In plastics processing, bridging refers to a condition where granulate fails to flow properly into the screw feed zone. This often occurs when coarse granules interlock mechanically or stick together due to excessive heat, forming a “bridge” that spans the hopper outlet. As a result, material cannot descend freely, creating a void underneath the bridge. This interruption in material flow can lead to process instability and poor product quality.
A uniform cooling of the part is important in the injection molding process in order to reduce shrinkage and warpage.
Especially in long and narrow areas the cooling layout is often difficult.
The reason is insufficient space to drill holes next to each other.
When there is only enough space for one hole, it is recommended to use a bubbler.
A tube is inserted into the hole.
The coolant flows inside the tube to the end of the hole and back on the outside.
If the air can’t escape, it will be compressed by the melt.
This leads to an increase in temperature and builds burn marks (black marks on the polymer).
A better venting or slower injection at lower temperatures can solve this issue in most cases.
Related topics:
Initially developed at the IKV in Aachen, Germany, Cadmould is a popular 2.5D injection molding simulation software in Germany.
Based on the shell approach the computation times are short and it is possible to modify wall thickness without changing the geometry.
Development and sales of the software are done by the company Simcon.
Filling, cooling and warpage can be simulated. Additional modules are available for other processes.
The use of computer software for the simulation, analysis, and optimization of plastic components and manufacturing processes is called CAE (Computer-Aided Engineering).
In plastics processing, CAE is used to examine mechanical stresses, flow behavior in injection molds, and thermal influences during the development phase. This helps reduce material usage, production times, and costs while improving part quality. Typical CAE tools include FEM (Finite Element Method) for structural and strength analysis, as well as mold flow simulations to predict filling behavior in injection molding. The use of CAE enables early error detection and optimization before physical prototypes are created. This leads to a more efficient product development process and improved process reliability.
Related topics:
