Multi-Layer Raft Design for Additive Manufacturing Shrinkage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Additive manufacturing processes, such as metal injection molding, often result in part cracking during thermal processing due to non-uniform shrinkage, constrained thermal processing, and incomplete chemical debinding, leading to structural weaknesses and failures.
Innovation Solution
The development of contracting build supports, including a raft with specific shrinking characteristics and drainage paths, is used to mitigate cracking by ensuring uniform shrinkage and reducing frictional resistance during thermal processing, with the raft's design reflecting the shrinking characteristics of the printed object and incorporating non-sintering ceramic layers for stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional build support structure is used during additive manufacturing, then the part can be supported during printing, but non-uniform shrinkage occurs during thermal processing causing part cracking
Solution Approach 1:
The build support structure is segmented into multiple functional layers: a traditional support structure for mechanical support, and a separate raft layer with drainage paths for uniform shrinkage. This segmentation allows each layer to perform its specific function without interfering with the other, resolving the contradiction between providing support and ensuring uniform shrinkage.
Solution Approach 2:
The raft acts as an intermediary layer between the build plate and the part/support structure. It mediates the shrinkage process by providing a controlled interface that distributes thermal stresses uniformly, preventing direct transmission of non-uniform shrinkage forces to the part and eliminating cracking.
2Manufacturing precision
If thermal processing is performed to densify the metal powder, then the desired metal object is produced, but friction or inclusions cause constrained thermal processing leading to part cracking
Solution Approach 1:
The raft incorporates drainage paths that create a porous or semi-porous structure. This allows controlled movement and reduces frictional resistance during thermal processing, enabling the metal powder to densify uniformly without being constrained by excessive friction from the build support structure.
3Reliability
If chemical debinding is performed to remove primary binder, then the feedstock is prepared for sintering, but incomplete debinding causes outgassing stresses that crack the part
Solution Approach 1:
The raft structure with drainage paths extracts or channels away gases and volatiles during the debinding process. This prevents gas entrapment and reduces outgassing stresses by providing escape routes for volatile byproducts, allowing complete debinding without part cracking.
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 proposed solution effectively reduces the tendency for printed objects to crack during thermal processing by promoting uniform shrinkage and minimizing frictional stresses, thereby enhancing the structural integrity and reliability of the manufactured parts.
Implementation Method 1
predicting a shrinking characteristic or receiving a predicted shrinking characteristic of the object that will occur during thermal processing of the object, once formed; generating, based on the shrinking characteristic of the object, instructions for forming a raft on which the object will be formed so that a shrinking characteristic of the raft reflects the shrinking characteristic of the object
Implementation Method 2
The instructions for forming the raft include instructions for forming a base layer and one or more top layers, where the base layer and one or more top layers collectively form one or more drainage paths extending through the raft
Data Source
AI summary
Systems and methods for forming an object using additive manufacturing. One method includes receiving a digital model of the object, predicting a shrinking characteristic or receiving a predicted shrinking characteristic of the object that will occur during thermal processing of the object, once formed, and generating, based on the shrinking characteristic of the object, instructions for forming a raft on which the object will be formed. The instructions for forming the raft are configured to form a raft having a shrinking characteristic that reflects the shrinking characteristic of the object.