Thanks for the input! The material is to be maintained at 350F. I like the compressed air idea, but would this be easy to controll small predictable amounts? Most of the molds I use are open molds that the plastic is hand poured into in up to three passes, each pass consisting of a different color and amount (cavity size is typically the size of a ink pen). The method of pouring/injecting must pour slowly as to not splatter in the open faced molds.
Also, the plastic I use sets up really fast, within 30 seconds in a ink pen sized cavity it is already solid enough to remove, though not good as it is still hot enough to damage quality. I am looking at a heating device to keep the molds warm long enough to make 3 passes on 30 or so cavities, I may still have to keep it down to just a handfull at a time.
My thoughts are to have 3 stepper contolled pump, screw, air (or whatever will work on a budget) driven dispense nozzles, each pouring a different color. These could all be mounted on the would be "z axis" of the Gantry style CNC machine, and controlled via G-code (offsetting each by the distance of the nozzle(s) in front of it). Each pass would dispense different quantities of plastic, in possibly different locations of the mold.
I would have to purge the lines after the entire run is completed, which I am still scratching my head about, but I like your idea of compressed air to do that.
Originally Posted by Evodyne There are different electrical heat tapes available, but what range of temperatures you can expect I don't know.
Another thought would be a steam trace-steam has a lot of heat-5 times more than water at 212 degrees! |
The "hoppers" in this system will be similar to crockpots with temp controll and a line to the pump from the bottom and from the pump it would travel up to 5' (probably closer to 3') to it's final destination in the mold. Would I need something like the steam trace for keeping the plastic at 350F or would the heat tapes work (where to find electrical heat tapes?).
Thanks again for all your wisdom (and please keep it comin!)