Sequential Injection Moulding Weld Line Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sequential injection molding in the automotive industry faces challenges in eliminating weld lines, which are aesthetically unacceptable and can compromise structural stability due to irregular profiles and vulnerable points, with existing solutions either being overly complex or resulting in increased article thickness.
Innovation Solution
The method involves controlling the opening and closing of injectors to define the shape and position of weld lines, allowing for a regular and aesthetically improved weld line formation, which can be positioned in non-aesthetic areas, thereby reducing the thickness of the molded article and avoiding pressure line defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sequential injection is used to fill large components, then productivity is improved, but weld lines are generated which compromise aesthetic quality and structural stability
Solution Approach 1:
The patent applies preliminary action by opening the lateral injectors before the central injector, so that the lateral material flows establish their paths first. This anticipates the weld line formation and allows the central material to fill remaining gaps without creating prominent weld lines, thus maintaining aesthetic quality while preserving productivity benefits of sequential injection.
Solution Approach 2:
The patent inverts the conventional injection sequence by opening lateral injectors first instead of the central injector first. This reversal changes the flow dynamics so that material from lateral injectors reaches the center first, eliminating the traditional weld line formation pattern and improving aesthetic quality without sacrificing productivity.
2Manufacturing precision
If lateral injectors are opened when central material reaches them, then weld line mixing is improved, but article thickness increases due to superimposition of flows
Solution Approach 1:
The patent opens lateral injectors in advance before central material arrives, allowing lateral flows to establish their paths first. This preliminary action enables better control of material distribution and prevents excessive superimposition, maintaining weld line quality while avoiding increased article thickness.
Solution Approach 2:
The patent uses dynamic control of injector opening sequences and timing to optimize material flow. By adjusting when each injector opens based on real-time flow requirements, the system achieves good weld line quality without unnecessary material accumulation that would increase thickness.
3Speed
If lateral injectors open instantaneously at maximum flow rate, then filling speed is improved, but pressure lines are generated on existing material
Solution Approach 1:
The patent applies periodic action by using progressive opening sequences for lateral injectors rather than instantaneous opening. The injectors open in staged increments, allowing material to flow at controlled rates that prevent pressure line formation while still achieving efficient filling through optimized sequencing.
Solution Approach 2:
The patent opens lateral injectors preliminarily before central material arrives, allowing them to establish flows at moderate speeds first. This preliminary action prevents the need for sudden high-speed opening that would cause pressure lines, while still achieving fast overall filling through the sequential approach.
Data Source
AI summary
A method and apparatus for the sequential injection moulding of plastic material into the mould cavity or by using a plurality of controlled open-close injectors, wherein the sequentially injected plastic material originates in mould flow fronts in different directions whose collision generates at least one weld line on the moulded article. The sequential injection is actuated with specific modes according to which the opening of the at least one of said injectors is anticipated or delayed with respect to other injectors and/or at least one of the injectors is closed partly and/or at least one of the injectors is gradually opened only partly. Such specific modes are managed to control and define the shape and/or the position of the weld line on the moulded article.