RECENT PROJECTS

Cost effective machining of ceramics

As with almost all manufacturing processes, there is frequently a tradeoff between cost and quality when ceramic components are ground. Quality indicators include surface texture, dimensional accuracy, mechanical properties and uniformity of physical appearance. Unfortunately, parts with uniformly smooth, fine surface finishes, precise geometry and high mechanical strength are usually the most expensive to produce. Our staff is experienced in optimizing the grinding process to achieve high quality at reasonable cost. This is usually accomplished by judicious selection of the proper grinding wheel, grinding method, coolant type and the various grinding parameters that control the process.

Grindability studies

The ease with which a specific ceramic material can be ground is an important factor in determining the overall manufacturing cost. Similar materials may have vastly different grindability. Our staff has specialized equipment for determining the relative grindability of materials. Grindability can often be improved by making simple changes in the grinding process. Because our equipment is fully instrumented, it is possible to see immediately the effect of changes in grinding parameters such as wheel speed, grit size and feed rate.

Material removal rate and Grinding ratio studies

Grinding ratio is defined as the volume of workpiece material removed divided by the volume of wheel material removed during a grinding process. The grinding ratio and material removal rate are two key factors that determine the cost of manufacture. Grinding ratio is difficult to measure in a laboratory setting because the volumes of materials removed are generally very small. However, our staff has devised a simple and effective method for determining grinding ratios.

Grinding wheel condition studies

An experiment was conducted recently to determine how the mechanical properties of ground components are influenced by the use of a worn diamond grinding wheel. A wheel that had been pre-conditioned to simulate various states of wear (freshly dressed, slightly worn, severely worn, etc.) was used to grind modulus-of-rupture (MOR) bars, which were subsequently tested for strength. To achieve each of the required wear conditions, the test wheel was deliberately worn by aggressively grinding a predetermined volume of silicon nitride material. Information obtained during the experiment is being used to improve our understanding of how abrasive particles wear, and to develop real-time methods for determining when a worn wheel should be re-dressed.

Precision dimensional and surface texture measurement capability

Many of the studies performed by our guest researchers require that the geometry and surface texture of specimens be measured very accurately "before and after" the experiment. Frequently, this is done to determine material removal rates or grinding ratios for specific materials and machining conditions. Other experimenters have been interested in determining accurate shrinkage rates due to a sintering process.

Correlation of grinding process variables with mechanical properties

Because our staff works very closely with the Mechanical Characterization and Analysis User Center it is easy to correlate the effect of the grinding process on the mechanical properties of the material being tested. Guest researchers also have convenient access to Material Properties, Physical Properties, Diffraction, and Residual Stress User Centers, all under one roof at the High Temperature Materials Laboratory.

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Last modified on December 04, 2003 .

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