Process for forming a molten material into molded article

A method of optimizing molding time to form a molded article comprising the steps of:

• (a) providing a mold containing a plurality of mold portions forming a mold cavity having cavity surfaces in a shape of said molded article, said mold portions comprising:
• (1) at least one die having at least one primary booster adjacent to and in thermal communication therewith, said die providing structural support for said primary booster;
• (2) said primary booster being disposed in the mold cavity and forming at least a part of the cavity surfaces, the primary booster being made of materia whose mathematical product of thermal conductivity, density, and specific heat is no more than 2.0.times.10.sup.-6 BTU.sup.2 /sec/in.sup.4 /.degree. F..sup.2 at room temperature, and having predetermined thicknesses (W.sub.b) as calculated from the equation ##EQU5## where t.sub.t is a time to fill the mold, k.sub.b is thermal conductivity, .rho..sub.b is density, and C.sub.b is specific heat of the primary booster;
• (3) thermal control means for applying temperature control stimuli to the die;
• (b) applying substantially constant temperature control stimuli to said mold die via said thermal control means, such that the cavity surfaces of the mold cavity are brought to predetermined temperatures that are initially below a mold filling temperature required to produce the molded article and upon contact with molten material introduced into the mold cavity at a temperature greater than the mold filling temperature, increase a temperature of the cavity surfaces at least to the mold filling temperature required to produce the molded article, whereby because of the mathematical product of thermal conductivity, density, and specific heat of the primary booster according to said equation, the temperatures of the cavity surfaces are lower than for materials with higher corresponding products;
• (c) introducing molten material into the mold cavity, whereupon heat flows from the molten material to the primary booster and temperatures of the cavity surfaces increase at least to the mold filling temperature required to produce the molded article;
• (d) while the cavity is filling with molten material, maintaining said cavity surfaces at least at the mold filling temperature required to produce the molded article;
• (e) after the cavity is substantially full, permitting heat flowing from the primary booster to the die to cool the primary booster and the cavity surfaces, thereby optimizing cooling time.