PP is one of the most commonly seen soft plastics on the market. It is applied to a variety of industries including packaging,automotive industry, like Step Pads, and other household products. Though for its wide use, PP is meanwhile is a very flexible, soft material with a relatively low melting point. Because of all these factorers, PP plastic molded part is most liable to get warped under heat,which becomes an annoying headache in daily production. .How to solve the warp on PP plastic parts? According to HS’s over 20 years of practical experience, there are basiclly 3 ways. Improve designIn product design, use reinforced ribs with appropriate size wherever possible. For large area of surface, design it as micro-arc shape with equal wall thickness to reduce the internal stress. Improve processing parameterMost warp in plastic injection molded part is caused by uneven stress. There are only 4 primary plastic processing variables…

One of most common seen molding defects is discoloration. It is a cloudy or hazy discoloration of the plastic on the surface of a finished part, but when you check the mold surface, you won’t see this on it.The defect is not only in color but also gloss visually unappealing, the plastic in that area can be weaker than in the rest of the part. Sometimes, no matter how hard you adjust the molding parameter, the issue is still there. It is more serious on textured plastic surface, some area is is dark cloudy while the rest is gloss. The whole part looks annoying. For some parts that require high image, application of painting to cover the defect maybe a choice, which may increase production cost as well. However, money could not solve all issues. Some products are environmental and require flame retardant, the discoloration becomes a challenge that puzzles a lot of technicians . This…

When it comes to Overmolding injection molding, the most common two defects that frustrate we see is flash and two plastic material not sticking tightly. What is overmolding injection then? It is a process when one material being is molded over a second material.The base layer is molded first and the additional plastic layer(s) are molded over and around the original part – resulting in a single, finished product.   What are the defects of overmolding and tips on how to fix them? Defect 1.: substrate part deformed This happens because the substrate part is too thin and it gets deformed under high temperature during the process of secondary molding. Besides, if the overmolding area is too thick and narrowly long, the shrinkage force of soft plastic will lead to the “bump”  or arch deformation of the substrate as well Suggestion:check gate position and add strengthening rib to the substrate part.   Defect 2.:…

In the process of plastic injection molding, it is common to see flow mark on plastic parts. Flow marks are lined patterns, often wavy, or discoloration on a part surface. For cosmetic medical plastics, the look is usually very critical and flow mark is a defect that must be eliminated. Cause of flow mark Flow mark defect could be traced to one of three sources,  the resin or dditives used, the injection molding process, or the mold itself. Resin Resin manufacturers supply specific formulations in a range of standard flow rates. Thin-walled products may require an easy flow material while thick-walled products can use a material that has a stiffer consistency. It is better to use the stiffest flow possible because it improves physical properties of the molded part. However, the stiff material will require higher injection pressures, which may blow the mold open and cause flash at the parting…