Free CNC Cutting Basics Question and Answers — Questions and Answers

Question 1: A CNC component program says that the center of the clockwise circular interpolation with radius from P3 (25, 10) to P2 (10, 25) will be at

(15, 10)
(10, 15)
(15, 15)
(10. 10) (Correct answer)

Correct answer: (10. 10)

For a clockwise circular interpolation from P3 (25, 10) to P2 (10, 25), the center of the arc must be equidistant from both points. If the center is (10, 10), the radius from P3 is sqrt((25-10)^2 + (10-10)^2) = 15, and the radius from P2 is sqrt((10-10)^2 + (25-10)^2) = 15. This confirms (10,10) is a valid center. A clockwise path from (25,10) to (10,25) around (10,10) would traverse through the bottom and left quadrants, forming a major arc.

Question 2: The definition of "baud rate" is the

speed at which computer process data
speed of feed motor in CNC
speed of an electronic device
electronic data transmission rate in number of bits per second (Correct answer)

Correct answer: electronic data transmission rate in number of bits per second

Baud rate is a measure of the speed at which data is transmitted electronically over a communication channel. Specifically, it refers to the number of signal changes or symbols per second. In many digital communication contexts, especially for serial communication like that used with CNC machines, baud rate is often equivalent to bits per second (bps) when each symbol carries one bit of information, quantifying the data transmission rate.

Question 3: The tapping cycle on a machine center is displayed using the G code, which is

G82
G81
G89 (Correct answer)
G83

Correct answer: G89

In CNC programming, G-codes are used to prepare the machine for specific types of motion or operations. G89 is the standard G-code specifically designated for a tapping cycle that includes a dwell at the bottom of the hole. Other G-codes like G81, G82, and G83 are used for various drilling cycles, which are distinct from tapping operations.

Question 4: The motors that regulate feed in CNC machine tools are

Induction motors
Servo Motors (Correct answer)
Hydraulic motors
Stepper motors

Correct answer: Servo Motors

Servo motors are the preferred choice for controlling feed axes in CNC machine tools due to their exceptional precision, rapid response, and ability to maintain exact position and speed. They operate with closed-loop feedback systems, allowing the CNC controller to continuously monitor and adjust the motor's movement. This ensures highly accurate and smooth tool paths, which is critical for machining complex parts.

Question 5: The process by which the controller determines the speed and intermediate points of the axis motor is referred as as

Integration
Interpolation (Correct answer)
MCU
Extrapolation

Correct answer: Interpolation

Interpolation in CNC refers to the process where the machine controller calculates and generates the precise intermediate points between a defined start and end point for tool movement. This capability allows the machine to create smooth, continuous paths, whether linear or circular, by coordinating the simultaneous movement of multiple axes. It is fundamental for accurately machining complex contours and shapes.

Question 6: BTR's role in the DNC is

emulate the tape reader (Correct answer)
operate machine tool when DNC fails
improve accuracy of the CNC machine tool
eliminate machine tool controller

Correct answer: emulate the tape reader

BTR stands for 'Behind The Tape Reader'. In a Direct Numerical Control (DNC) system, the BTR unit acts as an interface between the central computer and the machine tool's control unit. Its primary function is to bypass the machine's original tape reader, feeding data directly from the DNC computer to the machine controller. This effectively emulates the tape reader's function without physically using a punched tape, allowing for faster and more efficient data transfer.

Question 7: The _________ is constant in axis motors for CNC machines.

Current
Speed
Torque (Correct answer)
Power

Correct answer: Torque

In CNC axis motors (servomotors), constant torque is crucial for precise positioning and consistent feed rates, especially during acceleration and deceleration. These motors are designed to provide a high, constant torque output over a wide range of speeds to overcome inertia and cutting forces. This ensures accurate and repeatable movement of the machine axes, which is fundamental for machining accuracy and surface finish.

Free CNC Cutting Basics Question and Answers

A CNC component program says that the center of the clockwise circular interpolation with radius from P3 (25, 10) to P2 (10, 25) will be at