Compound Polymer Mold System for Cost-Effective Tooling
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Solution Overview
Problem
Conventional molding methods face limitations due to high costs and size constraints of metal molds, which restrict the size and complexity of parts that can be produced, and often result in high labor intensiveness and inefficiencies in plastics casting processes.
Innovation Solution
A compound tooling system using polymers as primary material, where the mold is divided into separate parts based on functions such as shape definition, filling, and part removal, with a flexible elastomer skin-mold bonded to a rigid backing-mold and supported by a standard backing-plate, allowing for more versatile and cost-effective production of various part sizes and shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hard metal molds are used for injection molding, then manufacturing precision and reliability are improved, but tooling costs and production time increase significantly
Solution Approach 1:
The mold is divided into two distinct segments: a permanent hard backing mold providing structural support and geometry definition, and a temporary soft skin mold enabling easy part removal. This segmentation allows each component to be optimized for its specific function, reducing overall production time while maintaining precision.
Solution Approach 2:
The skin mold is designed as a consumable, short-lived component made from soft materials that can be easily replaced. This eliminates the need for expensive, time-consuming hard molds while maintaining sufficient manufacturing precision for the application.
2Productivity
If hard metal molds are used, then molding efficiency is improved, but part size and complexity are constrained
Solution Approach 1:
The invention changes the material parameter of the mold from hard metal to soft elastomeric material. This parameter change allows the mold to be flexed during operation, enabling the production of larger and more complex parts that would not fit or be removable from rigid metal molds, while maintaining molding efficiency.
3Ease of manufacture
If soft tooling materials are used for casting, then tooling costs are reduced, but manufacturing precision and productivity decrease
Solution Approach 1:
The mold combines two different materials with complementary properties: a hard permanent backing mold for structural integrity and geometry precision, and a soft elastomeric skin mold for ease of manufacture and part release. This composite structure achieves both low tooling costs and acceptable manufacturing precision.
4Device complexity
If conventional single-piece molds are used, then device complexity is reduced, but ease of operation for part removal deteriorates
Solution Approach 1:
The skin mold is designed to be dynamically flexible, allowing it to be flexed and deformed during the part removal process. This dynamic property enables easy extraction of complex parts from the mold cavity without requiring complex ejector mechanisms, maintaining simple overall structure while improving operability.
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 system reduces tooling costs and production time, enabling the production of larger or more complex parts with improved dimensional accuracy and reduced labor intensity, while allowing for easier integration of heating and cooling systems, thus increasing the versatility and efficiency of molding processes.
Implementation Method 1
The skin-mold is preferably bonded to the backing-mold by vacuum pressure
Implementation Method 2
When the vacuum pressure is released, the flexibility of the elastomer may be used to deform the skin-mold to facilitate de-molding of the part
Data Source
AI summary
A compound mold or tooling system is designed to provide an alternative to conventional, expensive, metal molds for various plastics molding applications. The compound mold comprises a replaceable thin-walled liner, or skin-mold, defining the mold surface, temporarily bonded by vacuum means or mechanical means to a conforming backing-mold mold body supported by a rigid backing-plate. Both skin- and backing-molds are composed of suitable polymers with or without additives, fillers, reinforcements or other inclusions depending on mold requirements. The backing-plate contains standard features and fixtures common to all molds used in the particular process or of a particular geometry.