a method of molding a plastic is initiated by injecting molten resin into a mold at a high pressure . the energy of the high pressure is partially stored in the form of elongation of tie bars of a molding machine . after the gate seals completely , the restoring force of the tie bars due to elastic deformation acts on the molded article as the mold article cools down . each tie bar comprises a first member having a small modulus of elasticity and a second member . when the elongation of each tie bar is small , only the first member of small modulus of elasticity works . after the elongation reaches a certain amount of δl 1 , the two members are connected parallel . as a result , the apparent modulus of elasticity of each tie bar increases rapidly . this makes it possible to mold a plastic with high dimensional accuracy .