When it comes to selecting materials for injection mold […]
When it comes to selecting materials for injection molding barrel screws, several factors need to be considered, including the type of resin being processed, operating conditions, and desired performance characteristics. Here are some commonly used materials for injection molding barrel screws:
1. Nitrided Steel: Nitrided steel is a popular choice for barrel screws due to its excellent wear resistance and durability. It undergoes a surface treatment process called nitriding, which introduces nitrogen into the steel to form a hard nitride layer. This layer improves the screw's resistance to wear caused by abrasive resins and enhances its overall lifespan.
2. Tool Steel: Tool steels, such as H13 and D2, are commonly used for injection molding barrel screws. These steels offer good toughness, wear resistance, and thermal conductivity. Tool steel screws are suitable for processing a wide range of resins, including engineering plastics with high processing temperatures.
3. Bimetallic: Bimetallic barrel screws consist of two materials—a high-wear-resistant outer layer and a more cost-effective core material. The outer layer, typically made of a high-performance alloy like Colmonoy, Stellite, or tungsten carbide, provides excellent wear resistance, while the core material, usually a standard steel, provides structural strength. Bimetallic screws offer a cost-effective solution by combining the benefits of wear resistance and affordability.
4. Powder Metallurgy: Powder metallurgy screws are made by compressing and sintering powdered metal alloys. These screws can be customized with specific alloy compositions and properties to meet the requirements of different resins. Powder metallurgy screws are known for their excellent wear resistance and corrosion resistance, making them suitable for processing abrasive and corrosive materials.
5. Ceramic: In some high-performance applications, ceramic screws may be employed. Ceramic materials, such as alumina or zirconia, offer exceptional wear resistance and corrosion resistance. Ceramic screws are suitable for processing highly abrasive or corrosive resins, but they are more brittle compared to metal screws, requiring careful handling and operating conditions.
It's important to consider the specific requirements of the injection molding process and the properties of the resins being processed when selecting the barrel screw material. Factors such as resin abrasiveness, processing temperature, residence time, and shear forces should be taken into account to ensure optimal performance and longevity of the barrel screw. Consulting with screw manufacturers, materials specialists, or process engineers can provide valuable guidance in selecting the right materials for injection molding barrel screws.
