One THK SRS15M Linear Slide Block Bearing

THK · Linear Motion · SRS Series · 15mm Rail Width · In stock

What Is the THK SRS15M Linear Slide Block Bearing?

The THK SRS15M is a linear motion bearing carriage (block) from THK's SRS miniature guide series. Inside the block, precision-ground steel balls recirculate through internal pathways, rolling between the block's raceways and the grooves of a matching 15mm-wide rail. This rolling-element design eliminates the stick-slip friction of plain bearings, delivering smooth, predictable motion for CNC machinery, automated assembly stations, semiconductor wafer handlers, and optical inspection stages. The M preload class means the balls are sized to create a slight internal interference fit, boosting rigidity without excessive drag.

In short: A genuine THK carriage block engineered for a 15mm SRS rail — the precision motion component you install when positioning accuracy, travel smoothness, and repeatability are non-negotiable.

Three Things That Determine Linear Guide Performance

1. Ball Recirculation Quality

The defining feature of a THK guide is how smoothly the balls transition from the load-bearing straight section into the return path inside the end caps. Poor recirculation causes velocity ripple — microscopic speed variations that show up as chatter marks on a machined surface or blur in a vision system image. THK's injection-molded return guides maintain ball spacing and prevent jamming even at speeds above 1 m/s.

2. Preload Selection: Why M (Medium) Matters

Medium preload removes the microscopic clearance between balls and raceways, stiffening the joint without creating so much friction that it taxes the motor. This is the sweet spot for general automation — enough rigidity to hold position under moderate cutting or inertial loads, but not so tight that the drive needs to fight internal drag. If your application involves intermittent cutting forces (router, mill-drill), medium preload is the right starting point.

3. Seal Integrity and Contamination

The end seals are the first line of defense against particulate ingress. Inspect them upon arrival — a torn lip or missing seal lets chips, dust, or coolant into the ball path, where they act as grinding compound. In woodworking, graphite-heavy, or ceramic-powder environments, add secondary bellows or way covers. The seals are replaceable; if yours arrive damaged, contact us before installing the block.

Key Specifications

Where You Will Find the SRS15M Installed

• Benchtop CNC spindle carriage: Z-axis on small routers and engravers where space is tight and precision matters.
• SMT component placement: High-speed linear axes in pick-and-place machines cycling millions of strokes per year.
• DIY CoreXY 3D printers: Enthusiast upgrades from wheel-based linear motion to proper recirculating ball guides.
• Vision inspection gantries: Camera sleds traversing parts for automated defect detection.
• Lab automation workstations: Pipette tip changers and sample tray shuttles needing quiet, clean operation.

Frequently Asked Questions

Does this listing include the rail, or just the bearing block?

This is the bearing block (carriage) only. The matching SRS 15mm rail is sold separately. THK normally ships blocks and rails as factory-matched pairs to achieve the stated preload — mixing a used block with a new rail or swapping blocks between different rails can shift the preload outside the specified range. If you need a complete rail-and-block set, send us your rail length and we will quote the full assembly.

What lubrication schedule should I follow?

THK specifies lithium soap grease at NLGI 1-2 consistency, with the factory fill typically being THK AFB-LF. Re-grease every 100 km of travel or 3-6 months in clean environments. In dusty, wet, or washdown conditions, shorten that interval substantially. Apply grease through the nipple if fitted, or directly onto the rail grooves and stroke the block to distribute. Critically: never mix lithium soap and polyurea greases — the chemical reaction hardens the mixture and can seize the ball circuits.

Is this a genuine THK product or an aftermarket copy?

This is a genuine THK component. Authentic blocks carry laser-etched markings (model, lot code, THK logo) directly on the steel body. The end caps fit precisely with no gaps or visible glue. Counterfeit blocks typically have rougher surface finish, painted-on markings that rub off, and noticeably higher rolling resistance. We source through authorized THK distribution channels. Read about our supply chain standards.

How many blocks do I need for one linear axis?

A single block cannot resist moment (twisting) loads — when the load center of gravity is offset from the block center, the block experiences a torque that one bearing row alone cannot handle. Use at least two blocks on one rail, or ideally one block on each of two parallel rails (which also handles lateral moments). Installing a single block on a single rail is acceptable only for completely unloaded guide applications (camera sliders, sensor positioning) where the only force is the carriage's own weight.

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