Green Part Solid Loading Control for Sintering Dimensional Accuracy
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Solution Overview
Problem
Powder injection molding processes face challenges in manufacturing complex parts with anisotropic volume reduction during sintering, leading to shape changes and difficulties in achieving tight dimensional tolerances, especially for components like gas turbine engine panels with curved shapes and angled features, which require complex mold configurations.
Innovation Solution
The method involves forming green parts with varying solid loadings of binder and powder material to control local deformations during sintering, allowing for the transformation of initial shapes into desired final shapes with reduced mold complexity, using different proportions of binder and powder in different areas to achieve the desired final geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniform solid loading is used in green parts, then the molding process is simple, but anisotropic volume reduction occurs during sintering causing shape changes and poor dimensional accuracy
Solution Approach 1:
The patent applies local quality by varying the solid loading (proportion of powder material to binder) in different regions of the green part. Areas requiring greater shrinkage during sintering are assigned lower solid loading, while areas needing minimal shrinkage maintain higher solid loading. This regional variation in material composition enables control over anisotropic volume reduction and achieves the desired final geometry with high dimensional accuracy without requiring complex mold configurations.
Solution Approach 2:
The patent utilizes parameter changes by modifying the solid loading parameter across different zones of the green part. By adjusting the concentration of powder material and binder in specific regions, the patent controls the shrinkage behavior during sintering. This parameter variation allows the green part to transform from an initial simple shape to a complex final shape with precise dimensional tolerances, resolving the contradiction between manufacturing precision and device complexity.
2Shape
If complex mold configurations are used to manufacture parts with curved shapes and angled features, then the final part geometry is achieved, but the molding process becomes impractical and expensive
Solution Approach 1:
The patent applies preliminary action by designing the green part with a deliberate initial shape that is easier to mold than the final desired geometry. The green part is formed with simplified features, and the complex curved shapes and angled features are generated during the sintering process through controlled anisotropic shrinkage. This approach allows the use of simple, practical mold configurations while still achieving complex final part geometries, thereby improving ease of manufacture without sacrificing shape complexity.
Solution Approach 2:
The patent inverts the conventional approach by not trying to mold the final complex shape directly, but rather by molding a simpler intermediate shape (the green part) and allowing transformation during sintering. This inversion of the manufacturing sequence—creating the complement of the desired final shape in the green state—enables the production of complex geometries using simple molds, resolving the contradiction between shape complexity and manufacturing ease.
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 enables the production of components with precise dimensional accuracy and complex geometries by controlling volume reduction, allowing for simpler and less expensive mold configurations, while maintaining the structural integrity and thermal performance required for gas turbine engine components.
Implementation Method 1
the volume reduction of the part occurring during sintering
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A method of forming a component (28) from a part (28') in the green state, includes selecting at least one first portion (44) of the part (28') to undergo a different local volume reduction from at least one second portion (46) to obtain the component. The green part (28') is provided with the first portion(s) (44) having a first solid loading and the second portion(s) (46) having a second solid loading different from the first solid loading, then debound and sintered to obtain the component (28). The different first and second solid loadings produce the different local volume reduction in the first portion(s) (44). The first portion(s) (44) can be selected by determining a resulting final shape obtained from debinding and sintering a green part (28') having a uniform first volumetric proportion of binder, and selecting the first portion(s) (44) requiring a different local deformation than that producing the resulting final shape to obtain a desired final shape.