EDM Fixture 3-2-1 Contacts for Rough AM Workpiece Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Additively manufactured workpieces with rough surfaces, such as those made from nickel-based steel alloys, pose challenges during electrostatic discharge machining (EDM) due to reduced effective electrical separation and increased wear on EDM fixtures, leading to arcing and reduced precision in material removal operations.
Innovation Solution
An EDM fixture with a 3-2-1 alignment system comprising electrically conductive face contacts and electrically resistive point contacts, where the point contacts are made from ceramic materials with higher hardness and resistivity than the face contacts, is used to support and locate additively manufactured workpieces, ensuring effective electrical separation and minimizing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EDM fixtures are used with additively manufactured workpieces, then the workpiece can be supported during EDM operation, but the rough surface of the workpiece causes reduced effective electrical separation leading to arcing between the workpiece and fixture
Solution Approach 1:
The patent introduces dielectric material as an intermediary between the rough workpiece surface and the fixture contacts. This dielectric layer maintains adequate electrical separation even when the rough surface creates variable gaps, preventing arcing while still allowing mechanical contact for positioning. The dielectric material acts as a mediator that decouples the mechanical support function from the electrical isolation requirement.
2Reliability
If conventional EDM fixtures are used with additively manufactured workpieces, then the workpiece can be supported during EDM operation, but the rough surface of the workpiece increases wear on the fixture, reducing positioning precision
Solution Approach 1:
The patent changes the material parameters of the fixture contacts by using hardened materials or coatings with higher wear resistance. This allows the contacts to withstand the increased wear from rough additively manufactured surfaces while maintaining their dimensional stability and positioning precision over extended use. The parameter change in material hardness directly addresses both durability and precision requirements.
3Ease of manufacture
If the workpiece surface is left rough from additive manufacturing, then the article can be removed from the build plate using EDM, but the rough surface reduces effective electrical separation and causes arcing
Solution Approach 1:
The patent segments the contact interface into multiple discrete contact points rather than a continuous surface. This segmentation allows each contact point to accommodate surface irregularities independently, maintaining reliable electrical separation even with rough workpiece surfaces. The discrete contacts reduce the cumulative effect of surface roughness on electrical isolation.
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 reduces arcing and maintains precision in EDM operations by providing adequate electrical separation and wear resistance, thereby improving the accuracy and reliability of material removal from additively manufactured workpieces.
Implementation Method 1
two or more electrically resistive point contacts seated in the fixture body... The material forming the point contacts can have electrical resistivity that is greater than the material forming the face contacts
Implementation Method 2
electrostatic discharge machining (EDM)... it can be necessary to use an electrostatic discharge machining (EDM) to separate the article from an underlying build plate
Data Source
AI summary
An electrostatic discharge machining fixture includes a fixture body, two or more electrically conductive face contacts seated in the fixture body, and two or more electrically resistive point contacts seated in the fixture body. The electrically conductive face contacts and the electrically resistive point contacts define a 3-2-1 alignment system to locate an additively manufactured article relative to the fixture body during an electrostatic discharge machining operation. Electrostatic discharge machining arrangements and methods of supporting additively manufactured workpieces during electrostatic discharge machining operations are also described.