Anyone have an injection molding or similar technology point of contact?

[whysman]

I have a plastic part that I am looking to have produced. Tolerances and finish can be somewhat forgiving but each part is approx 8” long and 1” wide, so not exactly conducive to a gang mold. Not sure how many I would want to make (depends on cost) but probably anywhere between 1,000-5,000.

I’ve done some rudimentary internet searching, but wanted to see if anyone here had any leads.

I have 3D printed prototypes of the part, but using a 3D printer to make these parts is not very efficient (takes 3-4 hours to make each part).

 

[LarryDScott]

If your not familiar with the cost of having a mold made,
your in for a shock. I priced one for a shooting table top,
it was 25K. Not only pricy but big. It takes an overhead crane to load the molds into the injection machine. LDS

 

[whysman]

If your not familiar with the cost of having a mold made,
your in for a shock. I priced one for a shooting table top,
it was 25K. Not only pricy but big. It takes an overhead crane to load the molds into the injection machine. LDS

Yeah,....actually I was aware. The little research that I did discussed using aluminum or some other composite materials for the mold that significantly reduces the cost. These applications were for lower volume parts with tolerances that are a little less precise that what a SS mold would produce

 

[ireload2]

Depending on the material being molded, tolerances and quantity molded there are several different mold classes you can buy.
They run from something like an aluminum prototype mold, a soft steel insert mold or fully hardened inserts.
There is little point in buying a mold capable of 250,000 parts if you only need 1000.

Check out mold classifications here.

http://www.cjindustries.com/injection-molding-resource/spi-mold-classification

Down load the guide lines here.

http://www.craftechcorp.com/injection-moldmaking/spi-mold-standards

It has been a long time since I had a batch of molds built but I can still remember some of the lessons learned.

1. Know your part design so you under stand where they can put the gates and runners.
2. Don't buy an excessively expensive mold.
3. Make sure the mold builders are real pros that stand behind their work.
4. My employer had the molding machine so we were stuck with the warp, twist and shrinkage that resulted.
5. It is better to pay the molding company to acquire the mold many times. If they buy or make the mold they are totally responsible for meeting your part drawings. If you buy the mold and take it to the molder the 2 companies can blame each other if the parts are bad.

Send me a PM if you have more questions.

I have a plastic part that I am looking to have produced. Tolerances and finish can be somewhat forgiving but each part is approx 8” long and 1” wide, so not exactly conducive to a gang mold. Not sure how many I would want to make (depends on cost) but probably anywhere between 1,000-5,000.

I’ve done some rudimentary internet searching, but wanted to see if anyone here had any leads.

I have 3D printed prototypes of the part, but using a 3D printer to make these parts is not very efficient (takes 3-4 hours to make each part).

 

[TRA]

With part runs of 1-5000, if you cannot make your own molds the price per part will shock you. You could find ~ 10.00 each to be close in some cases. FYI, molded parts don't always result with parts to be to spec. I've seen molds requiring rework numerous times. If the part is machined with a mill the difference in mold materials may be not that far apart. If it has to be EDM'ed, different story. OH, you will also have to find someone willing to make such a small run of parts. It's not a simple process.

I'm sure your part does not relate to the above but be prepared to really want those parts. Good luck

 

[Rick300]

I occasionally do work for these guys. They are good people, have a really nice facility, and appear to do quality work from what I have seen.
http://eldoradomolds.com/HTML/Contact.html

 

[sean68]

I have been a project engineer, industrial engineer and tooling engineer in the plastic injection molding industry making parts for all the major auto manufacturers for the last 27 years. There are a lot of things to consider and there is good advice in the other posts. I will try to give some advice without making this the worlds longest internet post.

First off, the volume you are contemplating is very low for injection molding putting you squarely into needing an aluminum mold that most would consider a prototype mold. You will have to buy and be the owner of this mold. Aluminum molds are far cheaper than even soft steel prototype molds if you go to a place that specializes in it. If you try to use a tool shop that is more into building hardened steel production molds you will not see as much of a savings using aluminum.

I would suggest using a tool shop that has a few injection molding machines in house that they use for mold debug and small production/prototype runs. That will eliminate the need to work with more than one place and you will not have arguments between mold builder and molder if there are issues that arise.

Be very careful to make sure your part is designed for plastic. Uniform wall thickness, use of ribs, etc. The best money spent in the project is to buy a book or do a bunch of reading about how to design a part to be made by injection molding. You can't take a steel part design and just make it out of plastic. The mold shop should be able to help you with this somewhat. You can have them run a mold flow analysis on your part design and this can predict warp, sink, stress risers etc to make sure you part design is good.

Give some thought to the type of plastic you want to use. There is a huge range of price and performance in plastic types. Properties like resistance to chemicals can range from awesome to almost non-existent. Be aware that plastic shrinks as it cools and your mold will have to be made to a specific shrinkage rate to get the dimensions you want. If you want to change to a different type of plastic, you can only do that if you choose another one with a shrinkage rate close enough to meet your required dimensions.

I have a bunch of companies that I work with that can do all of this and will not care how small the run is. You will pay a set up fee for them to put the mold in the press and a price for each part. The more parts you ask them to run at a time spreads out the cost of the set up fee. I can send you a PM with some leads if you want. It won't be cheap!

 

[AndyA]

Protolabs.com

I spent a lot of time making and designing molds. Mostly making. If you want any help with part design to make your mold as simple as possible, let me know.

 

[Toolbreaker]

Steve,

Sean in the above post gives some good food for thought on the up-front side of molding (especially using AL cavities/direct cavity bases for such a short run). You're in a bit of a tough spot with the volumes that you stated. Were I doing this, I'd have a sit-down with an applications engineer versed in plastics about suitable materials, and see if machining from solid might be viable. If the material that you're contemplating using, along with the part's geometry is conductive to machining vs. molding, then milling may be a faster and less-costly approach.

P.S. There's an injection shop (non-affiliated) about 6 hours north of you that I can PM contact info on, if you'd like. They do good work and in-house tooling, but they are an injection shop, so they most likely will try to steer you in that direction.

 

[whysman]

Guys-
Thanks a lot for all the responses! I greatly appreciate all the insight!

 

[Jason Travitz]

I have a plastic part that I am looking to have produced. Tolerances and finish can be somewhat forgiving but each part is approx 8” long and 1” wide, so not exactly conducive to a gang mold. Not sure how many I would want to make (depends on cost) but probably anywhere between 1,000-5,000.

I’ve done some rudimentary internet searching, but wanted to see if anyone here had any leads.

I have 3D printed prototypes of the part, but using a 3D printer to make these parts is not very efficient (takes 3-4 hours to make each part).

As previous posts stated the cost varies depending on the mold cost, plastic material selected and cycle time / press size. You can PM if you are looking for a turnkey solution - the company that I work for frequently works with individual and companies to design/tool/mold low quantities of parts for an idea they have. Good luck with your endeavor!