Suggested Areas of Focus
Basic Technology Strategy
These proposed project areas are based on connecting the topography of the grinding wheel with the process and performance.
Successful completion of these projects substantially relies on methods for measuring abrasive media in the lab. Because of that, the Abrasive Process Lab's partnership with the Surface Metrology Lab is an important factor as we have been measuring abrasive media for a number of years.
Industrial Partner Involvement
The steering committee, made up of industrial partners, would create then select the projects and assign the resources to the projects. Engineers from the partner companies would be industrial advisors to the projects and would receive weekly emails with up dates. Updates could also be posted on the project web site so any of the partners could see the weekly updates. Web meetings and conference calls are scheduled as the participants: partners, students and professors feel appropriate.
All of these projects should result in improvements in productivity.
Abrasive Textures and Performance.
The objective of this work would be to establish correlations between the measured abrasive texture and the abrasive performance, i.e., sharpness, chip capacity and coolant capacity. The theory we would like to test is that the abrasive performance is related to geometric properties over a particular scale range. The sharpness should be related to the relative area, and that the chip and coolant carrying capacities related to the volume filling fraction.
The results of this work would support the design of better abrasive media and dressing techniques. It is largely the fine scale texture of the abrasive media that is responsible for creating chips or plowing, and for carrying chips out of the cutting zone and coolant into the cutting zone. Understanding the relation between the geometric features and the performance will avoid the use of cutting tests to verify performance. Experimental development of abrasive media and dressing methods will be shortened because grinding tests could be reduced by the ability to predict performance based on texture measurements. The knowledge of this correlation, combined with in-process wheel measurement, could be used to improve process control.
Workpiece Surface Texture and the Abrasive Texture and Process
The objective of this work would be to establish correlations between the ground or abraded surface texture and the abrasive media texture and the grinding process. This correlation should depend on the abrasive texture, as well as the abrasive process parameters and the workpiece material. There are clearly many of the latter. A simple one-to-one relationship does not exist. The normal force or stress in the contact zone, the time of sparkout, the difference in curvature of the two bodies, the wheel and work speeds and the wheel hardness (amount of bond) all are known to influence ground surface textures. Our intent would be to first isolate the wheel texture and then systematically investigate the influence of the other parameters.
The results of this work would support process, and abrasive designs that would improve the control of the workpiece surface texture. Experimental development of the abrasive and of the dressing process would be facilitated by being able to predict the resulting surface finish without actually producing it. The knowledge of this correlation, combined with in-process wheel measurement, could be used to improve process control.
Abrasive Texture and the Dressing Process
The objective of this work would be to establish the correlations between the abrasive texture and the dressing process.
The results of this work would support the design of the dressing process to optimize the wheel texture. Combined with the results of the above projects, this project would allow us to make predictions about the abrasive performance and workpiece surface texture from the dressing process.
In-process Measurement of Texture and Form
The objective of this work would be to develop the equipment and methods for making measurements of the abrasive media and the workpiece during the process.
The results of this work would allow for maintaining tighter tolerances on the form and finish. It would allow for optimization of the process and would allow for corrections to the process to be made during the process. It could also be used to trigger dressing.
CBN handbook and Courses
The objective is to provide up-to-date information on the use of CBN abrasives. This would be an electronic handbook that would be easily searchable and frequently updated.
The handbook would contain information for users so that they can better understand and optimize CBN abrasive technologies.
The objective of this work would be to find the best ways to exploit the potential of acoustic emissions to provide information on the abrasive process.
This technology provides process control.
Diamond roll dressing.
The objective of this work is to learn how to better optimize the process of diamond roll dressing.
There appears to be some excellent potential to improve this process, as there is little evidence in the literature that anyone has studied it in depth.
This is an active project at WPI, part of a senior thesis, and has been continuing with the involvement of several graduate students under the guidance of the legendary Bob Hahn http://www.aspe.net/about/awards.html#hahn and NAE. The project has provided material for one master's thesis and two papers, one is currently out for review after revisions and the other is in progress.
Findings to date
We have identified the existence of threshold forces in dressing. That is there are conditions where, should the contact forces between the dressing roll and the grinding wheel be light enough, no material will be removed. Our results suggest that three regimes with the current diamond roll dressing set-up on Bob Hahn's control force machine. One is below the threshold, with apparently no dressing, another is dressing with relative lower removal rates, i.e., lower removal-force ratios. This occurs at low feed rates. Then there is another at higher feed rates where we observed higher removal-force ratios. The first regime is somewhat speculative, as based on extrapolation of the force-removal results in the second. Further work would be needed to demonstrate this directly. We have also found that the texture of the dressed wheel varies between some of the dressing feed rates.
The consequences are that dressing in the first and second regimes can produce wheels that are larger than expected, resulting in ground parts that are the wrong size. And, since the texture of the grinding wheel may not be what is expected, the temperatures generated during the grind may be different than expected as well, so that the surface integrity can be influenced.
The work also raises concerns that the beneficial effects of dressing could be reduced during the retraction of the diamond roll. Current work is looking at the influence of the dwell time on the wheel texture.
Impact on the Factory Floor
The results of this work can be applied to improving the quality of parts made after diamond roll dressing. It can also be used to optimize the dressing process, possibly extending wheel life.
Research would be done on the factory floor to link the laboratory results with practice. The factory floor research would include looking for patterns in part quality associated with the dressing cycles, and measuring wheel diameters. Discovery of patterns in dimensions, surface quality, and wheel dimensions for understanding optimization could require observations over periods of the life of the grinding wheel. Once patterns are understood the compensation for wheel wear in between dressing can be adjusted appropriately.
This understanding could be also combined with sensor development to provide in-process information on the quality of the dressing.
The advanced understanding of diamond roll dressing could extend the life of the grinding wheel, reduce cycle times, reduce the dressing time, provide sharper wheels, and reduce the scrap and variation in the product.
Last modified: Jun 30, 2006, 15:45 EDT