Defects in Molded Plastic Components
Molded plastic components are used in a variety of products due to their light weight, low cost and ease of manufacture. They are also highly adaptable and can be designed to meet a variety of product requirements. However, molded plastic components can also have defects. Injection molding is a complex process, and any imperfections in the process can result in faulty components.
One of the most common defects found in molded plastic components is warpage. This is when the component becomes deformed either during or after the molding process, resulting in a warped or uneven shape. This can be caused by a variety of factors, such as an uneven cooling rate, uneven pressure in the mold or improper design of the part. Warpage can also occur when the plastic is exposed to changes in temperature or humidity.
Another common defect is sink marks. These are depressions in the surface of the component that occur when the plastic shrinks faster on the outside than on the inside. Sink marks can be caused by a variety of factors, such as an insufficient melt temperature, overpacking the mold cavity or inadequate venting of the mold.
Other defects in molded plastic components can include flashing, burrs, and misalignment of parts. Flashing is a thin layer of plastic left on the component after the mold is opened. It is usually caused by an excess amount of plastic being forced into the parting line of the mold. Burrs are small projections on the surface of the component due to the parting line of the mold not being machined correctly. Misdimensions of parts can occur when the mold is not designed correctly or when the wrong material is used.
Molded plastic components are also prone to contamination. They can be contaminated by either dirt or dust particles, or by potential contaminants in the plastic material itself, such as dye or plasticizer. Contamination can lead to changes in the color and texture of the part, as well as other issues, such as cracking or stress.
While imperfections aren’t always visible, molded plastic components must still be inspected for any visible defects prior to shipment. The inspection should be done by an experienced technician who is trained on recognizing and correcting the various defects. Manufacturers should also employ the latest technologies and practices to reduce the chances of defects occurring. This includes utilizing quality control protocols, such as statistical process control, Six Sigma, and Total Quality Management.
Molded plastic components are used in a variety of products, but they can be prone to defects. Warpage, sink marks, flashing and burrs are some of the most common flaws seen in plastic components. Contamination can also lead to changes in the part’s color and texture. To ensure that molded plastic components are of the highest quality, manufactures should employ the latest technologies and inspection techniques.
