Molded Support Structure for Sintering Greenbody Misalignment
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Solution Overview
Problem
During the sintering process of greenbodies, differential shrinkage between sections can lead to misalignment and deformation of casted products, necessitating costly secondary straightening operations and reducing product yield.
Innovation Solution
Incorporating a molded support structure that orients the greenbody to prevent misalignment between bulk and tail portions, with a mass and cross-sectional area ratio between 0.1 to 0.3, and using a pouring cup structure to distribute mass evenly, thereby stabilizing the product during densification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If greenbody sections with differential cross-sectional areas are fired, then sintering densification occurs, but differential shrinkage causes misalignment and deformation
Solution Approach 1:
A support structure with controlled mass (cross-sectional area ratio of 0.1 to 0.3 between tail and bulk portions) is integrated into the greenbody to counterbalance differential shrinkage forces during sintering. The support structure acts as a counterweight that compensates for the unequal mass distribution, preventing misalignment and deformation of the tail portion relative to the bulk portion.
Solution Approach 2:
The support structure is pre-formed and integrated into the greenbody before sintering occurs. This preliminary action ensures that the counterbalancing mass is already in position to prevent differential shrinkage effects during the densification process, rather than attempting to correct alignment after deformation occurs.
2Manufacturing precision
If secondary straightening operations are performed to correct misalignment, then shape defects are addressed, but production time and cost increase
Solution Approach 1:
The support structure is pre-formed and integrated into the greenbody before sintering occurs. This preliminary action ensures that the counterbalancing mass is already in position to prevent differential shrinkage effects during the densification process, rather than attempting to correct alignment after deformation occurs.
Solution Approach 2:
The invention converts the harmful effect of differential shrinkage into a beneficial outcome by using the support structure's controlled mass ratio (0.1 to 0.3) to create a counterbalancing effect. The very mass difference that causes shrinkage problems is transformed into a solution that prevents misalignment, eliminating the need for secondary straightening operations.
3Strength
If extensions are supported by connection to a body during firing, then structural integrity is maintained, but gravitational forces cause misshapening of extensions
Solution Approach 1:
The support structure with controlled mass ratio (0.1 to 0.3 between tail and bulk portions) acts as a counterweight that compensates for gravitational forces acting on extensions during firing. By positioning this counterbalancing mass strategically, the greenbody achieves better weight distribution that prevents extensions from sagging or deforming under gravity while maintaining structural integrity.
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 reduces the need for secondary straightening operations, minimizing tailwag and camber misalignment, resulting in more precise and cost-effective production of casted medical device parts with reduced deformation.
Implementation Method 1
During the heating and densification, the greenbody has a tendency to shrink
Implementation Method 2
sections of a greenbody that are extensions supported by a connection to a body can become misshapen during firing due to gravitational forces acting on the extension
Data Source
AI summary
Structures and methods for hindering molded part deformation during densification are discussed. Such devices and techniques can help alleviate stresses that tend to result in part deformation during firing, sintering, or other densification processes, and thus reduce the need for secondary straightening operations post-densification. In some instances, a support structure is utilized to orient a molded greenbody in a preferred direction to reduce deformation during firing (e.g., orienting a thin tail section is a plane parallel to the direction of gravity). The support structure can also be part of, or the entirety of, a thermal mass to help alleviate stresses that lead to part deformation. Though such structures and methods can be used for any molded piece, it can be particularly used to create a portion, or an entirety of, a medical device such as a jaw of an surgical instrument.