Like all metal-on-metal contact bearings, lubrication is critical for proper operation of dovetail slides, and oil (rather than grease) is required to ensure a proper lubricating film between the surfaces, which reduces friction and ensures long life. However, this full contact design also means that sliding friction is higher for dovetail designs than for ball or roller bearing guides. Full contact between the ways gives dovetail slides higher load capacities and better stiffness than rolling element guides. The full-contact design of the sliding surfaces, or ways, also makes dovetail slides well-suited for absorbing and damping shocks and vibrations, which would damage ball or roller bearings. But dovetail slides, with full contact between the machined surfaces of the base and saddle, typically have higher stiffness and higher load capacity than similar-sized rolling element guides, which operate with only point contact (ball types) or line contact (roller types) between the rolling elements and the raceway. With high load capacities and good stiffness, dovetail slides can be used in many of the same applications and operations as profiled rail-type guides and crossed roller slides. But they have poor stiffness and lower load capacities than boxways or dovetail slides. Plain bushings can be made from a wide range of materials, so they can be applied in a variety of applications with contamination, chemicals, and environmental hazards. But boxway designs require more contact surfaces, which must be machined for proper operation, making them more difficult and manufacture, and in turn, typically the most expensive option. In the family of plain bearings, boxways generally have the highest load capacities and are commonly used in applications such as machine tools and stamping machines. Plain bearing linear guides can be boxway, dovetail, or shaft and bushing design. These differ from modern rolling element linear bearings, which use balls or rollers to reduce friction between the load-bearing surfaces. Dovetail slides are a type of plain linear bearing - along with boxway slides and plain bushings made of plastic, composite, or bronze - that rely on direct contact between sliding surfaces to support a load.
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