In Fig. 12.73, the profile angle is the angle formed by the sides of the nose of the tool (or by the cutting edge and the following or relief edge); the front rake is the amount of slope from the cutting edge back towards the body or shank of the tool; the side rake is the side slope given to [...]
The behaviour of chip on rake face of the tool caught the attention of many investigators because it was found that the value of coefficient of friction at tool chip interface is very high. It has been established that the normal stress on the interface due to the cutting force reaches such a high value that yielding occurs and the [...]
The following points highlight the top five theories on mechanics of metal cutting in the industries. The theories are: 1. Ernst-Merchant Theory 2. Merchant Theory 3. Stabler Theory 4. Lee and Shaffer Theory. 1. Ernst-Merchant Theory: According to this theory: This is based on the assumptions: (i) That expenditure is minimum in the process, i.e., shear will take plane in [...]
Under normal conditions with high speed steel tools and comparatively low cutting speeds the continuous chips from a piece of cutting metal are seldom dangerous provided they are controlled and directed by suitable front and side rakes. When turning operation is being carried out at very high speed, then the hot sharp-edged cuttings are liable to become dangerous and it [...]
In this article we will discuss about the elements and observation of cutting process of metals in the industries. Elements of Cutting Process (Mechanics of Metal Cutting): Any cutting process involves work-piece, tool (including holding devices), chips and cutting fluid. For removing the metal, wedge shaped tool is constrained to move relative to the work-piece so that it removes the [...]
The following points highlight the six main factors affecting metal cutting in the Industries. The factors are: 1. Velocity 2. Size of Cut 3. Tool Geometry 4. Tool Material 5. Ductile Materials 6. Forces Involved in Metal Cutting. Factor # 1. Velocity: It directly affects the temperature at tool point. If velocity is so low that the temperature at tool [...]
For metal cutting to be effective, it is necessary that tool takes the form of a large angled wedge. This tool must be driven asymmetrically into the work material, to remove a thin layer from a thicker body. The layer removed must be thin so that imposed stress on tool and work is within limits. Further a clearance angle must [...]
The following points highlight the four main types of chips formed during metal cutting. The types are: 1. Discontinuous Chip 2. Continuous Chip 3. Continuous Chip with Built Up Edge 4. Inhomogeneous Strain-Chip. Type # 1. Discontinuous Chip: These chips are small segments which adhere loosely to each other and form slightly larger length. Discontinuous chips are formed when the [...]
In this article we will discuss about the meaning and geometry of chip formation from metals in the industries. Meaning of Chip-Formation: In any machining operation, the material is removed from the workpiece in the form of chips, the nature of which differs from operation to operation. As the form and dimensions of a chip from any process can reveal [...]
The following are the characteristics of strain rings: i. Strain-rings provide high ratio of sensitivity to stiffness at the same time having adequate stability against buckling. ii. A ring can be easily produced and is simple to mount. iii. The fact that the inside is always in an opposite state of strain from the outside, allows four active arms to [...]