JINYI manufactures bimetallic barrels and liners for all makes and types of bakelite & thermoset injection molding machinery. Our products are found worldwide operating in mild to severe abrasion and corrosion wear environments.
For thermoset materials:
Energy transfer and accurate control of temperature zones is vital to prevent premature cross-linking of the material in the barrel. Thermal jackets positioned around the outer diameter of the barrel and arranged in two or more control zones typically control process temperatures. Barrel outer diameters are designed with OD grooves to accommodate circulating thermal fluid. Length to diameter ratios are lower than that found in thermoplastic molding. The optimum L/D depends on the machine's capacity and the material processed. Most thermoset machines have L/D ratios of 12:1 to 15:1.
Thermoset materials are often reinforced with mineral and fiber fillers that create an extreme wear environment. JINYI recommends a barrel lined with JYK-3 tungsten carbide alloy to sustain life and productivity.
For Bakelite materials:
For Bakelite injection molding, the barrel temperature is set to 70-90'C to heat (with screw shear) the raw materials flowing. The screw is only for compressing and delivering the material into the mold, without melting it. Mold is heated to a temperature (180'C, for instance) to cure the raw materials
Screw configuration - The compression ratio of the screw for Bakelite is 1:1, and for thermoplastics, it's about 1:3 to 1:4.5.
Process - Molding of thermoplastics involve melting, but for molding of Bakelite, the fusing takes place between
particles so as no melting is involved.