DFSS Design for Six Sigma Process Evaluation. Kilian Eisenegger Executive Director Technics IWC Schaffhausen, Baumgartenstrasse 15, 8200 Schaffhausen

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1 DFSS Design for Six Sigma Process Evaluation Kilian Eisenegger Executive Director Technics IWC Schaffhausen, Baumgartenstrasse 15, 8200 Schaffhausen Smm/Kei Manufactringweek Seite 1, IWC 2005

2 Watch Industry Traditional industry A lot of classic empiric experience A lot of variance and individual components General industry Use of new methods Build more standards A mechanical watch is not better since 1975, compared to a digital camera where we have each year the double number of pixels. If we will make a better mechanical watch and increase the customer satisfaction, we have to use the same state of the art methods. Smm/Kei Manufactringweek Seite 2, IWC 2005

3 Why Six Sigma Cost-proportionate error rate Failure origin up to 75 % Failure origin Concept Construction AVOR Initial batch Serial Development and planning phase Failure elimination Failure elimination up to 80% Smm/Kei Manufactringweek Seite 3, IWC 2005

4 R&D Consequences Concept Construction Prototype Concept Construction Prototype Smm/Kei Manufactringweek Seite 4, IWC 2005

5 DFSS Smm/Kei Manufactringweek Seite 5, IWC 2005

6 Process and Data Analyse measure compress Process analyse Data analyse Y = f ( x, x2... x 1 n ) Smm/Kei Manufactringweek Seite 6, IWC 2005

7 OFD Opportunity for Defects OFD = 3 N + P + T + C + 2 N = Number of Needed process steps/iterations P = Number of Parts T = Number of Transfers (chemical/surface treatment) C = Number of Connections 2 = Number of in- and outputs (1 Input + 1 Output) P N1 3 1 N2 3 1 N3 3 1 N4 3 t1, t2,... Smm/Kei Manufactringweek Seite 7, IWC 2005

8 Complexity of Watches Number of new parts Spectrum of parts Springs (steel parts), Bridges Platinum, Gear-train, Regulate organs and escapements Number of operations (Process steps) in the manufacturing Exp. Complexity dial Number of maximum connections Assembly group Toothings Tolerances Quantitative Benchmarking Fault rate per individual part or function => OFD Number of different fault possibilities => FMEA Control and testing Checking of the process and not the product Smm/Kei Manufactringweek Seite 8, IWC 2005

9 Process Evaluation Process-Method Cpk, Cmk, Ppk Components QFD Method Smm/Kei Manufactringweek Seite 9, IWC 2005

10 Process Capability Verify the process capability on Components, OFD s Drawings, tolerances Verify the measure capability for the control Verify the price evaluation if you have different suppliers for the same process Verify the optimisation process => price and quality improvements Knowledge of noise factors Z in the production (Taguchi) Smm/Kei Manufactringweek Seite 10, IWC 2005

11 Classify Data ATTRIBUTES VARIABLES Customer Requirement Customer Requirement Defect Free (Χ 3 ) Defects (Χ 4) Non-Defects (x < 130 Min) Defects (x > 130 Min) Number of Mistakes Assembly Time (Minutes) Smm/Kei Manufactringweek Seite 11, IWC 2005

12 Dissecting Process Capability Inadequate Process Capability Measurement Error Supplier Variation Inadequate Design Margin LSL USL Defects Process Capability Smm/Kei Manufactringweek Seite 12, IWC 2005

13 Process Capability Key Figures Cp = T 6s = OTG UTG 6s UTG x OTG UTG x OTG UTG x OTG Cp = % Off-Spec Cp = % Off-Spec Cp = % Off-Spec Smm/Kei Manufactringweek Seite 13, IWC 2005 n

14 Process Capability Key Figures [ Cpo Cpu] Cpk = min ; Cpu = x UTG 3s Cpo = OTG 3s x x x UTG OTG UTG OTG Smm/Kei Manufactringweek Seite 14, IWC 2005

15 Capability vs. Performance CO2-Shrt Index Capability: Only random or short term variability (Cp & Cpk) Process Performance: Total Variation including shifts and drifts (Pp & Ppk) Smm/Kei Manufactringweek Seite 15, IWC 2005

16 Variation on the Average Values Real performance Long term Best performance Pp = 1 s = m T 6s m i= 1 si 1,5 σ Short term Long term process shift +/-1,5 σ Smm/Kei Manufactringweek Seite 16, IWC 2005

17 Evaluation of the Process For the process capability of single parts we aim for Cp values > = 2.00 With a Cp value of 2.00, the Ppk value is 1.5. The long term capability varies from the average +/- 1.5σ Example: Position tolerance +/ mm In order to assure the long term capability of Cp=2.00 and Ppk of 1.5, the machine capability Cm has to be 2.00 with +/ mm. The Cmk may, with an average fluctuation of 1.5σ, not be under 1. Cp = T 6s T = Cp 6s Cmk = OTG UTG = 6s ( 12 3) 6 = 1.5 UTG -4,5 σ -1,5σ+1,5σ + 4,5 σ OTG +/- 6 Sigma Smm/Kei Manufactringweek Seite 17, IWC 2005

18 Parameter of Capability To ascertain the machine capability Cm and Cmk, 30 parts have to be produced consecutively and measured. The tolerance field of the machine, results from a theoretical value of Cm=2 T=2*6σ. This value has to be 1.5 times better than the plan tolerance. With the measurement capability it has to be considered that it must be 10 times more precise than the tolerance field. In our example mm / 10 = mm Smm/Kei Manufactringweek Seite 18, IWC 2005

19 t1, t2,... P N1 3 1 N2 3 1 N3 3 1 N4 3 * Complexity of Parts processes Process evaluation DFSS Dok. Nr Treatment Process OFD Opportunities for Defects OFC Opportunities for Complexity Surface Procudtion costs Cp = 2.0, P pk=1.5 Milling Forming QS Cmk Machine capability Tolerance field T Plan at +/- 1.5s Cpk Process capability Cycle time in days Inte rna l External 1.5 +/ / / / / / / / / / / / / / / / HV / / /-5 +/-3 +/-7.5 +/-3 +/-6 +/-7.5 +/-7.5 +/-1.5 +/-4.5 +/-3 +/-3 +/-3 +/-7.5 +/-4.5 +/-3 +/-3 +/-3 +/-30HV +/-7.5 +/-6 +/ N P T C I/O OFD N=1 OFD e=9+d=6+s=3 N Gehäuse Werk Form Turning Turning Cutting Milling Machining centre Engraving Burnishing Wire erosion Teileklasse Movement plate x x x x x x x x x x Bridge x x x x x x x x Barrel x x x x x Spring x x x x x x x x x Lever x x x x x x x x x Wheels x x x x x x x x x x x x x Pinions x x x x x x x x x x Arbor, Cane x x x x x x x special steel parts x x x x x x x x Pin, Peg x x x Ruby Screw x x x x x Rolling x x x x x Escapment x x x x x x Balance / Spiral x x x x x x Shock absorber x x x x Button x x x x x x x x x x Joints x x Springs x x Pin x x x Movement fixation parts x x x Screw s x x x x x Glas Bezel x x x x Casering x x x x x Crow n x x x x x x x x x x Movement ring x x x x x x x Inner back x Back x x x x x Standard parts / others Gesamt / Toutes Polishing Electrolytic polishing Grinding Riveting Manual work/deburring Decoration Polishing (flat)/ lapping Electroplating Heat Treatment Stamping Pressing LIGA-method - electroforming Quality assurance x x Total of processes (Quantity of main process Number of parts Number of Transfers Number of Connections Number of in- and outputs OFD N=1 (OFD = N+P+T+C+2) OFD = 3N+P+T+C+I/O Complexity 1-6 Average durability in years elastic x x x x x 8.36 dynamic x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x Total of functional requirements Total of processes OFC=[e=9+d=6+s=3]*N Oil Fat epilamisied Average part-costs [CHF] Smm/Kei Manufactringweek Seite 19, IWC 2005

20 Complexity of Parts-families The production of wheels takes 11 different processes. The delivery times are accordingly long. It must be avoid to have two prototypeiterations with wheels. Smm/Kei Manufactringweek Seite 20, IWC 2005

21 Kilian Eisenegger Executive Director Technics IWC Schaffhausen, Baumgartenstrasse 15, 8200 Schaffhausen Smm/Kei Manufactringweek Seite 21, IWC 2005