CUTTING TOOL GEOMETRY Mach 122 Abrasive Machining CUTTING

CUTTING TOOL GEOMETRY Mach: 122: Abrasive Machining

CUTTING TOOLS FOR THE LATHE Cutting Tool Geometry The most important aspect of a lathe tool is its geometric form: � Side & back rake. � Front & side clearance or relief angles. � Chip breakers. The tool shank is that part held by the toolholder. Fig. I-78 The parts and angles of a tool.

CUTTING TOOLS FOR THE LATHE Cutting Tool Geometry The side rake directs chip flow away from the point of cut & provides for a keen cutting edge. � Rake is important to smooth chip flow, for a uniform chip & good finish, especially in soft materials. Grinding a tool provides a sharp cutting edge & the shape needed for the cutting operation. Fig. I-78 The parts and angles of a tool.

CUTTING TOOLS FOR THE LATHE Cutting Tool Geometry The end relief angle prevents the front edge of the tool from rubbing on the work. • The side relief angle provides cutting action by allowing the tool to feed into the work material. Fig. I-78 The parts and angles of a tool.

CUTTING TOOLS FOR THE LATHE Cutting Tool Geometry The side cutting edge angle may vary considerably. � For roughing, it should about 5 degrees. squaring shoulders or other light machining angles range 5 to 32 degrees. Fig. I-78 The parts and angles of a tool.

CUTTING TOOLS FOR THE LATHE Cutting Tool Geometry Nose radius varies according to the finish required. The smallest nose radius that will give the desired finish should be used. Fig. I-78 The parts and angles of a tool.

CUTTING TOOLS FOR THE LATHE Cutting Tool Geometry tab In finishing operations with a large nose radius and a light cut, SCEA is not an important factor. � SCEA directs cutting forces back into a stronger section of the tool point & helps direct chip flow away from the workpiece. � It also affects the thickness of the cut. Fig. I-79 Change in chip width with an increase of the side cutting edge angle. A large SCEA can cause chatter.

CUTTING TOOLS FOR THE LATHE Cutting Tool Geometry tab Left-hand tools are shaped just the opposite of righthand tools. � The right-hand tool has the cutting edge on the left side and cuts to the left or toward the headstock. Fig. I-80 Left- and right-hand roughing tools.