Question & Answer

What is the difference between peripheral milling and face milling?

What is the distinguishing feature of a radial drill press?

What is a blind hole?

How does a turret lathe differ from an engine lathe?

What is the difference between a live center and a dead center, when these terms are used in the context of workholding in a lathe?

Name the various ways in which a workpart can be held in a lathe

What is meant by the designation 12 x 36 inch lathe?

How does a boring operation differ from a turning operation?

What is the difference between threading and tapping?

Describe the turning process.

Give two examples of machining operations in which generating and forming are combined to create workpart geometry.

Distinguish between generating and forming when machining workpart geometries.

What are the differences between rotational parts and prismatic parts in machining?

During a turning operation, a tool-chip thermocouple was used to measure cutting temperature. The following temperature data were collected during the cuts at three different cutting speeds (feed and depth were held constant): (1) v = 100 m/min, T = 505°C, (2) v = 130 m/min, T = 552°C, (3) v = 160 m/min, T = 592°C. Determine an equation for temperature as a function of cutting speed that is in the form of the Trigger equation, Eq. (21.23)

A turning operation uses a cutting speed = 200 m/min, feed = 0.25 mm/rev, and depth of cut = 4.00 mm. The thermal diffusivity of the work material = 20 mm2 /s and the volumetric specific heat = 3.5 (10-3 ) J/mm3 -C. If the temperature increase above ambient temperature (20°F) is measured by a tool-chip thermocouple to be 700°C, determine the specific energy for the work material in this operation.

An orthogonal machining operation removes metal at 1.8 in3 /min. The cutting force in the process = 300 lb. The work material has a thermal diffusivity = 0.18 in2 /sec and a volumetric specific heat = 124 in-lb/in3 -F. If the feed f = to = 0.010 in and width of cut = 0.100 in, use the Cook formula to compute the cutting temperature in the operation given that ambient temperature = 70°F.

It is desired to estimate the cutting temperature for a certain alloy steel whose hardness = 240 Brinell. Use the appropriate value of specific energy from Table 21.2 and compute the cutting temperature by means of the Cook equation for a turning operation in which the cutting speed is 500 ft/min, feed is 0.005 in/rev, and depth of cut is 0.070 in. The work material has a volumetric specific heat of 210 in lb/in3 -F and a thermal diffusivity of 0.16 in2 /sec. Assume ambient temperature = 88°F.

An orthogonal cutting operation is performed on a certain metal whose volumetric specific heat = 110 in-lb/in3 -F, and thermal diffusivity = 0.140 in2 /sec. The cutting speed = 350 ft/min, chip thickness before the cut = 0.008 in, and width of cut = 0.100 in. The cutting force is measured at 200 lb. Using Cook's equation, determine the cutting temperature if the ambient temperature = 70°F.

Consider a turning operation performed on steel whose hardness = 225 HB at a speed = 3.0 m/s, feed = 0.25 mm, and depth = 4.0 mm. Using values of thermal properties found in the tables and definitions of Section 4.1 and the appropriate specific energy value from Table 21.2, compute an estimate of cutting temperature using the Cook equation. Assume ambient temperature = 20°C.

Orthogonal cutting is performed on a metal whose mass specific heat = 1.0 J/g-C, density = 2.9 g/cm3 , and thermal diffusivity = 0.8 cm2 /s. The cutting speed is 4.5 m/s, uncut chip thickness is 0.25 mm, and width of cut is 2.2 mm. The cutting force is measured at 1170 N. Using Cook's equation, determine the cutting temperature if the ambient temperature = 22°C.

In a turning operation on an aluminum alloy workpiece, the feed = 0.020 in/rev, and depth of cut = 0.250 in. The motor horsepower of the lathe is 20 hp and it has a mechanical efficiency = 92%. The unit horsepower value = 0.25 hp/(in3 /min) for this aluminum grade. What is the maximum cutting speed that can be used on this job?

A lathe performs a turning operation on a workpiece of 6.0 in diameter. The shear strength of the work is 40,000 lb/in2 and the tensile strength is 60,000 lb/in2 . The rake angle of the tool is 6°. The cutting speed = 700 ft/min, feed = 0.015 in/rev, and depth = 0.090 in. The chip thickness after the cut is 0.025 in. Determine (a) the horsepower required in the operation, (b) unit horsepower for this material under these conditions, and (c) unit horsepower as it would be listed in Table 21.2 for a to of 0.010 in. Use the orthogonal cutting model as an approximation of the turning process.

A turning operation is performed on an engine lathe using a tool with zero rake angle in the direction of chip flow. The work material is an alloy steel with hardness = 325 Brinell hardness. The feed is 0.015 in/rev, depth of cut is 0.125 in and cutting speed is 300 ft/min. After the cut, the chip thickness ratio is measured to be 0.45. (a) Using the appropriate value of specific energy from Table 21.2, compute the horsepower at the drive motor, if the lathe has an efficiency = 85%. (b) Based on horsepower, compute your best estimate of the cutting force for this turning operation. Use the orthogonal cutting model as an approximation of the turning process.

Solve Problem 21.27 but with the following changes: cutting speed = 1.3 m/s, feed = 0.75 mm/rev, and depth = 4.0 mm. Note that although the power used in this operation is only about 10% greater than in the previous problem, the metal removal rate is about 40% greater.

A turning operation is carried out on aluminum (100 BHN). Cutting speed = 5.6 m/s, feed = 0.25 mm/rev, and depth of cut = 2.0 mm. The lathe has a mechanical efficiency = 0.85. Based on the specific energy values in Table 21.2, determine (a) the cutting power and (b) gross power in the turning operation, in Watts.