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Cold forging Process and Product Development - Case study


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Cold forging, Head type Valve Tappet
Process improvement, reduction in rejection and waste by right engineering

Published in: Engineering

Cold forging Process and Product Development - Case study

  1. 1. Process and Product Development Valve Tappet Cold forging Process Abdullah Ansari
  2. 2. INDEX • Introduction • Nature of Problem • Existing Blank & Forging Die Analysis • Cold Forging Standard • Existing D2/d2 & l/d Ratios • Corrective Actions • Recalculations, Results Of Recalculations • Trials & Decisions • Previous Process & Revised Process • Results with Revised Tooling & Conlusion • Support During Development
  3. 3. INTRODUCTION  The problem of head offsetting while cold forging of item R 708‐13 is observed in since new product development.  To avoid the same several corrective actions [short method] were initiated such as using flat ejector etc. but effectiveness of the actions taken was not 100% satisfactory. The results were not consistent.  After all above it is concluded to analyze and re‐design of cold forging tooling & process.  While analyzing the same whatever the calculations, observations and the actions taken by undersigned are recorded here, which will be one guide line to attend this kind of problems in future. A. T. ANASRI Date : 22.08.2000
  4. 4. Nature of Problem ( Tappet R 708‐13 ) While cold forging 1st stage Head Diameter of Tappet getting more offsets & not getting controlled after several adjustments.
  5. 5. Existing Blank & Forging Die analysis • .Size of Cold forging blank: Total Length = 85mm Outer diameter ( d ) = 12.5mm • .Size of cold forged part: Head diameter ( D ) = 30mm Head thickness = 5.5mm Total length = 61mm OD of stem = 12.8 & 12.6mm • .Size of Cold forging Die: Length of die = 90mm Length of blank outside the die ( l ) = 30mm ( From flat face )
  6. 6. Cold forging standard Cold forging standard states that: D2/d2 and l/d should not exceed 3. Where 2 is ideal. In our case D = 30mm d = 12.5mm l = 30mm
  7. 7. In light of Cold Forging Standard Existing D2/d2 & l/d ratios D2/d2 = 302/12.52 = 5.76 l/d = 30/12.5 = 2.40  By above calculations it is noticed that value D2/d2 is exceeding the standard and l/d is almost in range.  So we may conclude that above exceeding value is affecting to forged head diameter offsetting.
  8. 8. What to do now ???  Corrective action planned : – Recalculate the die design as per cold forging standard. And manufacture the cold forging die as per new calculated dimensions.
  9. 9. Recalculations as per Cold forging standard D2/d2 = 2 ( as per standard ) Hence D2/12.52 = 2 D2 = 2 x 12.52 D = 17.67mm. ‘l’ of ‘D’ will be 17.67x17.67x l x /4 = 12.5x12.5x30x /4 l = 15.01mm
  10. 10. What Recalculations Indicating!!! Recalculations indicating that the forging is not possible in one operation & it will need double operation. For second operation stepped blank will be required, while first operation stepped blank will be produced. For preparing stepped blank separate die is required
  11. 11. Trials . For trials stepped blank is prepared by machining. While trials forming punch is used. Trials are taken with stepped blank on 22.08.2000 Results found satisfactory in all aspects. Head offsetting is very low & will not create any defect while head turning. Dimensions are found consistent. Trials are successful.
  12. 12. Way Forward. Based on successful trials, die designed for first operation for preparing the stepped blank (cold forging 1st operation).
  13. 13. # PREVIOUS PROCESS  Fig. Shows the blank ready for forging of R708‐ 13 tappet. 85 12.5
  14. 14. 1 ‐ PREVIOUS PROCESS  Fig. Shows the forging drawing of R708‐13 tappet.  Previously this was created in single setting. 30 12.8 5 40 12.6
  15. 15. # REVISED PROCESS Fig. Shows the blank ready for producing stepped blank for forging of R708‐13 tappet. 85 12.5
  16. 16. 1 ‐ REVISED PROCESS Fig. Shows the stepped blank ready for finish forging of R708‐13 tappet. 12.6 12.5 40 15 17.7
  17. 17. 30 12.8 5 40 12.6 2 ‐ REVISED PROCESS  Fig. Shows the finish forging of R708‐13 tappet.  Now it is created in second stage from stepped blank.
  18. 18. Die drawing for stepped Blank
  19. 19. Results with revised tooling. Implemented the new tooling & monitored for 1000nos for cold forging 1st & 2nd operation. No problem while preparing stepped blank. I.e. 1st operation. No problem of head forming while 2nd operation. Improved consistency in dimensions while cold forging 2nd stage. Setting time for cold forging is reduced. Minimizes rejection at cold forging drastically . Hence reduction in wastage.
  20. 20. FINAL CONCLUSION. The newly designed tooling is OK & Proven for production. 05.11.2000
  21. 21. Acknowledgements Mr. V Ramgopal Mr. M. GANAPATHY For Giving A Opportunity To Work On Such A Special Task. Mr. S.C.SALVI & Mr. P.S.KULKARNI Team members
  22. 22. Thank You