Theory of Metal Machining Flashcards
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 distinguishes material removal processes from other manufacturing processes?
In material removal processes, material is cut away from the work part so that the remaining material has the desired part geometry
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 part geometries;
(3) it can achieve closer tolerances than most other processes;
(4) it can create good surface finishes.
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 an example of
machining operations that use each tooling type.
The two categories are
(1) single-point tools, used in operations such as turning;
(2) multiple-edge cutting tools, used in operations such as milling and drilling.
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.
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.
8 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.
What is an orthogonal cutting operation?
Orthogonal cutting uses a wedge-shaped tool in which the cutting edge is perpendicular to the direction of speed motion as the tool is forced into the work material.
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.
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 separate 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
(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.
Identify the four forces that act on the chip in orthogonal cutting but cannot be measured directly in an operation.
The four forces that act on the chip are (1) friction force at the tool-chip interface, (2) normal force to friction, (3) shear force at the shear plane, and (4) normal force to shear.
Identify the two forces that can be measured in orthogonal cutting.
The two forces that can be measured in the orthogonal cutting are
(1) cutting force in the direction of cutting speed
(2) thrust force, which is perpendicular to cutting force. Thrust force is the force that causes the cutting edge to penetrate beneath the surface of the work
What is the relationship between the coefficient of friction and the friction angle in the orthogonal cutting model?
The relationship is that the coefficient of friction is the tangent of the friction angle (µ = tan β).
Describe in words what the Merchant equation tells us
The Merchant equation states that the shear plane angle increases when rake angle is increased and friction angle is decreased.
