What are the common problems of injection molding process?

The injection molding process is a very efficient and common method in the production of plastic parts, but it may also encounter some common problems in the actual production process, which may affect the quality, appearance and function of the product. Here are some common problems during injection molding and their possible causes:

Flow marks and burns: flow marks are linear marks on the surface of plastic, often caused by too fast material flow speed or uneven mold temperature; A burn is a black spot or spot where the plastic is scorched due to overheating or compression of the gas in the mold cavity.

Shrinkage mark: When the plastic parts are cooled, if the shrinkage is not compensated, it may produce a depression on the surface or inside.

Warping or deformation: If the cooling rate of plastic parts is inconsistent, or the cooling time is not long enough, it may lead to warping or deformation of the product.

Stress marking: When plastic parts are subjected to excessive internal stress, they may appear white, cracked or brittle on the surface.

Welding line: When the plastic flow will fit the gap formed in the flow channel, right Angle or slender hole, affecting the appearance and strength of the product.

Not full or short shot: the plastic does not completely fill the mold, resulting in incomplete products. It may be because the injection pressure or speed is too low, the temperature of the plastic is too low, or the temperature of the mold is not suitable.

Flash: Plastic parts leak outside the mold joint surface to form excess flakes. It may be caused by insufficient clamping force or mold quality problems.

Nozzle cold material: The plastic has begun to cure before entering the cavity, forming hard points in the product.

Insertion displacement or damage: During injection, insertions may be displaced or damaged due to improper positioning, poor fixation, or extrusion when the mold is closed.

Surface scratches or wear: If the injection mold surface is not properly treated or the plastic part is too sticky, it may cause surface scratches or wear.

To solve these problems, it is usually necessary to adjust the parameters of the injection molding machine (such as temperature, pressure, injection speed and pressure holding time, etc.), optimize the mold design (such as improving the gate, runner design, increasing ventilation, etc.), improve the treatment of plastic materials, or by adding or adjusting the cooling system to do so. Each problem may require a combination of factors to determine the best solution.