What is the purpose of adding glass fiber to plastic materials in injection molding?

Thermoplastics do have natural mechanical properties that impart strength, durability, impact resistance and other benefits in plastic molded parts, and adding glass fibers to plastics can further enhance the properties of the resin.

One problem that can occur in injection molding of materials with added glass fibers is increased brittleness due to the significant increase in strength and stiffness of the part.

However, if the glass-filled plastic part is not subjected to high impact stress and bending, but only to support weight, then it can be an ideal plastic resin for injection molding.

In addition, the range of glass filling percentages can be large (typically 13% to 45%), which will affect the performance of the final part accordingly.

If you are considering adding glass fibers to the injection molding process, it is important to note that adding glass fibers to molded parts increases strength, but also poses risks as the glass fibers may cause internal stresses and warpage as well as fill rate, cooling rate and shrinkage issues.

The addition of glass fiber is appropriate when the plastic mold has the following characteristics: uniform wall thickness; no sharp or 90 degree angles; few through holes and turns; and non-complex geometry.