High-pressure plastic injection molding is one of the most common manufacturing processes. Tens of thousands of factories in Ningbo, Shenzhen, and in many other places have at least a few machines running continuously.
If you develop your own product and it includes some custom plastic parts, you will probably need to invest in a mold. What should you know about this type of tooling, and what plastic injection mold manufacturing companies in China can help you?
Some context about this type of tooling
You can contact a tooling company or an injection molding factory (since some of them make their tooling in-house), give them a design, and request a quotation. But I would certainly not recommend being this cavalier.
Unfortunately, you can't approve a 3D printed sample and be 100% sure the tooling will make products that are exactly similar to that sample. It just doesn’t happen that way. There are always differences. There is actually a leap of faith needed — invest in the tooling, then see what it allows you to make.
Here are some best practices to follow in order to get the desired outcome when getting molds produced and manufacturing plastic injection molded parts or products:
1. Give clear and detailed specifications
You have to give a clear and detailed set of specifications, among which:
The exact material, the texture, and the finishing required
Tolerances on critical dimensions
Number of shots required
Number of cavities
Etc.
If you don't provide that level of detail, you can ask for 10 quotations from plastic injection mold companies in China and you will get prices ranging, like, from 2,000 USD to 10,000 USD. Very common. The reality is, those prices won't buy you the same results.
2. Perform a DFM review
You need an engineer to think of potential defects on the final part/product, after molding. We shot a video about common defects, for your reference. If nobody does this type of “Design for Manufacturing” review, you will probably regret it at some point.
3. The mold supplier should probably run trials before handing it over
You can't just work with a tooling shop without planning for the injection molding supplier. If they are not the same company, you will need the molding supplier to run trials with the tooling and to sign off on it once they consider it acceptable. There will probably need to be reworked on the mold.
4. Keep a close eye on your manufacturer at the start of production
You will be sent some of the first pieces of tooling. That's great. But keep in mind, they might have been reworked manually.
A bad supplier won't think twice about it. They will think "the production guys will tweak the process and it will be fine". And then, when they run a mass production and they realize they have to put in a lot of manual labor and/or they have a lot of scraps to regrind, they will tell you a piece of bad news – the price has to go up!
5. Be conscious of your IP when sourcing manufacturers
And finally, are you afraid of leakage of your intellectual property rights? Are you afraid your tooling might be held hostage and you won't be able to switch to another supplier even if the quality is horrible? Don't send your product design to parties you haven't vetted and you have no product development contract with.