Application of a coherent jet coolant system in creep-feed grinding of Inconel 718

The objective of the work described in this report is to reduce the occurrence of workpiece burn when creep-feed grinding Inconel 718. Workpiece burn is a form of thermal damage to the workpiece that renders it unusable. Burn is caused by high temperatures generated in the grinding zone by excessive material removal rates.;The necessary design changes to a Blohm Planomat 408 grinding machine to achieve a greater degree of jet coherency, and their implementation, are described. It was found that the coolant system design changes produced a jet that was 5 times more coherent than the original system.;An experimental procedure used to evaluate the design changes was developed. The experimental procedure incorporated sloped workpieces and grinding wheel spindle power measurements. The spindle power measurements indicate the occurrence and location of workpiece burn during a grinding pass. The material removal rate at the time of workpiece burn was then calculated based on the depth of cut at the instant workpiece burn was detected.;Using the experimental procedure it was found that the new coolant system results in a 61% higher achievable material removal rate before workpiece burn occurs in comparison to the original coolant system. It was also found that the position and orientation of the coherent jet does not affect the cooling performance as long as the jet is aimed at the area of contact between wheel and workpiece.;The report provides a literature survey identifying possible coolant system improvements and how such improvements may be evaluated. The principle of jet coherency was selected as the best coolant system improvement to be made to a conventional coolant delivery system. Jet coherency is the degree to which the coolant jet disperses with distance from the nozzle exit. A more coherent jet is said to be more readily aimed at a specific target, entrains less air and will direct a greater percentage of the applied coolant at the desired area.