Category Archives: Plastic


Dec05
7 Common Reasons for Elevated MFI (Melt Flow Index) in Plastic Resin Testing

Workingbear’s company recently encountered a quality issue with a plastic product. The problem was, “Why is it that products made from the same type of plastic resin sometimes show normal MFI (Melt Flow Index) values, while others have unusually high … Continue reading

Nov28
Understanding Melt Flow Index (MFI) for Quality Control in Plastic Injection Molding

The “Melt Flow Index” (MFI) of plastic refers to the weight (in grams) of molten plastic that flows through a standardized tube with a specific diameter under a defined load (in kilograms) and temperature (in °C) within a set period … Continue reading

May03
Trouble Shooting Guide for Plastic Injection

Trouble Suggested Remedies (Solutions) DIMENSIONAL PROBLEMS Shot-to-shot dimensional variations Increase injection pressure Maintain uniform pad (cushion) Repair leaking back flow value if pad cannot be maintained Increase screw forward time Maintain uniform cycle Eliminate un-melted particles (see below) Use larger … Continue reading

Jun24
Case study for the mold-in insert screw boss broken

In a previous discussion, WorkingBear identified potential root causes for screw boss cracking after mold-in screw nut insertion. Following a complaint from the field, we asked EMS and the plastic injection supplier to double-check their inventory and found that approximately … Continue reading

May01
Why Do Screw Bosses Crack After Mold-In Screw Inserts? Common Causes and Solutions

This story is long-standing memory, but WorkingBear is documenting it here for reference and as a learning record. One day, we received a customer complaint regarding a product with a plastic housing that had cracked. The issue was visually striking, … Continue reading