There are many common causes of a bubble defect in injection molding. Most of these defects happen when the plastic material injected into the mold is a little on the rough side. This plastic material will expand a tiny bit as it cools and then contracts when the curing process is complete. As this plastic cools, it may form a bubble, and when it cools enough, it will rupture (if cooled too much will not).
The best way to prevent a bubble defect in injection molding is to ensure that all of the pieces you use for your mold are consistent throughout the entire piece. If you have bubbles anywhere in your product, it is very easy to catch them when the plastic is cooled and cured. This is why you should try to put all of your pieces together before you heat them up and apply the plastic. You should also check to make sure that your molds have been appropriately cleaned. Any foreign materials or other items can cause your product to break apart prematurely, so you must make sure that you know what you are injecting in your molds..
Another common cause of a bubble defect in injection molding is when the cavity that the bubbles form in is already completely clogged by plastic pieces before the injection process has even started. As the plastic cools, it becomes more likely to form bubbles and then rupture when it cools enough. Injection gun tools that allow you to open clogs manually are often the best way to avoid breaking your mold. This tool can sometimes be challenging to use though and is often less effective than a pressure washer. This is why it is often recommended that injection gun users and operators switch to using a pressure washer because it can ensure that your mold pieces remain unclogged until it is time to finish injecting your product.
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