G17 (Block #5, Absolute in Inches)N10 M06 T3 (Tool Change to Tool #3)N15 M03 S1250 (Spindle on CW at 1250 RPM)N20 G00 X1.0 Y1.0 (Rapid over to X1.0, Y1.0)N25 Z0.1 (Rapid down to Z0.1)N30 G01 Z-0.125 F5 (Feed down to Z-0.125 at 5ipm)N35 X3.0 Y2.0 F10.0 (Feed diagonally to X3.0, Y2.0 at 10ipm)N40 G00 Z1.0 (Rapid up to Z1.0)N45 X0 Y0 (Rapid over to X0, Y0)N50 M05 (Spindle Off)N55 M30 (Program End)

CNC CODESThere are two major types of CNC codes, or letter addresses,in any program. The major CNC codes are called G-codes andM-codes.G-codes are preparatory functions, which involve actual toolmoves (for example, control of the machine). These includerapid moves, feed moves, radial feed moves, dwells,roughing, and profiling cycles.M-codes are miscellaneous functions, which include actionsnecessary for machining but not those that are actual toolmovements (for example, auxiliary functions). These includeactions such as spindle on and off, tool changes, coolant onand off, program stops, and related functions.

CNC CODESThere are two major types of CNC codes, or letter addresses,in any program. The major CNC codes are called G-codes andM-codes.G-codes are preparatory functions, which involve actual toolmoves (for example, control of the machine). These includerapid moves, feed moves, radial feed moves, dwells,roughing, and profiling cycles.M-codes are miscellaneous functions, which include actionsnecessary for machining but not those that are actual toolmovements (for example, auxiliary functions). These includeactions such as spindle on and off, tool changes, coolant onand off, program stops, and related functions.

Each designation used in CNC programming is called a letteraddress. The letters used for programming are as follows:N Block Number: Specifies the start of a blockG Preparatory function, as previously explainedX X Axis CoordinateY Y Axis CoordinateZ Z Axis CoordinateI X Axis location of Arc centerJ Y Axis location of Arc centerK Z Axis location of Arc centerS Sets the spindle speedF Assigns a feedrateT Specifies tool to be usedM Miscellaneous function, as previously explained

Each designation used in CNC programming is called a letteraddress. The letters used for programming are as follows:N Block Number: Specifies the start of a blockG Preparatory function, as previously explainedX X Axis CoordinateY Y Axis CoordinateZ Z Axis CoordinateI X Axis location of Arc centerJ Y Axis location of Arc centerK Z Axis location of Arc centerS Sets the spindle speedF Assigns a feedrateT Specifies tool to be usedM Miscellaneous function, as previously explained

THREE MAJOR PHASES OF A CNC PROGRAMThe three phases of a CNC program are:(1) Program setup: contains all the instructions thatprepare the machine for operation(2) Material removal: deals exclusively with the actualcutting feed moves(3) System shutdown: contains the G- and M-codesthat turn off all the options that were turned on inthe setup phase.

THREE MAJOR PHASES OF A CNC PROGRAMThe three phases of a CNC program are:(1) Program setup: contains all the instructions thatprepare the machine for operation(2) Material removal: deals exclusively with the actualcutting feed moves(3) System shutdown: contains the G- and M-codesthat turn off all the options that were turned on inthe setup phase.

The following shows the three major phases of a CNCprogram.

%:1001N5 G90 G20

Program setup N10 M06 T2N15 M03 S1200N20 G00 X1.00 Y1.00

Material removal N25 Z0.125N30 G01 Z-0.125 F5.0N35 G01 X2.0 Y2.0N40 G00 Z1.0N45 X0 Y0

System shutdown N50 M05N55 M30

The following shows the three major phases of a CNCprogram.

%:1001N5 G90 G20

Program setup N10 M06 T2N15 M03 S1200N20 G00 X1.00 Y1.00

Material removal N25 Z0.125N30 G01 Z-0.125 F5.0N35 G01 X2.0 Y2.0N40 G00 Z1.0N45 X0 Y0

System shutdown N50 M05N55 M30

Examine the following program to seehow it was written.%:1001N5 G90 G20N10 M06 T1N15 M03 S1200N20 G00 X1 Y1 Z0.125N25 G01 Z-0.125 F5.0N30 G01 X3.0N35 G01 Y2.0N40 G01 X1N45 G01 Y1N50 G01 Z-0.25N55 G01 X3N60 Y2N65 X1N70 Y1N75 G00 Z0.050N80 G00 Z1N85 X0 Y0N85 M05N90 M30

Program Start FlagProgram NumberUse Absolute Coordinates and inch programmingTool change, use Tool #1.Turn spindle on CW at 1200 RPMRapid move to X1 Y1 Z0.125Feed down into the part 0.125" at 5 ipmFeed to X3 (still at 5 ipm)Feed to Y2 (still at 5 ipm)Feed back to X1Feed back to Y1Feed down to Z-0.25" (still at 5 ipm)Feed across to X3Feed to Y2 (The G01 is MODAL)Feed back to X1 (G01 is still MODAL)Feed to start point at Y1Rapid to Z0.05Rapid tool up to Z1 or clearance planeRapid to home positionTurn spindle offEnd of program

%:1001N5 G90 G20N10 M06 T1N15 M03 S1200N20 G00 X1 Y1 Z0.125N25 G01 Z-0.125 F5.0N30 G01 X3.0N35 G01 Y2.0N40 G01 X1N45 G01 Y1N50 G01 Z-0.25N55 G01 X3N60 Y2N65 X1N70 Y1N75 G00 Z0.050N80 G00 Z1N85 X0 Y0N85 M05N90 M30

Program Start FlagProgram NumberUse Absolute Coordinates and inch programmingTool change, use Tool #1.Turn spindle on CW at 1200 RPMRapid move to X1 Y1 Z0.125Feed down into the part 0.125" at 5 ipmFeed to X3 (still at 5 ipm)Feed to Y2 (still at 5 ipm)Feed back to X1Feed back to Y1Feed down to Z-0.25" (still at 5 ipm)Feed across to X3Feed to Y2 (The G01 is MODAL)Feed back to X1 (G01 is still MODAL)Feed to start point at Y1Rapid to Z0.05Rapid tool up to Z1 or clearance planeRapid to home positionTurn spindle offEnd of program

USING A PROGRAMMING SHEETYou use the CNC program sheet to prepare the CNC program. Doing sosimplifies the writing of the CNC program

EQUIVALENT CNC BLOCKS --> N5 G20 G90N10 T02 M06N15 M03 S1200N20 G00 X0 Y0N25 Z0.1N30 G01 Z-0.1 F2.0N35 G01 X1.5

BLOCK FORMATBlock format is often more important than program format. It is vital that eachblock of CNC code be entered into the CPU correctly. Each block comprisesdifferent components, which can produce tool moves on the machine.

Following is a sample block of CNC code. Examine it closely and note how it iswritten.N135 G01 X1.0 Y1.0 Z0.125 F5.0N135 Block Number Shows the current CNC block number.G01 G-Code The G-code is the command that tells the machine what it is to

do in this case, a linear feed move.X1.0 Y1.0 Z0.125 Coordinate. This gives the machine an endpoint for its move.

X designates an X axis coordinate. Y designates a Y coordinate. Zdesignates a Z coordinate.

F5.0 Special Function. Any special function or related parameter is to beincluded here. In this case, a feed rate of 5 inches per minute isprogrammed.

BLOCK FORMATBlock format is often more important than program format. It is vital that eachblock of CNC code be entered into the CPU correctly. Each block comprisesdifferent components, which can produce tool moves on the machine.

Following is a sample block of CNC code. Examine it closely and note how it iswritten.N135 G01 X1.0 Y1.0 Z0.125 F5.0N135 Block Number Shows the current CNC block number.G01 G-Code The G-code is the command that tells the machine what it is to

do in this case, a linear feed move.X1.0 Y1.0 Z0.125 Coordinate. This gives the machine an endpoint for its move.

X designates an X axis coordinate. Y designates a Y coordinate. Zdesignates a Z coordinate.

F5.0 Special Function. Any special function or related parameter is to beincluded here. In this case, a feed rate of 5 inches per minute isprogrammed.

There are some simple restrictions to CNC blocks:Each may contain only one tool move.Each may contain any number of nontool move G-codes, provided they do notconflict with each other (for example, G42 and G43).Each may contain only one feedrate per block.Each may contain only one specified tool or spindle speed.The block numbers should be sequential.Both the program start flag and the program number must be independent ofall other commands.The data within a block should follow the sequence shown in the abovesample block, N-block number, G-code, any coordinates, and other requiredfunctions.Each may contain only one M-code per block.

There are some simple restrictions to CNC blocks:Each may contain only one tool move.Each may contain any number of nontool move G-codes, provided they do notconflict with each other (for example, G42 and G43).Each may contain only one feedrate per block.Each may contain only one specified tool or spindle speed.The block numbers should be sequential.Both the program start flag and the program number must be independent ofall other commands.The data within a block should follow the sequence shown in the abovesample block, N-block number, G-code, any coordinates, and other requiredfunctions.Each may contain only one M-code per block.

PREPARING TO PROGRAMBefore you write a CNC program, you

must first prepare to write it. Thesuccess of a CNC program isdirectly related to the preparationthat you do before you write theCNC program. You should do threethings before you begin to write aprogram:

1. Develop an order of operations.2. Do all the necessary math and

complete a coordinate sheet.3. Choose your tooling and calculate

speeds and feedrates.

PREPARING TO PROGRAMBefore you write a CNC program, you

must first prepare to write it. Thesuccess of a CNC program isdirectly related to the preparationthat you do before you write theCNC program. You should do threethings before you begin to write aprogram:

1. Develop an order of operations.2. Do all the necessary math and

complete a coordinate sheet.3. Choose your tooling and calculate

speeds and feedrates.

The CNC operator can also use coordinate and setup sheets.Using them as references makes generation of the CNC programeasier.

Program zero allows you to specify a position from which to start or towork. Once program zero has been defined, all coordinates used in a programwill be referenced from this point. When you work from a constant programzero, you are using absolute programming. In incremental programming, youhave in effect a floating program zero that changes at all timesTo specify absolute positions inthe X direction, use the X-address word. To specifyabsolute positions in the Y andZ directions, use the Y- and Z-address words, respectively.The position selected formilling is always the lower left-hand corner and top surface ofthe workpiece. The positionused for the lathe is always thecenter of the part in X and theright-hand end of the finishedworkpiece in Z.

To specify absolute positions inthe X direction, use the X-address word. To specifyabsolute positions in the Y andZ directions, use the Y- and Z-address words, respectively.The position selected formilling is always the lower left-hand corner and top surface ofthe workpiece. The positionused for the lathe is always thecenter of the part in X and theright-hand end of the finishedworkpiece in Z.

Generally, three types of tool motion are used on a CNCmachine:G00 Rapid tool move. Nonmachining command. Eachaxis trajectory is exhausted as fast as the motor can drivethe axes.G01 Straight-line feed move. Linear interpolation.Coordinated moves at a controlled feedrate.G02/G03 Two-dimensional arc feed moves. Circularinterpolation.

TOOL MOTION

Generally, three types of tool motion are used on a CNCmachine:G00 Rapid tool move. Nonmachining command. Eachaxis trajectory is exhausted as fast as the motor can drivethe axes.G01 Straight-line feed move. Linear interpolation.Coordinated moves at a controlled feedrate.G02/G03 Two-dimensional arc feed moves. Circularinterpolation.

TOOL MOTION

Canned, or fixed program, cycles are aids that simplifyprogramming. Canned cycles combine many standardprogramming operations and are designed to shorten theprogram length, minimize math calculations, and optimizecutting conditions to improve the efficiency of the machine.Examples of canned cycles on a mill are drilling, boring, spotfacing, tapping, and so on; on a lathe, threading, roughfacing and turning, and pattern repeating cycles. On thelathe, canned cycles are also referred to as multiplerepetitive cycles. You will find examples of these cycles asyou work through the milling and turning sections.

USING CANNED CYCLES

Canned, or fixed program, cycles are aids that simplifyprogramming. Canned cycles combine many standardprogramming operations and are designed to shorten theprogram length, minimize math calculations, and optimizecutting conditions to improve the efficiency of the machine.Examples of canned cycles on a mill are drilling, boring, spotfacing, tapping, and so on; on a lathe, threading, roughfacing and turning, and pattern repeating cycles. On thelathe, canned cycles are also referred to as multiplerepetitive cycles. You will find examples of these cycles asyou work through the milling and turning sections.

USING CANNED CYCLES

Tooling Not all cutting operations canbe performed with a singletool. Separate tools are usedfor roughing and finishing, andtasks such as drilling, slotting,and thread cutting requiretheir own specific tools. Thecorrect cutting tool must be used atall times. The size and shape of thecutting tools that you can usedepend on the size and shape of thefinished part. A tool manufacturer'scatalog will give you a completelist of the various types oftools available and theapplications of each

Not all cutting operations canbe performed with a singletool. Separate tools are usedfor roughing and finishing, andtasks such as drilling, slotting,and thread cutting requiretheir own specific tools. Thecorrect cutting tool must be used atall times. The size and shape of thecutting tools that you can usedepend on the size and shape of thefinished part. A tool manufacturer'scatalog will give you a completelist of the various types oftools available and theapplications of each

Remember: The depth of cut that can betaken depends on the workpiecematerial, the coolant, the type of tool,and the machine tool itself.

The tool most often usedto make holes is the fluteddrill. Drills are made withtwo, three, or four cuttinglips. The two-lip drill isused for drilling solid stock.The three- and four-lipdrills are used for enlargingholes that have beenpreviously drilled. Moderndrills can also havecoolant holes for directdelivery of coolantthrough the end of thedrill.

Tooling

The tool most often usedto make holes is the fluteddrill. Drills are made withtwo, three, or four cuttinglips. The two-lip drill isused for drilling solid stock.The three- and four-lipdrills are used for enlargingholes that have beenpreviously drilled. Moderndrills can also havecoolant holes for directdelivery of coolantthrough the end of thedrill.

The rotating cutter, termed themilling cutter, has almost anunlimited variety of shapes andsizes for milling regular andirregular forms. The most commonmilling cutter is the end mill. Othertools that are often used are shellmills, face mills, and roughing mills.When milling, care must be takennot to take a cut that is deeperthan the milling cutter can handle.End mills come in various shapesand sizes, each designed toperform a specific task. The threebasic shapes of standard end millsare flat, ballnose, and bullnose.

Tooling

The rotating cutter, termed themilling cutter, has almost anunlimited variety of shapes andsizes for milling regular andirregular forms. The most commonmilling cutter is the end mill. Othertools that are often used are shellmills, face mills, and roughing mills.When milling, care must be takennot to take a cut that is deeperthan the milling cutter can handle.End mills come in various shapesand sizes, each designed toperform a specific task. The threebasic shapes of standard end millsare flat, ballnose, and bullnose.

In lathe operations, the tool is driventhrough the material to remove chipsfrom the workpiece in order to leavegeometrically true surfaces. The typeof surface produced by the cuttingoperation depends on the shape ofthe tool and the path it followsthrough the material. When thecutting edge of the tool breaks down,the surface finish becomes poor andthe cutting forces rise. Vibration andchatter are definite signs of tool wear,although many forces such as depth ofcut, properties of materials, frictionforces, and rubbing of the tool nosealso affect tool vibration.

Tooling

In lathe operations, the tool is driventhrough the material to remove chipsfrom the workpiece in order to leavegeometrically true surfaces. The typeof surface produced by the cuttingoperation depends on the shape ofthe tool and the path it followsthrough the material. When thecutting edge of the tool breaks down,the surface finish becomes poor andthe cutting forces rise. Vibration andchatter are definite signs of tool wear,although many forces such as depth ofcut, properties of materials, frictionforces, and rubbing of the tool nosealso affect tool vibration.

It is very important to fully understand the value of the correctfeedrate and spindle speed. Too fast a speed or feedrate willresult in early tool failure or poor surface finish. Too slow aspeed or feedrate will lead to increased machining time and,possibly, greater part cost. New tool technology has produceda wide range of tools that can be used at greater speeds andfeed rates for longer periods.For milling, the correct speeds and feed rates are determined inpart by the diameter of the cutter, spindle RPM, number ofteeth on the cutter, chip load per tooth, and surface feet perminute for a particular material. For turning, the diameter ofthe workpiece and the surface feet per minute for the materialare factors in determining the proper speeds and feed rates.

FEEDRATES AND SPINDLE SPEEDSIt is very important to fully understand the value of the correctfeedrate and spindle speed. Too fast a speed or feedrate willresult in early tool failure or poor surface finish. Too slow aspeed or feedrate will lead to increased machining time and,possibly, greater part cost. New tool technology has produceda wide range of tools that can be used at greater speeds andfeed rates for longer periods.For milling, the correct speeds and feed rates are determined inpart by the diameter of the cutter, spindle RPM, number ofteeth on the cutter, chip load per tooth, and surface feet perminute for a particular material. For turning, the diameter ofthe workpiece and the surface feet per minute for the materialare factors in determining the proper speeds and feed rates.

There are three main reasons for using cutting fluidTo remove or reduce the heat being producedTo reduce cutting tool wearTo help clear chips from the workpiece area

CUTTING FLUIDS

CNC Milling ProgrammingCNC Milling Programming

To maximize the power of modern CNC milling machines, a programmer has tomaster the following five categories of programming command codes andtechniques:

1. Basic programming commands.2. Compensating an offset.3. Fixed cycles.4. Macro and subroutine programs.5. Advanced programming features.

To maximize the power of modern CNC milling machines, a programmer has tomaster the following five categories of programming command codes andtechniques:

1. Basic programming commands.2. Compensating an offset.3. Fixed cycles.4. Macro and subroutine programs.5. Advanced programming features.

1. Basic programming commands. Motion commands (G00, G01, G02, G03) Plane selection (G17, G18, G19) Positioning system selection (G90, 091) Unit selection (G70 or G20, G71 or G21) Work coordinate setting (G92) Reference point return (G28, G29, G30) Tool selection and change (Txx M06) Feed selection and input (Fxxx.xx, G94, 095) Spindle speed selection and control (Sxxxx, M03, M04,

M05) Miscellaneous functions (M00, M01, M02, M07, M08, M09,

M30)

1. Basic programming commands. Motion commands (G00, G01, G02, G03) Plane selection (G17, G18, G19) Positioning system selection (G90, 091) Unit selection (G70 or G20, G71 or G21) Work coordinate setting (G92) Reference point return (G28, G29, G30) Tool selection and change (Txx M06) Feed selection and input (Fxxx.xx, G94, 095) Spindle speed selection and control (Sxxxx, M03, M04,

M05) Miscellaneous functions (M00, M01, M02, M07, M08, M09,

M30)

2. Compensation and offset. The use of compensation andoffset functions in defining work coordinate systems,performing tool diameter compensations, and accommodatingtool length differences often results in reduced programmingeffort. The main compensation and offset functions are Work coordinate compensation (G54-G59) Tool diameter (radius) compensation (G40, G41, G42) Tool length offset (G43, G44, G49)3. Fixed cycles. The purpose of a fixed cycle is to execute aseries of repetitive machining operations with a single blockcommand. Fixed cycles may be classified into the followingthree categories: Standard fixed cycles (G80-G89) Special fixed cycles User-defined fixed cycles

2. Compensation and offset. The use of compensation andoffset functions in defining work coordinate systems,performing tool diameter compensations, and accommodatingtool length differences often results in reduced programmingeffort. The main compensation and offset functions are Work coordinate compensation (G54-G59) Tool diameter (radius) compensation (G40, G41, G42) Tool length offset (G43, G44, G49)3. Fixed cycles. The purpose of a fixed cycle is to execute aseries of repetitive machining operations with a single blockcommand. Fixed cycles may be classified into the followingthree categories: Standard fixed cycles (G80-G89) Special fixed cycles User-defined fixed cycles

4. Macro and subroutine programming. Most modem CNCcontrols furnish the power of computer programming todefine variables, perform arithmetic operations, executelogical decisions, and so on. These features allow easyimplementation of repetitive machining patterns andcomplex workpiece shapes that can be definedmathematically.

5. Advanced programming features. These commands aredependent on user control. They are used to simplifyprogramming effort and reduce programming time andprogram size. Typical features include scaling, rotation,and mirror image.

4. Macro and subroutine programming. Most modem CNCcontrols furnish the power of computer programming todefine variables, perform arithmetic operations, executelogical decisions, and so on. These features allow easyimplementation of repetitive machining patterns andcomplex workpiece shapes that can be definedmathematically.

5. Advanced programming features. These commands aredependent on user control. They are used to simplifyprogramming effort and reduce programming time andprogram size. Typical features include scaling, rotation,and mirror image.

G-codes are preparatory functions that involve