Chapter 2 Machining Operations Flashcards
What are the 2 classification of machined parts and how are they machined?
- Rotational > done by turning
- Non-Rotational > done by milling or drilling
What are the different shape generations?
- Straight, Taper and Contour Turning
- Plain and Profile Milling
What are the key ways to hold the work materials in an engine lathe taught in chapter 2?
- Chuck - to centre pieces about rotational axis
- Lathe Dog & Centre - used for long, thin, cylindrical parts
- Collet - squeeze workpiece
- Face Plate - for customized workpiece
What are the different shape formations?
- Form Turning
- Drilling
- Broaching
What are the other turning machines?
- Turret Lathe - key to mass production
- Chucking Machine - ideal for threading
- Bar Machine
- Automatic Screw Machine - makes fasteners
- Multiple Splindle bar Machine - 1 tool per spindle
Whats the difference between using “Chuck & Key” and “Lathe Dog & Centre”?
Chuck & key - to hold cylindrical parts (3 jaw) & non-cylindrical (4 jaw)
Lathe Dog & Centre - for high aspect ratios (long parts) to help stabilise (reduce vibration)
How does the Collet work?
It is mainly used for high aspect ratio parts, where it allows squeezing of the workpiece as the tool is cutting.
What is the purpose of boring?
To increase depth and diameter of a hole.
Note: Chips will be stuck during boring, so to fix it, after a certain depth the cutter will be moved out and remove the chips. And continue after.
When do you use vertical & horizontal boring?
Vertical is used when the part is too heavy for horizontal, e.g. turbine
How does the drill’s point angle affect the cutting of different materials?
Usually, greater angles are used to cut harder materials and vice versa for softer materials.
What are the different drill operations? (6) And what are they used for?
- Reaming - increase diameter of a drilled hole
- Tapping - create screw threads
- Counterboring - creation of final geometry (flat surface)
- Countersinking - creation of final geometry (tapered hole)
- Centre drilling - done prior to drilling
- Spot facing - to ensure a fastener is flushed with the surface
What are the different work holding for drill presses (3) and its purposes?
- Jigs - for positioning of cutting tool
- Vise - clamping of workpiece
- Fixtures - holds workpiece at predetermined positions
What are the 2 types of milling and their differences?
- Peripheral milling - axis of rotation is parallel to face
- Face milling - axis of rotation is perpendicular to face
Whats the difference between up and down milling? (5)
Up Milling:
1. Work piece fed in the opposite direction of the cutter
2. progressively thicker chips
3. Strong clamping required
4. Poor surface finish
5. Used for hard materials + Quick removal
Down Milling:
1. Fed in same direction as cutter
2. Progressively thinner chips
3. Allows weak clamping
4. Good surface finishing
5. For softer materials + Finishing operations
What are the principal types of Milling Cutters?
Plain milling cutter
Form milling cutter
Face milling cutter
End milling cutter
What are the types of Milling Machines? (6)
Horizontal
Universal Horizontal
Knee-and-column (KC)
Bed-type
Vertical
Ram-type vertical
What is the difference (2) & similarity (1) of planing and shaping?
Difference:
Shaping is just a linear feeding of tool onto a workpiece, while planing is to create new plane/surface geometry using different tool piece.
In shaping, the cutting tool is the one that moves to cut, while in planing, the workpiece moves into the cutter.
Similar:
Shaping and planing are both single point cutting tools operations
What is broaching?
Force feeding the cutting tool into an existing channel, then pulls out the material (done over multiple times)
Usually, has high temp due to frictional forces, hence coolant is widely used
What are the 2 types of broaching?
External - create a external geometry based on the cutting tool
Internal (surface) - most commonly used
What are the 3 different types of sawing?
- Hacksaw
- Vertical Bandsaw
- Circular Saw
What is thread milling?
Used for the creation of threads
Axis of rotation of horizontal milling cutter is parallel to feed direction of tool
What is gear milling?
Used for the creation of grooves
Axis of rotation of milling cutter is parallel to groove direction
What is gear hobbing?
Used for longitudinal gears.
Cutter axis of rotation is parallel to feed direction of workpiece.
What is gear shaping?
Workpiece + Cutter indexing
Primary cutting parallel to direction of rotation of workpiece
For High Speed Machining, what are the requirements? (6)
- Special bearings for HIGH RPM operation
- High Feed Rate (e.g. 50m/min)
- CNC motion controls to be equipped with ‘look-ahead’ (predictive) feature to avoid ‘undershooting’ OR ‘overshooting’ (to maintain precision)
- Balanced cutting tools, toolholders, and spindles (prevent vibration)
- Coolant delivery at high pressures
- Chip control (breakers) and removal systems
What are the different cutting fluids?
Coolants - reduce effects of heat in machining
Lubricants - reduce tool-chip and tool-work friction
Emulsions - Reduce heat and friction (coolant + lubricant mixture)
What are the types of peripheral milling?
- Slab
- Slotting
- Side
- Straddle
- Form
What are the types of face milling?
- Conventional
- Partial Face
- End
- Profile
- Surface
- Ball-end
What’s the difference between shape generation and forming for machining operations?
Generating is the creation of work geometry due to feed trajectory.
Forming is the creation of work geometry due to the shape of the cutting tool.
