In automation equipment, the linear slider is the core component that determines motion accuracy and service life. Taking the widely used Linear Motion Block SBR20UU as an example, many engineers focus only on load and speed when selecting components, while ignoring two critical details: locating holes and clamp plates. These directly affect system repeatability and long-term stability. This article briefly explains their functions and application scenarios to help you build a more reliable linear motion system.
Part 1: Locating Holes - The Guarantee of Repeatable Accuracy
A locating hole is a precision-machined hole on the bottom or side of a linear slider, designed to work with a dowel pin. During installation, the dowel pin passes through the locating hole and into a corresponding hole in the base plate, restricting the slider's in-plane movement and allowing it to be fixed in only one position. This mating method achieves micron-level repeatable positioning accuracy.
Main functions of locating holes:
- Precisely fix the slider position and eliminate installation deviation.
- Ensure consistent position after repeated disassembly and reassembly.
- Absorb lateral shear forces, preventing micro-slippage that bolts alone may allow.
- Improve overall system rigidity.
When are locating holes needed?
- High-precision motion applications such as CNC machines, laser cutters, and semiconductor inspection equipment.
- Modules that require frequent disassembly but must maintain accuracy.
- Gantry structures where multiple sliders must stay strictly aligned.
- Scenarios with high acceleration or heavy loads that generate significant lateral forces.
For open-type blocks like the Linear Motion Block SBR20UU, when mounting directly on aluminum extrusions, it is recommended to first fix a precision adapter plate, machine locating holes on the plate, and then mount the slider onto the plate to achieve high positioning accuracy.
Part 2: Clamp Plates - The Key to Reliable Fixation
A clamp plate (also called pressure plate or retainer plate) applies clamping force through bolts to secure a linear slider or guide rail to the mounting surface. For the Linear Motion Block SBR20UU, clamp plates are often used with aluminum extrusion T-slots, allowing quick installation without drilling holes and easy position adjustment.
Main functions of clamp plates:
- Securely fix the slider or rail and prevent loosening during operation.
- Distribute clamping force evenly, avoiding localized stress that can damage the slider housing.
- Allow quick position adjustment; loosen, slide, and re-tighten.
- Provide better vibration resistance than bolt-only fixation in high-vibration environments.
When are clamp plates needed?
- When building frames with aluminum extrusions and needing fast installation and adjustment.
- When the mounting surface is not perfectly flat or requires gap compensation.
- Equipment with continuous vibration, such as packaging machinery, food production lines, and woodworking machinery.
- Production lines where sliders need frequent replacement or maintenance.
Common clamp plate types include L-shaped (for T-slots), U-shaped (for heavy loads or vibration), and adjustable (to compensate for uneven surfaces). Always control torque during installation to avoid deforming the slider housing; tighten multiple bolts gradually in a diagonal pattern; in high-vibration environments, check torque every 500 hours.
For example, a packaging machine required re-tightening slider bolts every two weeks without clamp plates; after installing U-shaped clamp plates, no loosening occurred during three months of continuous operation.
Part 3: Frequently Asked Questions
Q: Do locating holes have to be machined directly on the slider?
A: Not necessarily. When space is limited, locating holes can be machined on an adapter plate or machine base, with dowel pins passing through through-holes on the slider.
Q: Will clamp plates affect the sliding movement of the Linear Motion Block SBR20UU?
A: If installed correctly, clamp plates only contact the fixed part of the housing and will not interfere with internal ball circulation. However, excessive clamping force can deform the housing and increase friction, so torque must be controlled and smooth movement verified.
Q: Can clamp plates replace locating holes?
A: No. Clamp plates provide clamping force but cannot eliminate position deviation during installation. Both are recommended for high-precision applications.
Part 4: Selection Recommendations Summary
- High precision, repeated disassembly → Locating holes with dowel pins are essential.
- High vibration, heavy load, aluminum extrusion mounting → Clamp plate fixation is strongly recommended.
- Frequent position adjustment → Prefer adjustable clamp plates combined with T-slots.
If you have any questions about linear slider selection, locating hole design, or clamp plate fixing solutions, feel free to contact our technical team. We specialize in linear motion systems and can provide selection advice and customized solutions for products.
