Introduction: The Mechanical Tug-of-War

In linear motion design, there is a constant trade-off between rigidity and smoothness. This tension is defined by Preload.

While increasing preload makes a TOCO Mono Stage or Linear Guide stiffer and more accurate, it also introduces internal friction.

For high-speed applications, getting this balance wrong can lead to overheating and premature failure.

1. What is Preload?

Preload is the process of using oversized rolling elements (ball bearings) to eliminate the internal clearance (play) between the block and the rail.

• Zero Preload: Maximum smoothness, but the carriage may "wiggle" under load.

• Heavy Preload: Maximum rigidity and zero vibration, but requires more torque to move.

2. The Hidden Cost of High Friction

Friction isn't just a resistance to motion; it is a generator of heat.

• Thermal Expansion: As friction increases, the temperature of the ball screw and rails rises. This causes the steel to expand, which can actually change your positioning accuracy by several microns.

• Motor Stress: Higher friction requires your motor to work harder even when moving no payload, increasing energy consumption and reducing the life of the motor drive.

3. Choosing the Right Preload for Your Application

At TOCO, we categorize preload into three common levels to help you optimize your system:

4. Engineering Tips for High-Speed Success

If your application requires speeds exceeding 2m/s, consider the following:

1. Reduce Preload: Use a lighter preload to minimize heat buildup.

2. Increase Lubrication: Use a low-viscosity grease designed for high-speed travel to carry heat away from the contact points.

3. Monitor Temperature: If the rail surface exceeds 50°C during operation, your friction levels are too high for your current cooling/lubrication setup.