Method of injection molding a low-melting-point alloy

A control method of an injection molding in which a low-melting-point alloy, which is a molding material, is melted in a cylinder of a screw-type low-melting-point alloy injection molding machine and is injected into a mold by a screw to effect molding, and control is provided such that an appropriate quantity of material is fed from a material feeder in correspondence with a shot and the quantity of material detained in said cylinder is maintained appropriately, comprising the steps of:

• setting a unit increment and a unit decrement as well as an upper limit and a control lower limit of a quantity of material detained;
• and
• automatically repeating the operation in which an injection process is executed by feeding the material in a quantity which is the unit increment greater than each shot weight, and when the quantity of material detained in said cylinder has reached the upper limit due to the accumulation of the unit increments, the quantity of material fed is changed to a quantity which is the unit decrement less than the shot weight, and in which
• after the changing, when the quantity of material detained in said cylinder has reached the control lower limit due to the accumulation of the unit decrements, the quantity of material fed is returned to a quantity which is the unit increment greater than the shot weight so as to increase the quantity of material detained, thereby optimally maintaining the quantity of material detained in the cylinder.