Mechanistic Models for Predicting the Cutting Force System and Chip Character In Drilling
 
 

Amy J. Bergstrom | MS | 1997

Manufacturers are currently attempting to reduce the amount of generated process wastes in response to the growing concern of the government and consumers for the environment. Drilling is one of the commonly used manufacturing process. In drilling operations, the process wastes are worn tools, generated chips, and used cutting fluid. While tooling and chips can be reduced or recycled, the used cutting fluid must be treated and properly disposed, both of which are costly. Reducing the amount of cutting fluid used or eliminating the cutting fluid completely is therefore desirable economically and for the environment.

To eliminate the cutting fluid from drilling processes, the operation must be fully understood, including the role of the cutting fluid in drilling. An extensive preliminary investigation was conducted to determine the effect of redusing the cutting fluid flow rates in drilling operations. Other machining parameters were also examined in an attempt to underastand the function of the cutting fluid in drilling. The results showed that more information about the formation and movement of chips in drilling process is necessary to describe the action of the cutting fluid and to possibly reduce or eliminate the fluid from the operation.

An existing mechanistic model that predicts the forces in drilling with drills of arbitary cutting edge shape is enhanced to include a minimum cutting energy model for the chip flow. The chip flow model is then extended to predict the average chip velocity and center of mass of the chip. This information about the nature of the generated chips can lead to the better design of drills, allowing for chip generation and chip movement without the assistance of cutting fluid.

Calibration of the drilling model is necessary using data gathered from orthogonal cutting operations. The model is validated in a series of drilling tests involving several drill geometries and varying feeds, speeds, and workpiece materials.

With the use of the drilling models for the chip flow, velocity, upcurl, and sidecurl, the geometry of the drill and the cutting conditions can be optimized. This can lead to the minimization or elimination of cutting fluids in the drilling operation.

If you have any comments or suggestions please e-mail jwsuther@mtu.edu.