Yesterday I had a customer request I add springs to a mold at the last minute. (Literally at the last minute I had just sent him a screen shot of the cut simulation and was getting ready to take it to the machine.)
Other than the irritation and disruption of last minute changes on fully approved designs I'm not against doing it, but I don't think I've seen that before. Now, I am not talking about ejector pins. I am familiar with them, although the types of molds I make don't make use of them He was talking about springs to help open the mold. I can't think about how I would do it, but I'm not sure its really of any use. Most hand injected or hand poured molds are just easily pried apart. For most of what I do the media doesn't not have any significant bond to the mold material and a release agent is not even used. Sure for some resins a release agent is used, but again the mold opens fairly easily.
I don't think I'd use springs in any automated operation either. The molds halves are just attached to the platens (?) of the hydraulic press portion of the injection machine. Hydraulic pressure pushes them together and hydraulic pressure pulls them apart. What purpose would springs serve?
I explained that adding a new feature at the last minute would delay his order and increase the cost. I also asked him if he had seen that before and how it was used. He decided to go with the original design, never answered if he had seen that before, but he did specify he wanted that on future molds. Ok... more money for me I guess.
Have any of you seen a mold with springs built in to assist with opening the mold? I visualize them in the types of molds I make and I just see them being an encumbrance.