Injection molding!

We've never done any injection molding at FM, but we've got a part in design that would be perfect for it. Problem is, our primary design guy has only dealt with injection molding once and he's convinced that the tools cost $50k. This part is relatively small, can be designed without overhangs and a consistent wall thickness and will have volumes of 1000/year or so. For us, that's high volume but in the injection molding world it's probably low volume. We could 3D print it but it would basically need a dedicated printer.

Who can point me to a good resource or manufacturer?

I know there are tons of companies that advertise in the southwest in flight magazine. But I have no direct feedback on this topic at all.

Look at Protolabs. They can do small volume injection molding at reasonable cost and have a great online quoting tool. Honestly their quoting tool is my first stop when I design a new part because it will catch little problem areas. I have used them several times for prototype quantity injection molding. https://www.protolabs.com/?utm_source=google&utm_medium=cpc&utm_campaign=us-brand-protolabs&utm_term=protolabs&gclid=CjwKCAiAhc7yBRAdEiwAplGxX63LRyERscsohCwMCXTkVz8ZZGz2BCSo9_JOsP53Lc7djum87MZ0dBoCzUwQAvD_BwE

Cost depends on where the tool is made, what the material of the tool is, what the material being injected is, and the size and complexity of the part. I have found that mold costs have dropped a lot over the past few years. Tools that were $25k have been $10k to $15k recently. The only tool I can remember dealing with that was $50k was for a ~14in long polycarbonate tube. But also I think most of my tools recently have been made in China even for times when I have been using a US based injection molder.

It seems like 1k a year could be done with an aluminum tool for not much money.

Depending on how small "small" is and how many cavities in the prospective tool your guy may not be far off.  Domestic tooling cost is a tough pill to swallow sometimes.  All of our domestic injection molding is done in house and we only shop around over seas so not much help. I do know that Bemis in Sheboygan,WI does everything from toilet seats and medical equipment up to UTV body panels and trash cans.  I interviewed with them a couple years back and they are the only domestic plastic injection molder I know by name.

In my line of business, everyone always wanted to jump to the tool solution that would support hundreds of thousands of parts, which our volume could never justify. 

Be sure when you investigate this, you make sure you know where you are on the scale of tool cost versus cycles/units before the tool needs to be replaced. 

Small: bigger than a Hot Wheels, but not much. 

I know there are options in tool material - 3D printed vs aluminum vs steel and possibly more of which I am not aware. If I know the cost of various tool materials, I can math from there. 

Ditto on 93EXCivic's comments. Protolabs does this every day. If I recall correctly from a couple years ago, they were going to use aluminum tooling due to our low volumes, and replace the tooling at their expense when it wore.

I haven't used Protolabs myself, but have heard good things about them.

what does the surface need to look like ?

There are Prototype machines that use simple single cavity molds ,  making one part at a time ,

I think if it can be done by 3D printer do it that way , 

you can make 10 or more at a time depending how big the 3D printer bed is , 

If you need more info send me a PM

Protolabs is the go-to vendor in the small volume/prototype molded stuff industry.

Pete

A part that small could be done as an insert for a mold base the injection molding company already owns that has most not the mod features already in place (spruce bushing, locating ring, mold mounting features, ejector system, cooling water connections, etc).  Depending on the material you wish to use to make the part, the insert could be aluminum.   

I’ve been in the plastics industry my entire career and I’d be happy to help with material selection and can refer you to a mold makers and injection molding companies that specialize in this low volume production space here in Detroit.  PM me if you’d like to discuss further.   

Todd

For a part that small I would almost definitely go the dedicated 3D printing route. 

I guess it also depends on the part, what it's going to be doing, and what material it needs to be produced out of. 

At least with a 3D printer you could churn out other parts/things with it and stretch that ROI. 

I was in the same boat a few years ago.

Bottom line is I paid a local prototype company to redesign my design for injection molding (proper draft, uniform wall thicknesses, etc).

They 3d printed the prototypes for fine tuning/approval.

They then facilitated having a mold made with 'their partners' in China. I ordered parts through the local prototype company.

It worked out great. 

Issues during my journey:

Local injection molders wouldn't deal with me. Too busy. The three other regional injection molders I contacted didn't want to deal with me.  (even though I sought out and received recommendations on who to contact.) One told me my mold would be 20k in aluminum and 30k+ in tool steel...and were negative about it.

I think US injection molders are doing more high end work in general. Could be wrong.

My mold cost around $11k and was tool steel. I ordered around 1000 parts at a time.

The printer would have to be dedicated to this product - based on projected print time, it would basically be doing nothing else. We're getting into 3D printing pretty heavily, ordering another $9k worth of printers today. But if we're going to dedicate a printer, it seems foolish to at least not investigate other production methods. Additive manufacturing is great for products up to a certain volume, but there's a point where it makes more sense to go into mass production. I don't know where that point is exactly.

We've requested a quote from Protolabs.

Todd, I may drop you a line. Jamscal, thanks for the experience.

93EXCivic said:

Look at Protolabs. They can do small volume injection molding at reasonable cost and have a great online quoting tool. Honestly their quoting tool is my first stop when I design a new part because it will catch little problem areas. I have used them several times for prototype quantity injection molding. https://www.protolabs.com/?utm_source=google&utm_medium=cpc&utm_campaign=us-brand-protolabs&utm_term=protolabs&gclid=CjwKCAiAhc7yBRAdEiwAplGxX63LRyERscsohCwMCXTkVz8ZZGz2BCSo9_JOsP53Lc7djum87MZ0dBoCzUwQAvD_BwE

Cost depends on where the tool is made, what the material of the tool is, what the material being injected is, and the size and complexity of the part. I have found that mold costs have dropped a lot over the past few years. Tools that were $25k have been $10k to $15k recently. The only tool I can remember dealing with that was $50k was for a ~14in long polycarbonate tube. But also I think most of my tools recently have been made in China even for times when I have been using a US based injection molder.

It seems like 1k a year could be done with an aluminum tool for not much money.

+ another one- we have one in SE MI that has an injection molding machine that members can use.  I'm not a member, but looked into it when it was part of an award.

China. 

American tooling is stupid expensive. China is incredible at cheap tooling, and fast turnarounds. I can email you a couple sources if you'd like. 

Keith Tanner said:

The printer would have to be dedicated to this product - based on projected print time, it would basically be doing nothing else. We're getting into 3D printing pretty heavily, ordering another $9k worth of printers today. But if we're going to dedicate a printer, it seems foolish to at least not investigate other production methods. Additive manufacturing is great for products up to a certain volume, but there's a point where it makes more sense to go into mass production. I don't know where that point is exactly.

We've requested a quote from Protolabs.

Todd, I may drop you a line. Jamscal, thanks for the experience.

Seems like you answered your own question there in regards to the 3D printing option. 

This thread answered a lot of questions I had for something I've been designing. So thank you Keith and everyone else. 

I never had a question about the 3D printing aspect, that I know how to do :) The real question is about where the line lies between injection molding vs printing.

Inlogauge, any leads would be appreciated.

Keith Tanner said:

I never had a question about the 3D printing aspect, that I know how to do :) The real question is about where the line lies between injection molding vs printing.

Inlogauge, any leads would be appreciated.

Not a plastics engineer, and didn't stay at a Holiday Inn last night.

That being said, I do have 20+ years experience with onesy-twosy and production runs of machined products.

I have a CNC mill in my garage (for various purposes, but pertinent to this thread, cutting custom molds) and an injection molding machine that fits on my drill-press for short-run products that are past the prototype stage, but not in the mass-production stage.

I could run off 1000 parts in a couple of days. This isn't an offer, more an insight into doing this in-house.

For the easiest "pro DIY" level to get into, 3D print your part, finish it to a high standard (how you want it to look when it's in the customers' hands), then pour a mold using SmoothOn products that are appropriate, then use the drill-press injection molder to knock out the parts.

Here's a link to the injection press I own: https://www.techkits.com/products/model-20a/

Here is one if you don't want to use your drillpress: https://www.techkits.com/products/model-150a/

I'm a contractor who moonlights in prototyping and product development, with a healthy portfolio of clients who utilize my skills on problems big and small.

Not everything has to be expensive, and not all things can be done cheaply. It's all about finding appropriate technologies for appropriate problems.

An addendum to my previous post:

I would SLA print rather than FDM print, for cosmetic parts. Finishing still requires time, skill and materials...some of which react with "soft" molds.

SmoothOn makes a platinum silicone mold material (2 part) that can be had in a high durometer blend, and is heat resistant. Depending on the size of the shot, it could easily last several runs of your 1000 part production.

Depending on the physical requirements of your part, pellets for the injection press can be had from PP, PE, ABS, PC, Nylon, etc.

Not sure if you have any shop-monkeys where you work, but this would be a great learning experience for a floor-sweeper, both the prototyping and the production run.

+1 for Protolab. There is no need to over complicate things. 

I was all excited for a minute, because somehow I was thinking that the description matched an interior component that a lot of people in the RX-7 world are also looking for, but the part I am thinking of was not shared by any generation of Miata.

Still very interesting nonetheless.  Also, $20k for a mold times 1000 minimum sales is not all that much depending on what you expect to sell the bit for.  $5, the profit margins are slim.  $20, now we're getting there.

Thanks, Gingerbeardman. We don't have the in-house capability to manufacture, unfortunately. 
 

Knurled, I think you slipped a decimal place in your math :)  At $20, you're covering the cost of the mold and nothing else...

Injection molding can create a durable and amazingly inexpensive part if you're selling enough to justify the tooling, which, while expensive, is probably not $50K for your application. Spend a long time designing, printing and trying prototypes, and go to town. A bonus is that often molding will be much stronger than you expect.

Protolabs is good.

We use a company called Polymer Molding which is really good.

https://www.polymermolding.com/

At my company, we use Spectrum Plastics pretty frequently.  They can also create the tooling offshore.