Micro-EDM Metrology for Non-Destructive Microstructure Measurement
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Solution Overview
Problem
Current metrology systems for measuring microstructures are limited by their need for surface contact, which can cause damage and require expensive, fragile sensors, and are often ineffective in machining environments with oils and residues, leading to high scrap rates and material waste.
Innovation Solution
A micro-electrical discharge machine (µEDM) based metrology system operating at pico-joule energy levels, using a non-contact, non-destructive method with a reliable spindle probe and sensing circuit that moves in multiple dimensions, capable of self-manufacturing probes and operating within existing EDM machines, to measure micro-sized components without material removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tactile sensors are used for measurement, then measurement precision can be achieved, but the sensors are fragile and have limited measurement scope
Solution Approach 1:
The patent replaces the mechanical tactile sensing system with an electrical discharge-based sensing system. Instead of using physical contact between a tactile probe and the workpiece, the system uses controlled electrical discharges (sparks) to detect the position and dimensions of the workpiece. This substitution eliminates the mechanical wear and fragility issues while maintaining measurement precision through electrical field interaction.
2Ease of operation
If surface contact measurement is used, then measurement can be performed, but witness marks and scratches are left on the part surface
Solution Approach 1:
The patent replaces mechanical surface contact with electrical discharge interaction. The sensing probe creates controlled electrical fields that interact with the conductive workpiece surface without physical contact. The electrical discharges occur in the air gap between the probe and workpiece, allowing measurement of surface position and dimensions without leaving mechanical marks or scratches on the measured surface.
3Measurement precision
If conventional EDM energy levels are used for sensing, then sensing can occur, but material erosion and surface deformation result
Solution Approach 1:
The patent fundamentally changes the energy parameters of the electrical discharge sensing process. Instead of using conventional EDM energy levels that cause material erosion, the system operates at pico-joule energy levels with carefully controlled voltage and current parameters. This parameter optimization allows the electrical discharges to provide sufficient sensing signal while being too low in energy to cause significant material removal or surface deformation, thus maintaining both sensing capability and surface integrity.
4Measurement precision
If parts are removed from the machining platform for measurement, then measurement can be performed, but repositioning accuracy is lost
Solution Approach 1:
The patent merges the machining function and measurement function into a single integrated system. The electrical discharge sensing probe is incorporated directly into the EDM machining platform, allowing both material removal and dimensional measurement to occur in the same coordinate system without part removal. This integration eliminates the time-consuming repositioning step while maintaining measurement precision through the shared reference framework of the machining platform.
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 system enables precise, non-destructive measurement of micro-sized components, reducing scrap rates and material waste, while being resistant to machining residues and oils, with minimal surface deformation and high repeatability, allowing for in-process quality assurance and control.
Implementation Method 1
as a gap between the work piece and the spindle probe becomes sufficiently small a dielectric breakdown occurs and the sensing circuit detects a current flux due to the dielectric breakdown
Data Source
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Figure 2
Figure 3~4.7
AI summary
A micro-electrical discharge machine based metrology system including a control unit with a sensing circuit and a micro -electrical discharge machine with a sensing probe. The micro -electrical discharge machine based metrology system capable of sensing dimensions of a work piece at pico-joule energy levels. The micro-electrical discharge machine based metrology system is a non-contact, non-destructive, and on-board metrology system capable of in-process quality assurance/quality control.