Optimization Device for Grinding Media Performance Parameters

The investment casting industry relies heavily on the use of grinding media during manufacturing. Typically, grinding media, when used in this application, have very short effective lifetimes. Determining the optimum life of grinding media is a key cost-containment and manufacturing-efficiency issue. However, current methods for determining optimum life as well as evaluating new grinding media products and optimum operating parameters are highly subjective and often is a matter of operator opinion. This subjectivity can lead to the premature retirement or overuse of grinding media, increasing cost and decreasing efficiency. A means of objectively and efficiently evaluating grinding media for optimum life and operating conditions, as well as evaluating new grinding-media products is needed. The approach taken in this work is to create a relatively low-cost test apparatus that uses grinding equipment, media, and specimens typically seen in the casting industry and measures key parameters. Also, the apparatus produces the fundamental motions and application forces typical of human operators. The resulting apparatus simultaneously moves a specimen in three orthogonal directions while applying a user-defined grinding force. Applied force, electric power input, grinding-motor rotational speed, test-specimen surface temperature and material removal are recorded. All operations of the device are autonomously performed through LabVIEW. The apparatus was constructed using standard commercial products for less than $15,000. Data comparing applied load versus material removal rate, surface temperature, and total material removed can be collected for different materials and grinding media. The device has been used to grind inconel specimens subjected to 10 to 70 pounds (45–312 N) of contact force corresponding to material removal rates of 0.26 to 5.26 grams/s at temperature changes of 90 to 210 degrees Fahrenheit (32.2–98.9 degrees Celsius). This data was used to determine a correlation between changes in performance parameters and a drop in material removal rate, total material removed, and belt life. No significant difference was found between the material removal rate of saw-cut and flame-cut Inconel specimens, dispelling a commonly held belief. Knowing key parameters that identify the effective lifetime of grinding media is significant to the casting industry. Methods described in this paper can be used to optimize grinding media life and determine optimum operating parameters.