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Top Sealing Surface (TSS) Shorts Shots test (applicable to PET Mold, if excess breathing is detected)


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TROUBLESHOOTING SHORT SHOT IN PLASTIC INJECTION MOLDING
The picture shows the defects that are caused when not enough plastic material are injected into the mold.Like with all manufacturing processes, plastic injection molded parts can come out of the process with issues and defects that require troubleshooting. One of the most common quality issues is the short shots (sometimes referred to simply as “shorts”), in which the final product is missing material due to the mold not filling completely. In this blog, we’re going to look at the most common causes of this problem, and how troubleshooting short shots is a vital part of quality control and lean manufacturing.

What is a Short Shot?
As the name implies, a “short shot” is when the mold stops short of completely filling the mold cavity, leaving voids or thin areas, and creating a deficient product. These holes are commonly found in very thin areas of the mold or at the edges of the final product – the last places a mold would normally fill. As one of the most common plastic injection molding issues, there are many reasons short shots form, but they fall into three major categories:

Issues with the plastic selection.
Issues with the mold design.
Issues with the plastic injection molding machine.
1: Short Shot Issues Due to Material Selection
A common theme with many of the issues is the flow – the movement of molten plastic throughout the mold cavity. Things that affect that flow and cause it to come up short from filling the mold are the most common cause, and one of the major contenders of flow problems is the plastic itself. Depending on your material selection, you may have a resin with a high viscosity, usually measures on the Melt Flow Index (MFI). While MFI does not give the whole story (the two other categories of issues may also be contributing), it’s a good place to start. Your molder may be able to advise you on what plastic you might want to use to avoid short shots, but you ultimately must make the decision.