Ultimate objecting of machining is to give intended shape, size and finish by gradually removing material from workpiece. Relevant steps such as removal of material, setting the job and cutting tool, and dispatching the machined job consume substantial amount of time, which are at least not negligible. For effective planning of the entire production, overall machining or cutting time must be incorporated. Now-a-days the primary goal of industries is to manufacture the product at a faster rate but at minimal cost and that too without sacrificing product quality. As long as conventional machining is utilized, in order to fulfill first requirement faster production rate , the cutting speed and feed rate should have to be increased.

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What is Clearance Angle in Cutting Tool? Its Derivative, Value, and Function Geometry, orientation and material of the cutting tool are the three important factors that determine ease and performance of machining machinability. Geometry of cutting tool consists of rake angles, clearance angles, auxiliary clearance angles, cutting angles and nose radius.

All these angles basically express orientation of various surfaces of a turning tool. The three important surfaces of a single point turning tool SPTT are: Rake surface—chip flowing surface. Schematic representation of single point turning tool SPTT that depicts various tool point surfaces. The inclination of this principal flank surface is expressed with the help of clearance angles. Similarly, inclination of auxiliary flank surface is expresses by auxiliary clearance angles. Orthogonal clearance angle of a turning tool is schematically represented here.

Various names of clearance angles Depending on the plane on which it is projected and measured, clearance angle have various names. Various systems use various names. Commonly used variants of clearance angle along with their definition are enlisted below. It is used in ASA system of tool designation.

It is also used in ASA system of tool designation. In turning, cutting plane is the plane that contains cutting velocity vector. It is used in ORS system of tool designation. It is also used in ORS system of tool designation. It is used in NRS system of tool designation. It is also used in NRS system of tool designation. As the name suggests, it provides the minimum value of principal clearance angle. It is beneficial while sharpening the cutting tool by grinding.

Typical values of clearance angle Clearance angle can never be negative or zero. Too small clearance angle will result intense rubbing and thus poor surface quality and smaller tool life. Too high clearance angle will make tool tip less strong and it may cause catastrophic failure of tool. Functions of clearance angles in machining In machining due to presence of small nose radius, the machined or finished surface rubs with the flank surface. Although length of the rubbing zone is tiny, it has significant effect on the finish and quality of the machined surface.

The scallop or feed marks produced during actual cutting or shearing are compressed automatically due to this small rubbing action. So a smooth surface is obtained, which is desirable. However, if clearance angle is very small then this contact length will be longer, and thus intense rubbing will happen which will generate high heat at that zone known as tertiary deformation zone. This may cause surface burning, chatter marks, etc.

Intense rubbing will also increase tool wear rate flank wear and consequently reduce tool life and accuracy of cutting. Small clearance angle also makes the tool prone to plastic deformation. Therefore, an optimum value of clearance is highly desirable. Singh S. Book: Machining and Machine Tools by A. Chattopadhyay Wiley.

Bhattacharya New Central Book Agency. Book: Manufacturing Processes by J. Kaushish PHI. Book: Manufacturing Science by M. Haque and S. Khan PHI. Secondary Sidebar.


Download: Theory Of Metal Cutting By Bhattacharya Pdf.pdf

Machining Machining is basically one material removal process where excess material is sheared off by the mutual interaction between workpiece and cutting tool. There exist several machining processes to cater the need of processing a wide variety of workpiece materials in innumerable ways. For examples, lathe operations such as straight turning, taper turning, internal turning, threading, grooving, etc. Milling operations are carried out primarily for generating flat surfaces. Similar to the lathe and milling operations, shaping and planing are two machining processes that can generate flat surfaces at different planes or orientations. However, the rotation of workpiece or cutting tool imparts necessary cutting velocity the lathe operations and milling processes.


What is Clearance Angle in Cutting Tool? Its Derivative, Value, and Function

What is Feed Rate in Machining? Its Unit, Value, Effects and Selection Machining is basically one material removal process where excess material is gradually removed from the workpiece in the form of chip by feeding the cutting tool against the workpiece. In order to smoothly remove material, three relative motions between tool and workpiece are to be provided. Such motions are cutting velocity or cutting speed , feed rate and depth of cut. Since these three parameters are inherent to any conventional machining process, so they are also called cutting parameters. What is feed rate?


Download: Metal Cutting By Amitabh Bhattacharya.pdf

Depending on the plane on which it is projected and measured, it may have various names. At the same time, rake angle may have positive, negative or even zero value based on the inclination of rake surface from reference plane. Each of these three types has specific advantages and disadvantages. This value can influence cutting force and power consumption in machining, life of the cutting tool, chip deviation, shear angle, tool life, etc. Rake angle also indirectly affects machinability. A positive rake reduces the wedge angle and thus shearing occurs smoothly with minimum shear deformation. Accordingly, cutting force and chip thickness ratio reduces.


Economics of Machining – Cutting Time, Tool Changing Time, Idle Time


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