ToolsTools

ManufacturingManufacturing

ProcessesProcesses

OutlineOutline

Types of ToolsTypes of ToolsTool GeometryTool GeometryCutting FluidsCutting Fluids

EffectsEffectsTypesTypes

Tool WearTool WearFormsFormsCausesCauses

Failure ModesFailure ModesCritical ParametersCritical Parameters

Horsepower UsedHorsepower UsedOperating TemperatureOperating Temperature

Feed and SpeedFeed and SpeedTool LifeTool Life

Types of ToolsTypes of Tools

Tool GeometryTool Geometry

Single Point ToolsSingle Point Tools

Multiple Point ToolsMultiple Point Tools

Chip BreakersChip Breakers

Effects of Material on DesignEffects of Material on Design

Single Point ToolsSingle Point Tools

Multiple Point ToolsMultiple Point Tools

Chip BreakersChip Breakers

Important Tool Important Tool PropertiesProperties

- High hardnessHigh hardness- Resistance to abrasion, wear and Resistance to abrasion, wear and

chipping of the cutting edgechipping of the cutting edge- High toughness/impact strengthHigh toughness/impact strength- High hardness at high High hardness at high

temperaturestemperatures- Resistance to bulk deformationResistance to bulk deformation- Chemical stability (does not react Chemical stability (does not react

or bond strongly with the work or bond strongly with the work materialmaterial

- High modulus of elasticity High modulus of elasticity (stiffness)(stiffness)

- Consistent tool lifeConsistent tool life- Proper geometry and surface finishProper geometry and surface finish

Tool MaterialsTool Materials

- Carbon and medium-alloy Carbon and medium-alloy steelssteels

- High-speed steelsHigh-speed steels- Cast-cobalt alloysCast-cobalt alloys- CarbidesCarbides- Coated toolsCoated tools- Alumina-based ceramicsAlumina-based ceramics- Cubic boron nitrideCubic boron nitride- Silicon-nitride-base ceramicsSilicon-nitride-base ceramics- DiamondDiamond- Whisker-reinforced materialsWhisker-reinforced materials

Cutting Speeds ofCutting Speeds ofTool MaterialsTool Materials

Cutting FluidsCutting Fluids

EffectsEffects- coolantcoolant- lubricantlubricant- flushes chipsflushes chips- reduces oxidation of heated reduces oxidation of heated

surfacessurfaces

TypesTypes- cutting oilscutting oils- emulsified oilsemulsified oils- chemical fluidschemical fluids

Cutting Fluid Cutting Fluid ApplicationApplication

FloodingFlooding- ≥ ≥ 3 gallons per minute per tool3 gallons per minute per tool

MistingMisting- atomized fluidsatomized fluids- a health hazard (OSHA limit a health hazard (OSHA limit

= .2 mg/m= .2 mg/m33))

High Pressure SystemsHigh Pressure Systems- often applied through the tooloften applied through the tool

Tool WearTool Wear

FormsForms- crater wearcrater wear- flank wearflank wear- chippingchipping

CausesCauses- abrasionabrasion- adhesionadhesion- diffusiondiffusion- plastic deformationplastic deformation

Crater Wear and Crater Wear and Flank WearFlank Wear

Crater wear

Flank wear

Failure ModesFailure Modes

FractureFracture

Temperature FailureTemperature Failure

Gradual WearGradual Wear

Critical ParametersCritical Parameters

Horsepower UsedHorsepower Used

Operating TemperatureOperating Temperature

Horsepower UsedHorsepower Used

MaterialMaterialBrinellBrinell

HardnessHardness

Unit HorsepowerUnit Horsepower

hphpuu hp/(in hp/(in33/min)/min)

CarbonCarbon

SteelsSteels

150-200150-200 0.60.6

201-250201-250 0.80.8

251-300251-300 1.01.0

CastCast

IronsIrons

125-175125-175 0.40.4

175-250175-250 0.60.6

AluminumAluminum 50-10050-100 0.250.25

Values of Unit Horsepower forVarious Work Materials

Operating TemperatureOperating Temperature

Feed and SpeedFeed and Speed

Speed – the rate at which the Speed – the rate at which the tool point moves as it rotates tool point moves as it rotates (in a lathe, the rate at which (in a lathe, the rate at which the cutting point on the the cutting point on the workpiece rotates)workpiece rotates)

Feed – the rate at which the tool Feed – the rate at which the tool is fed into/along the workpieceis fed into/along the workpiece

Feed and SpeedFeed and Speed

V = V = ππDN/12DN/12

V = surface cutting speed (ft/min)V = surface cutting speed (ft/min)

D = diameter of rotating object (in.)D = diameter of rotating object (in.)

N = rotation rate (RPM)N = rotation rate (RPM)

Feed and speedFeed and speed

Example: Assume a high-speed steel saw with 100 Example: Assume a high-speed steel saw with 100 teeth and a diameter of 6 inches is used to cut teeth and a diameter of 6 inches is used to cut aluminum. Determine the proper RPM and feed aluminum. Determine the proper RPM and feed rate.rate.

V (HSS, aluminum) = 550-1000 ft/min [in table]V (HSS, aluminum) = 550-1000 ft/min [in table]N = 12V/(N = 12V/(ππD) = 12(550-1000)/(D) = 12(550-1000)/(ππ6)6)= 350-637 RPM= 350-637 RPM

Feed (aluminum, saw) = .006-.01 in/tooth [in table]Feed (aluminum, saw) = .006-.01 in/tooth [in table](.006-.01)100 teeth = .6-1in(.006-.01)100 teeth = .6-1in(.6-1)350 RPM = 210-350 in/min(.6-1)350 RPM = 210-350 in/min

Start with the lowest values. They can be increased Start with the lowest values. They can be increased so long as the finish is acceptable.so long as the finish is acceptable.

Tool LifeTool Life

F. W. Taylor, 1907Taylor Tool Life Equation

vTn = CvTn = C(Tn )

ref

Cutting PerformanceCutting Performance

How do we know if cutting How do we know if cutting parameters are optimal?parameters are optimal?

1.1. Surface finishSurface finish

2.2. Tool wearTool wear

3.3. Chip shapeChip shape

4.4. SoundSound

5.5. Cutting timeCutting time

6.6. HeatHeat

SummarySummary

Tools fail slowly with gradual wear or Tools fail slowly with gradual wear or suddenly with fracturesuddenly with fracture

Cutting fluids help reduce the effects of Cutting fluids help reduce the effects of wear and temperature failurewear and temperature failure

The materials of the tool and the workpiece The materials of the tool and the workpiece affect the tool shape and lifeaffect the tool shape and life

Higher cutting speeds increase the Higher cutting speeds increase the operating temperature and decrease tool operating temperature and decrease tool lifelife

It is necessary to calculate proper feed and It is necessary to calculate proper feed and speed to prevent excessive tool wearspeed to prevent excessive tool wear

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