Manufacturing-ch22
Identify the alternative ways by which a cutting tool is held in place during machining
There are three principal ways: (1) solid shank, in which the cutting edge is an integral part of the tool shank, an example being high speed steel tooling; (2) brazed inserts, used for some cemented carbides; and (3) mechanically clamped inserts, used for most hard tool materials including cemented carbides, coated carbides, cermets, ceramics, SPD, and CBN.
What is the physical interpretation of the parameter C in the Taylor tool life equation?
r. The parameter C is the cutting speed corresponding to a one-minute tool life. C is the speed-axis intercept on the log-log plot of the tool life data.
In addition to cutting speed, what other cutting variables are included in the expanded version of the Taylor tool life equation?
. The expanded version of the Taylor equation can include any of the following: feed, depth of cut, and/or work material hardness.
What are some of the tool life criteria used in production machining operations?
As identified in the text, tool life criteria used in production include (1) complete failure of the tool, (2) visual observation of flank or crater wear, (3) fingernail test to feel flank wear, (4) sound of the tool, (5) chip disposal problems, (6) degradation of finish, (7) power increase, (8) workpiece count, and (9) length of cutting time for the tool.
Why are ceramic cutting tools generally designed with negative rake angles?
Ceramics possess low shear and tensile strength but good compressive strength. During cutting, this combination of properties is best exploited by giving the tool a negative rake angle to load the tool in compression.
What is the difference in ingredients between steel cutting grades and nonsteel-cutting grades of cemented carbides?
In general, non-steel cutting grades contain only WC and Co. Steel cutting grades contain TiC and/or TaC in addition to WC-Co.
Identify some of the common compounds that form the thin coatings on the surface of coated carbide inserts.
The common coatings are: TiN, TiC, and Al2O3.
Identify the mechanisms by which cutting tools wear during machining
The important tool wear mechanisms are (1) abrasion, (2) adhesion, (3) diffusion, and (4) plastic deformation of the cutting edge.
Name the three modes of tool failure in machining.
The three tool failure modes are (1) fracture failure, (2) temperature failure, and (3) gradual wear.
Name the two main categories of cutting fluid according to function.
The two functional categories of cutting fluids are: (1) coolants and (2) lubricants
What are the two principal aspects of cutting-tool technology?
The two principal aspects of cutting tool technology are (1) tool material and (2) tool geometry.
Identify three desirable properties of a cutting-tool material.
Three desirable properties are (1) toughness to resist fracture failure, (2) hot hardness to resist temperature failure, and (3) wear resistance to prolong the life of the tool during gradual wear.
What are the two principal locations on a cutting tool where tool wear occurs?
Wear occurs on the top face of the cutting tool as crater wear and on the side or flank of the tool, called flank wear. Portions of flank wear are often identified separately as notch wear, corresponding to the surface of the work; and nose radius wear, corresponding to the tool point.