Machining Operations and Machine Tools Review Questions Flashcards
What are the differences between rotational parts and prismatic parts in machining?
Rotational Parts
Cylindrical / disk shaped and are machined on a turning machine
Prismatic Parts
Blocked shaped or flat and are generally produced on a milling machine, shaper, or planer
Distinguish between generating and forming when machining workpart geometries.
Generating
Geometry of the workpart is determined by the feed trajectory of the cutting tool. The path followed by the tool during its feed motion is imparted to the work surface in order to create the shape
Forming
Shape of the part is created by the geometry of the cutting tool. The cutting edge of the tool has the reverse of the shape to be produced on the part surface
Give two examples of machining operations in which generating and forming are combined to create workpart geometry
- thread cutting on a lathe
- slotting on a milling machine
Describe the turning process
Machine process in whic a single-point tool removes material from the surface of a rotating workpiece. Toll fed linearly in a direction parallel to the axis of rotation to generate a cylindrical geometru
What is the difference between threading and tapping?
Threading performed on a turning machine and produces external threads
Tapping performd on a drilling machine and prdocues internal threads
How does a boring operation differ from a turning operation?
Boring produces internal cylindrical shape from an existing hole
turning produces an external cylindrical shape
What is meant by the designation 12 x 36 inch lathe?
Has a 12 inch swing (maximum work diameter that can be accomodated) and a 36 inch distance between centers (maximum work length that can be held between carriers)
R16.8Name the various ways in which a workpart can be held in a lathe
- Between centers
- Chuck
- Collet
- Face plate
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?
Center
Holds the workpiece at the tailstock end of the live
Live Center
Mounted in bearings and rotates with the work
Dead Center
Does no rotate, the work rotates about it
What is a blind hole?
Blind Hole
Does not exit the work
Through Hole
Hole exits both sides of the work
wHAT IS THE DISTINGUISHING FEATURE OF A RADIAL DRILL PRESS?
Large drill press designed to cut holes in large parts. Has a radial arm along which the drilling head can be moved and clamped.
What is the difference between peripheral milling and face milling
Peripheral Milling
Axis of the tool is parallel to the surface being machined, and operation is performed by cutting edges on the outside periphery of the cutter
Face Milling
Axis of the cutter is perpendicular to the surface being milled, and machining is performed by cutting edges on both ends and outside periphery of the cutter
Describe profile milling
Generally invovles the milling pf the outside periphery of a flat part
What is pocket milling
Uses an end milling cutter to machine a shallow cavity (pocket) into a flat workpart
Describe the difference between up milling and down milling?
Upmilling
Cutter speed direction is opposite of the feed direction
Downmilling
direction of cutter rotation is the same as the feed direction
How does a universal milling machine differ from a conventional knee-and-column machine
Knee and column milling machine
basic machine tool for milling. Holds a single cutting tool. Main components are a column that supports the spindle and a knee that supports the worktable
Universal Milling Machine
Has a worktable that rotates about the vertical axis to present a part at a certain angle
What is a machining center
A highly automated machine tool capable of performing multiple machining operations under a computer numerical control in one setup with minimal human attention
What can a mill-turn center do that a conventional turning center cannot do?
CNC mill-turn center
Has general configuration of a turning center; can position cylindrical workpart at a specified angle so that a rotating cutting tool can machine features into the outside surface of the part
How do shaping and planing differ
Shaping
Speed motion is accomplished by moving the cutting tool
Planing
Speed motion is accomplished ny moving the workpart
What is the difference between internal broaching and external broaching
External Broaching
performed on outside surface of the work to create a certain cross-sectional shape on the surface
Internal Broaching
Accomplished on internal surface of the hole in the part
What is the difference between a machining center and a turning center
Machining Centers
Can be applied to every surface of the workpiece
Turning Centers
Mainly used for cutting rotated workpieces
How do a turning lathe differ from an engine lathe
Turret Lathe
has a toolholding turret in place of a tailstock; tools in the turret can be brought to work to perform multiple cutting operations on the work without needing to change tools
Engine Lathe
Requires manually replacing the tool for a specific machining operation
Identify the 3 basic forms of sawing operations
- hacksawing
- bandsawing
- circular sawing
Why do costs tend to increase when better surface finish is requried on a machined part
Additional operations such as grinding , lapping, or similar ginishing processes must be included in the manufacturing sequence
What are the basic factors that affect surface finish in machining
- geometric factors
- type of operation
- feed
- tool shape
- work material factors
- built up edge effects
- tearing of the work surface when machining ductile materials
- Vibration and tool factors
- setup
- work part rigidity
- backlash in the feed mechanism
*
- backlash in the feed mechanism
What are the parameters that have the greatest influence in determining the ideal surface roughness in a turning operation
- tool nose radius
- feed
Name some of the steps that can be taken to reduce or eliminate vibrations in machining
- increase stiffness or damping in the setup
- operate at speeds away from the natural frequency of machine tool system
- reduce forces in machining by changing feed or depth and cutter design
