THK4RSR15UU+430LMiniature LM Guide Assembly — Two Size-15 Carriages with UU End Seals on One 430 mm Rail

Product Description

What this part is

A THK miniature LM Guide assembly from the RSR series: two size-15 RSR LM blocks with UU end seals supplied on one 430 mm LM rail. The RSR is THK’s miniature four-way equal-load linear guide — two rows of balls contact the raceways at 45° and circulate through endplates in the block, so a single block carries load in the radial, reverse-radial and both lateral directions.

Decoding the order code

Read 2RSR15UU+430L field by field. The leading 2 is the number of LM blocks used on the same rail. RSR is the miniature LM Guide series. 15 is the size, which fixes rail width at 15 mm and block height at 16 mm. UU is the contamination protection code — end seals fitted at both ends of the block, THK’s standard dust protection for this series. +430L is the LM rail length in millimetres. There is no accuracy letter, which is normal grade, and no radial clearance letter, which is normal clearance rather than the C1 light preload option. Normal clearance and C1 preload are different products: C1 raises axis stiffness and repeatability and also raises running drag, so match what the machine was built with.

Identifying the block body

THK builds size 15 in two body lengths and the marking here does not carry the body letter. Measure the block along the rail: the short V-type body is 42.9 mm long overall with a 25 x 20 mm four-hole M3 pattern and is rated C 4.41 kN / C0 6.57 kN; the long N-type body is 60.7 mm long with a 25 x 25 mm pattern and is rated C 7.16 kN / C0 10.7 kN. Everything else — 16 mm block height, 32 mm block width, 15 mm rail width, 9.5 mm rail height, 40 mm rail hole pitch — is common to both, so either body drops onto the same rail and the same mounting shoulder.

Scope — what is in the box

A matched assembly, not a bare carriage: both RSR15 blocks and the 430 mm rail are included. That is the expensive combination to source, because on any profiled linear guide the rail is normally the larger part of the cost and cannot be substituted across brands. In THK’s own terms a single-rail unit is one set — if your machine runs two rails in parallel you need two of these.

Published ratings and mounting data

Model: RSR15, size 15, UU end sealsBlock height M: 16 mmBlock width W: 32 mmBlock mounting screws: 4 x M3, 4 mm deepBlock shoulder dimension K: 12 mm; N: 3.5 mm; H3: 4 mmRail width W1: 15 mm (0 / −0.025)Rail height M1: 9.5 mm; W2: 8.5 mmRail mounting hole pitch F: 40 mmRail bolt holes: 3.5 x 6 x 4.5 mm, for M3 socket screwsRail length supplied: 430 mmRail mass: 0.925 kg/m (approx. 0.40 kg at 430 mm)Standard maximum RSR15 rail length: 1600 mmService temperature limit: 80 °CGreasing: PB107 grease nipple provisionBasic load ratings per block: 4.41 kN dynamic / 6.57 kN static (short V body); 7.16 kN dynamic / 10.7 kN static (long N body)

What these specs mean in practice

A 16 mm tall, 32 mm wide guide fits where a size-15 profiled rail like an HSR15 or SHS15 will not — small stages, pick-and-place heads, camera and sensor slides, benchtop test rigs. Two blocks on one rail is the configuration that gives moment capacity: two blocks in close contact take roughly 2.7 times the pitch moment of one, and spacing them apart along the 430 mm rail multiplies that again. Because the blocks are miniature, the mounting surface does most of the work — a wavy or burred mounting face shows up immediately as varying drag, and there is very little capacity in the guide to absorb it.

Fitting notes

Bolt the rail down through the 3.5 x 6 x 4.5 mm counterbores on the 40 mm pitch with M3 socket screws, working from one end so the rail pulls against the datum shoulder rather than being fought into place. Mount the block from the top face with M3 screws and respect the 4 mm thread depth — bottoming a screw in a miniature block will pinch the raceway and destroy the running feel. Never slide a block off the end of the rail: the endplates only retain the balls while the block is on the raceway.

Interchange guidance

Miniature linear guide blocks are not cross-brand interchangeable. The RSR raceway profile and ball diameter are specific to THK, so an IKO, NSK, Hiwin, PBC or generic size-15 miniature block will not run correctly on this rail even though the nominal rail width is also 15 mm, and this block will not run on theirs. Within THK, the stainless equivalents are RSR15VM and RSR15M (block, rail and balls stainless), and the wide-rail forms are RSR15WV and RSR15WVM — related sizes with different footprints and ratings, not substitutes. The number is also written RSR 15UU, RSR-15-UU, RSR15UU1, RSR15V UU and RSR15N UU.