CNC (Computer Numerical Control) is revolutionizing the manufacturing process of precision stamping parts. There are numerous enhancements to make the process simple and metal stamping parts more precise.
However, like any other complex manufacturing process, CNC-machined parts fail. At Supra, as a stamping parts manufacturer, our technical experts dedicate considerable time to researching these failures, as studying them provides valuable clues for enhanced precision.
In this blog, we have addressed these issues and suggested ways you can prevent them for smoother and efficient CNC operations.
5 Common CNC-Machined Parts Failures:
1. Surface Finish Irregularities
The problem: A metal part leaves the machines with poor detail. These irregularities lead to weak spots and shorten component life.
Why it happens: Worn tools, poor fixturing, excess vibration in the CNC machine setup, or wrong feeds, such as too fast feed rates.
How to prevent it: Regularly maintain your tools for sharpness, secure the metal properly, use a correct milling strategy, and optimise machining parameters such as feed rate and spindle speed.
2. Weak, Brittle, or Warped Parts
The problem: A part that fails under stress can cause breakdowns in the field.
Why it happens: Wrong material choice, poor heat treatment, or residual stress during machining.
How to prevent it: Always match material to application. If strength, ductility, or heat resistance matter, don’t compromise. Use stable and consistent materials.
3. Chatter Marks
The problem: “zebra-stripe” pattern across a surface is a sign of instability. Chatter reduces accuracy and can damage both the part and the tool.
Why it happens: Poor rigidity, unwanted vibrations, unstable tool, wrong spindle speeds, or tool deflection.
to prevent it: Improve fixturing, use stiffer tooling, and fine-tune spindle speeds. Use tools specially designed to dampen vibrations.
4. Tool Marks
The problem: Tool drag, scratches, or loss of fine detail show up when machining isn’t under control. For precision metal parts, this can mean rejected batches.
Why it happens: Improper tools, aggressive cutting parameters, or improper tool entry-exit strategy.
How to prevent it: Use the right tool for the geometry, adjust the tool pressure, replace tools before they wear out, and simulate toolpaths to check for unnecessary tool contact. Polish the metal parts for any remaining marks.
5. Dimensional Inaccuracy
The problem: The part doesn’t match its intended dimensions.
Why it happens: Incorrect tolerances, poor calibration. It can also occur because of Built-up Edge (BUE), i.e., chips adhering to the tools due to high pressure or heat.
How to prevent it: Define realistic tolerances, use sharp tools, apply coolant or lubricant, and run inspections to catch early deviations.
The Mechanics Behind the Failure
Precision metal stamping parts produced by CNC machining are influenced by various mechanics, such as cutting speed, depth of cut, and feed rate
- Improper speed can lead to excessive heat and thermal damage
- High feed rate can lead to tool breakage and poor finish
- Low feed can lead to increased time
- Too deep a cut can put excessive strain
- A shallow cut can lead to wrong cutting and increased time
- Insufficient support can lead to the distortion of the metal part
- Thermal expansion causes dimensional inconsistencies
Conclusion:
Understanding the nuances of CNC machining is essential to prevent CNC-machined parts failure and create precision metal stamping parts.
As a precision stamping parts manufacturer, Supra treats every failure as a lesson. We value precision. For 45 years, we have worked hard to strengthen our quality process to deliver only precise metal parts, especially for heating components. As a stamping supplier in the European and USA markets, we create metal parts that meet international quality standards.
Speak with our experts to ensure your parts are precise and high-quality.
