Design and Creation of NC code to fabricate Mold for a Plastic Gear Using PTC Creo 2.0

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The specification of the gear is:

• Module= 4mm • Number of teeth= 25 • Pitch circle diameter= 100mm • Pressure angle= 20 • Addendum circle diameter= 108mm • Dedendum circle diameter= 90mm • Tooth thickness= 6.2mm • Base circle diameter= 100(cos20)= 93.969mm

Figure1CreatingtheequationdrivenCartesiancurve

TheEquationforthecurveis:

• Base_circle_radius = 93.969/2 • Angle = t*90 • Cir_len = (PI * Base_circle_radius * t ) / 2 • X_ins = Base_circle_radius * cos(Angle) • Y_ins = Base_circle_radius * sin(Angle) • X = X_ins + (Cir_len * sin(Angle)) • Y= Y_ins - (Cir_len * cos(Angle)) • Z = 0

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Figure2TheCartesianCurve

Figure3Geartoothintheintersectionoftheinvoluteandtheprimecircle

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Figure4MirroringandExtruding

Figure5ThefinalPattern

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Figure6DraftcheckinMoldAnalysis

Figure7Moldandpartinglinecreation

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Figure8SelectingCoreandCavity

Figure9NCMachiningoperationsetup

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Figure10MillWindowandRoughening

Figure11SpindleSetupforcore

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Figure13ThefinalMold

Figure12SurfaceMillingofCavity

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The brief NC code for the surface milling is

% N0005(FADAL VMC 6030 - VH65) N0010G90G40G80 N0015T2M6 N0020S2000M3 N0025G0X-86.872Y-126.241 N0030G43Z20.H2 N0035Z-8.05 N0040G1Z-10.05F300. ………………………… ………………………… N1295X-87.306Y-22.59Z-1.042 N1300X-87.435Y-22.588Z-1.301 N1305X-87.54Y-22.586Z-1.645 N1310X-87.548Z-1.723 N1315X-87.576Y-22.585Z-10.05 N1320X-88.508 N1325X-88.44Y-22.386 N1330X-87.679 N1335X-87.785Y-22.188 N1340X-88.37 N1345Z20. N1350M5 N1355M2 %