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engineering
materials science engineering
Materials and process in manufacturing 9th edition E. Paul DeGarmo, J T. Black, Ronald A. Kohser - Solutions
Show how the approximate equation 24-5 for MRR in drilling was obtained. What assumption was needed?
An indexable-insert drill can produce a hole four times faster than a spade-drill but may cost (with inserts) 50% to 75% more than the equivalent spade blade and holder. For making only a couple of holes, the extra cost is not justified.Manufacturer's charts will help determine the best feed and
What machining difficulties would you expect to have in making the legs?
What do you think has caused the failures?
What do you recommend to solve this problem in the future in terms of materials, design, and manufacture?
What do you recommend to be done with the units in the field to stop the failures?
Why does milling have a high metal removal rate?
In a typical solid arbor milling cutter shown in Figure 25-8, why are the teeth staggered?
How would you set up a plain column-and-knee milling machine to make it suitable for milling the flutes on a large twist drill?
How would you set up a horizontal milling machine to cut both sides of a block of metal simultaneously?
What is the distinctive feature of a column-and-knee type milling machine?
Explain how controlled movements of the work in three mutually perpendicular directions are obtained in column-and-knee-type milling machines.
What is the basic principle of a universal dividing head?
The input end of a universal dividing head can be connected to the feed screw of the milling machine table. For what purpose?
For producing flat surfaces in mass-production machining how does face milling differ basically from peripheral milling?
Explain how a standard universal dividing head, having hole circles of 21,24,27,30, and 32 holes, would be operated to cut an 18-tooth gear.
Explain how table feed (ipm) and spindle rpm are specified or computed for a milling machine.
Why is the question of up or down milling more critical in horizontal slab milling than in vertical spindle (end or face) milling?
Suppose you wanted to machine a cast iron with BHN of 275. The process to be used was face milling and a HSS cutter was going to be used. What feed and speed values would you select?
Which type of milling (up or down) do you think uses the least power? Explain.
Why may down milling dull the cutter more rapidly than up milling in machining sand castings?
What are the parameters you need to specify in order to calculate MRR?
What is the advantage of a helical-tooth cutter over a straight-tooth cutter for slab milling?
What would the cutting force diagram for Fc look like if all eight teeth are considered? See right side of Figure 25-5 inset.
In Question 24, you were asked to select a feed per tooth and a cutting speed for a milling process. Reasonable values for feed and speed are 0.005 to 0.010 in. per tooth and 200 sfpm. Compute the input values for the machine tool. Use the information in Problem 6 as input when needed
Suppose you want to do the job described in Problem 6 by slab milling. You have selected a 6-in.-diameter cutter with an eight tooth TiN coated HSS cutter. The cutting speed will be 500 sfpm and the feed per tooth will be 0.010 in./tooth. Determine the input parameters for the machine (rpm of arbor
How much time will be required to face mill an AISI 1020 steel surface that is 12 in. long and 5 in. wide, using a 6-in. diameter, eight-tooth tungsten carbide inserted-tooth cutter? Select values of feed per tooth and cutting speed from Table 25-1.
If the depth of cut is 0.35 in., what is the metal removal rate in Problem 2?
Estimate the power required for the operation of Problem 3. Do not forget to consider Figure 25-5.
Examine the part shown in Figure 41-22. The slot on the left end must be produced by machining. Provide a process plan (a description of how the part would be machined and the details regarding cutting tools, such as material, sizes, and so on) for specified machine tools, cutting parameters, and
A gray cast iron surface 6 in. wide and 18 in. long may be machined on either a vertical milling machine, using an 8 in.-diameter face mill having 10 inserted HSS teeth, or on a hydraulic shaper with a HSS tool. If milling is used, the feet per tooth is 0.01 in. For shaping, a feed of 0.015 in. per
In Problem 6, what percentage of the total time for the job is consumed in nonmetal-removal activities (setup time and part loading/unloading) assuming that 10 parts are to be made?
In Figure 21-10, figure on left, the feed is .006 in. per tooth. The cutter is rotating at an rpm which will produce the desired surface cutting speed of 125 sfpm. The cutter diameter is 5 in. The depth of cut is 0.5 in. The block is 2 in. wide. What is the feed, in inches per minute, of the
What is the MRR for this situation described in Problem 8? Is up milling or down milling depicted?
Broaching machines are simpler in a basic design than most other machine tools. Why is this?
Why are broaching speeds usually relatively low, as compared with other machining operations?
What are the advantages of shell-type broach construction?
Why are most broaches made from alloy or high-speed steel rather than from tungsten carbide?
What are the advantages of TiN coated broaching tools?
The sides of a square, blind hole must be machined all the way to the bottom. The hole is drilled to full depth and the bottom end milled flat. Is it possible to machine the hole square by broaching? Why or why not?
The interior, flat surfaces of socket wrenches, which have one "closed" end, often are finished to size by broaching. By examining one of these, determine what design modification was incorporated to make broaching possible.
Explain why tooth spacing is important in sawing.
Explain why tooth spacing is important in sawing. Discuss.
Explain what is meant by the "set" of the teeth on a saw blade.
How is tooth set related to saw kerf?
What are the advantages of using circular saws?
Explain how the hole in Figure 26-18 is made on a contour bandsawing machine.
How do you calculate or estimate Tm, for a horizontal band-saw cutting a 3 in. round of 1040 steel?
What is the disadvantage of using gravity to feed a saw in cutting round bar stock?
What is a safe edge on a file?
How does the process of shaping differ from planing?
How is feed per stroke in shaping related to feed per tooth in milling?
What are some ways to improve the efficiency of a planer? Do any of these apply to the shaper?
Why is broaching particularly well suited for mass production?
Why is it necessary to relate the design of a broach to the specific workpiece that is to be machined?
Why are the pitch and radius of the gullet between teeth on a broach of importance?
A surface 12 in. long is to be machined with a flat, solid broach that has a rise per tooth of 0.0047 in. What is the minimum cross-sectional area that must be provided in the chip gullet between adjacent teeth?
How many strokes per minute would be required to obtain a cutting speed of 36.6 m (120 ft) per minute on a typical mechanical-drive shaper if a 254-mm (10-in.) stroke is used?
How much time would be required to shape a flat surface 254 mm (10 in.) wide and 203 mm (8 in.) long on a hydraulic drive shaper, using a cutting speed of 45.7 m (150 ft) per minute, a feed of 0.51 mm (0.020 in.) per stroke, and an overrun of 12.7 mm (1/2in.) at each end of the cut?
What is the metal-removal rate in Problem 11 if the depth of cut is 6.35 mm (1/4in.)?
If the work material in Problem 11 is 6 gray cast iron, what will be the power required?
A planer has a 10-hp motor, and 75% of the motor output is available at the cutting tool. The specific power for cutting cast iron certain metal is 0.03 W/mm3 or .67 hp/in3/min. What is the maximum depth of cut that can be taken in shaping a surface in this material if the surface is 305 × 305 mm
Calculate the Tm for planing the block of cast iron in Problem 14 and then estimate Tm for milling the same surface. You will have to determine which milling process to use and select speeds and feeds for an HSS cutter.
The pitch of the teeth on a simple surface broach can be determined by Equation 26-1. If a broach is to remove 0.25 in. of material from a gray iron casting that is 3 in. wide and 17.75 in. long, and if each tooth has a rise per tooth of .004 in., what will be the length of the roughing section of
Estimate the (approximate maximum) horsepower needed to accomplish the operation described in Problem 2 at a cutting speed of 10 m/min. (Hint: First find the HP used per tooth and determine the maximum number of teeth engaged at any time. What are those units?)
Estimate the approximate force acting in the forward direction during cutting for the conditions stated in Problems 2 and 3.
In making a 6-in. cut in a piece of AISI 1020 cold rolled steel that is 1 in. thick, the material is fed to a bandsaw blade with teeth having a pitch of 1.27 mm (20 pitch) at the rate of 0.0001 in. per tooth. Estimate the cutting time for the cut.
The strength of a pull broach is determined by its minimum cross section, which usually occurs either at the root of the first tooth or at the pull end. Suppose the minimum root diameter is Dr, the pull end diameter is Dp and the width of the pull slot is W. Write an equation for the allowable
Suppose you want to shape a block of metal 7 in. wide and 4 in. long (L = 4 in.), using a shaper as set up in Figure 26-1. You have determined for this metal that the cutting speed should be 25 sfpm, the depth of cut needed here for roughing is 0.25 in., and the feed will be 0.1 in. per stroke.
Could you have saved any time in Problem 7 by cutting the block in the 7-in. direction? Redo with L = 7 and W = 4 in.
Derive Equation (26-6), the shaping cutting speed.
The Cochran Company estimated that its annual requirements for the socket component shown in Figure CS-26 will be at least 50,000 units and that this volume will continue for at least 5 years. Consequently, it wants to consider all practical methods for making the component and has assigned you the
What are machining processes that use abrasive particles for cutting tools called?
What is crush dressing?
How does loading differ from glazing?
What is meant by the statement that grinding is a mixture of processes?
How is the feed of the workpiece controlled in centerless grinding?
Why should a cutting fluid be used in copious quantities when doing wet grinding?
If grinding machines are placed among other machine tools,what precautions must be taken?
What is the purpose of low-stress grinding?
Why are centerless grinders so popular in industry compared to center-type grinders?
Explain how a SEM micrograph is made. Check the Internet or the library to find the answer.
Why are vacuum chucks and magnetic chucks widely used in surface grinding and not in milling (see Chapter 29 on workholders for more discussion)?
How does creep feed grinding differ from conventional surface grinding?
Why does a lap not wear, since it is softer than the material being lapped?
Why is friability an important grit property?
Why is a honing head permitted to float in a hole that is being honed?
In what respect does a coated abrasive differ from an abrasive wheel?
Figure out why the bottoms of chips shown in Figure 27-8 are so smooth. The magnification of the micrograph is 4800X. How thick are these chips?
What is the inclined angle in honing and what determines it?
In grinding, what is infeed versus crossfeed?
Why is CBN superior to silicon carbide as an abrasive in some applications?
What materials commonly are used as bonding agents in grinding wheels?
Why is the grade of a bond in a grinding wheel important?
How does grade differ from structure in a grinding wheel?
Perhaps you have observed the following wear phenomena: A set of marble or wooden stairs shows wear on the treads in the regions where people step when they climb (or descend) the stairs. The higher up the stairs, the less the wear on the tread. Given that soles of shoes (leather, rubber) are far
Explain why it is that a small particle of a material can be used to abrade a surface made of the same material (i.e., why does the small particle act harder or stronger than the bulk material)?
In grinding, both the wheel and workpiece are moving (or rotating). Using the data in Figure 27-11 and assuming that you are doing surface grinding (see Figure 27-1), what are some typical MRR values? How do these compare to MRR values for other machining processes, such as milling? What is the
The Langley Corporation has to make 5000 retainer rings, as shown in Figure CS-27. It is essential that the surfaces be smooth with no sharp corners on the circumferential edges. Determine the most economical method for manufacturing these rings.
Explain the basic principle involved in electrochemical deburring.
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