Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

66.6 PRACTICE PROBLEMS

 

1. A block of metal 5" by 5" by 5" will be milled to 5" by 5" by 4" and then will have two separate holes drilled 2" deep. The hole will be finished with a reamer.

Part: - Mild Steel

Drilling: - High speed steel

- 15/32" diameter

- C.S. = 80 ft/min.

- feed = .010" per revolution

- setup time = 5 min. per part

- cost is $40.00 per hour

Reaming: - Carbide Steel

- 1/2" diameter

- C.S. = 60 ft./min.

- feed = .015" per revolution

- setup time = 2 min. per hole

- cost is $45.00 per hour

Milling: - High speed steel

- C.S. = 100 ft./min.

- cutter diameter = 1"

- 10 teeth with a tooth load of .004" per tooth

- setup time = 1 min. per part

- cost is $47.50 per hour

  1. a) Estimate the machining time required to make 50 parts.
  2. b) Estimate the cost of the 50 parts.
  3. c) Estimate the machine horse power required for the drill, reamer and the mill.

 

2. Calculate the machine tool spindle speeds for the following:

  1. a) Milling with a tungsten carbide tipped face cutter on a stainless steel work piece. C.S. = 65 m/min., cutter dia. = 150mm.
  2. b) Drilling with a High Speed Steel drill in Machine Steel work, with C.S. = 70 ft./min., and a drill diameter of 19/32"
  3. c) Turning on a lathe with a High Speed Steel tool in a mild steel work piece. Surface cutting speed = 100 ft./min., and a workpiece diameter of 2.75"
  4. d) Milling with a High Speed Steel cutter in tool steel work with a cutter speed of 60 ft./min., and a cutter diameter of 3/4".

 

3. The part below has three turned diameters, on one end there is a square tang that has been milled. The part is made of aluminum. (Note: R indicates radius)

 

 

a) Write a process plan that describes the operations necessary to produce the part.

b) If the milling cutter is a 1/2" diameter end mill with 6 teeth, determine a reasonable feed and speed for cutting the tang.

c) What are reasonable speeds and feeds for turning the part for rough and finish turning? (Note: pick one cut for your calculations)

 

 

4. Develop a process plan for the part below. You should include speeds, feeds and times. Hint: The part will be easy to make if a combination of milling, drilling and turning is used.

 

 

 

66.6.1 Case Study Problems