# Assignment # 3: Cutting Parameters and Machining –

Assignment # 3: Cutting Parameters and Machining –
Issue Date: Sept  29, 2015        Due Date: Oct. 6, 2015 Name:    Student ID:
Instructions

This assignment has two sections. The first section is a practicum related to reinforcing basic calculations and knowledge with respect to simple machining. The calculations and discussion questions are to be done independently. Show all your calculations, and your formulae. You will have to find the necessary information on the Internet or using library resources. Clearly indicate your reference material on the last sheet. See the on-line spreadsheet on the course site for the material assigned to you. The second part of the assignment focuses on general principles.

(Up to -5 Marks) – if the work is not neat, calculations are not shown, and not properly referenced
•    The work piece material to be    cut is    for calculations for M10x1.50 mm and ¼-20 tapped hole and a 0.500 reamed hole.

Calculate the feeds and speeds for HSS & Carbide cutting tools where appropriate.

Calculate a speed and feed rate for the drill, reamer and a boring bar (one insert) with the same diameter as the reamer. Show the calculations on the last sheet (neatly). Clearly state the units. Assume a depth (min. 10 mm) to calculate the cutting time. Hint: draw a detailed sketch prior to calculating the cutting time. (12)

Drill Speed/Feed parameters (assume 31/64 inch)
Drill parameters    HSS    Carbide
Drill rpm:
Drill feed rate:
Drill cutting time:
Drill material removal rate
Reamer Speed/Feed parameters (assume 0.500 inch)
Reamer parameters    HSS    Carbide
Reamer rpm:
Reamer feed rate:
Reamer cutting time:
Reamer material removal rate
Boring Speed/Feed parameters (assume 0.500 inch)
Boring parameters    HSS    Carbide
Boring rpm:
Boring feed rate:
Boring cutting time:
Boring material removal rate
When would you use a reamer versus a boring bar? Discuss. (1)

Tapping: M10x1.50 mm & ¼-20 tapped hole (2)
What is the drill diameter of your drills?
.
.
What is the percentage thread engagement for this diameter? (1.5)
.
.
What are the speed and feed values of these drills and taps? Clearly state your cutting speed data along with the references, and the appropriate units. (4)

List three typical tap types, and when they are used (1.5).

Reaming: For an 8F7 hole: (5)
What is the diameter of your drill you would use?         . What reamer would you use and why?     .

Material Feeds Speeds Time
Other characteristics:

Drill    Reamer

Quickies (3)
Which of the following statements is not correct?
a)    Core drills have 3 or 4 flutes.
b)    High helix drills help in chip removal.
c)    Straight fluted drills are used for sheet metal.
d)    centre drills are for long holes, such as gun barrels.

If we want a hole with a 1/2-13-UNC thread, what size of tap drill should be used? (1) If we want a hole with a 6 x 1.0 thread, what size of tap drill should be used? (1/2) What size is an F drill? (1/2)

List three reasons that machining operations may be required, and provide an example for each. Do not provide duplicate information. (3)

What special precautions are needed when cutting magnesium, and thermoplastic materials (such as ABS plastic)? (3)

When considering the basic metal-cutting process, what are the important physical and chemical properties of a cutting tool? (2)

Tool materials can have conflicting properties when used for machining operations. Discuss. Use numerical examples to justify your answer, and reference appropriately. (Hint: consider tool costs, tool life, processing time, potential failure modes). (8)

Explain whether it is desirable to have a high or low (a) n value and (b) C value in the Taylor tool-life equation. You may develop an example to assist with your explanation. (2)

Describe the difficulties that may be encountered in clamping a workpiece made of a soft metal in a three-jaw chuck or a vise. (1)

It has been stated that titanium-nitride coatings allow cutting speeds and feeds to be higher than those for uncoated tools. Survey the technical literature and prepare a table showing the percentage increase of speeds and feeds that would be made possible by coating the tools. (4)

List the concerns you would have if you needed to economically machine carbon-fiber reinforced polymers or metal-matrix composites with graphite fibers in an aluminum matrix. (5)

Contact several different suppliers of cutting tools, or search their websites. Make a list of the costs of typical cutting tools as a function of various sizes, shapes, and features. (5)

Hint: Good sources for such a literature search are trade magazines, and cutting-tool vendors whose product specifications will include data on speeds and feeds – Kennametal, Iscar, Sandvik, Carboloy, and Valenite, Precision Twist Drill, ….

Calculation Worksheet