manufacturing-ch20

Why is the orthogonal cutting model useful in the analysis of metal machining?

. Orthogonal cutting is useful in the analysis of metal machining because it simplifies the rather complex three-dimensional machining situation to two dimensions. In addition, the tooling in the orthogonal model has only two parameters (rake angle and relief angle), which is a simpler geometry than a single-point tool.

What is a machine tool?

A machine tool can be defined as a power-driven machine that positions and moves a tool relative to the work to accomplish machining or other metal shaping process.

Explain the difference between roughing and finishing operations in machining.

A roughing operation is used to remove large amounts of material rapidly and to produce a part geometry close to the desired shape. A finishing operation follows roughing and is used to achieve the final geometry and surface finish.

What is a tool-chip thermocouple?

A tool-chip thermocouple is comprised of the tool and chip as the two dissimilar metals forming the thermocouple junction; as the tool-chip interface heats up during cutting, a small voltage is emitted from the junction that can be measured to indicate cutting temperature.

What are the three basic categories of material removal processes?

As organized in this text, the three basic categories of material removal processes are (1) conventional machining, (2) abrasive processes, and (3) nontraditional processes.

What are the parameters of a machining operation that are included within the scope of cutting conditions?

Cutting conditions include speed, feed, depth of cut, and whether or not a cutting fluid is used.

What distinguishes machining from other manufacturing processes?

In machining, material is removed from the work part so that the remaining material is the desired part geometry.

What is an orthogonal cutting operation?

Orthogonal cutting involves the use of a wedge-shaped tool in which the cutting edge is perpendicular to the direction of speed motion into the work material.

What is the specific energy in metal machining?

Specific energy is the amount of energy required to remove a unit volume of the work material.

Name and briefly describe the four types of chips that occur in metal cutting

The four types are (1) discontinuous, in which the chip is formed into separated segments; (2) continuous, in which the chip does not segment and is formed from a ductile metal; (3) continuous with built-up edge, which is the same as (2) except that friction at the tool-chip interface causes adhesion of a small portion of work material to the tool rake face, and (4) serrated, which are semi-continuous in the sense that they possess a saw-tooth appearance that is produced by a cyclical chip formation of alternating high shear strain followed by low shear strain.

6 How is the power required in a cutting operation related to the cutting force?

The power required in a cutting operation is equal to the cutting force multiplied by the cutting speed.

Identify some of the reasons why machining is commercially and technologically important.

The reasons include the following: (1) it is applicable to most materials; (2) it can produce a variety of geometries to a part; (3) it can achieve closer tolerances than most other processes; and (4) it can create good surface finishes.

What does the term size effect mean in metal cutting?

The size effect refers to the fact that the specific energy increases as the cross-sectional area of the chip (to x w in orthogonal cutting or f x d in turning) decreases

Name the three most common machining processes.

The three common machining processes are (1) turning, (2) drilling, and (3) milling

What are the two basic categories of cutting tools in machining? Give two examples of machining operations that use each of the tooling types.

The two categories are (1) single-point tools, used in operations such as turning and boring; and (2) multiple-edge cutting tools, used in operations such as milling and drilling.