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r/manufacturing•
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Small run 2-part urethane RIM production insourcing

We outsource several urethane elastomer parts to China. Typically 70-90 durometer, black. Quantity is typically 300-1000pcs per month of each part. They charge us about $1.50usd and the parts are about 20-50 grams each (I'd have to confirm this)

Does anyone have experience doing this molding in their shop? I see rim presses on alibaba. I'm a die maker myself or we could outsource the molds to China.

Looking to reduce costs and lead time. And provide more control over design changes and general quality. But maybe it's not economical after buying the machines and tools, given our low production. I don't even know where to get the raw materials or their cost.

I presume we need the press machine to open and close the mold, we need the 2-component mixing system for the urethane, and injection system. And we need the molds. Am i missing something?

Any thoughts would be appreciated.

Posted Sep 13, 2020, 1:44 PM UTC

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space-magic-ooo•

Is this something that could be injection molded out of a TPE/TPU?

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DeleteFromUsersOP•

Injection molding (high pressure) is an even more involved process with more expensive tools and machines. We wouldn't want to invite further cost and complexity.

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a_pope_called_spiro•

Tooling costs would go up, sure. But part price would come down dramatically. Quality would also be better, and a lot more consistent.

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DeleteFromUsersOP•

Tooling would go up considerably. Urethane molds are about $2k while injection molds are $10k+. And the machines are larger and more expensive. Remember, we're only making between 3500 and 12k pieces per year so the amortization for each part would jump dramatically.

Also we don't have molding experience so the curve would be even greater for a complex process like injection molding.

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oliveoyl_or_butter•

The teams to maintain .

Cant you machines the parts yourself? or get quotes for it?

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DeleteFromUsersOP•

Elastomers are pretty much impossible to machine on a production basis. Our main business is lights out cnc turning of plastics, brass, and aluminum. Rubber is pretty much not possible to machine on a production basis and really fussy on a single part basis (liquid nitrogen, fixturing, ultra sharp cutters, etc)

These molded components do not lend themselves to production machining anyhow.

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citrus_based_arson•

I too am curious about where to buy the equipment.

Cost wise I don’t see how you’d compete. Consider the fact that you’d have the same manual steps as they do (unloading the machine/injecting/etc....) and then consider how much lower their labor rate is, even for the most menial task.

You’d save a little bit in shipping cost but at those volumes/weights It’s not much.

If however, R&D speed, iteration and IP concerns matters to you then it’s certainly worth investigating.

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DeleteFromUsersOP•

Do you know the price of rim raw materials? That would have a tremendous effect on cost competitiveness.

We're actually FAR more competitive on lights out CNC machining with 5-8 axis lathes than any Chinese machine shop. That's just the nature of insourcing.

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citrus_based_arson•

Right, on a high knowledge process requiring high end machinery.

You said it yourself, RIM is fairly simplified so I’m not sure why you think re-shoring it would make it cheaper, unless, as I said all of the other aspects make for a better process in the end.

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DeleteFromUsersOP•

In sourcing typically makes sense when your in-house volumes go up enough to justify the capital cost and ongoing work. It really depends on what the machines are worth, and what the raw materials are worth. We in source a lot of work that we do. It's a competitive advantage because we can be much more nimble (I can have any part on a machine in 24hrs with material, compared to 4-6 weeks from China/USA outsoucing).

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Tic_Toc_Wordclock•

Side note, the comments and discussion on the post are quite interesting. Thanks everyone!

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jubilantj•

Have you investigated 3D printing? There's a benefit of a design change wouldn't need new or reworked tooling.

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DeleteFromUsersOP•

3d printing wouldn't be able to accommodate the physical requirements of the parts. I should have specified earlier. These urethane parts are often used as shock absorbers so i don't believe any fdm would have nearly the material characteristics of a molded part.

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jubilantj•

I recommend investigating the other options available. You're doing enough parts that I would see about getting them done with SLS or HP MJF. There are lots of good materials out there that would probably work really well for shock.

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DeleteFromUsersOP•

I just don't see the part cost getting down to below the price we need, about $0.75 each, to make the investment worthwhile

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mhiszem•

We make cast urethane parts using aluminum molds. I am pretty sure that’s right in our sweet spot of durometer. Maybe this is something we could quote for you?

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DeleteFromUsersOP•

Where are you located?

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[deleted]•

[removed]

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Tic_Toc_Wordclock•

Why not check out us based urethane mfg? There are some that do a lot in the us.

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DeleteFromUsersOP•

I've never come across a local shop that was even nearly competitive with simple mature processes like this, versus China.

Local shops are great for highly value added processing. Something that China has difficulty with. High tech, new tech, very fine tolerances... Something like that. But RIM molding is pretty simple stuff, China is great for that.

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Tic_Toc_Wordclock•

Sure, I agree is you just look at the per unit quoted price. But that is not the total cost. Your post calls out those costs: quality, lead time, flexibility. If you factor those into the per unit quoted price, is it still less expensive in China?

My point is if you bring it in house, you have just created the most expensive US option. You now need personnel, maintenance, space for the equipment, etc. Those are hard to justify if only making your own parts at the quantity your suggested. But another US based factory would spread those costs across all their customers and would 99.9999% of the time be less expensive than for you to make them i house.

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DeleteFromUsersOP•

We have all of the things you've described. I think the most expensive option is to outsource to a US/Canada shop.

We in source a lot of work, mostly high complexity CNC lights-out machining. The machines for RIM are pretty cheap (especially compared to thermoplastic injection molding). I think we could amortize our investment in less than a year, as long as the raw materials (resin) aren't too expensive. I have some quotes out for materials. I've just never run a molding machine so I'm interested in knowing how fussy it is.

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spankymacdougal•

In defense of your Chinese molder, your piece part costs are high because your quantities are very low. I'm almost positive what is happening is that they are charging you a setup cost to make the short runs worthwhile. Just for the hell of it, tell your molder that you have a prospective customer wanting prices on quantities of 5k, 10k, 25k hell even 100k and see what they come back with.

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DeleteFromUsersOP•

Possibly true but of little value.. We have no interest in larger orders of more than a couple thousand units. It's too much forward inventory and cash tied up.

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spankymacdougal•

Understanding your costs is the first step to reducing them

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DeleteFromUsersOP•

Well that's a fair point. A negotiation on how to reduce costs is an important step in this realm. You're right.

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JunkmanJim•

Check out these guys, just saw an ad for them and the price looked right: https://ashindustries.com/products/supermold?utm_source=fb&utm_medium=1%25+LAL+Targeting+Lists&utm_campaign=Hometown+-+July+2020+-+Conversion&utm_content=Supermold+Static+v2+%28July+2020%29

With your cnc capabilities, maybe pick up some other other parts to make it worth doing in house. There are some contract websites where engineers offer their services. Perhaps pay for a professional consultation with a background in RIM that can design your process and molds.

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DeleteFromUsersOP•

Hmmm not sure they do rim molds. Rim molds are a lot less picky than high pressure injection molds. That price is certainly good though. I could contact them when we're ready to proceed on tooling.

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[deleted]•

[deleted]

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ufi911•

It seems to me you asked for help and turned it down at every opportunity. Good luck with your project.

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DeleteFromUsersOP•

No I've read and understood everyone's responses. No one has described experience with running a RIM setup in their shop.

Trying to run a manufacturing business in North America, not give out blue ribbons.

I am carefully reading, understanding, and responding to everyone's messages. We spend thousands and thousands of dollars on 3d prints ever year, the machinery is running right now by itself (Sunday night), we've been developing and building novel technologies for more than a decade, we source parts from two continents and ship to 6. This isn't my first rodeo.

I asked a very specific question.

Thank you for your input, though. I read your post, too.

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