manufacturing processes - fitstaff.fit.ac.cy/eng.os/microsoft powerpoint - lecture7.pdf ·...

1

MANUFACTURINGMANUFACTURING

PROCESSESPROCESSES

-- AMEM 201 AMEM 201 ––

Lecture 7Lecture 7:: Machining ProcessesMachining Processes

DR. SOTIRIS L. OMIROU

ShapingShaping DrillingDrillingBroachingBroaching

22

ShapingShapingShapingShapingShapingShapingShapingShaping

Shaping uses a singleShaping uses a single--point tool that is moved point tool that is moved

horizontally in a reciprocating motion along a slide. It horizontally in a reciprocating motion along a slide. It

is used to create a planar surface, usually to prepare is used to create a planar surface, usually to prepare

rectangular blocks that can later be used as rectangular blocks that can later be used as

workpiecesworkpieces for machining on a milling machine etc. for machining on a milling machine etc.

2

33

ShapingShapingShapingShapingShapingShapingShapingShaping

44

�� Broaching is the process of removing metal with a Broaching is the process of removing metal with a tool which has “teeth” arranged in a row. Each tool which has “teeth” arranged in a row. Each tooth is successively higher than the previous tooth is successively higher than the previous tooth and removes more material. tooth and removes more material.

�� Thus the first few sets of teeth remove most of Thus the first few sets of teeth remove most of the material, while the last few provide a finishing the material, while the last few provide a finishing cut with very small amount of material removal. cut with very small amount of material removal. The geometric shape of the last set of teeth is The geometric shape of the last set of teeth is identical to the required geometry of the designed identical to the required geometry of the designed part.part.

�� In broaching, one stroke or cycle of the machine In broaching, one stroke or cycle of the machine produces a finished part. Broaching is used to produces a finished part. Broaching is used to produce both internal and external features. produce both internal and external features. Production rates are high and tolerances ofProduction rates are high and tolerances of

+/+/-- 0.01 mm are possible.0.01 mm are possible.

BroachingBroachingBroachingBroachingBroachingBroachingBroachingBroaching

3

55

Broaching Broaching Broaching Broaching Broaching Broaching Broaching Broaching ToolsToolsToolsToolsToolsToolsToolsTools

66


Broaching cutter detailsBroaching cutter details

4

77

�� Design and construction considerationsDesign and construction considerations

–– Material to be broachedMaterial to be broached

–– Size and shape of cutSize and shape of cut

–– Quality of surface finishQuality of surface finish

–– Part tolerancePart tolerance

–– Productions ratesProductions rates

–– Type of machineType of machine

–– WorkholdingWorkholding methodmethod

–– Strength of the Strength of the workpieceworkpiece


88

Tool Feed DirectionGullet

Workpiece

Depth ofcut per tooth

Tool

Broaching Broaching Broaching Broaching Broaching Broaching Broaching Broaching mechanismmechanismmechanismmechanismmechanismmechanismmechanismmechanism

5

99

Broaching Broaching Broaching Broaching Broaching Broaching Broaching Broaching -------- AdvantagesAdvantagesAdvantagesAdvantagesAdvantagesAdvantagesAdvantagesAdvantages

�� Rough to finish in one passRough to finish in one pass

�� Cutting time is quickCutting time is quick

�� Rapid load and unload of partsRapid load and unload of parts

�� External and internal features External and internal features

�� Any form that can be produced on aAny form that can be produced on a

broaching tool can be producedbroaching tool can be produced

�� Production tolerances are excellentProduction tolerances are excellent

�� Surface finishes are equal to millingSurface finishes are equal to milling

�� Operator skill is lowOperator skill is low

�� Production rates are highsProduction rates are highs

1010

��Tooling cost can be highTooling cost can be high

Broaching Broaching Broaching Broaching Broaching Broaching Broaching Broaching -------- DisadvantagesDisadvantagesDisadvantagesDisadvantagesDisadvantagesDisadvantagesDisadvantagesDisadvantages

��In some casesIn some cases----not suited for low not suited for low production ratesproduction rates

��Parts to be broached must be strongParts to be broached must be strongenough to withstand the forces of theenough to withstand the forces of theprocessprocess

��Surface to be broached must be accessibleSurface to be broached must be accessible

6

1111

––Pull broaching Pull broaching -- broach is pulled broach is pulled

through or across stationary workthrough or across stationary work

––Push broaching Push broaching -- broach is pushed broach is pushed

through or across workthrough or across work

––Surface broaching Surface broaching -- either the work or either the work or

the broach moves across the otherthe broach moves across the other

Broaching Broaching Broaching Broaching Broaching Broaching Broaching Broaching -------- Methods of OperationMethods of OperationMethods of OperationMethods of OperationMethods of OperationMethods of OperationMethods of OperationMethods of Operation

1212

Broaching Broaching Broaching Broaching Broaching Broaching Broaching Broaching MachinesMachinesMachinesMachinesMachinesMachinesMachinesMachines

7

1313

Complex hole shapes cut by broachingComplex hole shapes cut by broaching

Broaching Broaching Broaching Broaching Broaching Broaching Broaching Broaching productsproductsproductsproductsproductsproductsproductsproducts

1414

Drilling is one of the most common machining process. A large amount of all metal-cutting material removed comes from drilling operations.

Drilling is one of the most common machining process. A large amount of all metal-cutting material removed comes from drilling operations.

DrillingDrillingDrillingDrillingDrillingDrillingDrillingDrilling

By drilling are creating holes that are right circular cylinders. This operation is accomplished most common by using twisted drills (that is the tool).

By drilling are creating holes that are right circular cylinders. This operation is accomplished most common by using twisted drills (that is the tool).

In order to perform the drilling operation the tool has to have o rotation motion, that is the cutting motion and the tool or work part will achieve the feeding motion, which is a translation one, on the same direction with rotation axis.

In order to perform the drilling operation the tool has to have o rotation motion, that is the cutting motion and the tool or work part will achieve the feeding motion, which is a translation one, on the same direction with rotation axis.

8

1515

Feeding

motion

Cuttingmotion

Work

Part

Twisted

Drill

DrillingDrillingDrillingDrillingDrillingDrillingDrillingDrilling

1616

Some features of drilling set it apart from other metal cutting operations. Among these are:

Characteristics of DrillingCharacteristics of DrillingCharacteristics of DrillingCharacteristics of DrillingCharacteristics of DrillingCharacteristics of DrillingCharacteristics of DrillingCharacteristics of Drilling

* The chips must exit out of the hole created by thecutting tool, so the friction and as a consequence thetemperature is very high.

* The chip exit can cause problems when chips are largeand/or continuous.

* The drill can wander when the holes are deep

* For very deep holes the coolant may need to bedelivered through the drill shaft to the cutting front area

9

1717

Drilling,Drilling,Drilling,Drilling,Drilling,Drilling,Drilling,Drilling, Reaming, Boring, TappingReaming, Boring, TappingReaming, Boring, TappingReaming, Boring, TappingReaming, Boring, TappingReaming, Boring, TappingReaming, Boring, TappingReaming, Boring, Tapping

All four methods produce holes of different types.

Drilling produces round holes of different types.

Reaming is used to improve the dimensional tolerance on a drilled hole.

Boring uses a special machine operating like a lathe, to cut high precision holes.

Tapping creates screw-threads in drilled holes.

For drilling in brick, stone, concrete, slate, plaster and other masonry materials

For drilling cast iron or non-ferrous material.

For drilling cast iron, plastic or non-ferrous materials

These heavy duty drills featurea regular helix and polished flutes

for rapid chip removal. Ideal for drilling steel, cast iron, and non-ferrous materials.

DDDDDDDDrillingrillingrillingrillingrillingrillingrillingrilling ToolsToolsToolsToolsToolsToolsToolsTools

10

Straight shank taper length drills are standard for general purpose work in drilling relatively deep holes. Shanks are of the same diameteras the drill body

Especially suitable for deep holedrilling in low tensile

strength materials, such as aluminum magnesium and zink alloys


Counterbore drills havemultiple diameters. They make a chamfered/stepped hole, which isuseful for inserting screws/bolts.The larger diameter part of the hole accommodates the screw/bolt head;

For countersinking, chamfering, and deburring holes. Produces a smoother finish.


11


Center-drills

It is common to machine a small hole in the material, called a center-hole, before utilizingthe drill. Center-holes are made by special drills called center-drills.They also provide a good way for the drill bit to get aligned with the location of the hole center.

2222

Suitable for general purposethrough hole reaming

For accurate hand reaming of Morse Taper holes in sockets, sleeves and spindles

Is especially suited for use in stringy materials or in through holes where a slot or keyway is present.


For general reaming in deep holesrequiring precision tolerances.

Reamers

12

Drilling head

Vertical Column

Machine table

Base

Vertical guides

Main spindle

Twisted drill

The work part that have to be machined is clamped on the machine table and the tool (twisted drill) is monted on the main spindle. The main spindle, with tool, will perform both the cutting (rotation) and feeding (translation) motion.

The work part that have to be machined is clamped on the machine table and the tool (twisted drill) is monted on the main spindle. The main spindle, with tool, will perform both the cutting (rotation) and feeding (translation) motion.

DDDDDDDDrillingrillingrillingrillingrillingrillingrillingrilling Machine ToolsMachine ToolsMachine ToolsMachine ToolsMachine ToolsMachine ToolsMachine ToolsMachine Tools

Column

Radial beam

Radial guides

Work Part

Bed

Drilling head

Tool

Vertical motion

1

Rotation motion

2

Radial motion3

1,2,3 – Auxiliary motions for adjusting the

relative position between the work part and tool

The radial drilling machines are used for machining of large work parts. Here, it is so difficult to adjust the relative position between the tool and work part by moving a heavy part. For this reason there are three

auxiliary motions. The cutting and feeding motions are performed by tool.

The radial drilling machines are used for machining of large work parts. Here, it is so difficult to adjust the relative position between the tool and work part by moving a heavy part. For this reason there are three

auxiliary motions. The cutting and feeding motions are performed by tool.


13

Drilling head

Portal frameZ

Y

X

Machine Table

Z Screw

Y Screw

X Screw

Bed

X Guides

Z Guides

Y Guides


manufacturing processes - fitstaff.fit.ac.cy/eng.os/microsoft powerpoint - lecture7.pdf ·...

Documents