Has anyone ever heard of heating the platens on horizontal injection molding machines? How do you do it, and what is it supposed to help with?

Hello Nick, Normaly with thermoset material you have to heat the platen, but als with high temperatures on thermoplastics it will do the job.
I have used drilled holes in the platten with a standard oilheater. This was supplied by the machine supplier. Als we have used seperate platen with induction coils build in it. That was the best solution. Als clean and very strong. And efficién.

Heating the platen will cause expansion of the steel and will stress the wear points on the tiebars. You are better off to insulate the platen and use the mold or a subplate for heat. The closer the heat or cool is to your product, the more efficient it is. The platen and tiebars are a substantial area of heat loss just like a radiator.

Thanks for the responses.

Hello yes i have seen it done mainly on thermoset presses it does help and if your running a thermoplastic material with hot sprues and magnetic platens this could also work to help prevent freeze off

i dont think it is so much as heating the platens as to keep them from getting to hot mainly for thermoset insulating the molds will help but to run any kind of high heat in the platens i agree with Jim it may cause more trouble than you want

Hello: I don't why somebody needs to heating the plates. Normally only gets mechanical problems. Usually, we need to cool the plates for protect them. The best is insulate between mould and plate. You reduces the mould heating costs, and the mould temp is more stable . In Our machines with durolpastic ( baquelite ) the plates are cooled.

You would probably use electric cartridge heaters, that are slipped into heater holes drilled into the platen.
We are Thermoset Composite molders and platens are sometimes heated to help heat soak the molds. However, this can cause problems with the molding machine as the platen bearings expand. Normally we insulate our molds to minimize heat transfer into the molding machine platens. Most thermoset molds are heated to between 310 and 375 F