design for manufacturing the yo-yo production process

Design for Manufacturing&

The Yo-yo Production ProcessME2110 Creative Decisions and Design

22 August 2018Prof. Tom Kurfess

Kyle Saleeby

DFM & The Yo-yo Production Process

Design for Manufacturing

Manufacturing Tradeoffs

SPC, Assembly,

and Machines

Manufacturing Metrics

Yo-yo Design

Design Decisions

Critical Specs

Version revisions

Yo-yo Production Process

Production Line Flow

Station Overview

Signup Info


Trade-offs in DFM

Cost

Quality

Rate

Flexibility


Design of a part, assembly, and manufacturing

process with the appropriate quality, lowest

cost, fastest and most flexible method.

Easy, right?

Part and Assembly Design

Specifications– The intended dimension

– The “ideal” length

Tolerance– The allowable error

– An acceptable range

1.75” ± 0.05”

Specification Tolerance


Parts have tolerances because Assemblies have tolerances

Assemblies have variation because parts have variation

Assembly-level variations are largely due to areas where parts assemble to each other.

“Tolerance is what you need, and

Variation is what you get!”

- Dr. Dan Whitney

1” ± 0.1”

Source: Dan Whitney

1” ± 0.1” 1” ± 0.1” 1” ± 0.1” 1” ± 0.1”Vs.

1”

5.0” ± 0.1”

1” 1” 1” 1”


Interference– Space intentionally occupied by more than one body

– Results in deformation of one (or multiple) bodies

Clearance– Space intentionally left unoccupied

NEMA Motor Shaft & Coupling Bore

Interference Fit Chart

https://www.efficientplantmag.com/wp-content/uploads/images/stories/2010/mt0510easa5.gif


Source: Dan Whitney


Source: Dan Whitney

0.0005” Clearance Ratio

100 inch Dia.

Manufacturing Methods

Selecting a method, based on the part requirements

CNC Machining– Quality: Best -- Highest precision

– Cost: High

– Rate: Moderate to fast

– Flexibility: Depends

Additive manufacturing– Quality: Low to Moderate

– Cost: Low to Moderate

– Rate: Slow

– Flexibility: Extremely Flexible

Strengths: Strong, durable parts.

Very flexible with CNC. Use for

critical components.

Limitation: Set-up

Strengths: Realize complex designs

with (almost) fixed setup time. Proof

of concept mechanisms.

Limitation: Weak parts.

High rate of failure



Laser Cutter– Quality: Moderate

– Cost: Low

– Rate: Fast

– Flexibility: Extremely flexible

Waterjet– Quality: Moderate

– Cost: Moderate

– Rate: Fast

– Flexibility: Extremely flexible

Strengths: Very fast, 2D to 3D

structures. Moderately strong parts.

Very easy to modify parts.

Limitation: Chlorine

Strengths: Very fast, 2D to 3D

metal structures. Extremely strong

parts. Limitation: Water



Injection Molding– Quality: Very High

– Cost: Very Low

– Rate: Extremely fast

– Flexibility: Low

Thermoforming– Quality: Low to Moderate

– Cost: Very Low

– Rate: Extremely Fast

– Flexibility: Low

Strengths: Very fast.

Moderately strong and complex

parts, with good design choices.

Limitation: Complexity of molds

Strengths: Very fast. Low resolution,

difficult to achieve sharp features.

Limitation: Excess material

(recyclable)


We’ve chosen a method, how do we evaluate the results?

Statistical Process Control

https://xkcd.com/552/

Mfg. Metrics - Run Chart

Measurement of critical dimension for every part

USL – Upper Specification LimitSpecification + UpperTolerance

LSL – Lower specification LimitSpecification - LowerTolerance

Mfg. Metrics – Shewhart Control Chart

Also called an “X-bar Chart”– Average measurement of a subgroup of parts

UCL – Upper Control Limit

UCL = 𝑋 + 3σ𝑠𝑔 σ𝑠𝑔 = SubGroup Standard dev.

LCL – Lower Control Limit

LCL = 𝑋 − 3σ𝑠𝑔 σ𝑠𝑔 = SubGroup Standard dev.

Manufacturing Metrics

Source: Dr. Jung-Hoon

Chun, MIT 2.008 Sp’17

Control ChartSub-Group n=10

Run Chart

Statistical Process ControlMonitor Quality of Parts

Identify Random or Causal Variations

Provides Metric of Success

Production Line Manufacturing

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0 10 20 30 40 50

Pu

ck L

engt

h

Puck #

Run Chart, Fall 2017Band Saw, n = 50

Band Saw

USL - Up. Spec. Limit

LSL - Low Spec. Limit


Need a moment?

Chew it over with Twix!

Twix Fun Size Mass Distribution



Process Control and Capability



Yo-yo Design for Manufacturing

Version 1 Design Choices

Good or bad design choices for manufacturing?

Good or bad design choices for yo-yo performance?

Interference / Press-fit Axle

Inner Chamfers

Inner Edge Chamfer

Outer Edge Chamfer

Engraving

Assembly Diagrams

Distance and angle are important

θ

Assembly: The Good, The Bad, and The Ugly

Yo-yo V1 vs. V2

Version 1Titanium Version Version 2 Modifications

1. Thicker Rim

2. Thinner Center

3. Spacer for

Assembly

Yo-yo Manufacturing Process

How do you make 400 Yo-yo’s?

Overall Process - Profile

Production Run Process

Montgomery Machining Mall

Station A

Okuma CNC Lathe #1

• Inner Profile, L = 0.75 ± 0.065”

Station B

Okuma CNC Lathe #2

• Outer Profile, L = 0.67 ± 0.01”

• Press-fit Hole

Buffer

(20ct.)

Buffer

(20ct.)

Pucks Pre-Cut

1,020ct. Dia = 2.25”

L = 0.75” +0.065”/-0.0”

Station A – Okuma CNC Lathe #1

• Measure puck (ensure L = 0.75 ± 0.065”)

• Place puck in jaws

• Ensure feed and spindle speed knob are at 100%

• Press the green button

• Take puck out, measure, place in outgoing hopper

• After Inner Profile, L = 0.73 ± 0.01”

Station B – Okuma CNC Lathe #2

• Measure puck (ensure L = 0.73 ± 0.01”)

• Place puck in jaws

• Ensure feed and spindle speed knob are at 100%

• Press the green button

• Take puck out, measure, place in storage container.

• After Outer Profile, L = 0.67 ± 0.01”

Instruction Sheet

Instructions will be posted at every station.

TA’s will have in-depth guides, and trouble shooting instructions.

Do NOT get complacent.

If in doubt....


Process Time

Okuma #1 – Front Side 1min 40 seconds

Okuma #2 – Back Side 1min 40 seconds

Quality & Post Processing ~45 seconds

Total: 4min 5seconds

Optimization

Balancing act between:– Tool wear

– Chip size

– Surface finish

Anodizing and Second Production Run

Yo-yos will be shipped for anodizing

Adds ~0.004” layer on surface

Extremely Hard

Second Production Run

Two stations– CNC Mill for Engraving

– Arbor Press for assembly

Occur ~ two weeks after first production run

Sign up after first run

Volunteer Process

Sign-Up Links:Signup Form: bit.ly/2110YoyoSignUp

Contact Info Form: bit.ly/2110YoyoContact

Volunteers will be trained for first 30mins

Run production line for 1h 30m after

Please sign up for multiple shifts!

bit.ly/2110YoyoContact

bit.ly/2110YoyoContact

Volunteer Process

Thank you to all volunteers!

Acknowledgements

Dr. Tom Kurfess

Dr. Chris Saldana

Steven Sheffield

Matt Carroll

Scott Elliot

Nate Mauldin

Louie Boulanger

Team Kurfess

Roby Lynn

Chelsea Silberglied

James Collins

Muyang Guo

ME2110 TA’s

References

1. Prof. William Singhose, Prof. Tom Kurfess, ME2110 Fall 2013, Georgia Tech

2. Prof. Dr. Jung-Hoon Chun 2.008, MIT

3. Prof. Dan Whitney, MIT

4. EML2322L – University of Florida Design and Manufacturing

Reserve Slides

Defects

Feed and Spindle Speed

Mislocated on jaws

Short puck

Questions

Do I need prior experience to run the machines?– No. Our TA’s will train you for all of the jobs, regardless of which machine you sign up for.

The process is also very straight-forward and well documented. Please follow the instructions and you will pick it up very quickly.

Do I need to stay for the entire shift?– Yes. We’re do not have too much slack time to spare. We need to keep the machines

running as much as possible.

Can I adjust parameters of the machines?– Please do not press buttons other than ones you are instructed to use on the instructions

sheet. This could cause SEVERE damage to the machines.

Other Questions?

design for manufacturing the yo-yo production process

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