Epdm /rubber injection molding

[Mxdan]

I was wondering if anyone could point me in the right direction. I'm trying to learn how to make a motorcycle grip like this

http://www.odigrips.com/half-wafflemotocrossgrips.aspx

I believe it would be epdm injection molded.

Im really not sure what style of machine would accommodate a grip or if epdm would be the best material for the job. Looking for the the smallest machine possible to easily accommodate.

Thank you in advanced, to the new newbie.

[Suhas]

Hi Mxdan,

There are several materials this can be molded out of. They are all injection molded. A regular conventional machine will be good enough. Mold design may bet a little tricky since these materials tend to 'stick' to the mold. Your best bet is to talk to a material supplier in your area - Polyone, GLS, etc and see what they recommend. They will probably even point to a molder in your area.

Hope this helps.

Suhas

[Mxdan]

So in your opinion what machine would you recommend to me. Wanting to do this as a hobby. So smallest footprint machine / bench top model. And or a good older machine that could be picked up cheep. Would the small hobby models just be a complete pain for this type of injecting.

Thanks again.

[rickbatey]

You will need to calculate the surface area, then use the 3-5 tons per square inch of surface to size the press. Then based on wallstock, approximate peak injection pressures and shot volume, to properly size the injection unit. You will need an air cooled chiller to keep the press and mold cooled. Then possibly a drier for the resin. You should get two vacuum loaders if you need the drier so you don't have to hand load the press and drier, material hose and a suction wand. Clamps, bolts and washers for the mold mounting and ejector rod(s). Hoses and fittings for the press and mold cooling. Mold release, cleaner and grease. A forklift, A frame, or small hoist to set the mold with. Nozzle tips and anti seize Then power to run it all.
I feel you may have to build the mold with hand loaded cores to get the price down. But gut feeling is around 100t or so press, but I don't know shot volume or surface area.
Rick.

[Mxdan]

This is most likely smaller than you think. It's under 5 inches long and I'm guessing about 20 square inches of mold surface area and approx 3 cubic inches for the shot. Of course this will be completely dependent on final mold design and grip pattern. Would I really need a hoist to lift this mold.

Just trying to get things straight.

So what brand / model of 100t presses would anyone personally suggest for me or other model if you think I need smaller or bigger.

Thanks again.

[ruhlj]

Hi Mxdan,
If you like expensive hobbies, you picked the right one!! Any owner of a plastic company will tell you it is a capital intensive investment. This is why many plastic companies run 24 hours a day, 5 to 7 days a week. If you were to go buy a good used 100 ton machine and all the auxilary equipment needed, you could spend $50,000 to $100,000 easily. You would then need a building that has 240 or 480 volts, 3 phase electricity, a means to get the mold in the molding machine, etc.

There are a lot of good molding machines, any USA, Europe, and Japanese machines are good. There are also plastic companies that will sample molds and run parts for you, this would probably be the best way to start.

[Mxdan]

Truth is maybe yes I like expensive hobbies. But seriously speaking I was hopping I could mold these grips as a hobby I don't mind doing one at a time or together in one mold. Individually would make a more manageable mold size and injection mold size.

100t is a big machine for me I was hopping I could do this on something much smaller like a 22t but the shot size on those machines seems to small and I'm not 100% sure I'm calculating shot size properly. That's why I was asking about machine size recommendations here. Not for production but just big enough to get the job done. A manual machine would be best.

I have a large building it would go in. It's actually used as a transport truck repair shop. I would just possibly need a three phase converter wired in to run the machine no big deal there. I have hoists jacks era for moving and placing everything. But I was really hoping that I could hove a mold I could pick up my self or with a friend.

So I guess I'm asking for a ball park on minimum machine size that one could use to mold a grip as a hobby and if you could ballpark a shot size so I know I'm looking in the right direction. Just your best guess so I have something to work from. The 22t boy is a great size machine but shot size on these seems to small.

Yes I could pay someone a good couple grand to make my mold and run what I need off but what's the fun in that.

Thanks again Dan.

[rickbatey]

Dan, I'm afraid you don't realize the amount of money your " hobby" will require. For your " Couple of grand", you may only get a few bags of resin!! "Shop" resins start around $3.00 per pound! I doubt you could purchase the clamping plates for your mold, for the money you're thinking.
Rick.

[Mxdan]

I dont mind buying a few grand of resin. It still leaves me wondering what the best molder a hobbiest would need to get the job done. And what would be the best smallest machine to use. Looking for mostly manual machine. No dryer no ejector, low volume is fine. Just looking for opinions on best older machines to get the job done. Low maint cost best run time strongest machine small footprint etc.

Clamping plates seem to be the easiest thing to make on the machine, I could probably whip a set together myself in a couple hours.

Well if anyone could look at the photo and recommend the smallest nicest easiest to work with manual older machine for me to make one grip at a time that would be great.

Thanks Dan

[ruhlj]

Hi Dan,
If you built a mold to make one part at a time, and if you laid the part horizonal in the mold you would have about 5 to 6 square inches of projected area. if you used 3 to 5 tons per inch, then you would need a machine size of somewhere in the 15 to 30 tons of clamp force. Your next step would be to get on the internet and look for used injection molding machines. Once you find something, come back and ask our opinions of that machine. I would also search the internet for companies that build pronto-type molds. They are the cheapest and could get you started.

A friend of mine tried to use a phase converter on a 15 ton machine, did not work, too much of a load.

Another point, a mold has to be built to close tolerances. Most plastics will flash in a .002 inch gap. Steel plates need to be ground flat, etc.

Good luck

[Mxdan]

Thanks guys it's been a big help. I'll do a little window shopping and try and nail down somthing that looks good. I'm going to try and have my mold done in cad so I'll have exact numbers to work with but my cad work is a little rusty.

Thanks again.

[moldingppm]

Dan,

For a mold like that, by the time it gets designed, built, polished and tested, you'll Be in it at least $30k just in the mold.
The machine, I just bought a 96 80t Demag for $25k. So you're at least going to be at (reasonably) $30k.
Resin is (when I bought TPE a few weeks ago) is about $4.50 /lb.
Your part is (let's say) 20 grams. At 1000 pcs you're at $200 in resin.

It seems to me you're going to be making these for a short run (under 100 pcs).
Please don't take me wrong but I have a feeling you don't 100% understand what amount of overhead you're looking at.

Not only do you have to purchase everything, but you also have to learn the actual molding process. You need to learn how the mold works, how injection pressures make a difference, how holding times and pressures for the holding can make sticking or short parts. There's so much more than just hanging it in a machine and going. Hell, I even have to change the setup when I reload it out of the machine. Even using regrind for some parts requires changes.

I'm not trying to be a douche, I'm just trying to give you a heads up on what you'll have going on. If you need anything else, let us know. We're here to help

[moldingppm]

CRAP. I didn't realize this thread is from October. Oh well.

[tomslack34]

I have never made a motorcycle grip, but after seeing all these posts, i think i can. Thanks guys for your wonderful tips.
________________________________
plastic injection molding companies (http://www.actionmold.com/)

[ronaldduck]

I would say you to get the training on injection molding to accomplish your task in a nice way.

[Edward Brooks]

Hello Everyone,
when you come to know about this rubber injection moulding please give me some idea I have no more information about it .. I also searched this techniques but I didn't successful..please help when you successful in rubber injection moulding..
Thanks..