China Injection Molding Process – Learn with Jade

The China injection Molding Process affects your Injection Mold build.

So, your injection mold that was made by your China mold maker has been shipped to you. You get it out of the crate, clean it up, load it into your press, and run some parts. Result? The parts are terrible, nothing like the test parts and QC report you received from your China mold supplier. Now you must pay to get it fixed and your production is behind schedule. Why were the test parts good? Why can’t you recreate the results? Where is the disconnect?

Why does 2 + 2 = banana in China?

There are many possible reasons why you might be having problems with making injection molds in China. One big reason is that the China injection molding process ≠ the standard Western injection molding process. I am talking about the actual injection mold cycle time, the data you input into your injection mold press to tell your press how to work with the mold you have inserted. I’ll say it again. The Chinese injection molding process is NOT the same as the standard Western injection molding process. This blog series dives into not only the physical China injection molding process and how that can affect your offshore mold build but also into how China business culture affects your mold build.

The injection molding process is the proof of concept. The ‘concept’ being your part design, mold design, and mold that you fabricated or had fabricated for you. The ‘proof’ being good parts coming out of your injection mold press, the validation of your design and the quality of the mold.

For this statement to be 100% true we must assume that there is no way to have a poorly fabricated injection mold create good parts. But the reality is that bad injection molds (by Western standards) create good parts all the time, if production is done in China. But these results will never be able to be replicated in your factory if you want to turn a profit.

We all know that there can be and often are problems with a newly built injection mold. Which is why we trial molds to diagnose problems. We run sample parts and QC those parts and adjust the mold and trial again and re-verify and repeat as needed before we certify a mold as ready for production. That is our Western thinking, our Western methodology, fix problems that are in the mold so that production can run smoothly and at pace.

That is not how a typical China injection mold maker thinks…at all. This is the crucial thing you need to understand. Forget engineering, forget science, forget skill, forget norms, you need to get into Chinese business culture and between the layers to truly understand what drives a China injection mold maker. Otherwise 2 + 2 will continue to = banana for you when making an offshore injection mold using a China supplier.

We will talk about China business culture later in this blog series, for now, back to the injection molding process and how the standard Western injection molding process differs from the China injection molding process.

First off, the injection mold process is pretty far down the list for most designers and engineers to worry about as they are busy with so many other design elements, plus, in the West we don’t really consider the injection molding process as a potential trouble area because our assumption is that the standard injection molding process is what everyone in the world uses and builds molds with this process in mind. China is completely different. Here are some simple tips to help you qualify a China offshore mold maker.

1. Make sure your China mold maker programs their injection mold press to trial your injection mold the same way that you will program your injection mold press to run production. You need an apples to apples comparison.
2. Make the emphasis with your China supplier about speed. They need to hit the cycle time you want to achieve during the mold trial. This needs to be a top qualifying factor that you need specific confirmation on from your China supplier in that they completely understand this point.
3. Make sure you fully understand their QC process and reporting before committing to a mold build. Get beneath the surface numbers anyway you can.
4. Make sure they are running the mold at temperature and ask them to qualify how they are achieving temperature. Ask for photos during the mold trial to prove this point. It is very common for a typical China mold maker to throw a mold in a press and run test parts as fast as possible. You don’t want that.
5. Basically, all the things you take for granted as normal for trialing and diagnosing a newly built injection mold, don’t take for granted. Qualify everything about the mold trial and the injection molding process they are using to produce test parts. This is where the proof of the quality of your mold lies.

This introduction into how the China injection molding process DOES NOT EQUAL the standard Western injection molding process all comes down to SPEED. The speed at which the Chinese runs their injection mold presses. The fill is too slow, the mold open and close is too slow, the ejectors are too slow. Everything about their process is too slow.

China mold makers are using long cycle times to mask problems and to ‘fix’ mold problems with their Chinese injection molding process instead of focusing on actually fixing the mold, in their factory, before they ship the mold to your factory. If you don’t understand the China injection molding process and how China trials molds to produce test sample parts you will continue to experience problems with offshore injection molds in your facility.

Look for our next blog that focuses on the detailed stages of the China injection molding process. Below is the video intro that corresponds to this blog series.

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