problems for practice

PROBLEMS FOR PRACTICE

1. In a two-dimensional cutting of mild steel with a sintered carbide tool the following data were observed

Rake angle = 12°

Depth of cut = 0.2 mm

Width of cut = 5 mm

Cutting force = 1500 N

Thrust for = 1000 N

Thickness of the chip = 0.55 mm

Find the mean shear stress and mean compressive stress on the shear plane.

2. In an orthogonal cutting operation, the following data have been observed

Uncut chip thickness = 0.127 mm

Width of cut = 6.35 mm

Cutting speed = 2 m/s

Rake angle = 20°

Cutting force = 567 N

Thrust force = 277 N

Chip thickness = 0.228 mm

Determine the shear angle, the friction angle, shear stress along the shear plane and power for the cutting operation.

3. The following is the data from an orthogonal cutting list.

Rake angle = 12°

Chip thickness ratio = 0.36

Uncut chip thickness = 0.5 mm

Width of cut = 2.8 mm

Yield stress of material in shear = 275 N/mm2.

Average coefficient of friction on the tool face as 0.8

Determine the normal and tangential forces on the tool face.

4. For a turning operation with HSS tool for hot rolled 0.2% carbon steel, the following data is given

Cutting speed = 0.2 m/s

Depth of cut = 3.2 mm

Feed = 0.5 mm/rev 

Rake angle = 15°

Determine: (i) cutting power, (ii) motor power, (iii) specific cutting resistance and (iv) unit power.

5. During machining of C20 steel, a double carbide-cutting tool of 0 −10 – 6 – 6 – 8 − 75 – 1 mm (ORS) shape has been used.

Feed = 0.15 mm/rev

Depth of cut = 1.5 mm

Cutting speed = 120 m/min

Chip thickness = 0.3 mm

Calculate the following:

 (i) chip reduction coefficient and (ii) shear angle.

6. The Taylor tool-life equation for machining C-40 steel with a HSS cutting tool at a feed of 0.2 mm/min and a depth of cut of 2 mm is given by VTn = C, where n and C are constants. The following V and T observations have been noted:

V, m/min       25     35

T, min           90      20

Calculate

(1) n and C,