Injection Molding Cosmetic Defects And What They Could Mean

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While the design of your product is important and the type of plastic you use is important, your mold is equally important. Just like any other device, through regular wear and tear, the effectiveness of your injection mold can decline over time for a number of different reasons. Make sure you know what to do.

Recognizing A Problem

Recognizing a problem with your injection mold is as simple as a quick visual inspection of your finished product. An indication of a problem with the mold is evident through a cosmetic defect that seems to be the same, batch after batch. When you start to see recurring mistakes, it's likely not human error, but a greater problem to blame.

Air Bubbles

A defect can occur when air bubbles from trapped air form in the injection mold during production. In many instances, this is an indication that the mold has been slightly bent out of shape over the years or is damaged as each of these problems allow air to enter inside the mold and cause bubbles to form. In some instances, this problem could be the result of too much decompression on the side of the equipment used on the molds. However, either way, until the issue is resolved, the defects will continue to form on your product.

Uneven Wear

Another problem that can cause defects within the form of your products is uneven wear. This is especially true if the uneven wear is caused around the back plates on the face of the part-line shutoff. In term of the back plates, these devices are responsible for keeping the mold in place during production. When the plates don't have the same level of wear, this can allow the injection mold to shift slightly during production which can lead to defects on your finished product.


The defects in your products could be the result of flashing. Flashing is basically a problem that results in certain parts of the object having excess plastic on it, making certain areas thicker or appear uneven. This problem can arise when there is damage around the injection mold shutoff area. Damage in this area allows the molten plastic to penetrate into areas of the mold that it is not intended to. Repairing the mold shutoff is necessary in the case.

Having a high-quality finished product is the main outcome when using injection molds. If your finished product has defects, make sure you are getting to the bottom of the issue to restore quality. Contact a local manufacturer, like Qualicase Ltd, for more help.