Posted by Jamie on August 26, 1999 at 14:19:47:
We manufacture and repair plastic injection molds. I have a customer that is currently having TREMENDOUS problems with a series of molds that were originaly constructed in Portugal. This customer purchases their molds from several different sources and countries worldwide. The molds that were constructed in Portugal have 420 stainless steel inserts that are heat treated to 46-48rc. These are very high production molds and are overbuilt and over engineered accordingly. (I think they should last longer than a lifetime by the degree of over engineering and massive amounts of extra steel cross section used in these molds.)
The problem with these molds stems from the stainless steel inserts cracking while in production. I currently have an insert here that is approximately 8 in. x 10in. x 16in. and it has a crack that runs approx. 60% through it. It really is amazing to see steel crack this way. It is something I rarely encounter and I've been in this industry for 25 yrs. All off these Portugese molds seem to have the same problem!
I know this might be a bad batch of steel or just might be incorrectly heat treated, but its a little too late to do anything about that now. What I would like to do is stop this cracking problem if possible.
My questions for you:
1. How much if any would these inserts warp or move after being stress relieved using your process? (these are finished molds)
2. Do you think your process would help in this situation?
3. Do you think the stainless steel may be building up thermal stresses while in production? (hot plastic being injected at 400deg.F and these inserts being cooled by water at approx. 65deg.F)
4. Will your process eliminate or reduce the chances of buiding up thermal stress in these inserts after your process?
This problem is costing my customer major bucks!
This one insert I am referring to weighs approx. 350 lbs. Do you give tonnage discounts?
Thanks,
Jamie