How to solve the surface sag in 2K mold

The basic reason for surface sag: from the perspective of plastics, when the plastic cools and shrink, insufficient filling will lead to product surface sag or internal cavity.

The causes and solutions of defects are different depending on the location of sag.

  1. When the sag occurs at the final cooling position of the thick-walled product, or at a distance from the sprue:

Cause analysis: The typical thick wall and the surface sag or hole far from the sprue are usually due to the increase of effective viscosity and pressure loss, resulting in insufficient pressure in the mold cavity, resulting in insufficient pressure for filling.

Solution: Increase the feeding pressure and speed up feeding speed

  1. When surface sag or hole appears near the sprue

Cause analysis: sag occurs near the gate, usually due to lack of gate freezing.

There are several reasons affecting gate freezing: it may be caused by the decrease of effective viscosity; In most cases, the gate does not freeze because the plastic temperature increases; High mold temperature will also affect gate freezing.

Solution: By adjusting the mold temperature, plastic temperature, increase the holding time to ensure the gate freezing.

  1. Note: holes and bubbles are easy to confuse. Holes are sometimes mistaken for bubbles. A bubble is a gas trapped inside, and a hole is empty inside.

About JasonMould Industrial Company Limited

Jasonmould is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer, mold manufacturer China– plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: JasonMould Industrial Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]


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