A computer-implemented simulation method for use in a molding process by a computer process is disclosed. The method includes steps of specifying a simulating domain comprising a mold cavity and a barrel of an injection machine, wherein the barrel is configured to connect to the mold cavity; creating at least one mesh by dividing at least part of the simulating domain; specifying boundary conditions of the mesh by taking into consideration at least one motion of a screw in the barrel; and simulating a first injection-molding process of a molding material by using the boundary conditions to generate a plurality of molding conditions.

A computer-implemented simulation method for use in a molding process by a computer process is disclosed. The method includes steps of specifying a simulating domain comprising a mold cavity and a barrel of an injection machine, wherein the barrel is configured to connect to the mold cavity; creating at least one mesh by dividing at least part of the simulating domain; specifying boundary conditions of the mesh by taking into consideration at least one motion of a screw in the barrel; and simulating a first injection-molding process of a molding material by using the boundary conditions to generate a plurality of molding conditions.

An object of the present invention is to provide a polyethylene for injection molding, which has an excellent balance between moldability and durability, and a molded article such as an injection-molded plastic fuel tank that has an excellent balance among injection moldability, durability, and impact resistance. The invention relates to a polyethylene for injection molding, the polyethylene comprising at least two types of specific polyethylenes, wherein the density, the high load melt flow rate, and the relationship between the weight ratio and the density of the polyethylene satisfy specific characteristics.

Systems and approaches for controlling a molding machine having a mold forming a mold cavity and being controlled according to a mold cycle include injecting a molten polymer into the mold cavity. A first and a second sensor are used to obtain first measurements of respective first and second variables during the injection cycle. The second sensor is positioned downstream from the first sensor. The first and second sensors are used to obtain second measurements of the respective first and second variables during the injection cycle. A first difference value is determined between the first measurements of the first and second variables. A second difference value is determined between the second measurements of the first and second variables. The first and second difference values are compared, and at least one control parameter is adjusted based on a difference between the first and the second difference values.

An object of the present invention is to provide a polyethylene for injection molding, which has an excellent balance between moldability and durability, and a molded article such as an injection-molded plastic fuel tank that has an excellent balance among injection moldability, durability, and impact resistance. The invention relates to a polyethylene for injection molding, the polyethylene comprising at least two types of specific polyethylenes, wherein the density, the high load melt flow rate, and the relationship between the weight ratio and the density of the polyethylene satisfy specific characteristics.