- Workpiece Overcutting
Causes:
Tool deflection – The tool may be too long, too thin, or insufficiently rigid, causing it to deflect during cutting.
Improper operator handling.
Uneven machining allowance – e.g., 0.5 mm on the curved surface vs. 0.15 mm on the bottom.
Inappropriate cutting parameters – such as overly large tolerance or excessively fast spindle/feed rate (SF) settings.
Solutions:
Tool selection principle: Use larger and shorter tools whenever possible to enhance rigidity.
Add a corner-cleaning program and ensure consistent machining allowance (keep both side and bottom allowances even).
Adjust cutting parameters appropriately, especially in areas with large allowance—use arc transitions to reduce sudden tool load.
Use the machine’s SF adjustment function to fine-tune cutting speed for optimal performance.
- Incorrect Workpiece Centering
Causes:
Manual centering errors by the operator; inaccurate input data.
Burrs around the mold.
Magnetized centering rod.
Mold sides are not perpendicular.
Solutions:
Double-check manual centering operations, and ensure the reference point and height are consistent.
Deburr the mold edges using a file or oil stone, clean with a cloth, and confirm by hand.
Demagnetize the centering rod before use, or use non-magnetic materials such as ceramic rods.
Check verticality of mold sides. If deviation is large, consult with the tooling team.
- Tool Length Setting Errors
Causes:
Manual operation or input error.
Improper tool clamping.
Flying cutter blade installed incorrectly (the tool body may have built-in deviation).
Mismatch between ball-end, flat-end, and flying cutter lengths.
Solutions:
Double-check tool setting operations and ensure consistency in tool length reference points.
Clean the tool holder thoroughly with compressed air or a cloth before clamping.
When using a flying cutter, measure the tool shank and bottom surface using the same blade for consistency.
Use a dedicated tool setting program to eliminate tool length mismatch between different cutter types.
- Collisions During Programming
Causes:
Insufficient or missing safety height – tool or chuck collides with the workpiece during rapid (G00) movement.
Mismatch between tool number on the program sheet and actual program.
Incorrect tool/blade length or cutting depth listed.
Incorrect Z-axis depth readings.
Incorrect coordinate settings in the program.
Solutions:
Accurately measure the workpiece height, and always set a safe clearance above it.
Ensure tool numbers and program data match – use automated or illustrated program sheets if possible.
Measure actual cutting depth, and clearly indicate tool and blade length (usually, tool holder should be 2–3 mm longer than the workpiece; blade 0.5–1 mm to prevent gouging).
Record Z-axis depths from actual measurements, and double-check the program sheet.
Verify coordinate settings during programming to prevent misalignment.
- Collisions During Manual Operation
Causes:
Z-axis depth setting error.
Incorrect operation sequence or missing steps (e.g., missing radius when collecting data on one side).
Using the wrong tool (e.g., using a D10 tool instead of a D4).
Running the wrong program file (e.g., executing A9.NC instead of A7.NC).
Turning the handwheel in the wrong direction.
Incorrect axis direction during rapid manual feed.
Solutions:
Be mindful of Z-axis reference points – bottom, top, or analysis surface.
Double-check all steps and data collection operations.
Verify tool type and size with the program sheet before clamping and installing.
Follow the program execution order strictly.
Improve operator proficiency in machine control.
Raise the Z-axis before manual movements to avoid crashes.
- Surface Finish Issues
Causes:
Unreasonable cutting parameters leading to rough surface finish.
Dull or worn cutting edge.
Tool overhang too long; blade projection excessive.
Poor chip removal, air blow, or oil flushing.
Improper cutting strategy (e.g., consider climb milling instead).
Burrs on the workpiece.
Solutions:
Optimize cutting parameters, tolerances, feed rates, and allowances.
Regularly inspect and replace cutting tools.
Minimize tool overhang and blade projection to prevent vibration.
Ensure proper chip removal and lubrication.
Use down (climb) milling strategies when appropriate, especially for flat or ball-end mills.
Address burr formation by understanding tool-machine interaction and choosing the right cutting method and post-processing.
