CNC Flashcards
Work pieces made by EDM are submerged in what?
Dielectric Fluid
Where are the CNC programs created and stored?
The Machine Control Unit (MCU)
Which quadrant of the coordinate plane is positive in the Y axis and negative in the X axis?
2
Which quadrant of the coordinate plane is negative in both the X and Y axis?
3
What code causes the cutter to move directly to the specified coordinates without cutting?
G00
What code would move a cutter from Point A to Point B through a clockwise curve?
G02
What code would move a cutter from Point A to Point B through a counterclockwise curve?
G03
What is the difference between G00 and G01?
G00 moves the cutter as fast as the machine will allow, G01 requires a Feed Rate for cutting
How would you specify a clockwise curve with a radius of 8, traveling at less than half a circle at 500 inches per minute?
G02 R8 F500
How would you specify a counterclockwise curve with a radius of 6, traveling at more than half a circle at 300 inches per minute?
G03 R-6 F300
Point A is X5, Y0, Point B is X5, Y5. Feed Rate is 700 inches per minute. Rank all 5 methods of cutting from point A to point B from lowest to highest X value, using N in place of the radius.
- G02 Y5 R-N F700
- G02 Y5 RN F700
- G01 Y5 F700
- G03 Y5 RN F700
- G03 Y5 R-N F700
What function does a CNC machine do when prompted with an N-Code?
None. N-codes are for the user to identify which set of instructions they are looking at, and are ignored by the program.
What is a “Dog Leg”?
In a G00, the machine reaches one axis of its destination before it reaches the others.
How do you calculate Inches Per Minute for a Spot Drill or Split Point Drill?
Rotations per Minute x Inches per Revolution = Inches per Minute
How are Inches per Revolution calculated?
Diameter of cutting tool / 0.0625 x 0.001
How are rotations per minute calculated for aluminum?
3.82 x 300 / diameter of cutting tool
How are inches per minute calculated for an end mill?
Rotations per Minute x Number of Flutes x Chip Load
Define the following set of commands:
N05 G00 X0 Y0
N10 G01 X1 Y8 F500
Step 1: Set point A to 0,0
Step 2: At 500 inches per minute, proceed in a straight line to point B at 1,8
Define the function of M30
End the program and reset to starting point
What is G54 used for?
Defining the 0 point
What is the easiest way to crash a CNC machine?
Incorrectly set tool length
What is the recommended RPM for an Edge Finder?
750
How does G90 work?
Use absolute coordinates for all subsequent moves
What is the difference between G20 and G21?
G20 sets the program to run in Inches, G21 sets the program to run in Millimeters.
Which G-Code sets the active plane for circular motion along the X and Y axis?
G17
Which G-Code sets the active plane for circular motion along the X and Z axis?
G18
Which G-Code sets the active plane for circular motion along the Y and Z axis?
G19
If the cutting tool has a diameter of 10, and the cutter is to the right of the stock, how would you define that in G-Code?
G42 P5.0
If the cutting tool has a radius of 4, and the cutter is to the left of the stock, how would you define that in G-Code?
G41 P4.0
The sequence G0 G20 G17 G40 G80 G90 M05 is known as a Safety Line. What does it do, and what is it’s purpose?
The safety line resets and cancels all functions in the event that a program is interrupted and needs to start over
Where does a Safety Line go in sequences?
At the beginning of every program
What is the function of M06?
Switching between tools
Explain the function of S2292 M03
Run the cutting tool clockwise at 2292 RPM
Explain the function of S3667 M04
Run the cutting tool counterclockwise at 3667 RPM
Which M-Code turns off all Coolant?
M09
What does M05 do?
Stops the rotation of the cutting tool
What is the difference between M07 and M08?
M07 uses light misting coolant, M08 uses heavy flooding coolant
Tool Length Offset is defined by which G-Code?
G43
What does G28 do?
Returns the tool to its 0 position
What does G91 do?
Uses incremental coordinates for all subsequent moves
What is the purpose of G80?
It cancels all canned cycles to ensure no axis motion will occur
What are canned cycles?
Canned cycles are a shortened code for a repetitive action such as drilling multiple holes of the same size
What operation is performed under G81?
Canned drilling Cycles
What does G99 do, and why is it necessary?
It returns the cutter to the rapid plane in order to avoid obstacles such as the vice clamps
What does G98 do?
It returns the cutter to the initial start plane
What symbol must all programs begin and end with?
%
Describe the formula for calculating the RPM for a mild steel workpiece with a 1/4 inch drill.
(3.82 x 100) / .250
382 / 0.250 = 1528 RPM
Describe the formula for calculating the RPM for an aluminum workpiece with a 5/8 inch end mill.
(3.82 x 300) / (5/8)
1146 / 0.625 = 1833 RPM
Describe the formula for calculating the RPM for a cast iron workpiece with a 3/8 inch reamer.
( (3.82 x 70) / (3/8) ) x 0.5
(267.4 / 0.375) x 0.5
713.07 x 0.5 = 357 RPM
Describe the formula for calculating the Feed Rate for a 1/4 inch diameter drill.
( (1/4) / (1/16) ) x 0.001
(0.25/0.0625) x 0.001
4 x 0.001 = 0.004 Feed per Revolution
