Types of Feed Screw Materials
Your specific applications and needs utilize different types of plastics, from general purpose resins to filled engineered resins, abrasive and/or corrosive, whatever the combination will determine which screw material is best for production. From general purpose to high wear or corrosion, by matching your feed screw material to the characteristics of the plastic, you can further your feed screw’s durability and function, increase longevity and minimize problems all while improving the quality and consistency of the final part product.
Some common materials used for molding machine feed screws include:
1. Alloy Steels
Alloy steels have very high yield strengths and low costs. However, they don’t offer much abrasion or corrosion resistance, so they often receive welded hard-surfacing and root treatments such as nitriding and chrome. Our alloy steel feed screw options include American Iron and Steel Institute (AISI) 4140, 4150 and 4340, as well as Nitralloy 135M.
2. Stainless Steels
Stainless steel feed screws have good corrosion resistance and high yield strengths, with our 17-4PH and 51-5PH options sporting higher yield strengths than most alloy steels. However, wear resistance is poor, so many stainless steels are heat-treated or hard-faced welded to provide protection from corroded internal threads. We offer feed screws for molding machines in the 300 and 400 series, as well as the 17-4PH and 15-5PH options. Specialty steels such as Hastelloy C-276 and Duranickel are also available for extremely corrosive materials.
3. Tool steels
Once heat-treated, tool steel feed screws provide high abrasion resistance and better corrosion resistance than alloy steels but have a very low yield strength. Small screws are more affordable and a very good choice when abrasion and corrosion resistance is needed. On large screws, the cost of materials, heat-treating, and machining can make them quite costly, but should still be considered for specific applications. We carry injection molding feed screws with AISI S-7, D-2, M-2, H-13, CPM-9V and CPM-440V materials.