Layered Metal Mold Channels for Temperature and Vacuum Control
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Solution Overview
Problem
Existing additive manufacturing techniques face challenges in producing large, non-porous metal molds for plastic processing, such as aluminum molds, due to difficulties in temperature control, vacuum application, and void formation, which affect production efficiency and quality.
Innovation Solution
The method involves Cut Layer additive manufacturing, where layers of metal are stacked and machined to form channels for temperature-controlled liquid circulation and vacuum application, using CNC routing to create aligned holes and slots for efficient thermal management and air evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional subtractive manufacturing is used to produce large metal molds, then the molds can achieve good structural integrity, but significant time and material are required to remove excess material to produce the desired cavity shape
Solution Approach 1:
The mold is divided into multiple thin layers that are manufactured separately and then stacked to form the complete mold structure. This segmentation allows each layer to be manufactured efficiently using additive manufacturing, avoiding the need to machine large blocks of material and significantly reducing both production time and material waste.
Solution Approach 2:
Instead of starting with a solid block and removing material (traditional subtractive manufacturing), the invention builds the mold by adding material layer by layer in the desired final shape. This inverted approach eliminates excessive material removal and reduces production time for large, complex mold geometries.
2Temperature
If cooling tubes are attached to the underside of the mold face, then temperature control can be achieved, but contact between the tubes and the mold face is difficult to achieve
Solution Approach 1:
The mold layers serve multiple functions: they form the cavity structure and simultaneously incorporate cooling channels within their thickness. This multi-functionality eliminates the need for separate cooling tube attachments, as the cooling channels are integrated directly into the mold structure during manufacturing.
Solution Approach 2:
The cooling channels are manufactured in advance as integral parts of the mold layers during the additive manufacturing process, before the mold is assembled. This preliminary action ensures proper alignment and contact between cooling channels and mold faces, eliminating the difficulty of achieving contact through post-manufacturing tube attachment.
3Temperature
If cast aluminum molds are used with cast-in cooling lines, then temperature control is beneficial, but manufacturing inaccuracies and inconsistent distance between lines and mold face occur
Solution Approach 1:
The invention replaces traditional casting processes with additive manufacturing (3D printing) to create mold layers with integrated cooling channels. This substitution enables precise digital control of cooling channel locations and dimensions, achieving manufacturing precision of ±0.05 inches or better, compared to the inaccuracies inherent in cast-in cooling lines.
Solution Approach 2:
The manufacturing process parameters are changed from conventional casting to additive manufacturing, which allows for precise control of cooling channel geometry and position. This parameter change enables consistent placement accuracy and uniform distance between cooling channels and mold faces, resolving the precision issues of cast-in lines.
4Productivity
If vacuum holes are drilled into the mold, then air evacuation can be achieved, but the holes may create distortions or marks on the face of the plastic part
Solution Approach 1:
The mold layers have different properties at different locations: the face layers have smooth surfaces for part quality, while internal layers contain vacuum channels. This local quality differentiation allows vacuum holes to be positioned in non-critical areas where they won't mark the plastic part surface, while still achieving efficient air evacuation through strategically placed channels.
Solution Approach 2:
Instead of drilling vacuum holes through the mold face (one-dimensional approach), the invention creates vacuum channels within the internal structure of the mold layers (three-dimensional approach). This dimensional change allows vacuum application points to be distributed throughout the mold volume, achieving efficient air evacuation without surface holes that would mark the plastic part.
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 approach allows for precise control of mold temperature and rapid air evacuation, improving thermal heat transfer and reducing surface marks, thereby enhancing the production of high-quality plastic parts.
Implementation Method 1
The temperature at which this process works properly may be different for different formulations of thermoplastic sheet. For this reason, it is generally beneficial for the temperature of the mold face to be properly controlled. This can be performed by attaching metal tubes to the underside of the mold face and circulating temperature-controlled liquid through the tubes.
Implementation Method 2
The temperature should also be sufficiently cool, such that once the heat-softened thermoplastic sheet is in full contact with the mold, the sheet can cool sufficiently to retain its shape when removed from the mold.
Data Source
AI summary
A part formed by additive manufacturing includes a plurality of layers including a first layer and a second layer, the first layer and the second layer being stacked along a stacking direction, and a work surface formed on an upper surface of the first layer and an upper surface of the second layer. The part also includes a first through-hole formed in the first layer, a second through-hole formed in the second layer, the second through-hole being at least partially aligned with the first through-hole, and a wall extending from the first through-hole to the work surface.