The Wear Of CNC Machining Solving Techniques

- Aug 17, 2018-

The wear of CNC machining solving techniques.


Common types and characteristics of mechanical wear

(1) Running wear: The corresponding wear of the machine under normal load, speed and lubrication conditions, the wear development is very slow.

(2) Hard grain wear: the abrasive grains dropped by the parts themselves and the hard particles entering the outside, causing mechanical cutting or grinding, and destroying the parts.

(3) Surface fatigue wear: Under the action of alternating load, tiny cracks and spot-like pits are generated, which cause damage to the parts. Such wear is related to pressure magnitude, load characteristics, machine material, and size factor.

(4) Hot wear: During the friction process, the metal surface wears and the internal matrix generates hot zone or high temperature, which causes the parts to have temper softening, burning and wrinkling, etc., which often occur in high-speed and high-pressure sliding friction, the destructiveness of wear is prominent, accompanied by the nature of accidental wear.

(5) Corrosion wear: The chemical corrosion causes wear, the surface of the part is attacked by acid, alkali, salt liquid or harmful gas, or the surface of the part is combined with oxygen to form a hard and brittle metal oxide which is easy to fall off and the parts are worn.

(6) Phase change wear: The parts work in the high temperature state for a long time, the metal structure grains on the surface of the parts become larger, and the small gaps are generated around the grain boundaries to make the parts fragile, the wear resistance is reduced, and the wear of the parts is accelerated.

(7) Hydrodynamic wear: wear of the surface of the part caused by the liquid velocity or particle flow velocity impacting the surface of the part.


Causes of parts wear and their prevention methods

(1) Normal wear and tear

a. Mutual friction between parts: to ensure the cleaning and lubrication of parts

b. Wear caused by hard particles: keep the parts clean and cover the exposed parts of the parts

c. Fatigue wear of parts under long-term alternating load: eliminate the gap, choose the appropriate grease, reduce the additional vibration, and improve the accuracy of the parts.

d. Corrosion of chemical substances on parts: remove harmful chemicals and improve the corrosion resistance of parts

e. Metallographic changes or matching properties of the surface of the part under high temperature conditions: try to improve working conditions, or use high temperature and wear resistant materials to make parts.

(2) Abnormal wear

a. Repair or manufacturing quality does not meet design requirements: strict quality inspection.

b. Violation of operating procedures: familiar with mechanical properties, careful operation.

c. Improper transportation, loading and unloading, and proper storage: master the lifting knowledge and operate with caution.


Reasons and measures for shortening mechanical life after overhaul.

(1) Deformation of the basic parts: Since the deformation changes the relative position of each part, the wear of the parts is accelerated, and the life of the parts is shortened. Reasonable installation and adjustment can be taken to prevent deformation.

(2) Part balance damage: Unbalanced parts rotating at high speed accelerate the damage of parts under the action of centrifugal force and shorten the life of parts. Strictly carry out dynamic balance test measures to prevent.

(3) No running-in is performed: the replacement parts are not properly grounded, and the wear of the parts mating surface will increase and the life of the parts will be shortened. The precaution is to run the fittings together.

(4) Low hardness: improperly selected parts are repaired, the surface hardness is not up to standard, or the heat treatment is unqualified. Precautionary measures: select materials as required and perform reasonable heat treatment.