Draw die radius
draw radius
The size of the draw die radius is one of the major factors affecting metal to draw properly. If the radius is too large, wrinkles will occur on the part. If the radius is too small, it will restrict the flow of the material and cause cracking to the part.
As a general rule, three ( 3 ) times the material thickness can be used for the starting point of the draw die radius. If the part cracked or showing evidence of splitting after drawn, the die radius can be enlarged further.
The table below is the general guide line extracted from some of the tool design books. We have tested it through some years, it work just fine with us. Readers may like to take it as reference for their tool design consideration.
Material Thickness ( inch ) Draw radius ( inch )
0.015-0.020 0.156 – 0.250
0.021-0.030 0.187 – 0.281
0.031-0.040 0.187 – 0.312
0.041-0.050 0.187 – 0.343
0.051-0.062 0.250 – 0.375
0.063-0.093 0.312 – 0.437
0.094-0.125 0.344 – 0.460
Hi, Any recommendations on the minimum punch radius
?
thanks for posting, this looks really useful
Dear Sir
Thanks for wise tool helping in the manner of some technical douts.
it is true that the die radius is one of the most crucial factor affecting the metal flow around die opening. The other crucial factor is punch radius. If the shell that you are drawing tears off at the top it’s due to smaller (than appropriate) punch radius.If the shell tears off at the flange portion (that is the bottom portion)of the shell it’s due to smaller (than appropriate) die radius.
However, all kinds of tear-offs can’t be attributed to inappropriate radii-sometimes when blank holder pressure is too great metal flow is arrested leading to progressive thinning of metal and consequent failure in the form of tear-off. The table certainly is a great help in minimizing trials.
Thanks for sharing very valuable piece of information.
Hello Girish
Thank You very much for your valued information and comment.
Would you able to contribute some articles to our blog?
Dear wisetool
Thanks for giving me an opportunity to contribute. Yes, sure.I would want to contribute in a meaningful way.