First article inspection in CNC Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start the first article inspection program.

CNC Programming

M98 P[1]

Drag options to blanks, or click blank then click option'

A2002

B3003

C1001

D4004

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong subprogram number.

Forgetting the M98 command.

M98 P1001 calls the subprogram 1001 which is the first article inspection routine.

2fill in blank

medium

Complete the code to measure the part diameter during inspection.

CNC Programming

G65 P[1] Q1 R[2]

Drag options to blanks, or click blank then click option'

A5100

B5000

C5200

D5300

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect macro program number.

Confusing parameter Q and R.

G65 P5100 calls the macro program 5100 which measures diameter; Q1 specifies the measurement type; R is the nominal diameter value.

3fill in blank

hard

Fix the error in the code to correctly probe the part surface.

CNC Programming

G31 X[1] Y0 Z0 F100

Drag options to blanks, or click blank then click option'

A50

B100

C0

D-50

Attempts:

3 left

💡 Hint

Common Mistakes

Using positive X value causing no probe contact.

Setting zero which does not move the probe.

G31 probes in the negative X direction to find the part surface at -50 mm.

4fill in blank

hard

Fill both blanks to set the inspection tolerance limits.

CNC Programming

IF [#[1] GT [2]] THEN M30

Drag options to blanks, or click blank then click option'

A100

B200

C0.05

D0.1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable number.

Confusing tolerance value.

Variable 100 holds the measured value; if it is greater than 0.1 (tolerance), the program ends with M30.

5fill in blank

hard

Fill all three blanks to create a dictionary of inspection results with conditions.

CNC Programming

results = [1]: [2] for [3] in measurements if measurements[[3]] <= 0.1}

Drag options to blanks, or click blank then click option'

A'feature'

Bmeasurements[feature]

Cfeature

Dmeasurement

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names causing syntax errors.

Misplacing the condition in comprehension.

Creates a dictionary with keys as 'feature', values as measurements[feature], iterating over feature in measurements, filtering by tolerance <= 0.1.

Practice

1. What is the main purpose of First article inspection in CNC programming?

easy

A. To program the CNC machine without running it

B. To check the first part made by the CNC program for errors and quality

C. To clean the CNC machine before starting production

D. To speed up the CNC machine for faster production

Solution

1. Step 1: Understand the term 'First article inspection'

   It means checking the very first part produced by the CNC machine to ensure it meets quality standards.

2. Step 2: Identify the main goal of this process

   The goal is to catch errors early and confirm the part is made correctly before making many parts.

3. Final Answer:

   To check the first part made by the CNC program for errors and quality -> Option B

4. Quick Check:

   First article inspection = check first part quality [OK]

Hint: Remember: First article means first part check [OK]

Common Mistakes:

• Thinking it speeds up production
• Confusing it with machine cleaning
• Assuming it is programming without running

2. Which of the following is the correct sequence for performing a first article inspection?

easy

A. Run program, measure part, adjust program if needed

B. Measure part, run program, adjust program

C. Adjust program, run program, measure part

D. Run program, adjust program, measure part

Solution

1. Step 1: Identify the logical order of steps

   You first run the CNC program to make the part, then measure it to check accuracy.

2. Step 2: Adjust the program if measurements show errors

   If the part is not correct, you adjust the program and repeat as needed.

3. Final Answer:

   Run program, measure part, adjust program if needed -> Option A

4. Quick Check:

   Run -> Measure -> Adjust = A [OK]

Hint: Think: Make part first, then check and fix [OK]

Common Mistakes:

• Measuring before making the part
• Adjusting before measuring
• Skipping measurement step

3. Given this CNC program snippet for first article inspection:

G01 X10 Y10 F100
M30

What will be the expected output after running this program once?

medium

A. The tool moves in a circular path to X=10, Y=10

B. The tool will not move because feed rate is zero

C. The program will cause a syntax error and stop

D. The tool moves in a straight line to X=10, Y=10 at feed rate 100

Solution

1. Step 1: Understand G01 command

   G01 means linear move to specified coordinates at given feed rate.

2. Step 2: Analyze the given coordinates and feed rate

   The tool moves straight to X=10, Y=10 at feed rate 100 units/min.

3. Final Answer:

   The tool moves in a straight line to X=10, Y=10 at feed rate 100 -> Option D

4. Quick Check:

   G01 = linear move, feed 100 = speed [OK]

Hint: G01 means straight line move [OK]

Common Mistakes:

• Confusing G01 with circular move (G02/G03)
• Assuming feed rate is zero
• Thinking program has syntax error

4. You run a first article inspection program but the part dimensions are off. The program code is:

G01 X20 Y20 F150
M30

What is the likely error if the part is smaller than expected?

medium

A. Coordinates are incorrect, should be larger values

B. Program missing M03 spindle start command

C. Feed rate is too high causing tool deflection

D. M30 command is placed too early

Solution

1. Step 1: Check coordinates vs part size

   If the part is smaller, the tool likely did not move far enough, so coordinates are too small.

2. Step 2: Evaluate other options

   Feed rate affects speed, not size; missing spindle start or M30 early stop won't cause smaller size directly.

3. Final Answer:

   Coordinates are incorrect, should be larger values -> Option A

4. Quick Check:

   Wrong coordinates = wrong part size [OK]

Hint: Check coordinates first if part size is wrong [OK]

Common Mistakes:

• Blaming feed rate for size error
• Ignoring coordinate values
• Assuming spindle commands affect size

5. During first article inspection, you notice the part passes all measurements except one hole diameter is slightly too small. What is the best next step?

hard

A. Increase feed rate to cut the hole faster

B. Ignore the small hole difference and start full production

C. Adjust the CNC program tool path or tool size for that hole and rerun inspection

D. Replace the entire CNC program with a new one

Solution

1. Step 1: Identify the issue with the hole diameter

   The hole is too small, so the tool path or tool size needs adjustment to correct it.

2. Step 2: Decide the best corrective action

   Adjusting the program and rerunning inspection ensures quality before full production.

3. Final Answer:

   Adjust the CNC program tool path or tool size for that hole and rerun inspection -> Option C

4. Quick Check:

   Fix program, then re-inspect = correct approach [OK]

Hint: Fix program for errors before full production [OK]

Common Mistakes:

• Ignoring defects and producing many parts
• Changing feed rate without reason
• Replacing program unnecessarily