Thermoplastic Molding

The Thermoplastic family of materials is what most people relate to when they think about plastics because of the many domestic products that are produced from them including items such as telephones, computers, auto parts, and appliances to name a few. Highly critical parts having specialized requirements are also made from thermoplastic materials engineered to meet these requirements. Components for aircraft, medical devises, engines, machinery, electrical and other industrial items are produced from engineered thermoplastics. Plastic resins having specific properties are compounded with additives such as reinforcements (ie: glass or carbon fibers), U.V. inhibitors, flame retardants, conductive elements, lubricants or toughening agents, to attain desired properties. Optimal properties of components molded from engineered plastics can be attained only through the proper and precise control of the molding process. Our 45 years of molding experience and investment in state of the art process control equipment ensures the best outcome for our customer’s critical parts. Be it high volume production as for automotive or irrigation industries or low volume as for aerospace applications, Southwest Plastics will be a valuable partner for your next injection molding project.

Thermoplastic Injection Molding

Injection molding is a high production method of producing a vast variety of thermoplastic parts into shapes ranging from fairly simple to quite complex. Injection mold cavities are fed with melted plastic material which is forced under high pressure through a sprue which feeds a runner system then through a gate into the cavity. The material is then cooled to the point that the material is solid and then ejected from the mold as a finished part. The injection molding machine consists of two basic components: the clamp unit and the injection unit. The clamp unit holds and clamps the tool into position while the injection unit plasticizes and injects the material into the mold which has been positioned by the clamp unit. The clamp force must be sufficient to hold the mold closed against the hydraulic pressure of the material being injected under high pressure by the injection unit. The rule of thumb is that there must be three tons of clamp force for every square inch of cavity projected area in the mold. Both units are coordinated by a computer controller on the machine which is programmed to efficiently to produce high quantities of consistent quality parts on an automated cycle.

Thermoplastic Resins

Generic Name Acralonitrile Butadine Styrene Acetal Acrylic Butyrate Polyimide Polycarbonate Polyester (PBT, PET) Polyetherimide Polyphenelene Sulfide Polyphenelene Oxide Polypropylene Polystyrene Polyurethane Polyetherether Keytone Styrene Acralonitrile Thermoplastic Elastomers	Trade/ Common Name(s) ABS Delrin, Celcon Lucite, Plexiglas Tenite Nylon Lexan Valox, Celanex Ultem Ryton Noryl PP PS PU PEEK SAN Santoprene, Krayton		Manufacturer(s) Dupont, Ticona Dupont, Rhom & Haas Eastman Dupont General Electric General Electric, Ticona General Electric Phillips General Electric ExxonMobile, Shell
Engineered Compounds Any of the above resins can be tailored to a specific requirement by compounding in additives to enhance properties.
Enhancements Tensil strength Toughness U.V. resistance Flame Retardance Conductivity Lubrication Cost reducing fillers		Typical Additive Glass, Carbon fibers Elastomer Color Stabilizers Extinguishing additive Carbon, metal flakes Teflon, Moly Mineral