Mid term Flashcards
What is the formula for calculating spindle RPM?
CS x 4 / Diameter
For lathing, what is the feed rate?
The feed rate is how far the tool bit advances with each revolution of the work piece.
When making a rough cut on the lathe it requires a ____ _____ ____.
Faster feed rate
When making a finishing cut on the lathe it requires a _____ _____ _____.
Slower feed rate
For lathing, what is the depth of cut?
How far the tool bit advances into the stock material.
There are several angles ground on a lathe tool which provide the necessary shape for efficient cutting. The angles used depend on:
1) The hardness of the material being cut.
2) The rigidity of the lathe.
3) The amount of metal to be removed each cut.
4) The quality of finish required.
For a lathe bit, when the tool angle is large (NOT a knife edge), the tool:
1) has maximum strength
2) provides good heat dissipation
3) requires more power to cut
For a lathe bit, when the tool angle is smaller (sharper edge), the tool:
1) has a weaker cutting edge
2) machines a good finish
3) gives little tearing
4) cuts easily
What is the purpose of a relief angle on a lathe bit?
Relief angles ensure that only the cutting edge contacts the work. If a relief angle is not
correct, the side or end of the tool will rub, preventing the sharp edge from doing its job.
What is the purpose of rake angles on a lathe bit?
Rake angles help the material slide away from the work as it is cut off.
What is the purpose of side and end cutting angles for lathe bits?
Cutting material; Side and End cutting angles are usually not critical, but allow you to approach the work from
various orientations.
What is the angle for a center drill and counter sink?
60 and 82 degrees
What are all the main components of a drill bit?
Chisel point, cutting edge, flute.
What is the typical metal drill angle?
118 degrees
What style of chuck jaws is least accurate on the lathe?
3 jaw
When using a lathe, what is the recommended cutting speed for mild steel?
90 for a rough cut and 100 for a finish cut.
When using a lathe, what is the recommended cutting speed for Aluminum?
200 for a rough cut and 300 for a finish cut.
When using a lathe, what is the recommended cutting speed for tool steel?
70 for a rough cut and 90 for a finish cut.
What are the angles of a tool bit?
Cutting Edge
The Point
Relief Angle
Rake Angle
When milling, what is the cutting speed for aluminum?
500-1000 sfpm
When milling, what is the cutting speed for low carbon steel?
100 – 300 sfpm
What is the formula for Spindle RPM for Milling machines?
CSx4/D (Diameter of the milling cuttre in inches)
What is the Feed formula for Milling? (inches per minute)
(Number of cutter teeth) x (Feed per Tooth) x (RPM)
Example:
0.5” Diameter 2 flute end mill cutting
Aluminum
Spindle RPM = 500 x 4 /0.5 = 4000 RPM 0.5
Feed Rate = 2 x 0.011 x 4000 = 88 Inches/min
What is climb milling?
work is fed in the same direction as the cutter rotation. The cutting action tends to pull the workpiece under the cutter so any backlash will cause vibration, chatter, and possible cutter breakage. It produces a smoother surface and also allows the machining of small parts as cutter action tends to push parts into the table. On some
materials the cutters dull more rapidly.
What is an end mill cutter?
End mills cut on their ends & their sides (unlike a drill bit)
* 2 flute & multi-flute end mills
* multi-flute end mill will produce a better finish than the two.
What is a face mill cutter?
- face mills are used to cut with the ends of the cutter
rather than their sides - they create a face or flat surface
- they usually have a larger diameter than the width of the
work piece and the whole surface is processed in one pass
What is the difference between hot rolled and cold rolled steal?
Hot rolled has fewer sizes, fewer internal stresses, and a mill scale finish. Whereas, CR is more precise, glossy finish, and is higher in cost.
How do you identify high carbon steels?
- High amount of sparks from a spark test.
How do you identify stainless steel?
- most of them are non-magnetic.
- by its shiny appearance.
- it has chromium and nickel inside it.
What do you need to watch out for when working with Stainless steel?
- treat it as 2 gauges thicker on the sheers.
- it has poor heat transfer.
- it can be contaminated.
What is the difference between brass and bronze?
Brass is 60% copper and 40 % zin. Whereas, Bronze is 80% copper and 20% tin. Additionally, bronze is much harder than brass, and is used for bushings.
How do you read the numbers for aluminum? EX: 6061
6 - content
0 - impurity levels
6 and 1 - alloys that are incorporated.
What is the included angle on a thread cutting tool?
60 degrees
Angles on a drill bit may vary depending on the material. What are the angles used for general, soft, and hard materials?
General - 118
soft - 60 - 90
Hard - 135 - 150 degrees
Explain the process when reaming holes?
- slow rpm
- heavy cutting fluid
- never reverse direction
- go full depth because the ream is tapered.
What is a broaching tool used for?
- used to cut shapes inside or outside a work piece. Ex, a key way on a cam shaft.
What should you do before mounting a new grinding wheel?
- test it by tapping the side (listen for a ring).
Name off some typical grinding safety.
- never exceed grinding speed/rpm on the wheels.
- never force a wheel to its arbor
- never over tighten a grinding wheel
- always wear a face shield/ safety glasses.
Always install jaws ___ ____.
in order
What are 4 jaw chucks used for?
- accuracy
- hold on to odd shapes
- and to face objects.
What does a fast taper do?
- anything more than 3 degrees
Examples: milling machine spindle, and lathe spindle nose.
What is a morse taper?
- a slow taper
- an adapter for a drill bit, so you can use it on another machines arbor.
What is the clearance angle on a normal twist drill?
8 to 12 degrees.
What angle do you set your compound rest to when cutting threads on a lathe?
29 degrees straight in. 29 degrees avoids rubbing that would occur at 30 degrees.
When setting up TPI for threading, what part of the lathe is adjusted to ensure correct thread pitch?
The gear box. The lathe must be switched to threading mod, then set the gear box to the desired thread pitch.
