Cutting Variables 200

This class describes some of the variables that impact common machining operations. Includes an Interactive Lab.

Class Details

Class Name:
Cutting Variables 200
This class describes some of the variables that impact common machining operations. Includes an Interactive Lab.
Number of Lessons:
Additional Language:
Spanish, Chinese
Related 2.0 Class:
Basic Cutting Theory 201

Class Outline

  • Objectives
  • What Is Machinability?
  • Machinability, Cost, and Quality
  • Machinability Ratings
  • Variables Affecting Machinability
  • Effect of Strength and Hardness
  • Effect of Work Hardening
  • Additives
  • Tool and Material Chemistry
  • Distinguishing Cutting Variables
  • Cutting Variables for Turning
  • Cutting Variables for Milling
  • Cutting Variables for Drilling
  • Comparing Cutting Variables
  • Reducing Tool Wear
  • Selection of Cutting Variables
  • Summary


  • Define machinability.
  • Describe how machinability impacts cost.
  • Describe machinability ratings.
  • Describe the variables that affect machinability.
  • Explain the effect of strength and hardness on machinability.
  • Explain how work hardening impacts machinability.
  • Describe how additives affect machinability.
  • Describe tool and workpiece compatibility.
  • Define speed.
  • Define feed.
  • Define depth of cut.
  • Identify cutting variables for turning.
  • Identify cutting variables for milling.
  • Identify cutting variables for drilling.
  • Distinguish between the cutting variables of turning, milling, and drilling.
  • Describe the common causes of tool wear.
  • Describe the selection of cutting variables.



Vocabulary Term Definition
1020 steel A particular grade of plain carbon steel that contains 0.20% carbon. 1020 steel has approximately a 0.65 machinability rating.
abrasion The physical wearing away of material through friction.
additive A substance that has been intentionally added to a metal to improve its properties.
B-1112 A particular grade of steel that acts as the norm for machinability ratings. B-1112 steel has a 1.00 machinability rating.
bismuth A white, brittle metal with a pinkish tinge that is added to steel to improve machinability.
brasses A nonferrous alloy containing copper and zinc.
carbide insert A cutting bit made of hard material that has multiple cutting edges. Once a cutting edge is excessively worn, it can be indexed to another edge, or the insert can be replaced.
case hardening The heating of a metal within a carbon-rich environment to increase carbon levels on the metal surface. Case hardening creates a hardened exterior shell.
chipping Tool wear resulting in the loss of small slivers from the cutting edge of the tool. Chipping is often caused by an excessive feed.
cold working The shaping of metal below its recrystallization temperature. Steel is cold worked at room temperature.
crater wear Tool wear that creates a concave depression in the face of the cutting tool above the cutting edge.
depth of cut The thickness of material removed by one pass of the cutting tool.
diamond A special formation of carbon that is the hardest known substance.
diffusion The wearing away of material due to the exchange of atoms.
ductile Able to be drawn, stretched, or formed without breaking.
feed The rate that the cutting tool as a whole travels along the surface of the workpiece.
flank wear Tool wear resulting in the gradual wearing away of the cutting edge. Flank wear is mostly caused by abrasion, and it is the most desired form of tool wear.
free-machining steel A particular grade of steel that has small amounts of additional alloying elements to improve machinability.
hardness The ability of a metal to resist scratching and penetration.
inclusion A substance that is unintentionally present in a metal and that often has undesirable properties.
lead A bluish white metal that is very soft and ductile. Though lead can be added to steel to improve machinability, it is less desirable because of the risk of lead poisoning.
machinability The relative ease with which material can be removed from metal by machine processes such as cutting or grinding.
machining The process of removing metal to form or finish a part, either with traditional methods like turning, drilling, milling, and grinding, or with less traditional methods that use electricity or ultrasound.
speed The rate at which the cutting edge of the tool moves past the workpiece surface at the point of contact. For turning, speed describes the rotation of the workpiece. For milling and drilling, speed describes the rotation of the cutting tool.
spindle The part of the machine tool that spins. On the mill, the spindle holds a cutting tool. On the lathe, the spindle holds the workpiece.
strength The ability of a metal to resist forces that attempt to break or deform the metal.
sulfur A pale, yellow, brittle element that is added to steel in order to improve machinability.
superalloy An alloy consisting of numerous alloying elements that is very expensive and designed to exhibit certain mechanical properties at elevated temperatures.
tool failure The point at which a cutting tool is no longer useful for machining. Flank wear, chipping, and cratering all eventually lead to tool failure.
tool life The length of time that a cutting tool can function properly before it begins to fail.
tool wear The rate at which the cutting edge of a tool wears away during machining.
work hardening The hardening of a metal that occurs due to the bending or shaping of a metal.