1. Sliding rails

The sliding guide has the advantages of simple structure, convenient manufacture, good rigidity and high vibration resistance. The traditional cast iron-cast iron, cast iron-quenched steel guide rail has the disadvantage that the static friction coefficient is large, and the dynamic friction coefficient changes with the speed, the friction loss is large, and it is easy to creep at low speed/(1-60mm/min/). It reduces the positioning accuracy of moving parts, so it is not used in other CNC machine tools except economical CNC machine tools.

At present, most CNC machine tools use plastic guide rails, that is, a layer of plastic film soft tape composed of plastic and other chemical materials is pasted on the friction surface of the moving guide rail.

There are two common types of guide rail plastics: PTFE guide rail soft tape and epoxy wear-resistant guide rail coating. The characteristics of plastic-coated sliding guides are good friction characteristics, good wear resistance, smooth movement, good vibration damping and good manufacturability.

2. Rolling guide

The rolling guide is to place rolling elements such as balls, rollers, needles, etc. between the guide surfaces, so that the sliding friction between the guide surfaces becomes rolling friction. Compared with sliding guide rails, the advantages of rolling guide rails are: high sensitivity, and the difference between the coefficient of dynamic friction and static friction is very small, so the movement is stable, and when moving at low speed, it is not easy to show the phenomenon of crawling; (high positioning accuracy, repeat positioning accuracy can reach 02um; The friction resistance is small, the movement is cumbersome, the wear is small, the precision is good, the life is long, but the vibration resistance of the rolling guide is poor, and the protection requirements are high.

The rolling guide is especially suitable for the places where the working parts of the machine tool require uniform movement, sensitive movement and high positioning accuracy. This is the reason why rolling guides are widely used in CNC machine tools.

3. Hydrostatic guide rail

Hydrostatic guide rails can be divided into hydrostatic guide rails and gas static pressure guide rails.

There is an oil cavity between the working surfaces of the two guide rails of the hydrostatic guide rail. After the lubricating oil with a certain pressure is introduced, a hydrostatic oil film can be formed, so that the working surface of the guide rail is in pure liquid friction, and there is no wear and tear, and the precision is good. At the same time, the friction coefficient is also extremely low, which greatly reduces the driving power; there is no crawling at low speed, the bearing capacity is large, and the rigidity is good; in addition, the oil has the effect of absorbing vibration and has good vibration resistance.

The disadvantage is that the structure is complex, there must be an oil supply system, and the cleanliness of the oil is required to be high. Hydrostatic guideways are increasingly used in machine tools.

The types of CNC machining centers suitable for these three guide rails are also different, so everyone still chooses the one that suits them according to their professional understanding.