Injection Molding Screw Control for Jetting Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing injection molding processes face challenges in preventing molding failures such as flow marks and jetting due to rapid resin flow into cavities, which is attributed to high inlet velocity and pressure changes as the molten resin passes through the runner and gates.
Innovation Solution
A control method for an injection molding machine that involves stopping the screw or plunger just before the leading flow end of the resin reaches the gate portion and holding for a predetermined period before resuming the advance, allowing the resin to expand and preventing rapid flow into the cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the screw or plunger is stopped just before the leading flow end of the resin reaches the gate portion and held for a predetermined period, then molding failures such as flow marks and jetting are prevented, but the injection process time is increased
Solution Approach 1:
The screw or plunger is stopped just before the leading flow end of the resin reaches the gate portion, and the resin is held in a compressed state for a predetermined period. This preliminary action prevents the resin from rapidly expanding and flowing into the cavities, thereby preventing molding failures such as flow marks and jetting while maintaining efficient injection molding.
2Object-generated harmful factors
If the screw or plunger is stopped for a set period at the position where the gate portion is reached by the leading flow end of the resin, then jetting is prevented, but the position of the screw and pressure in the injection cylinder vary for each molding cycle
Solution Approach 1:
The screw or plunger is stopped just before the leading flow end of the resin reaches the gate portion, rather than at the gate portion itself. This preliminary anti-action prevents the resin from rapidly expanding and flowing into the cavities, thereby preventing jetting while maintaining consistent screw position and pressure for each molding cycle.
3Ease of operation
If the resin is injected at a constant speed, then the injection process is simple to control, but the pressure on the resin does not constantly increase and molding failures occur due to sharp or slow pressure increases
Solution Approach 1:
The screw or plunger is stopped just before the leading flow end of the resin reaches the gate portion, and the resin is held in a compressed state for a predetermined period. This preliminary action ensures constant pressure increase and prevents molding failures such as flow marks and jetting, while maintaining simple constant speed injection control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively prevents molding failures like flow marks and jetting by controlling the resin flow, ensuring a consistent and reduced pressure at the gate, thereby improving the precision and quality of molded products.
Implementation Method 1
the pressure on the molten resin in the runner is reduced by stopping the plunger for the set period
Implementation Method 2
the molten resin is a viscoelastic body
Data Source
AI summary
In an injection process in which a screw or a plunger is advanced to inject a molten resin into a mold, the advance of the screw or the plunger is stopped and held just before a leading flow end of the resin reaches a gate portion, and the advance of the screw or the plunger is resumed for an injection operation after the passage of a predetermined period.