Single Point Cutting  Tool Description and Report

Introduction to machine tool:

      Machine tools are devices used to build parts of machines; but usually the concept is interpreted more narrowly, denoting tools that cut or drill, press or shear, or otherwise shape hardened materials into specific forms. Although casting is often one of the most important steps in producing a part, casting per se does not use machine tools. A mold may, however, have been shaped by machine tools. A classic description of how a sculptor works says that the sculptor takes a block of marble and removes everything that does not look like the statue in mind. Most machine tools work the same way, removing metal or ceramic a little at a time until the part the designer had in mind is all that is left.

Classification of cutting tools:

A) According to number of cutting edge-

      1.  Single point cutting tool

         It is the simple form of cutting tool and it have only one cutting edge. Examples – shear tools, lathe tools, planer tools etc.

     2.    Multi point cutting tool

It has more than two cutting edge arranged together as a unit. The rate of machining is speedy & surface finish is also better in this case.
Example- milling cutter, grinding wheels,abrasive sticks, drills, brooches, grinding wheels,etc.

N.B:In grinding wheel every particle work as single point cutting tool which known as abrasive tool.

 B) According to motion-

       1.Linear motion tools – lathe tools, brooches

                    2.  Rotary motion tools – milling cutters, grinding wheels

       3.    Linear & rotary motion tools – drills, taps, etc.

Single point cutting tool:

      A single-point tool is a cutting tool having one cutting part (The functional part of the tool comprised of the chip producing elements.) and one shank (That part of the tool by which it is held). They are commonly used in lathes, turret lathes, planers, shapers, boring mills and similar machine tools. The single point cutting tool mainly consist of tool shank & cutting part called point. The point of cutting tool is bounded by cutting face, end flank, side/ main flank, & base. The  chip slide is along the face. The side / main cutting edge ‘ab’ is formed by intersecting of face &  side / main flank. The end cutting edge ‘ac’ is formed by the intersection of end flank & base. The  point ‘a’ which the intersection of end cutting edge & side cutting edge is called nose. Mainly the   chip cuts by side cutting edge.

Terminology of single point cutting tool:

    1.              Shank – It is main body of tool. The shank used to gripped in tool holder.

2.              Flank – The surface or surface below the adjacent of the cutting edge is called flank of the tool.   3

3.              Base – It is actually a bearing surface of the tool when it is held in tool holder or clamped directly in a tool post.

4.              Heel – It is the intersection of the flank & base of the tool. It is curved portion at the bottom of the tool.

5.              Cutting edge – It is the edge on face of the tool which removes the material from work piece. The cutting edges are side cutting edge (major cutting edge) & end cutting edge ( minor cutting edge)

 Tool angles:

1.Side cutting edge angle (lead angle )

  It is the angle between side cutting edge & side of tool flank

2.End cutting edge angle 

This is the angle between end cutting edge & line normal to tool shank. It satisfactory value is 80 to 150. 

3.  Top rake angle:

It is the angle between face of tool & plane parallel to base. 

4.Side rake angle:

It is angle between face of tool & the shank of the tool

5.Side clearance:

This formed by the side surface of the tool with a plane normal to the base of the tool.
It avoid rubbing between flank & workpiece when tool is fed longitudinally

6.Nose radius:

Nose Radius makes the finish of the cut smoother as it can overlap the previous cut and eliminate the peaks and valleys that a pointed tool produces. Having a radius also strengthens the tip, a sharp point being quite fragile.

Characteristics of Tool Material:

For efficient cutting a tool must have the following properties:

Hot Hardnes

This means at high temperatures it has ability to retain its hardness.All metal create heat at machining process so it is important to have hardness that can not harm metal from created heat.

Strength and Resistance to Shock

At the start of a cut the first bite of the tool into the work results in considerable shock loading on the tool. It must obviously be strong enough to withstand it.

Low Coefficient of Friction

The tool rubbing against the workpiece and the chip rubbing on the top face of the tool produce heat which must be kept to a minimum.

Tool Materials in Common Use:

High Carbon Steel

Contains 1 - 1.4% carbon with some addition of chromium and tungsten to improve wear resistance. The steel begins to lose its hardness at about 250° C, and is not favoured for modern machining operations where high speeds and heavy cuts are usually employed.

High Speed Steel (H.S.S.)

Steel, which has a hot hardness value of about 600° C, possesses good strength and shock resistant properties. It is commonly used for single point lathe cutting tools and multi point cutting tools such as drills, reamers and milling cutters.

Cemented Carbides

An extremely hard material made from tungsten powder. Carbide tools are usually used in the form of brazed or clamped tips. High cutting speeds may be used and materials difficult to cut with HSS may be readily machined using carbide tipped tool.

Tools required:

1.      Grinding machine

2.      Cast iron metal piece

3.      Water

4.      File

5.      Hammer

6.      Grease

7.      Paper

  

Procedure:

1.      At first, we need to select the metal. Then we need to choose the side of the metal.

2.      With grinding machine, we start to cut the metal through one side. Metal must be formed in curved. We have to make it perfectly curved at the middle of the side. They should not exist above 60ᵒ angle.

3.      After finishing that, we need to clear the every surface of the metal with file.

4.      Then we punch our id in the one surface of the metal.

5.      After that, we have to put crater wear on the upper side of the curve with grinding machine.

6.      Then we need to flat out the edge of the curve.

7.      Then we have to lapper the metal with grease and fold it with paper.

Precaution:

1.      After every grinding, we need to put the metal to the water for safety of the hand because of the increasing temperature of the metal.

2.      We must use paper or cloth piece to hold the metal for heat.

3.      We must make a distance of our hand with the grinding machine for safety.

4.      We must wear apron and glass for safety.