Cutting Tool Geometry MoManufacturingWINs Precision Machining Technology ME 100 – Measurement, Materials & Safety

Cutting Tool Geometry Cutting Tool geometry and how To grind a High Speed Steel blank For turning. This is a depiction of a high speed Steel blank. They come in various Sizes usually ¼ or 5/16 square. Definition:  The term `high speed steel' was derived from the fact that it is capable of cutting metal at a much higher rate than carbon tool steel and continues to cut and retain its hardness even when the point of the tool is heated to a low red temperature. Tungsten is the major alloying element but it is also combined with molybdenum, vanadium and cobalt in varying amounts.

Grinding a tool bit is Usually done on an Ordinary pedestal grinder Fitted out with a rest set At about 7 degrees. It Doesn’t matter if the support Is above or below the Centerline of the wheel As long as it’s set at 7 Degrees with respect to a line passing through The center of the wheel.

You will be Grinding three Sides on the Bit. Since each Side has two Angles (compound Angles) there Are a total of Six angles that Have to be Considered as You are grinding.

First you will grind the “side cutting edge angle” and the “Side relief angle” Refer To the previous page or the Machineries Handbook for angles depending on the Material you will be cutting. The side cutting edge angle Provides for gradual Entrance of the tool into the Stock. The side relief angle prevents The flank of the tool from Rubbing the stock and Generating excessive heat. This is one of two angles Required in order for the tool To cut at all.

Next you will grind the “Nose angle” And “End relief angle”. The Nose angle Allows the tool to be plunged into the Stock and when swiveled to the left To take light cuts close to the chuck Or to turn to a shoulder. The end relief Allows the tool to be plunged into the Stock and prevents the end of the Tool from rubbing and generating Excessive heat. This is the other angle that is required In order for the tool to cut.

The side angle and Back rake angle Are ground together. The side rake Provides a keener cutting edge. The back rake permits the chips to Flow away from the point of the tool

Grind a radius on the edge between the side (side #1) and nose (side #2). The radius you use Will depend on the purpose of the bit. The larger the radius the better the Surface finish but you also run the risk of machine chatter. Generally use less Radius on lighter machines. Carbide tools and even rotary tools use Different angles but the principals are the Same. When working around grinders it is an absolute necessity to wear EYE PROTECTION. Grinding debris is thrown out at high velocities and can damage not only eyes, but also expensive glasses. Wear safety glasses or a full face shield.

Tool bits can be ground for specific applications Tool bits can be ground for specific applications. The description above was for Grinding a general purpose, right hand, tool bit. The images below show some Of the other varieties. This workforce solution was funded by a grant awarded by the U.S. Department of Labor’s Employment and Training Administration. The solution was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership. This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.