AMILAN® Nylon Resin. Technical Information|Injection-molding|Common injection-molding defects and their countermeasures. Short shot or short molded. Possible Defects. Many of the above defects are caused by a non-uniform cooling rate. A variation in the cooling rate can be caused by non-uniform wall thickness or non-uniform mold temperature.‎Process Cycle · ‎Equipment · ‎Tooling · ‎Materials. Test tool heat and eliminate any external sources contributing to heat on the tool, check cooling in area of tool. Slow down the injection speed and/or test.


Author: Admin
Country: Chile
Language: English
Genre: Education
Published: 7 January 2016
Pages: 259
PDF File Size: 13.37 Mb
ePub File Size: 16.49 Mb
ISBN: 320-4-74236-837-5
Downloads: 69538
Price: Free
Uploader: Admin


Stop using mold parting agents.

AMILAN® Nylon Resin

Change the gate locations so that the weldlines occur in locations less susceptible to external forces if weld strength is an issue. Causes Injection molding defects in density as the material changes from a molten to a coagulated state.

The surface of the molded product loses injection molding defects rapidly through the mold wall and the polymer hardens. Jetting refers to a situation where molten plastic fails to stick to the mold surface due to the speed of injection.

Common injection-molding defects and their countermeasures | AMILAN® | TORAY PLASTICS | TORAY

Being fluid, the molten plastic solidifies in a state that shows the wavy folds of the jet stream on the surface of the injection molded part. Jetting occurs mostly when the melt temperature is too injection molding defects and the viscosity of the molten plastic becomes too high, thereby increasing the resistance of its flow through the mold.

When the plastic comes in contact with the mold walls, it is rapidly cooled and the viscosity is increased.

The material that flows injection molding defects behind that viscous plastic pushes the viscous plastic further, leaving scrape marks on the surface of the finished product. Increase mold and melt temperatures.

Injection Molding Defects Glossary

Increase the size of the gate so that the injection speed becomes slower. Optimize gate design to injection molding defects adequate contact between the molten plastic and the mold. Flash is a molding defect that occurs when some molten plastic escapes from the mold cavity.


Typical routes for escape are through the parting line or ejector pin locations. This extrusion cools and remains attached to the finished product. Flash can occur when the mold is not clamped together with enough force a force strong enough to withstand the opposing forces generated by the molten plastic flowing through the moldwhich allows the plastic to seep through.

The use of molds that have exceeded their lifespan will be worn out injection molding defects contribute to the possibility of flash. Additionally, excessive injection pressure may force the plastic out through the route of least resistance.

Creative Mechanisms Blog

Increase the clamp pressure to ensure that the mold parts remain shut during shots. Sometimes the material is too viscous or the mold is too cold to allow the molten material to completely fill the mold before cooling.

And other times trapped air pockets may be hindering proper flow or injection pressure may be inadequate. Consider the following steps to prevent short shot: Redesign the mold with wider channels or gates for better flow Increase injection speed or pressure or choose a thinner base material to improve flow Increase mold temperature to prevent material from cooling too rapidly Add additional air vents or enlarge existing vents injection molding defects the mold to allow trapped air to escape Flash appears because material has flowed outside of the intended flow channels and into the space between the tooling plates or at the injector pin.


Flash is usually subtle but might be considered a major defect if particularly obvious on a product. The process for reworking a molded product with flash often includes trimming the excess material.

Injection Molding Defects Glossary

Common causes of flash and prevention in molded products A poorly-designed or worn and degraded mold is the most common contributor to flash.

Excessively high mold temperature or injection pressure can injection molding defects cause flash.

  • Injection Molding Process, Defects, Plastic
  • Top Injection Molding Defects And How To Fix Them
  • 6 Common Injection Molding Defects and How To Avoid Them | The Rodon Group®
  • Short shot or short molded

Material flowing through the mold cavities can force its way between injection molding defects when plate clamping force is inadequate. Common methods for addressing flash in molded products include: Defects related to the molding process or material tend to be easier and less costly to solve.

But no matter the cause, defects in molded products can hurt your bottom line tremendously. Do you have any other advice for addressing defects in injection-molded products?