Ways How To Repair Burr Defects In Injection Molding

Close-up of a plastic part showing a burr defect along the edge

Burr defects in plastic injection molding can compromise the quality and integrity of your products. At Bigmate Philippines, we strive for manufacturing excellence by addressing and mitigating such defects to ensure high-quality output for our clients.

What is a Burr?

 What is a Burr in Plastic Injection Molding?

Burr is the excess plastic that escapes from the mold cavity during the injection process, creating thin layers or excess on the part. These unwanted protrusions can affect the aesthetics and functionality of the final product.

Causes of Burr -by Mold improvement measures

What is the cause of Burr-related Mold conditions?

Basically most Burr comes from two kinds of types one is caused by Mold and another one is caused of injection parameters.

Below are the causes due to Mold conditions.



①Poor mold alignment accuracy on parting line (During Mold Fabrication).

Re-alignment of the Parting line to eliminate the gap on it.

②Insufficient design of Ventilation on the Mold.

Provide additional ventilation and proper location to make smooth injection flow.

③Mold Wear and Damage. Specially worn out of the parting Line due to long-term use.

Mold repair by welding process to eliminate gaps.

Causes of Burr -by Injection Parameter Setting

What is the cause of the Burr-related Injection Parameter setting?

Even though you have a good condition of the Mold, there is a possibility of encountering Burr because of your injection parameter setting.




①The clamping pressure of the mold is too weak compared to the injection pressure.

Increase the clamping pressure.

②The Holding pressure is too high so the material goes out from parting.

Optimize proper Holding pressure based on proper injection size and clamping force. The projected part was completed by holding pressure little by little with an appearance check.

③The mold temperature or Barrel temperature is too high so resin viscosity will be high also and then it makes easy going out from parting.

Optimize proper Mold and Barrel temperature to avoid making high viscosity of the resin. Refer Recommended setting by Material Maker.

Those are only basic countermeasures to improve Burr.

It depends on the conditions, the action will be different.

The important thing is immediate judgment which is the cause of Burr between Mold or Injection parameters.

The fastest way to check if the Burr coming from the cause of Mold is to provide “Short shot” products.

Even making a short shot then if there is still Burr, it means you need to repair the mold to eliminate the gap of mold.

If there is no Burring with a short shot condition it means still there is possibility to eliminate the Burr by Injection parameter.

However, if that condition is tough to find, you should proceed parting line investigation to check if it’s touching each parting part. 

The Burr problem makes only additional cost in your production line.

Additional deburring process, Additional Manpower, Additional space if the deburring process can’t finish in 1 injection cycle…

Immediate solution is needed with Burring products.

Bigmate Philippines Inc. will support you in improving your mold condition with proper verification and judgment.

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