In injection molding material is fed through a hopper into an extruder, where a reciprocating screw mixes and melts the material then injects it into a mold. Injection molding machines, or presses, are rated by tonnage, which expresses the amount of clamping force that the machine can exert to keep the mold closed during the process. Most polymers can be injection molded. The types of products that are molded are wide and varied, ranging from large automotive parts to tiny gears. Navigate from the Injection Molding Zone to more specific topics on all-electric/hybrid machine technology, liquid-silicone rubber molding, micro-molding and multiu-component molding.