Spiral Hot Runner Injection Mold for Reproducible Marbling
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Solution Overview
Problem
Existing injection molding processes struggle to produce marbled moldings with reproducible and variable marbling patterns, requiring complex machinery and leading to undesirable homogeneous mixing of molding compounds, sprue formation, and energy inefficiencies.
Innovation Solution
An injection mold with a hot runner system featuring at least two ducts forming spirals, and a process where molding compounds are fed separately in time and space to ensure defined color boundaries and reproducible patterns, using a single screw injection molding machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If homogeneous mixing of molding compounds is achieved through uniform plastification, then temperature uniformity is improved, but marbling pattern visibility deteriorates due to complete mixing of color components
Solution Approach 1:
The hot runner system is segmented into multiple separate ducts (at least two ducts) that are connected to the cavity inlet. Each duct can carry different molding compounds separately, preventing homogeneous mixing while maintaining temperature control. This segmentation allows color components to remain distinct and visible in the finished component while still achieving uniform temperature distribution through the heated ducts.
2Manufacturing precision
If separate injection units are used to supply different molding compounds, then reproducible marbling patterns are achieved, but device complexity increases due to multiple screws, barrels, and hydraulic systems
Solution Approach 1:
Multiple molding compounds are fed separately in time and space into a single injection unit, which then distributes them through the segmented hot runner ducts. This merging approach combines the advantages of separate supply (reproducible patterns) with the simplicity of a single injection unit, avoiding the complexity of multiple complete injection systems while maintaining pattern reproducibility through controlled feeding sequences.
3Ease of manufacture
If traditional gate systems without hot runners are used, then manufacturing simplicity is maintained, but energy efficiency deteriorates due to sprue formation and solidification losses
Solution Approach 1:
The gate system parameters are changed by implementing a hot runner system with controlled temperature parameters. The hot runner maintains the molding compounds in a molten state through the gating system, preventing solidification and sprue formation. This parameter change (temperature control) eliminates the need for sprue removal operations and reduces energy losses associated with reheating and reprocessing solidified material, while the segmented duct design maintains manufacturing simplicity.
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
The process achieves reproducible marbling patterns with high detail and variability, allowing the same mold to produce different patterns with minimal modification, reducing energy consumption and eliminating sprue formation.
Implementation Method 1
the hot runner has at least two ducts that are connected at a first end of each duct to the inlet into the cavity and at a second end of each duct to the entry opening into the injection mold
Implementation Method 2
the hot runner is thermally insulated and its temperature may be controlled separately
Implementation Method 3
the at least two ducts each at least partly form a spiral
Data Source
AI summary
Disclosed herein is an injection mold for production of marbled moldings, including at least one hot runner, a cavity, an entry opening into the injection mold and an inlet into the cavity, where the hot runner has at least two ducts that are connected at a first end of each duct to the inlet into the cavity and at a second end of each duct to the entry opening into the injection mold, where the at least two ducts each at least partly form a spiral, and the at least two ducts are bounded by a one-piece component. Further disclosed herein is a process for producing the injection mold and a process for producing marbled moldings.