Acme Yo-yo CompanyAcme Yo-yo Company

Omar Hernandez, Alex Slocum, Jr. –

Yo-Yo BaseKimberlee Collins & Rosa Rodriguez -

Wiley Cover

Dayan Paez – Clear Cover and Snap-fit

retaining ring

Assembly

Base OptimizationOptimization Order

– Shot size– Cool Time– Hold Size –Sprue-

break

Results:– SS: 3.25 in– HT: 60 sec– CT: 90 sec

Cycle time– 100 sec

Distribution of snap diameter for entire production

05

10152025303540

2.351 2.3568 2.3626 2.3684 2.3742 2.38 More

Diameter (in)

Shewhart Control Chart with LCL and UCL (at 2 Std. Dev)

2.360

2.365

2.370

2.375

2.380

2.385

0 2 4 6 8 10

Data Point

Ave

rage

Base Process Details

• Process capacity– Cp = .298

• Higher since actual tolerances spec range is greater than 0.005 in.

• Cycle Time– 100 seconds, steady state

• Production– 125 bases producted

• Some got stuck on mold• Several short shots.

Conclusion• Rate: very difficult to increase.• Problems:

– Cooling Time.– 1st generation mold was too big.

• Flexibility– Geometry: limited

• Cooling time– Color: whatever was in the hopper.

• Cost: relatively high due to low rate/large part size.• Ways quality can be increased:

– Draft angles– MoldFlow™– Address uneven cooling

Wiley CenterpieceWiley Centerpiece

Injection Molding Piece by Rosa Rodriguez and Kimberlee Collins

InspirationCan you find him???

Drawing

Optimization Order

– Shot size– Hold time– Cool time

Results– SS: 0.62 in– HT: 5 sec– CT: 9 sec

“Cycle time”– 15 sec on

automatic

Diameter vs. Cooling Time

1.685

1.686

1.687

1.688

1.689

1.69

1.691

1.692

1.693

1.694

0 2 4 6 8 10 12 14 16

Time (s)

Snap

Fit

Dia

met

er (i

n)

cooling time hold time

Production

Production Run by Settings

1.678

1.68

1.682

1.684

1.686

1.688

1.69

0 20 40 60 80 100 120

Part No.

Snap

Fit

Dia

met

er [i

n]

1-80 1-80 avg80-134 80-134 avg

Distribution of Diameters Before and After Shift

0

5

10

15

20

25

30

1.679 1.68 1.681 1.682 1.683 1.684 1.685 1.686 1.687 1.688

Snap Fit Diameter [in]

Freq

ueny

before shift after shift

• Process capacity– Cp = 8.33

• Cycle Time– 8 seconds, steady state

• Number produced– 133 parts, of 3 distinct colors

Shewart Control Chart withLCL and UCL (at 3 Std.Dev.)

1.6761.6781.68

1.682

1.6841.6861.688

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Data Point

Ave

rage

Conclusion

• Rate: hard to increase without another machine (2 at a time)

• Flexibility– Geometry: limited

• Cool time

– Color: great• Cost: low due to small volume• Quality: using a ball end mill, the core finish

could be improved; avoid clear plastic

Retaining RingRetaining Ring

Injection Molding by Dayán Páez

Drawing

OptimizationOrder

– Shot size– Hold time– Cool time

Results– SS: 0.70 in– HT: 3 sec– CT: 3 sec

“Cycle time”– 8 sec on

automatic

Snap Fit Diameter vs. IM Parameters

2.3452.3502.3552.3602.3652.3702.3752.3802.3852.390

0 5 10 15 20

Time (s)

Snap

Fit

Dia

met

er (i

n)

Cool Time Hold Time

Average (in) for Snap Fit Diameter

2.320

2.330

2.340

2.350

2.360

2.370

2.380

2.390

2.400

A B C D E F G

Batch #

Dim

ensi

on (i

n)

Average (in) Target Low er Tol. Limit

Process Details

• Process capacity– Cp = .307

• Higher since actual tolerances spec range is greater than 0.005 in.

• Cycle Time– 8 seconds, steady state

• Number produced– 200 parts, of 5 distinct colors

Conclusion

• Rate: hard to increase without a bigger machine (2 at a time)

• Flexibility– Geometry: limited

• Cool time– Color: great

• Cost: low due to small volume• Quality: can be increased through use

of proper equipment (e.g. CNC Lathe)

Clear CoverClear Cover

Thermoform by Dayán Páez

Drawing

Optimization

Criteria: visual qualityOrder

– Form time– Varied between temperature and heat time.

Results– Heat time: 30 sec– Form time: 15 sec– Temperature: 575 °F

“Cycle time”– ~60 sec in steady state

Process Details

• Process capacity– Cp = 4.71 (!)

• High due to flexibility in spec range.

• Cycle Time– 60 seconds, steady state

• Number produced– 100 parts at 1% error

Conclusion

• Rate: can best be increased by doing more at a time.

• Flexibility– Plastic thickness: limited to ≤ 0.030 in

• Cost: low due to small error rate• Quality: heavily dependent on operator

Overall

• Integration of parts– Tight snap fit

• Assembly: 50 yoyos• Functionality

– Stable