Analysis And Solution Of Cracking In Injection Molding

Cracks, including filament cracks, microcrack, whitening, cracking on the surface of parts, as well as cracks and fracture time due to component adhesion, flow path adhesion or traumatic damage. The main reasons are as follows:

1. Processing:

(1) Excessive processing pressure, too fast, the more filling materials, injection, holding pressure for too long, will cause excessive internal stress and cracking.

(2) Apintejinust the speed and pressure of mold opening to prevent the quick and strong drawing parts from causing demoulding cracking.

(3) Apintejinust the mold temperature appropriately to make the parts easy to demoulding, reduce the material temperature appropriately to prevent decomposition.

(4) Prevent cracking due to low mechanical strength caused by welding mark and plastic degradation.

(5) Proper use of release agent, pay attention to often eliminate the mold surface adhere to the mist and other substances.

(6) The residual stress of the workpiece can be eliminated by annealing immediately after molding to reduce the formation of cracks.

2. Mold:

(1) Ejecting shall be balanced, such as the number and sectional area of ejecting rod shall be enough, ejecting inclination shall be enough, and cavity surface shall be smooth enough, so as to prevent cracking due to the concentration of ejecting residual stress caused by external forces.

(2) The structure of the parts should not be too thin, the transition part should use arc transition as far as possible, avoid sharp Angle, chamfer cause stress concentration.

(3) Use metal insert as little as possible to prevent internal stress increase due to different shrinkage rate of insert and product.

(4) Suitable demoulding air inlet channel should be set for deep bottom parts to prevent the formation of vacuum negative pressure.

(5) The main channel is enough to release the sprue material before it is cured, which is easy to release the mold.

(6) The joint between the main channel bushing and the nozzle should prevent the products from sticking to the fixed die due to the dragging of the cold material.

3. Materials:

(1) Recycled material content is too high, resulting in the product strength is too low.

(2) Excessive humidity causes chemical reaction between some plastics and water vapor, which reduces the strength and leads to roof cracking.

(3) The material itself is not suitable for the processing environment or poor quality, pollution will cause cracking.

About PTJMould Industrial Company Limited

PTJmould 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.