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Why there are CNC machining tool marks? How to eliminate them?

Metal processing mainly relies on the fine workmanship of large mechanical equipment to achieve the required precision. CNC machining is one of the main methods of precision machining, but it is a mechanical operation after all, and there will be deviations, knife marks and other reasons during the operation process, resulting in the abandonment or waste of processed products. The reasons for the CNC machining knife lines are What? What ways can we eliminate it? For this reason, the editor summarizes this article.

  1. The machine tool itself

Spindle winding and coaxiality errors, coaxiality errors between bearings; uneven wear and installation quality of the guide rails of various machine tool components, and errors caused by the wear and tear of each component of the transmission chain during use. These errors will directly affect the accuracy of the workpiece.

  1. Knives

Different types of knives, the wear produced during the manufacturing process of the knives, caused during the cutting process.


  1. Fixtures

The position deviation caused between the tool and the machine tool will also cause the cutting deviation.

  1. Positioning

The different geometric elements of the workpiece that need to be used are the positioning datum during processing, if the selected positioning datum deviates from the surface size and position determined by the design;


  1. Stiffness of machine tool components


The stiffness of machine tool components has not yet found a suitable calculation method, and the stiffness of machine tool components is still measured through experimental operations. If the contact surface deformation, friction, low-rigidity parts, gaps and other influencing factors cause the stiffness of machine tool components to be low, insufficient force will also cause workpieces to appear. scratches.

  1. Affected by heat

In precision machining and large-scale machining and cutting, the frictional heat between the workpiece, tool, and machine tool causes deformation, which also affects the processing of the workpiece.

  1. Internal stress

The internal stress generated inside the part will make the metal of the workpiece be in a high-energy unstable state, which will transform into a low-energy state, thus causing the workpiece to lose its original accuracy.

The causes of knife marks in CNC machining include: friction and wear and heating between the machine tools themselves; tool wear; deviations in the size and position of various parts of the machine, but this is limited by the machine itself, which can be adjusted and checked. Routine maintenance can be effectively improved, but after all, in the operation practice, the problem of knife marks is unavoidable.

How to eliminate knife marks in CNC machining? For precision small parts or machine installation parts, with shallow knife marks on the surface, a magnetic polishing machine (magnetic grinding machine) can grind for 15 minutes to achieve the polishing effect. At present, magnetic polishing machines include stand-alone small magnetic polishing machines and translational polishing machines.

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