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You are here: Home / Quality Control Tips / Inspections of moulds and tools in China

Inspections of moulds and tools in China

October 17, 2013

Quality Control TipsMany buyers want to have a Chinese manufacturer work on their own designs. And, very often, it means mould(s) need to be created for each new product design.

But creating a mould is expensive. If the supplier doesn’t already know the buyer, he will probably ask the buyer to send a payment.

In the importer’s side, it means they need to send money to a new supplier (who hasn’t demonstrated his ability to produce at the right quality standard).

And then, to send money again before production starts (the famous “deposit” which is actually an advance payment).

It is understandable that the buyer wants to check whether the moulds were done right. But how to check the mould’s quality?

Here is what I usually write to clients who need an inspection on plastic injection moulds.

Regarding the material composition

You want to make sure the steel is hard enough. But how to make sure about this?

In the best case, the factory has XRF testing capability.

If they don’t, the inspector can ask for certifications of materials. Sometimes they are fake, but that’s not as frequent for moulds or tools as it is for a production batch.

Another option is to send samples of the tooling to a testing laboratory. They will run a chemical analysis, and confirm whether the grade of steel you requested was in fact used.

Regarding the dimensions

There are two cases:

1. You gave the drawing of the mould/tool to the supplier.

In this case, all we need to do is check the mould’s dimensions.

In an ideal world, the manufacturer should have CMM testing capabilities. If not, using calipers is possible but not very precise.

Another option is to ask the manufacturer to physically bring the whole mould to a testing laboratory that has CMM capability.

2. You only gave the drawing of the finished product (to be made with the mould) to the supplier.

We’ll need to know the material of the finished products, because we need to estimate its shrink rate (after it gets out of the mould). For example, nylon has a higher shrink rate than polycarbonate.

We can use software to estimate by how much each dimension will shrink, and it allows us to know the dimensions the mould should have. And then, we can use CMM or calipers to estimate whether dimensions are right (back to point 1).

Filed Under: Quality Control Tips

Comments

  1. Davide says

    October 19, 2013 at 8:59 AM

    Former GM here.

    Molds are great but you get tied hands and feet to your supplier.
    The suppliers know very well that moving a mold to a new supplier is a pain in the neck.
    When you find the new supplier, they always covers their backs saying they are not responsible for quality problems because the mold was done wrong, and it has to be repaired, and it does not fit their equipment and so on, an endless list of complains.
    It would be nice to have two or even more suppliers doing the same thing and have them compete, but very few factories have the numbers to maintain two sets of molds.
    Does anybody have something to share on this?

    • Renaud Anjoran says

      October 19, 2013 at 9:43 AM

      What you describe is a frustration experienced by nearly all buyers who pay a Chinese supplier to make a mould.
      I can think of 2 alternatives. I listed them below, for what they are worth…
      – The buyer pays a mould specialist (independent from the supplier), and then sends an engineer in the supplier’s factory to run tests and ensure the mould is good. This requires a high level of professionalism.
      – Get a legally enforceable contract that details what the supplier will pay you in case things go bad (some good lawyers have experience with this and know what can go bad).


Weekly updates for professional importers on better understanding, controlling, and improving manufacturing & supply chain in China.

This is the official blog of Sofeast.com.

This blog is written by Renaud Anjoran, an ASQ Certified Quality Engineer who has been involved in chinese manufacturing since 2005.

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