Clients often come to us with just an idea and let us help design models and CNC parts.
Usually, when we receive such an inquiry, we will assign it to our corresponding engineer as soon as possible. Our engineer will proactively understand the points that customers care about from the initial communication, and provide cost-effective and rationalized suggestions from design, material, production process, manufacturability, etc.

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In the milling process, due to the different material properties of the workpiece, the complex and diverse structure of the workpiece, the repeated positioning of the workpiece, the cooling system, cutting parameters and tool geometry, etc. Factors often lead to part size out of tolerance, part deformation and surface finish. The problem is very likely to cause the bad phenomenon of the workpiece.

The following Yijin hardware experts share the analysis and solutions of common problems in the CNC milling process with years of practical experience to see if they can help you.

YIJIN Hardware CNC Milling Undesirable Phenomena – Solutions

1. Aluminum Alloy Non – Machined Surface Mildew Phenomenon

Fault Cause: Residues on the machined surface affect post-cleaning, insufficient aluminum corrosion inhibition ability of cutting fluid, and insufficient microbial control ability of cutting fluid.

Solution: Clean the finished parts in time to prevent the residual oil and impurities from chemically reacting on the surface of the workpiece; add and replace new cutting fluid regularly; effectively improve the foam performance of the cutting fluid

2. Tapping Teeth, Adhesive Processing Surface Is Not Up To Standard

Causes of failure: Unreasonable processing parameters, long-term use of tools without replacement, irregular use of lubricating oil and coolant.

Solution: Change the machining parameters to avoid medium-speed machining that is easy to stick to the tool, and use cutting fluids with good lubrication and cooling properties according to the characteristics of the material.

3. Machining The Vibrating Tool, The Surface Has Obvious Vibration Stability

Causes of failure: poor fixture rigidity, vibration at rounded corners, excessive tool overhang, poor axial rigidity of the workpiece, milling of square shoulders with a poorly rigid spindle


1) Poor fixture rigidity: analyze the direction of the cutting force and provide sufficient support or improve the fixture; by reducing the amount of back engagement ap; select positive rake angle cutting, sparse and unequal pitch tools;

Choose an L-Groove with a small fillet radius and small parallel lands.

2) Tool overhang is too long: minimize overhang; use sparsely-pitch cutters with unequal pitch; balance radial and axial cutting forces; increase feed per tooth fz;

Use light cutting insert geometry L/M; reduce axial back-feed tool ap; use up milling in finishing.

3) Milling square shoulder with poor rigidity spindle: Choose the smallest possible tool diameter; choose positive and light-cutting tools and inserts; try milling upwards.

4) Vibration at rounded corners: Large fillet radius is used in programming to reduce the feed.

5) Poor axial rigidity of the workpiece: consider a square shoulder tool with a positive rake geometry (90° entering angle); choose an insert with an L geometry;

Reduce the lower axial cutting force of back cutting, smaller fillet radius and parallel edge belt; Choose sparring tools with unequal pitch.


4. Processing Plane Is Not Smooth, Not Smooth

Causes of failure: The performance of the finishing cutting oil cannot meet the processing requirements, the tool feed speed is too fast, causing the vibration tool to leave an uneven path on the workpiece surface, and the cutting direction of the tool is inconsistent

Solution: adopt full down milling; choose special cutting oil

5. Tool Change Marks During Fine Milling

Cause of failure: The traces that appear when the parameters are adjusted without paying attention to the tool change operation

Solution: Replace the small tool for the finishing of the concave corner, carry out and adjust the parameters accordingly

6. Burrs And Drapes Left On The Surface Or Sides After Finishing

Cause of failure: caused by tool wear or thermal effect

Solution: Regularly check the wear degree of the tool to ensure that the tool is sharp for cutting; do a good job in the planning of the tool path, first machine the surface, then machine the side surface, and then machine the surface; increase the secondary finishing tool path.

7. Machining Errors Of Special Shape Workpieces

Cause of failure: software fitting error

Solution: Error control of programming software