Machining Machining Plastic PartsPlastic Parts

Luke KwisnekLuke Kwisnek

Patrick SlaterPatrick Slater

Matt JacksonMatt Jackson

ObjectiveObjective

Differences between metal and Differences between metal and plasticplastic

Materials Materials AdvantagesAdvantages DisadvantagesDisadvantages

OutlineOutline

Why Machine PlasticsWhy Machine Plastics Process ConsiderationsProcess Considerations Material ConsiderationsMaterial Considerations

Why Machine Plastic?Why Machine Plastic?

Cost EffectiveCost Effective Low Volume ProductionLow Volume Production Secondary OperationsSecondary Operations

Material LimitationsMaterial Limitations ThermosetsThermosets CompositesComposites Ultra-High Mw MaterialsUltra-High Mw Materials

Machining Plastics vs Machining Plastics vs MetalsMetals

Ventilation ConcernsVentilation Concerns AnnealingAnnealing

To Avoid WarpageTo Avoid Warpage Robust FixturingRobust Fixturing Tooling ConsiderationsTooling Considerations

SharperSharper More Clearance (“Rake”)More Clearance (“Rake”)

Factors Affecting Cutting Factors Affecting Cutting Action In PlasticsAction In Plastics

HeatHeat Thermal Conductivity < MetalThermal Conductivity < Metal

Resists Compressive FractureResists Compressive Fracture Factors Promoting Tensile Fracture:Factors Promoting Tensile Fracture:

Sharp ToolsSharp Tools Large Rake AnglesLarge Rake Angles

Factors Affecting Cutting Factors Affecting Cutting Action In PlasticsAction In Plastics

Chip FormationChip Formation Want Continuous Flow TypeWant Continuous Flow Type

Smooth and ContinuousSmooth and Continuous High Elastic DeformationHigh Elastic Deformation

Process Specific Process Specific ConsiderationsConsiderations

Lathe CuttingLathe Cutting

ToolingTooling Standard Tool MaterialsStandard Tool Materials High Rake AngleHigh Rake Angle

Water Soluble CoolantsWater Soluble Coolants Close Chucking and Follow RestsClose Chucking and Follow Rests

Prevent chatterPrevent chatter

Lathe Tool Bit Lathe Tool Bit TerminologyTerminology

MillingMilling

ToolingTooling Standard Tool MaterialsStandard Tool Materials High ClearanceHigh Clearance

Water Soluble CoolantsWater Soluble Coolants Slower Cutting FeedsSlower Cutting Feeds Same as Metal OtherwiseSame as Metal Otherwise

Drilling/ReamingDrilling/Reaming

ToolingTooling Wide, Highly Polished FlutesWide, Highly Polished Flutes Large Helix AnglesLarge Helix Angles Point angles of 60-90° (included)Point angles of 60-90° (included)

120° for PMMA and PVC120° for PMMA and PVC

Dimensional Concerns Dimensional Concerns Thermal ExpansionThermal Expansion Drill OversizeDrill Oversize

Drill TerminologyDrill Terminology

Reamer TerminologyReamer Terminology

Tapping/ThreadingTapping/Threading

ToolingTooling Same Tools as MetalSame Tools as Metal Blunt Withdrawal Edges Blunt Withdrawal Edges

SpeedsSpeeds 50 ft/min Most Plastics50 ft/min Most Plastics 25 ft/min Filled Materials25 ft/min Filled Materials

New Cutting New Cutting TechnologiesTechnologies

Water JetWater Jet UltrasonicUltrasonic Laser-assisted turningLaser-assisted turning

Material Specific Material Specific ConsiderationsConsiderations

Machining Neat PlasticsMachining Neat Plastics

Teflon, Acetal, AcrylicsTeflon, Acetal, Acrylics Generous RakeGenerous Rake Low Cutting Speeds (< 1m/min)Low Cutting Speeds (< 1m/min)

NylonNylon Continuous ChipsContinuous Chips Rake, Depth and SpeedRake, Depth and Speed

AnnealingAnnealing StandardStandard Double Anneal (Teflon)Double Anneal (Teflon)

Machining ThermosetsMachining Thermosets

Base Resin MixturesBase Resin Mixtures Phenolic, Urea, Melamine, SiliconePhenolic, Urea, Melamine, Silicone

Most similar to metalMost similar to metal High speeds and feeds High speeds and feeds Finishing requiredFinishing required

Machining Reinforced Machining Reinforced PlasticsPlastics

Fiber-Reinforced Plastics (FRPs)Fiber-Reinforced Plastics (FRPs) Base MaterialsBase Materials

Polyesters, Polyamides, Expoxy ResinsPolyesters, Polyamides, Expoxy Resins Matrix (Filler) MaterialsMatrix (Filler) Materials

Glass, Carbon, Aramid FibersGlass, Carbon, Aramid Fibers

Machining Reinforced Machining Reinforced Plastics Plastics cont.cont.

Usage LimitationsUsage Limitations Chip/Dust ProductionChip/Dust Production Surface DetailsSurface Details

Unique Modes of FailureUnique Modes of Failure Different Fracture CharacteristicsDifferent Fracture Characteristics

Chip CharacteristicsChip Characteristics

Powder Ribbon

Brush

Fracture CharacteristicsFracture Characteristics

Machining Reinforced Machining Reinforced Plastics Plastics cont.cont.

ToolingTooling Longer Life With K-CarbideLonger Life With K-Carbide

Cutting Speed 38 m/minCutting Speed 38 m/min Single Crystal Diamond ToolingSingle Crystal Diamond Tooling

Better LifeBetter Life Cutting Speed 426 m/minCutting Speed 426 m/min

ConclusionConclusion

Cost EffectiveCost Effective Low VolumeLow Volume Difficult to Mold MaterialsDifficult to Mold Materials

Promote Tensile FracturePromote Tensile Fracture Continuous Flow ChipsContinuous Flow Chips Generous RakeGenerous Rake Sharp ToolsSharp Tools

Low Cutting SpeedsLow Cutting Speeds