- Industry: Software
- Number of terms: 1241
- Number of blossaries: 0
- Company Profile:
Moldflow develops plastic injection molding software.
The cushion is the distance between the forward screw position and the zero screw position, and contains polymer left in the barrel after the cavity is filled. Most of the melt in the cushion is then used for compensation flow during the packing stage.
Industry:Software
An air shot is the injection of polymer melt into the air, instead of into the mold. The main purpose of an air shot is to act as a "test run," to make sure that the machine is operating properly.
The cylinder is pulled back from contact with the sprue bushing and the injection piston is moved forward, forcing melted plastic from the nozzle. If the melt is caught in a metal cup, a pyrometer probe can be used to check the temperature of the melt as it exits from the nozzle. This is one of the more accurate measurements of the melt temperature.
Industry:Software
An air trap is an air or gas bubble that has been trapped by converging flow fronts or trapped against the cavity wall. This causes a surface blemish on the part. Air traps can be prevented by changing the gate location or part thickness. Good practice is to place vents in the mold at the air trap location.
Industry:Software
Amorphous polymers are a family of polymers that are characterized by entangled polymer chains that are loosely bound. The term amorphous indicates that there is no preferred orientation of the molecules, relative to each other, without external force. During injection molding amorphous polymers have orientation.
Amorphous polymers are in a super-cooled liquid state and generally shrink less than semi-crystalline polymers. Amorphous polymers exhibit no x-ray diffraction pattern, because they are not crystalline in nature.
See also Crystalline Polymers, Semi-crystalline Polymers.
Industry:Software
Anisotropic shrinkage is shrinkage that has different magnitudes in different directions. Anisotropic shrinkage occurs in filled materials due to the restriction of shrinkage along the fiber length, which tends to be in the flow direction. It also occurs in un-filled materials when the molecules have insufficient time to relax from the viscous elongation due to shear during flow.
Industry:Software
Aspect ratio normally refers to the relation between width and height of a mesh element. These are important because they affect analysis accuracy. Aspect ratios are especially important in sensitive areas such as gates, or gas channels in a gas-injection simulation.
The term aspect ratio is also used when describing fibers. In this context, aspect ratio is the ratio of the length of the fiber to the diameter.
Industry:Software
Automation is the science of machinery or mechanisms which are so self-controlled and automatic that manual input is not required during operation. Automation is the technique of making a process automatic.
Industry:Software
Back pressure is pressure that opposes the screw as it returns.
The purpose of increasing back pressure is to make it harder for the screw to return. This increases the shear heating and the mixing of the material, which results in improved polymer melt quality.
Industry:Software
A baffle is a cooling system component which is constructed by inserting a metal plate in the cooling lines which forces the coolant to flow up one side of the plate and down the other. It is used to regulate and direct the passage of coolant fluid so that the coolant can travel into difficult areas for more efficient cooling. By interrupting the flow in the cooling lines the baffles create turbulence around bends and improve the heat transfer capability of the coolant.
Industry:Software
Flow is balanced when the extremities of the mold fill at the same time and pressure, as shown in the illustration below. Balanced flow leads to uniform orientation, uniform shrinkage and less internal stress and warpage of the part. It also leads to cost savings with reduced material usage.
Gate location, runner system design and part thickness affect flow balance.
Industry:Software
