Linear guide slide pre-pressure is the key technology to ensure high precision and stable operation of the equipment, can be analyzed in depth from the principle of the role, grade classification, performance impact, setting method, scene selection, common problems six aspects.
First, the principle of pre-pressure and the core role of
pre-pressure by applying initial pressure to the linear guide slider, so that the slider rolling body (ball or roller) and the guide rail raceway close together and produce elastic deformation, thereby eliminating the gap between the two. This operation effectively avoids "scurrying" when the equipment is unloaded or commutated, and dramatically improves the smoothness of movement. In precision machining, semiconductor manufacturing and other fields, pre-pressure is the core technology to achieve micron-level positioning accuracy, while enhancing the rigidity of the guideway system to resist load deformation.
Second, pre-pressure level classification and characteristics
pre-pressure is generally divided into four levels:
| Preload level | Pressure Strength (vs. Rated Load) | Typical application scenarios |
| No preloading (free) | Stress-free | Low-speed conveyor line, light-load material handling |
| Light preloading | Low pressure (about 1% to 2%) | 3C product automatic production line, high-speed transplanting equipment |
| Medium preload | Moderate pressure (3%-5%) | Machining centers, precision testing instruments |
| Heavy preloading | High pressure (6%-10%) | Punch presses, large machine tools, heavy-duty mold equipment |
No pre-pressure: there is a clear gap between the slider and the guideway, suitable for low-speed conveying, light load handling and other low precision requirements of the scene;
light pre-pressure: 1%-2% of the rated load pressure, to eliminate the gap, commonly used in 3C automated production lines and other high-speed light equipment;
medium pre-pressure: the pressure up to 3%-5% of the rated load, resulting in a small amount of overload to meet the machining centers, testing instruments, etc., ± 0.01mm level of precision needs; heavy pre-pressure: 6%-5% of the rated load, resulting in a small amount of overload, to meet the machining centers, testing instruments, etc. heavy pre-pressure: 6%-10% high pressure, significant interference, suitable for punch presses, large machine tools and other heavy-duty high-frequency impact equipment.
Third, the impact of pre-pressure on the performance of the guide rail
pre-pressure size directly affects the performance of the guide rail operation:
Friction and temperature: the greater the pre-pressure, the higher the friction of the slider operation, high speed is easy due to friction heat caused by temperature rise;
life: too high pre-pressure will accelerate the rolling body and raceway wear, there has been an automotive production line due to the misuse of heavy pre-pressure, run a thousand hours that is anomalous wear and tear;
Rigidity and precision: the appropriate pre-pressure can enhance the rigidity of pre-pressure can enhance the rigidity of guideway 40% -60%, reduce the deformation of the load.
Fourth, the pre-pressure settings and debugging methods
There are two ways to realize the pre-pressure: adjust the diameter of the ball (increase 5-20μm to form an interference fit), or through the disc spring and other elastic components to provide adjustable pressure. When debugging, you need to use a torque wrench to measure the running resistance of the slider (no-load torque of about 0.5-1.0N・m in medium preload), and use a micrometer to control the gap (≤5μm in medium preload).
Fifth, different scenarios of the pre-pressure selection strategy
pre-pressure level should be adapted to the specific working conditions:
Semiconductor equipment: light/medium preload with non-magnetic materials to ensure uniformity and high precision;
CNC machine tools: heavy preload to cope with heavy load impacts, long guide rails need to be adjusted in segments;
3C sorting line: no preload or light preload to avoid high-speed jamming.
Sixth, pre-pressure common problems and solutions
In practical applications, the slider may be stuck due to excessive pre-pressure or insufficient lubrication, need to replace the low-pre-pressure slider and strengthen lubrication; running noise abnormalities due to uneven pre-pressure, you can calibrate the parallelism of the guideway; precision degradation may be due to insufficient pre-pressure or load fluctuations, you need to increase the level of pre-pressure and strengthen the support structure.
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