Cutting speed and feed determines the surface finish, power requirements, and material removal rate. The primary factor in choosing feed and speed is the material to be cut. However, one should also consider material of the tool, rigidity of the workpiece, size and condition of the lathe, and depth of cut.

Factors affecting the calculation of cutting speed are: The material being machined (steel, brass, tool steel, plastic, wood) (see table below) The material the cutter is made from (High-Carbon Steel, high speed steel (HSS), Carbide, Ceramics, and Diamond tools)

When the cutting speed increases, the normal wear stage becomes shorter and the tool wear rate grows larger. Because of the variations of cutting force and tool temperature, the tool wear mechanisms change with different combinations of cutting parameters even at the same cutting speed.

Effects of Cutting Speed Increasing cutting speed by 50% decreases tool life by 80%. 2. Cutting at low cutting speed (20–40m/min) tends to cause chattering. Thus, tool life is shortened.

Increasing cutting speed by 20% decreases tool life by 50%. Increasing cutting speed by 50% decreases tool life by 80%. Cutting at low cutting speed (20– 40m/min) tends to cause chattering. Thus, tool life is shortened.

How to improve tool life in turning

1. Reduce cutting speed, vc (to reduce heat)
2. Optimize feed, fn (for shortest cutting time)
3. Optimize depth of cut, ap (to reduce the number of cuts)

The variation of tool life with different process parameters has been plotted. Feed rate has the most significant effect on tool life followed by spindle speed and depth of cut. published works on metal cutting has regarded these three parameters as having the greatest influence on tool wear and tool life.

Tool life definition: Tool life is the duration of actual cutting time after which the tool is no longer usable. There are many ways of defining the tool life, and the common way of quantifying the end of a tool life is by a limit on the maximum acceptable flank wear.

7 Factors Influencing Tool Life | Metals | Industries |…

• Factor # 1. Cutting Speed:
• Factor # 2. Physical Properties of Work Piece:
• Factor # 3. Area of Cut:
• Factor # 4. Ratio of Feed to Depth of Cut (f/d):
• Factor # 5. Shape and Angles of Tools:
• Factor # 6. Effect of Lubricant:
• Factor # 7. Nature of Cutting:

Main purposes of cutting fluids are to cool and lubricate machining region as well as to flush away the chips produced. Cutting fluids have various merits over dry machining. During machining, use of cutting fluids improves machined surface finish and reduces cutting tool wear.

The equation for Taylor’s basic model is vC * Tm = CT, where vC is cutting speed, T is tool life, and m and CT are constants with CT representing the cutting speed that would result in a tool life of one minute.

The tool life can be defined in following different ways: (i) The time elapsed between two successive grindings. (ii) The period during which a tool cuts satisfactory. (iii) The total time accumulated before tool failure occurs. Tool life is expressed in minutes.

The abrasion wear was measured using maximum flank wear (VBmax) and the length over which the flank wear occurred. The chipping wear was measured using the surface area of the material chipped off from the cutting edge or tool nose.

To setup a Cutting Tool for Machining Mount a toolholder in the toolpost so that the set screw in the toolholder is about 1 inch beyond the toolpost. Insert the proper cutting tool into the toolholder, having the tool extend . 500 inch beyond the toolholder.

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.

The generation of surfaces oriented primarily perpendicular to the workpiece axis are called facing. In turning, the direction of the feeding motion is predominantly axial with respect to the machine spindle. In facing a radial feed is dominant.

Kinds Of Cutting Tools Used In Machining

• Lathe. If you have ever wondered how to turn stairway posts, a lathe is the answer.
• Drill Press. The drill press bores precision holes, reams openings and cuts threads.
• Milling Machine.
• Grinder.
• Chop Saw.
• Welders.
• Handheld Rotary Tools.

Lathes can be dangerous if not used properly. Read the owner’s manual carefully. Make sure you understand instructions and are properly trained before operating a lathe.

Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates. Thus the phrase “turning and boring” categorizes the larger family of processes known as lathing.

30.2. Face milling generates a surface normal to the axis of rotation. It is generally used for wide flat surfaces. The peripheral portions of the teeth do most of the metal cutting.

Facing is an operation of machining the ends of a workpiece square with its axis. To produce a flat, square surface when facing, the lathe might be true. The purpose of facing are: To provide a true, flat surface, square with the axis of the workpieces.