High Density Polyethylene - Injection Molding
HDPE (High Density PolyEthylene) is a polyethylene plastic commonly used in injection 
molding applications because of its high tensile strength, impact resistance, and melt flow index, not to mention its relatively low cost.
HDPE is just one type of polyethylene, and is usually defined as being polyethylene with a density of 0.941 grams per centimeter cubed or greater. Under the umbrella of HDPE, there are several different grades of product. In most instances, the grade of the HDPE is determined by its MFI, or melt flow index. This is a measurement that describes the viscosity of the HDPE when melted, and it is a crucial element where injection molding applications are concerned.
Injection molding HDPE must have a high MFI, as injection molding involves squirting HDPE resin into a die through many holes, filling it within seconds, and setting it quickly. Slow flowing HDPE would be disastrous in an injection molding application and would undoubtedly result in malformed and misshapen products.
Injection molding is commonly used to produce items which have unusual shapes, such as children’s toys. Due to its translucent color, virgin HDPE can be colored brightly, which adds to the appeal of using HDPE in applications where aesthetics are important. HDPE injection molding can be carried out to a recommended minimum thickness of about .020 inches. Anything thinner than 0.010 inches is likely to crack and otherwise degrade too quickly to be commercially viable.
Recycled HDPE can also be used in injection molding applications, though it may not possess the translucence of virgin HDPE. Recycled HDPE is usually obtained from post consumer and post industrial sources, and therefore has been exposed to many contaminants and colorants during its life. In the case of high quality recycled HDPE pellets and granules, contamination is a negligible factor, but coloration can be an issue. It is common for manufacturers to add a black or other dark dye to recycled HDPE to overcome this problem, and recycled HDPE is considered to be safe for all injection molding applications with the exception of any products designed for food contact applications.
HDPE Prices and Quote
Please contact us through this form below and let us know your detailed requirements. We will get back to you with current HDPE availability and price quote