EngMark
Automotive
- Jan 4, 2008
- 46
I have a need to make a 24/410 polypropylene bottle caps with a unique external shape. Money is short and time is more plentiful. I know that bottle caps are most often made in 30+ cavity molds running short cycle times. I'd be happy to get one cycle per minute or two from four cavities with a full time operator to start at least. I've previously made 300+ caps by pour casting two part urethane into a silicone mold then finishing with three machining operations - a *lot* of work, 1000 mixing cups, and not a class A surface finish. I have a Morgan prototype press and a 3 axis CNC on which I could create the cavit(y/ies). I have trouble with the threaded mold core because a) While basic dimensions are readily available I can't find the detailed dimensions needed to actually design a working mold core. b) This is very specialized (but common) geometry that I don't know how to draft properly. c) machining / grinding such a core would be very difficult on the equipment available to me.
Questions / Needs:
- I can probably use and design around any existing 24/410 mold cores which I assume are fairly common in the right circles. Where could I obtain these? Are they so common that they are shelf items in the way that ejector pins are? (one inquiry I made says no) If so, who do I need to order from? I'm thinking $500 or less. Reasonable?
- Where is there a 'mold junkyard' that I might be able to find usable used 24/410 cores at? There should be lots of them out there somewhere given the commonality of this thread form and cavitation.
- Does anyone have CAD geometry they can share with me if I end up having to make my own (even if its a different size so I can figure out the draft scheme?
Bonus questions:
- What would you think of making a core from JB Weld by casting the JB Weld into an existing cap, said cap having its cavity extended by means of a concentric cylindrical addition? JB weld seems to handle high temperatures. 1000 shots of polypropylene?
- Where can I buy small lots (say, 50 lb at a time) of polypropylene resin pre-colored to a particular Pantone color (or how would I go about pigmenting it myself in a manner that would be consistent from part to part and batch to batch)?
Thanks,
Mark
Questions / Needs:
- I can probably use and design around any existing 24/410 mold cores which I assume are fairly common in the right circles. Where could I obtain these? Are they so common that they are shelf items in the way that ejector pins are? (one inquiry I made says no) If so, who do I need to order from? I'm thinking $500 or less. Reasonable?
- Where is there a 'mold junkyard' that I might be able to find usable used 24/410 cores at? There should be lots of them out there somewhere given the commonality of this thread form and cavitation.
- Does anyone have CAD geometry they can share with me if I end up having to make my own (even if its a different size so I can figure out the draft scheme?
Bonus questions:
- What would you think of making a core from JB Weld by casting the JB Weld into an existing cap, said cap having its cavity extended by means of a concentric cylindrical addition? JB weld seems to handle high temperatures. 1000 shots of polypropylene?
- Where can I buy small lots (say, 50 lb at a time) of polypropylene resin pre-colored to a particular Pantone color (or how would I go about pigmenting it myself in a manner that would be consistent from part to part and batch to batch)?
Thanks,
Mark