The document discusses redesigning the cold forging process and tooling for producing a valve tappet part. The original single-stage process resulted in inconsistent and excessive head offsetting. Analyzing the process found the D2/d2 and l/d ratios exceeded standards. Recalculations determined a two-stage process with an intermediate stepped blank was needed. Trials with new tooling produced satisfactory results with low, consistent head offsetting. Implementation of the redesigned two-stage process and tooling solved the issues, improved dimensions consistency, reduced setup time and waste.

1. Process and Product
Development
Valve Tappet Cold forging Process
Abdullah Ansari

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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Way Forward.
Based on successful trials, die
designed for first operation for
preparing the stepped blank
(cold forging 1st operation).

13. # PREVIOUS PROCESS
 Fig. Shows the
blank ready for
forging of R708‐
13 tappet.
85
12.5

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. # REVISED PROCESS
Fig. Shows the
blank ready for
producing
stepped blank
for forging of
R708‐13 tappet.
85
12.5

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. 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. Die drawing for stepped Blank

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. FINAL CONCLUSION.
The newly designed
tooling is OK & Proven
for production.
05.11.2000

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. Thank You
abdullahta@gmail.com