ME 383 Exam 3- CH 22: Machining Operations and Machine Tools
Vertical Boring Mill
Applications: Large, heavy workparts that have low L/D ratio
Sawing
Cuts narrow slit in work by a tool consisting of a series of narrowly spaced teeth
Variations of turning performed on a lathe:
Facing Contour turning Chamfering Cutoff Threading
Methods of Holding Workpiece in a Lathe:
(a) Holding the work between centers, (b) chuck, (c) collet, and (d) face plate
Operations Related to Drilling:
(a) Reaming, (b) tapping, (c) counterboring d) countersinking, e) center drilling, f) spot facing
Types of Peripheral Milling
(a) Slab milling, (b)slotting, (c) side milling, (d)straddle milling, and (e) form milling
22.11 MC End milling is most similar to which one of the following: (a) face milling, (b) peripheral milling, (c) plain milling, or (d) slab milling?
A
22.7 What is meant by the designation 12 x 36 inch lathe?
A 12 x 36 lathe has a 12 inch swing (maximum work diameter that can be accommodated) and a 36 inch distance between centers (indicating the maximum work length that can be held between centers).
22.11 What is a blind hole?
A blind hole does not exit the work; by comparison, a through hole exits the opposite side of the workpart.
22.18 What is a machining center?
A machining center is a CNC machine tool capable of performing multiple types of cutting operations involving rotating spindles (e.g., milling, drilling); the machine is typically equipped with automatic tool-changing, pallet shuttles to speed workpart changing, and automatic workpart positioning.
22.19 What is the difference between a machining center and a turning center?
A machining center is generally confined to rotating spindle operations (e.g., milling, drilling); while a turning center performs turning type operations, generally with single-point tools.
Broaching
A multiple tooth cutting tool is moved linearly relative to work in direction of tool axis
22.12 What is the distinguishing feature of a radial drill press?
A radial drill has a long radial arm along which the drill head can be positioned to allow the drilling of large work parts. The radial arm can also be swiveled about the column to drill parts on either side of the worktable.
22.5 What is the difference between threading and tapping?
A threading operation is performed on a turning machine and produces an external thread, while tapping is normally performed on a drilling machine and produces an internal thread.
22.3 MC A lathe can be used to perform which of the following machining operations (three correct answers): (a) boring, (b) broaching, (c) drilling, (d) milling, (e) planing, and (f) turning?
A, C, F
Turret Lathe
Applications: high production work that requires a sequence of cuts on the part
22.12 MC The basic milling machine is which one of the following: (a) bed type, (b) knee-and-column, (c) profiling mill, (d) ram mill, or (e) universal milling machine?
B
22.14 MC A broaching operation is best described by which one of the following: (a) a rotating tool moves past a stationary workpart, (b) a tool with multiple teeth moves linearly past a stationary workpart, (c) a workpart is fed past a rotating cutting tool, or (d) a workpart moves linearly past a stationary single-point tool?
B
22.4 MC A facing operation is normally performed on which one of the following machine tools: (a) drill press, (b) lathe, (c) milling machine, (d) planer, or (e) shaper?
B lathe
22.1 MC Which of the following are examples of generating the workpart geometry in machining, as opposed to forming the geometry (two best answers): (a) broaching, (b) contour turning, (c) drilling, (d) profile milling, and (e) thread cutting?
B and D
22.10 MC Reaming is used for which of the following functions (three correct answers): (a) accurately locate a hole position, (b) enlarge a drilled hole, (c) improve surface finish on a hole, (d) improve tolerance on hole diameter, and (e) provide an internal thread?
B, C, D
22.13 MC A planing operation is best described by which one of the following: (a) a single-point tool moves linearly past a stationary workpart, (b) a tool with multiple teeth moves linearly past a stationary workpart, (c) a workpart is fed linearly past a rotating cutting tool, or (d) a workpart moves linearly past a single-point tool?
D
22.9 MC A tap is a cutting tool used to create which one of the following geometries: (a) external threads, (b) flat planar surfaces, (c) holes used in beer kegs, (d) internal threads, or (e) square holes?
D
Boring
Difference between boring and turning: -Boring is performed on the inside diameter of an existing hole -Turning is performed on the outside diameter of an existing cylinder -In effect, boring is internal turning operation
22.2 Distinguish between generating and forming when machining workpart geometries.
Generating refers to the creation of work geometry due to the feed trajectory of the cutting tool; examples include straight turning, taper turning, and profile milling. Forming involves the creation of work geometry due to the shape of the cutting tool; common examples include form turning and drilling.
Machining Center
Highly automated machine tool that can perform multiple machining operations under CNC control in one setup with minimal human attention - Typical operations are milling and drilling
Mill-Turn Centers
Highly automated machine tool that can perform turning, milling, and drilling operations in one setup
22.13 What is the difference between peripheral milling and face milling?
In peripheral milling, cutting is accomplished by the peripheral teeth of the milling cutter and the tool axis is parallel to the work surface; in face milling, cutting is accomplished by the flat face of the cutter whose axis is perpendicular to the work surface.
Milling
Machining operation in which work is fed past a rotating tool with multiple cutting edges
Machining
Material removal process in which a sharp cutting tool is used to mechanically cut away material so that the desired part geometry remains
22.8 Name the various ways in which a workpart can be held in a lathe.
Methods of holding the work in a lathe include: (1) between centers, (2) chuck, (3) collet, and (4) face plate.
22.20 What can a mill-turn center do that a conventional turning center cannot do?
The mill-turn center has the capacity to position a rotational workpart at a specified angular location, permitting milling or drilling to be performed at a location on the periphery of the part.
22.23 Identify the three basic forms of sawing operation?
The three forms of sawing are: (1) hacksawing, (2) bandsawing, and (3) circular sawing.
22.3 Give two examples of machining operations in which generating and forming are combined to create workpart geometry.
The two examples given in the text are thread cutting on a lathe and slot milling.
22.17 How does a universal milling machine differ from a conventional knee-and-column machine?
The universal milling machine has a worktable that can be rotated about a vertical axis to present the part at any specified angle to the cutter spindle.
22.4 Describe the turning process.
Turning is a machining process in which a single-point tool removes material from the surface of a rotating cylindrical workpiece, the tool being fed in a direction parallel to the axis of work rotation.
lathe
machine that turning is performed on
HP/RPM Ratio
ratio of horsepower to maximum spindle speed
Forming to create shape
(a)form turning, (b)drilling (c) broaching
22.8 MC The twist drill is the most common type of drill bit: (a) true or (b) false?
A
22.5 MC Knurling is performed on a lathe, but it is not a metal cutting operation: (a) true or (b) false?
(a). It is a metal forming operation.
Generating shape
(a) straight turning, (b) taper turning, (c) contour turning, (d) plain milling, (e) profile milling
Combination of forming and generating to create shape
(a) thread cutting on a lathe, and (b) slot milling
drill press
machine tool for drilling
Generating
part geometry determined by feed trajectory of cutting tool
Forming
part geometry is created by the shape of the cutting tool
Two Forms of Milling
peripheral and face
Types of Face Milling
(a)Conventional face milling, (b) partial face milling,and (c) end milling (d)Profile milling, (e)pocket milling,and (f)surface contouring
DN Ratio (for High Speed Machining)
bearing bore diameter (mm) multiplied by maximum spindle speed (rev/min)
Other Production Turning Machines:
Turret lathe Chucking machine Bar machine Automatic screw machine Multiple spindle bar machine
drill or drill bit
cutting tool for drilling
Each machining operation produces a characteristic part geometry due to two factors:
1. Relative motions between tool and workpart • Generating - part geometry determined by feed trajectory of cutting tool 2. Shape of the cutting tool • Forming - part geometry is created by the shape of the cutting tool
22.6 MC Which one of the following cutting tools cannot be used on a turret lathe: (a) broach, (b) cutoff tool, (c) drill bit, (d) single-point turning tool, or (e) threading tool?
A
22.9 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?
A center holds the work during rotation at the tailstock end of the lathe. A live center is mounted in bearings and rotates with the work, while a dead center does not rotate - the work rotates about it.
22.16 MC Gear hobbing is a special form of which one of the following machining operations: (a) grinding, (b) milling, (c) planing, (d) shaping, or (e) turning?
B
22.2 MC In a turning operation, the change in diameter of the workpart is equal to which one of the following: (a) 1 x depth of cut, (b) 2 x depth of cut, (c) 1 x feed, or (d) 2 x feed?
B
22.15 MC The three basic types of sawing, according to type of blade motion involved, are (a) abrasive cutoff, (b) bandsawing, (c) circular sawing, (d) contouring, (e) friction sawing, (f) hacksawing, and (g) slotting?
B, C, F
22.6 How does a boring operation differ from a turning operation?
Boring produces an internal cylindrical shape from an existing hole, while turning produces an external cylindrical shape.
22.10 How does a turret lathe differ from an engine lathe?
A turret lathe has a toolholding turret in place of a tailstock; the tools in the turret can be brought to work to perform multiple cutting operations on the work without the need to change tools as in operating a conventional engine lathe.
22.7 MC Which one of the following turning machines permits very long bar stock to be used: (a) chucking machine, (b) engine lathe, (c) screw machine, (d) speed lathe, or (e) turret lathe?
C
Broaching advantages:
Good surface finish Close tolerances Variety of work shapes possible CON: expensive
22.21 How do shaping and planing differ?
In shaping, the work is stationary during the cut, and the speed motion is performed by the cutting tool; while in planing, the cutting tool is stationary, and the workpart is moved past the tool in the speed motion.
22.16 Describe the difference between up milling and down milling?
In up milling, the cutter speed direction is opposite the feed direction; in down milling, the direction of cutter rotation is the same as the feed direction.
22.22 What is the difference between internal broaching and external broaching?
Internal broaching is accomplished on the inside surface (hole) of a workpart; while external broaching is performed on one of the outside surfaces of the part.
22.15 What is pocket milling?
Pocket milling uses an end milling cutter to machine a shallow cavity (pocket) into a flat workpart.
22.14 Describe profile milling.
Profile milling generally involves the milling of the outside periphery of a flat part.
Classification of Machined Parts (2)
Rotational - (a) cylindrical or disk‐like shape Nonrotational - (b) block‐like and plate‐like
22.1 What are the differences between rotational parts and prismatic parts in machining?
Rotational parts are cylindrical or disk-shaped and are machined on a turning machine (e.g., a lathe); prismatic parts are block-shaped or flat and are generally produced on a milling machine, shaper, or planer.
Typical Sawing functions:
Separate a work part into two pieces Cut off unwanted portions of part Cut outline of flat part
Shaping and Planing
Similar operations, both use a single point cutting tool moved linearly relative to the workpart
Turning
Single point cutting tool removes material from a rotating workpiece to generate a cylindrical shape
milling cutter
cutting tool for milling
Blind Hole
drill does not exit opposite side of work
Through Hole
drill exits opposite side of work
milling machine
machine tool for milling