Additive Manufacturing Mold Buffer Layer Crack Prevention
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Solution Overview
Problem
Molds produced by additive manufacturing face issues with cooling water leaks due to cracks caused by thermal fatigue, which occur from temperature differences between the melt and release agent, leading to potential heat medium leakage.
Innovation Solution
A mold with a buffer layer having a low-melting percentage portion between the mold surface and the heat medium channel, composed of unsintered or unmelted metal powder, and a heat-conducting portion with a higher melting percentage, allowing for effective temperature control and crack prevention, along with a heat medium channel of three-dimensional or two-dimensional honeycomb shape for improved flow and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling water channel is created closer to the mold surface to improve cooling ability, then the cooling efficiency is improved, but the temperature gradient becomes steeper causing cracks to occur more easily
Solution Approach 1:
The buffer layer is applied locally at the inner peripheral surface of the cooling water channel, creating a localized region with different thermal properties. This allows the channel to remain close to the mold surface for efficient cooling while the buffer layer locally mitigates the steep temperature gradient that causes cracks.
Solution Approach 2:
The buffer layer acts as an intermediary substance between the cooling water channel and the mold surface. It mediates the thermal stress by providing a transition zone that reduces the temperature gradient, preventing crack propagation while maintaining effective heat transfer.
2Ease of manufacture
If additive manufacturing is used to create complex cooling water channels, then manufacturing flexibility and cooling ability are improved, but thermal fatigue cracks occur more frequently
Solution Approach 1:
The buffer layer is selectively applied only at the inner peripheral surface of the cooling water channel where thermal stress concentrates, rather than throughout the entire mold. This localized treatment maintains the manufacturing advantages of additive manufacturing while specifically addressing the crack resistance issue at the critical location.
Solution Approach 2:
The mold structure becomes a composite system combining the additively manufactured mold material with the buffer layer material. This composite structure leverages the geometric flexibility of additive manufacturing for complex channel shapes while the buffer layer provides enhanced thermal stress resistance.
3Temperature
If the cooling water channel is enlarged to improve cooling coverage, then the cooling ability is improved, but the wall thickness is reduced making cracks more likely
Solution Approach 1:
The buffer layer is specifically applied at the inner peripheral surface of the cooling water channel, creating a localized reinforcement zone. This allows the channel to be enlarged for improved cooling coverage while the buffer layer compensates for the reduced wall thickness by providing enhanced strength and crack resistance at the critical location.
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 solution effectively prevents heat medium leaks by minimizing crack growth and enhancing temperature control, reducing material requirements and production time, while minimizing residual stress and deformations in the mold.
Implementation Method 1
the buffer layer includes a low-melting percentage portion having a lower melting percentage than does any portion inside the mold other than the buffer layer
Implementation Method 2
the buffer layer further includes a heat-conducting portion having a higher melting percentage than does the low-melting percentage portion
Data Source
AI summary
A mold (1) according to an embodiment of the present invention is a mold which is formed by additive manufacturing. The mold includes: a heat medium channel (10) for a heat medium to flow through, the heat medium channel being provided inside the mold; a medium introduction port (4) at which the heat medium is to be introduced into the mold; a medium discharge port (5) at which the heat medium is to be discharged out of the mold; and a buffer layer (20) located between a mold surface (1a) and the heat medium channel. The buffer layer includes a low-melting percentage portion (21) having a lower melting percentage than does any portion inside the mold other than the buffer layer.