Work Process Analysis of 4-170 Pizoelectric accelerometer at CECVP Project Writeup RESUME VERSION
- 1. 1 Work Process Analysis and Improvement of 4-170 Piezoelectric Accelerometer at CEC Vibration Products in Covina, CA By: Joey Uken, Gilbert Sun, Dariusz(Darek) Tyrawa, Clint Stark, Isaac Hwang See Appendix R for Project teams resumes Project Completed for Cal Poly Pomona Work Analysis Class IME 224 IME 224 Professor: Luiz Armendariz See Appendix R for Luiz Armendariz resume February 25, 2015
- 2. 2 Statement of Disclaimer This engineering work analysis project is the result of a class assignment that was graded and accepted in fulfillment of a Cal Poly Pomona IME 224 class. Acceptance does not imply any technical accuracy or reliability of the material included in this report. Any use of this information or material is done at the user’s risk. Neither California State Polytechnic University, Pomona, nor its faculty are liable for any problems or damages that result from the use of any material contained in the report. Acknowledgement We would like to thank CEC Vibration Products employees Thomas Wong and Jeff Copeland for allowing us access to the facility and answering any questions we had; both critical to the success of this project. We would also like to apologize for any inconvenience we may have created during the course of data collection or question gathering.
- 3. 3 Product Description of 4-170 Piezoelectric Accelerometer
- 4. 4 Performance specifications of 4-170 Piezoelectric Accelerometer
- 5. 5 Abstract: CEC Vibration Products in Covina, CA has been working on the 4-170 piezoelectric accelerometer design for at least the last 20 years. Features of this piezoelectric accelerometer includes self generated (no external power), balanced differential output, and operates in high temperatures up to +500 degreees Farenheit. Applications for Piezoelectric Accelerometer include gas turbine engine monitoring, ground testing, APU testing and compressor/gear box monitoring. The main objective for this project was to analyze the entire work process of the 4-170 piezoelectric accelerometer and provide suggestions to improve the process. However since CECVP can’t really change their work stations of welding and nonesuch we focused primarily on the shim stack assembly where CECVP could actually change the work stations in order to improve the work process. Numbered below is a brief summary of some of the items that we accomplished in order to provide a meaningful work process analysis. 1. Created a work process flow chart 2. Created a floor plan of the current setup of the work stations for this work process 3. Created work instructions for the process that show the flow of product and people 4. Video taped the process and used protime and excel to analyze the data collected 5. Analyzed non-value added and value added parts of the operation in order to reduce the cycle time of the entire work process. 6. Classified every work element as Internal or External so that we could use SMED to reduce setup time to improve the run time of the various operations in the process 7. Determined the Labor Productivity Index. 8. Made Pareto Chart in order to determine number of inspections needed after various steps 9. Safety standards practiced by CECVP is ISO 9000 and AS 9100. This simple representation is helpful in understanding how a piezoelectric accelerometer works In this picture the piezoelectric accelerometer is actively vibrating.
- 6. 6 Brief Summary of Work Instructions: Materials needed for work process Floor plan of the work stations for our work process
- 7. 7 Work Station (A) (Work elements 1 -3) During this station we cut 3 shims out of the shim sheet, two of which are connected with two wires. Spot Welding Station (B) (Work elements 4 -6) This is our spot-weld station here we will weld stainless steel wire right on the edge of the shims.
- 8. 8 Work Station (A) (Work elements 7 -13) 1) We are coming back to our work station where we place one of the connected shims with welded wire on 10 pico-coulomb stack. Then we place first crystal with positive charge facing down. 2) Then we place the single shim with welded wire over the first crystal making sure wires are not crossing over. Then place the second crystal with positive charge facing upwards. 3) fold the second of the two connected shims over the entire pile. Chemical Storage Area D (Work elements 14-15): Now we are going to chemical storage area to spray glue on the two insulators. Now we going back to our work stations.
- 9. 9 Work Station (A) (Work elements 16-24) 1. Place the insulator on central shaft. 2. Transfer the Pile on central shaft. 3. Place the tungsten weight 4. Place the second insulator, , central piece, nut bolt. 5. After this we inspect the assembly and tighten the nuts. 6. Check for any crystal and shim for proper alignment, wire should not touch each other
- 10. 10 Testing Station (C) (Work elements 26) During this station test the stack to make sure there are no 1. broken crystals 2. missing insulators 3. upside-down flipped crystals Assembly of Part B and A: Below is the second portion of the work process. During this process we will be attaching the previously assembled part A inside of part B.
- 11. 11 Work Station (A) (Work elements 27 -31) 1) Take the two wires and start positioning them inside the two pins of the connector. 2) Slowly keep pulling the wires, while placing the stack in the connector. 3) Make sure that the wires don’t touch each other. 4) Cut off the extra wire. Brazing/Welding Station (J) (Work elements 32-34):We now walk to braze welding station because after cutting off extra wires it is required to apply brazing on top of the pins. Water Welding Station (E) (Work elements 35-38):Then we walk to water welding Dremel Station (F) (Work elements 39-41):After water welding we go to the Dremel station. This is important to remove hard edges.
- 12. 12 EB Welding Station (T) (Work elements 42-44) Now we using E.B welding machine to weld the bottom of the assembled part. Testing Station (C) (Work elements 45-46) Inspection of the assembly part. Arc Welding Station (G) (Work elements 46-49):At the Arc welding station we are tacking the nut EB Welding Station (T) (Work elements 50-52): At the E.B welding station we are welding the top part of the assembly Testing Station (C) (Work elements 53): We now do final inspection of the assembled parts. Etching Station X (Work elements 54-56):Walk to the Etching station for engraving information.
- 13. 13 Precedence Chart for entire work process: Data: See Appendix D for Raw Data in the form of a work process chart Calculations: **See appendix G for general formulas of all calculations shown. 1. Labor Productivity Index (LPI) = P(new)/P(baseline) = (1/60)/(1/30) = .5 or 50% 2. Work Process Chart has the total cycle times 3. Percent Cycle Efficiency of the entire work process (%PCE) %PCE = VA / (VA+NVA) = 1159/(1159+4068) = .221= 22.1% 4. Baseline for the shim stack is 1 every 60 seconds if there are 5 stations each with a max of 30 seconds and the cycle time of the shim/stack is 207 then the balance delay = ((Max station time * Stations) - cycle time) / (Max station time * Stations) = ((30*5)- 207)/(30*5) = .38 or 38% Input Data not in work process chart 1. Rough annual demand of 1000 units per year 2. material cost per part is $396 3. labor cost is $12.80 per hour
- 14. 14 Protime Calculations: Batch Internal/External Seconds 1. Cycle Time (Tc)=715.38 mins, 2. Standard Time (Tstd)=822.68mins 3. labor cost/unit=$175.51 Protime Calculations:Batch Value Added /Non Value Added Seconds 1. Cycle Time (Tc)=753.43 mins, 2. Standard Time (Tstd)=866.44mins 3. labor cost/unit=$184.84
- 15. 15 Shim Stack Assembly Line Balancing Calculations:
- 16. 16 Analysis: **See Appendix G for general concepts of work process analysis Using External(EXT)/Internal(INT) classification: Classify every work element as internal or external so that SMED can be used to reduce setup time which in turn will improve the run time of various operation in the work process. Using Value Added (VA) and Non-Value Added (NVA) classification: Classify every work element as NVA or VA. Then try to reduce the Non Valued Added parts of the work process in order to reduce the cycle time of the entire work process.
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- 19. 19 Recommendations continued: Tools to use for improvement: 1) Cause and Effect Diagram- Use this in order to determine the cause of various problems with the process.
- 20. 20 2) Takt Time Chart- Use this in order to determine the takt time needed in order to achieve a particular demand. 3) Production Rate Chart- Use this in order to determine the production rate needed in order to achieve a particular demand. 4) Defects Diagram- Use this after the cause and effect diagram is made.
- 21. 21 5) Pareto Chart- Use pareto excel file to create a pareto chart in order to determine the number of inspections needed after various work elements.
- 22. 22 Items provided to CECVP in soft copy folder: 1. A Cause and Effect diagram 2. Information about predetermined motion time systems, Therblgs, MOST, General formulas, SMED, and lean production 3. A diagram displaying visualy where the defects are most likely to appear on the part 4. A pareto chart that just needs information put into it to display a histogram of problems 5. Explanations on how to use the preto chart 6. A picture and layout of an efficient work station Appendix D: Raw Data
- 23. 23 Appendix G: General formulas and concepts used to make Calculations and Analysis 1) Labor Productivity Index (LPI) Labor Productivity=P P=Output/Input Labor Productivity Index=LPI LPI=Pnew/Pbaseline Ex1) LPI=1.5= increase in productivity of 5O% Ex2) LPI=.5=Decrease in productivity of 5O% 2) Cycle Time (Tc) Tc=Tn/Pw or Tn=Tc*Pw Tc=Time*Pw/Demand, Tn=normal time, Tc=Actual time Tc=Cycle Time, Pw=worker pace Ex1) Find: Tn Given: Worker is working at 11O% for 5 sec Tc=5 sec,Pw=11O% Tn=Tc*Pw=5*1.1= >>>Tn=5.5sec<<< Ex2)Given:Route walked=1.85mi Time To complete=3Omin Benchmark of normal Performance=3mi/hr Find:a) how long @ Normal performance. b)mans performance when completion tim=3Omin solutions: a)1.85*(1hr/3mi) *3Omin/hr=37min b)method 1 Tc=Tn/PwPw=Tn/Tc Pw=37/3O=1.233 Method 2 V=1.85mi/.5hr =3.7mi/hr 3.7mi/hr*1hr/3mi Pw=1.233 123.33% Pw 3) Standard Time (Tstd) Tstd=Tn(1+PFD) or Tstd=Tc*Pw(1+PFD) Tstd=standard time=allowed time, Tn=normal time Tc=cycle time, Pw worker pace 15%PFD time is Standard 4)
- 24. 24 5) PFD’s PFD’s P=personal time Ex)bathroom breaks Phone calls F=fatigue Ex)rest breaks Used to reduceFatigue D=Delays Ex)interruptions, Equipment Breakdowns 15%PFD time is standard 6) Standard Hours(Hstd) Hstd=Q*Tstd Hstd=standard hrs = work actually accomplishd (hrs) Q=quantity ofwork units(pc) Tstd=standard time=Allowed time per Work unit(hr/pc) 7) Worker efficiency (Ew) Ew=Hstd/Hsh Ew=worker efficiency (normally in%) Hsh=#of shft hrs (hrs) Hstd=#of standard hours of work accomplished during shift (hrs) 8) percent cycle efficiency (PCE) %PCE=%VA= %PCE=VA/(VA+NVA) PCE=percentage cycle efficiency VA=value added NVA=Non-val added Value added(3F’s)means it modifies 1)Fit 2)Form 3)Function Ex)O=2Omin Trngl=1OOmin D=1Omin,=1Omin O=VA,trngl,D=NVA %VA=2O/15O=15% O=VA, Sqr,trngl,D,=NVA
- 25. 25 9) SYMBOLS O-operation Procesng matrl Square=inspection Chk for quantity or quality(sqr) =move-transport Of material D=delay-material Waiting to be Processed Triangle=storage-material kept in Protected spot 10) One Best Method (OBM) OBM-One Best Method Princple 1bst method that Minimizes time and Effort. *Main Objective in work Design is determinea one best method and standardize its use. *always try to reducelearning Curve of workers 11) Bottleneck (BTLNK) Bottleneck=slowest operation in the sequence 12) Single Piece Flow (SPF) SPF=single pieceFlow Sngle pc flow is preferable to batch processing *2main problems with batch processing 1)set up changeovers between batches 2)work-in-process=Multiple batches Competing for same Equipment. Ex)queues form in front of equipment resulting in large inventories 13) Work Cell Work cell=a gourp of workstations *u-shaped work cells are preferred cuz better communication among workers.
- 26. 26 14) Largest Canidate Rule (LCR) Largest Canidate Rule (LCR) = Minimize the time difference between work elementsor work stations. Ex)S1=1,S2=.81 S3=.98,S4=59, S5=.62 the bottlneck=S1. However according to LCR combine S4 and S5 operations and make that the new bottlneck 15) TAKT Time Takt time=Time availble/demand (hrs/pcs) Rp=Demand/time availble(pcs/hr) Rp=hourly production rate Tc in this is Tc=Time available*Pw/Demand 16) Balance Delay balance delay=d=(At-ΣTc)/At At=A*#of stations A=allowble time per station ΣTc=total of all Tc Tc=cycle time 17) Production Rate (RP) RP= Hstd/Tc RP=Daily Production rate Hstd=Standard Hours Tc=Cycle Time 18) SUM Tc ΣTc or ΣTe is Work content Time
- 27. 27 Safety Standards Currently Used by CECVP