Surface Grinding Method for Hard Brittle Materials
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Solution Overview
Problem
Conventional surface grinding methods for hard brittle materials like sapphire wafers face challenges in achieving high accuracy and machining rate due to rapid wear of grinding wheels and thermal expansion issues, leading to surface roughness and flatness deterioration.
Innovation Solution
A surface grinding method using a cup grinding wheel with a slurry containing abrasive grains, where the grinding wheel is rotated at a low peripheral speed of no more than 500 m/min and the slurry is supplied at a controlled flow rate of 1.0 to 2.0 ml/cm2/h to promote self-sharpening and maintain wheel sharpness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the grinding wheel rotates at high speed (6000 rpm) to improve machining rate, then productivity increases, but the abrasive grains cannot perform self-sharpening effectively, causing rapid wear and deterioration of grinding wheel sharpness
Solution Approach 1:
The invention changes the rotation speed parameter of the grinding wheel from conventional high speed (6000 rpm) to low speed (30-430 rpm). This parameter change enables the abrasive grains to perform self-sharpening effectively while maintaining acceptable productivity, resolving the contradiction between machining rate and wheel sharpness maintenance
Solution Approach 2:
The invention introduces slurry as an intermediary substance that facilitates the self-sharpening process. The slurry contains abrasive grains that interact with the grinding wheel surface, promoting continuous sharpness maintenance even at low rotation speeds, thus enabling both acceptable productivity and sustained wheel sharpness
2Productivity
If the grinding wheel is fed strongly with high rigidity machine to improve machining rate, then productivity increases, but wear of abrasive grains advances quickly, causing rapid deterioration of grinding wheel surface
Solution Approach 1:
The invention changes the feeding force parameter by operating at low rotation speeds, which reduces the impact loads and wear rates on abrasive grains. This allows for sustained grinding wheel service life while maintaining acceptable productivity through continuous self-sharpening
Solution Approach 2:
The invention enables the grinding wheel to self-shARPEN through the interaction of abrasive grains in the slurry with the wheel surface. This self-service mechanism continuously restores sharpness without external intervention, extending the grinding wheel's effective service life during operation
3Productivity
If the grinding wheel rotates at high speed to improve machining rate, then productivity increases, but heat generation in workpiece and chuck becomes large, causing thermal expansion and deterioration of flatness (TTV)
Solution Approach 1:
The invention changes the rotation speed parameter from high to low (30-430 rpm), which directly reduces the heat generation during grinding. This parameter change maintains acceptable productivity while preventing excessive temperature rise and thermal expansion that would deteriorate workpiece flatness
4Manufacturing precision
If a fine-grained grinding wheel (#1500 or more) is used to improve surface roughness, then manufacturing precision increases, but the wheel becomes unfit quickly with slight change in machining conditions, causing low productivity
Solution Approach 1:
The invention changes the rotation speed parameter to low speed (30-430 rpm), which allows fine-grained wheels (#1500 or more) to maintain their sharpness and effectiveness for extended periods. This enables the use of fine wheels for high surface quality without the rapid deterioration that would otherwise limit productivity
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 method significantly improves machining accuracy and rate for hard brittle materials by reducing wear and thermal issues, maintaining grinding wheel sharpness, and preventing brittle fractures, resulting in improved surface roughness and flatness.
Implementation Method 1
supplying a slurry containing abrasive grains... promotes self-sharpening of the grinding wheel by the abrasive grains within the fluid of the slurry
Implementation Method 2
the high speed rotation of the dull abrasive grains of the grinding wheel causes... heat generation in the workpiece and a chuck during the grinding becomes large
Data Source
AI summary
[Problem] To machine a workpiece such as a hard brittle material or difficult-to-cut material innovatively and accurately and to improve the machining rate significantly.[Solution Means] In grinding a workpiece W by a cup grinding wheel 3 while supplying a slurry 5 containing abrasive grains, the grinding wheel 3 is rotated at low peripheral speed. No more than 500 m/min., preferably 30 to 430 m/min., is appropriate for the peripheral speed of the grinding wheel 3. The slurry 5 at a flow rate of no more than 4.0 ml/cm2/h, preferably of 1.0 to 2.0 ml/cm2/h is dropped or sprayed little by little onto a ground surface of the workpiece W.