[Name Sponged] Consulting Project (2)

Spoolshaft Defect Correction

Split the Dictionary:

(Part) No ContrastParts were found out of specification randomly.

(Model) No ContrastOut of specification parts were found on both gas and diesel models on both machines in the same locations

(Machine) No contrastBoth Huffman #11 & #16 both had out of specification parts in the same locations with roughly the same volume of scrap.

Location to Location

Same Part

Part to Part

Same Machine

Machine to Machine

Same Model

Same Time

Model to Model

(Location) Strong Contrast Out of specification locations were found concentrated to one location radially around the Spoolshaft.

Clue Descriptions

Strategy Plan

Spool Blanks

Spool Raw Machining

Grind/ Stamp

Huffman Grind/ Wash

Grind Slots and Flats

Feature Machined

Valve Assembly

Process Flow Diagram

Root Cause – Flat Width Scrap

Δ PΔ M

Measurement Verification• View Measurement System was found capable of

measuring flat width within 2%

Measurement Position Meas. 1 Meas. 2 Meas. 3 Meas. 4 Meas. 5 Meas. 6 Meas. 7 Meas. 8 Meas. 9 Meas. 10 Max Meas. Min Meas. Range Range x2 Capability

Tolerance 1 5.101 5.101 5.101 5.101 5.101 5.101 5.101 5.101 5.101 5.101 5.101 5.101 0.000 0.000 0%5.135 2 5.082 5.081 5.082 5.082 5.082 5.081 5.081 5.081 5.082 5.082 5.082 5.081 0.001 0.002 2%5.035 3 5.073 5.072 5.072 5.072 5.072 5.072 5.072 5.072 5.072 5.072 5.073 5.072 0.001 0.002 2%

.100 mm 4 5.065 5.065 5.065 5.065 5.065 5.065 5.065 5.065 5.065 5.065 5.065 5.065 0.000 0.000 0%5 5.06 5.06 5.06 5.06 5.06 5.06 5.06 5.06 5.06 5.06 5.06 5.06 0.000 0.000 0%6 5.081 5.081 5.08 5.081 5.081 5.08 5.08 5.08 5.08 5.08 5.081 5.08 0.001 0.002 2%7 5.123 5.123 5.123 5.123 5.123 5.123 5.123 5.123 5.123 5.123 5.123 5.123 0.000 0.000 0%8 5.121 5.121 5.121 5.121 5.121 5.121 5.121 5.121 5.121 5.121 5.121 5.121 0.000 0.000 0%

Capability = [(Xmax – Xmin) x 2] / (Print Tolerance)

Root Cause Tree

Root Cause – Low Effort

Δ P (Defect)Δ M

Not Dimensional Dimensional

Dimensional Defect• Parts are being scrapped as falling above or below

a specified tolerance range

Root Cause Tree


Δ P (Defect)Δ M


Too much Range piece to piece

Process Mean not Centered

Dimensional Defect• Of data gathered, it was found that while the

mean of the process stays within the tolerance, the range from piece to piece is too large to constrain.

Too much Variation piece to piece

Root Cause Tree


Δ P (Defect)Δ M


Too much Range piece to piece Process Mean not CenteredToo much Variation piece to

piece

Root Cause Tree

Concentration Diagram

Min Specification 5.035 Measurement #1 5.144 Min Specification 5.035 Measurement #1 5.081Max Specification 5.135 Measurement #2 5.124 Max Specification 5.135 Measurement #2 5.064Spec. Range 0.100 Measurement #3 5.114 Spec. Range 0.100 Measurement #3 5.051Min Measurement 5.087 Measurement #4 5.087 Min Measurement 5.025 Measurement #4 5.025Max Measurement 5.144 Measurement #5 5.093 Max Measurement 5.084 Measurement #5 5.034Range 0.057 Measurement #6 5.112 Range 0.059 Measurement #6 5.064Average 5.119 Measurement #7 5.135 Average 5.060 Measurement #7 5.079

Measurement #8 5.142 Measurement #8 5.084Spec. Range on Effort 2.95-3.75 Spec. Range on Effort 2.95-3.75R.Effort 3.520 R.Effort 3.290L.Effort 3.430 L.Effort 3.270Differential 0.090 Differential 0.020


Measurement #8 5.137 Measurement #8 5.074Spec. Range on Effort 2.95-3.75 Spec. Range on Effort 2.95-3.75R.Effort 3.460 R.Effort 3.360L.Effort 3.520 L.Effort 3.470Differential -0.060 Differential -0.110


Measurement #8 5.141 Measurement #8 5.073Spec. Range on Effort 2.95-3.75 Spec. Range on Effort 2.95-3.75R.Effort 3.470 R.Effort 3.300L.Effort 3.590 L.Effort 3.240Differential -0.120 Differential 0.060

Huffman #11Huffman #11

Part #8Huffman #11

Part #9Huffman #11

Part #10

Part #1

Part #2

Part #3

Huffman #11

Huffman #11

Sample DataANALYSIS

A-Start

8

7

6

5 4

3

2

1

• There Are Eight Slots With Flat Widths Ground Around the Spoolshaft. • Starting With A-start, and Measuring Clockwise, the View Measurement

System Supplied the Data Where it was Found That All Measurements Near the Top (or A-start) Were High in the Range and All Measurements on the Bottom Were at the Minimum of the Range

Concentration Diagram


Measurement #8 5.142 Measurement #8 5.084Spec. Range on Effort 2.95-3.75 Spec. Range on Effort 2.95-3.75R.Effort 3.520 R.Effort 3.290L.Effort 3.430 L.Effort 3.270Differential 0.090 Differential 0.020


Measurement #8 5.137 Measurement #8 5.074Spec. Range on Effort 2.95-3.75 Spec. Range on Effort 2.95-3.75R.Effort 3.460 R.Effort 3.360L.Effort 3.520 L.Effort 3.470Differential -0.060 Differential -0.110


Measurement #8 5.141 Measurement #8 5.073Spec. Range on Effort 2.95-3.75 Spec. Range on Effort 2.95-3.75R.Effort 3.470 R.Effort 3.300L.Effort 3.590 L.Effort 3.240Differential -0.120 Differential 0.060

Huffman #11Huffman #11

Part #8Huffman #11

Part #9Huffman #11

Part #10

Part #1

Part #2

Part #3

Huffman #11

Huffman #11

Sample Data

A-Start

8

7

6

5 4

3

2

1

This data was supplied to the appropriate Manufacturing Engineer who listed many things that could be done to the two Huffmans to improve the range and variability. All of these options were not financially viable to fix this issue when weighted against cost to implement and scrap savings.

MID-PROJECT CONCLUSION

Correlation – Built Into Valves

BOBs

WOWs

Valv

e Eff

ort

High Effort Spec

Low Effort Spec

Old Low Flat Width Spec

Current Low Flat Width Spec

High Flat Width Spec

Flat Width

ANALYSIS• The Specification of flat widths

is to prevent High & Low Effort Valve Assemblies

• Recently the grind sheets were updated:• Previous 4.985 - 5.135 • Status Quo 5.035 -

5.135

• We collected BOBs/WOWs that were above and below the current specification limit to correlate flat width to effort.

Prop

osed

CORRECTIVE ACTION

Corrective Action

Proposal would be to adjust the Low Flat Width Spec Limit lower by 20μm. This would allow the Huffman to adjust the mean and produce less scrap at the current machine capability.

• Productivity

• Daily Scrap Cost

• Annual Scrap Cost

Spoolshaft Scrap Improvement: Before

Track the Improvement & Control: Before

Productivity 90.00%Shift Time (Hours) x 8.00Operational Activity (Hours) 7.20Cycle Time (Parts/Hour) x 45.00 Parts Made/Day (Gross) 324.00

Parts Made/Day (Gross) 324.00Scrap Rate x 6.0%Scrap Parts/Day 20.00Scrap Cost/Part x $7.48Scrap Cost/Day $149.60

Scrap Cost/Day $149.60Production Days x 240.00Scrap Cost/Year $35,904.00


• Productivity



• Comparison


Track the Improvement & Control: After





Scrap Cost/Day $35,904.00Production Days $ 7,180.80Scrap Cost/Year $28,723.20

𝑂𝑙𝑑−𝑁𝑒𝑤𝑂𝑙𝑑 =𝑃𝑒𝑟𝑐𝑒𝑛𝑡 h𝐶 𝑎𝑛𝑔𝑒

Track the Improvement & Control: Before

𝑂𝑙𝑑−𝑁𝑒𝑤𝑂𝑙𝑑 =𝑃𝑒𝑟𝑐𝑒𝑛𝑡 h𝐶 𝑎𝑛𝑔𝑒


• Productivity



• Comparison


Track the Improvement & Control: After





Scrap Cost/Day $35,904.00Production Days $ 7,180.80Scrap Cost/Year $28,723.20

$ 35,904.00−$7,180.80$35,904.00 =𝟖𝟎%

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[Name Sponged] Consulting Project (2)