CNC NC Programming Routine

Do you know how to deal with these problems in CNC machining?

CNC NC Programming Routine explain your question! More information about CNC machine or router control panel buttons & keys, please read: “what are the mean of CNC machine buttonS & keys?

cnc machine programming plc
cnc machine programming plc

CNC NC Programming Routine, Normal Machining problems & Solution

Overcutting of Machining workpiece:

over cutting Reason:

  1. Ballistic cutter, tool strength is not too long or too small, resulting in tool bouncing cutting tool.
  2. The operator operates improperly.
  3. Cutting allowance is not uniform. (e.g. 0.5 on the side and 0.15 on the bottom of the curved surface)
  4. Improper cutting parameters (such as too big tolerance, too fast SF setting, etc.).

Improve methods:

  1. The principle of using knives/cutters: big or small, short or short.
  2. Add angle clearing procedures, and keep the margin as evenly as possible. (The side and bottom margins remain the same.)
  3. Reasonably adjust the cutting parameters and round the corner with large margin.
  4. Using SF function of machine tool, the operator can adjust the speed slightly to achieve the best effect of machine tool cutting.

Centering problems ( to find the position of the machining workpiece in the coordinate system of the CNC machine center.

Reason analysis of centering problems in NC machining process:

  1. Operator’s manual operation is inaccurate.
  2. There are burrs around the die.
  3. There is magnetism in the middle bar.
  4. The four sides of the die are not vertical.

Improve centering operation:

  1. Manual operation should be carefully checked repeatedly, and the points should be as high as possible at the same point.
  2. Use oil stone or file to deburr the periphery of the die and wipe it clean with rags, and finally confirm it by hand.
  3. Demagnetize the middle bar before dividing the die. (Ceramic can be used to divide the middle bar or other parts.)
  4. Calibration check whether the four sides of the die are vertical. (Verticality error needs to be checked with fitter scheme.)

Cut tool setting problem:

Reason analysis of cutting tool setting :

  1. Operator’s manual operation is inaccurate.
  2. Error in tool clamping.
  3. The blade on the flying knife is wrong (the flying knife itself has some errors).
  4. There are errors between R knife and flat bottom knife and flying knife.

Improve methods of cutter setting:

  1. Manual operation should be checked repeatedly and carefully, and the knife should be checked at the same point as possible.
  2. Clean the tool with air gun or rag when clamping.
  3. A blade can be used when measuring the tool rod and smooth bottom of the blade on the flying knife.
  4. The error between the flat and flying knives of R-knife can be avoided by setting up a tool-setting program separately.

machine collision – Programming:

Reason of machine collision:

  1. Insufficient or no safety height (knife or chuck hitting workpiece when fast feed G00).
  2. Writing errors of tool on program sheet and actual program tool.
  3. Writing errors in tool length (edge length) and actual depth of machining on program sheet.
  4. Writing errors of Z-axis number of depth and actual Z-axis number on program sheet.
  5. Error of coordinate setting in programming.

Improve method:

  1. Accurate measurement of workpiece height also ensures that the safety height is above the workpiece.
  2. The tool on the program sheet should be consistent with the actual program tool (try to use the automatic program sheet or the picture to produce the program sheet).
  3. Measure the actual depth of the workpiece. Write clearly the length of the tool and the length of the edge on the program sheet (the general tool clamp length is 2-3MM higher than the workpiece, and the length of the blade avoids void is 0.5-1.0MM).
  4. Take the actual Z-axis number on the workpiece and write it clearly on the program sheet. (This operation is usually written for manual operation to be checked repeatedly).

cut tool collision – Operator:


  1. Deep Z-axis tool alignment error.
  2. Errors in the number of collisions and operations (e.g. the number taken unilaterally has no radius of feed, etc.).
  3. Use wrong knife (e.g. D4 knife and D10 knife).
  4. Program error (e.g. A7.NC goes A9.NC).
  5. The handwheel is rocking in the wrong direction during manual operation.
  6. Manual fast feed in wrong direction (e.g. – X press + X).


  1. Deep Z-axis tool alignment must pay attention to the position of tool alignment. (Bottom, top, analysis, etc.).
  2. The number of collisions and operands in points should be checked repeatedly after they are completed.
  3. When clamping the tool, it should be checked repeatedly against the program sheet and program before loading.
  4. Procedures should go one by one in order.
  5. When using manual operation, the operator himself should strengthen the operation proficiency of the machine tool.
  6. When moving rapidly by hand, Z-axis can be raised to the workpiece and moved.

Surface Accuracy:


  1. The cutting parameters are unreasonable and the workpiece surface is rough.
  2. The cutting edge is not sharp.
  3. Tool clamping is too long and blade avoidance is too long.
  4. Scrap removal, air blowing, oil flushing is not good.
  5. Programming cutter-walking mode, (you can consider milling as far as possible).
  6. Workpiece has burrs.


  1. Cutting parameters, tolerances, allowances and speed feed should be set reasonably.
  2. Tools require operators to inspect and replace them irregularly.
  3. When clamping the tool, the operator is required to clamp it as short as possible and the blade avoidance is not too long.
  4. For flat knife, R knife and round nose knife, the setting of speed feed should be reasonable.
  5. Workpieces have burrs: the root of our machine tools, cutting tools, the way we move the knife has a direct relationship. So we need to understand the performance of machine tools and repair burred edges.

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