Short-Shot Plastic Injection Molding Issues: How to Diagnose

short shot plastic injection molding

Plastic plays an integral part in almost every person’s life. It helps make products and components that are durable, corrosion-resistant, strong, and light.

Plastic is used in almost every industry. These include consumer goods, construction, aerospace, computer, and automotive technologies, to name a few.

Most components are made using plastic injection molding. This is an efficient and reliable method, but there are a few common challenges that technicians can face, including short-shot plastic injection molding issues.

This article covers how to diagnose and fix short-shot problems. It will help you get your production line running again. Keep reading to learn more.

What Is Short-Shot Plastic Injection Molding?

Short-shot plastic injection molding refers to a common issue in the molding process. This occurs when the melted plastic resin fails to fill every space within the mold cavity. This results in a malformed component that must be remade.

Short-shot issues are often detectable during quality control checks. These can include visible changes in the part’s appearance or dimensions. Other signs are holes or thinner segments on the product’s surface.

What Are the Causes (and Solutions) to Short-Shot Problems?

There are several main causes of short-shot issues. A common one is a high plastic viscosity. This restricts flow, so smaller crevices in the mold do not get filled.

You can easily fix this by either increasing the melt temperature or choosing a different resin with a lower viscosity. Also, better control over mold and melt temperatures throughout the process can help ensure the right viscosity.

A similar cause is inconsistencies in the material. This means that not all of the resin will fill the mold cavity as intended. For this problem, you should do quality control checks on the storage of the resin or change sources to get a more consistent product.

Another common cause of short-shotting is improper venting. The air inside the mold that the resin displaces needs a space through which to escape.

If not, it will become trapped in the mold, causing inadequacies. Checking your vents or adding more vents during the design phase may help alleviate this problem.

Another mold-design problem that can cause a short shot is an imbalance in the mold or inadequate dimensions of runners and gates. Inconsistent mold thickness can lead to temperature control issues as well.

Misplaced nozzles, sprues, runners, and gates also can cause uneven polymer flow. Making minor adjustments to the placement of these–or mold design in general–can produce a more natural melt flow.

Finally, short-shot issues can be caused by molding machine defects. A machine that produces inadequate pressure is a common culprit.

Recalibrating your machine is a good place to start. Also, ensure that the reciprocating screw or the barrel has not been compromised.

Find Plastic Injection Molding Services Near You

Now that you understand how to diagnose and fix a short-shot plastic injection molding issue, you can take steps to minimize downtime and optimize output. Catching these problems early can help you avoid major losses down the road.

Nova Stevensville is an original equipment manufacturer (OEM) that serves automotive and other industries. We pride ourselves on meeting the unique needs of each client by supplying the precise parts they need to be successful. Contact us today for pricing or to learn more about our products and services.

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