Linear Guide Blocks by Series

A block is ordered by model, a rail by length. The block — also called a linear bearing block or carriage — carries the load and takes the mounting holes; the rail under it is one size of profile. Mixing the two is the most common ordering mistake, which is why the block and rail pages are kept apart.

Five families cover 7 to 65 mm: standard HG blocks, low-profile HGL, miniature MGN, wide-rail MGW and roller RG. All follow the HG-standard mounting dimensions for their size, so a machine designed around one block takes another without re-machining the rail.

Square or flange

The square block bolts down through the body; the flange block has ears that spread the mounting holes wider. On the same rail the flange version gives a wider bolt pattern, which helps when the carriage plate is thin or the load sits away from the rail centreline. Height and footprint differ, so the choice is usually made by the frame, not by the load rating.

Sizes 7 to 65 mm

Miniature sizes 7, 9, 12 and 15 mm carry a light carriage on a small rail. Sizes 15 to 45 mm cover most machine-tool axes. 55 and 65 mm are for gantries and press frames. Going up a size raises the load rating and the moment capacity, but it also raises the height and the cost, so go up only when the load or the overhang demands it.

How to pick a series

Start from the machine type: printers, laser heads and small slides take MGN; cantilevered heads take MGW because the wider rail resists overturning moment; machining centres and grinders take HG; frames that cannot be raised take HGL; heavy cutting where deflection has to stay small takes RG. Accuracy and preload are then chosen inside that family, not across families. If two families both look possible, compare the mounting height first: it is the number that decides whether the frame has to change, and it is cheaper to settle before the plate is machined.

Interchangeable or matched set

Interchangeable means the block and the rail are made to the same tolerance band separately, so a replacement block can be fitted to an existing rail. It covers preload Z0 and ZA at accuracy C, H and P. Matched set means the pair is lapped together: SP and UP accuracy and ZB preload are only supplied this way, and a block from one set cannot be moved to another rail without losing the grade. This is the single point where a quotation changes shape, so it is agreed before the order rather than after.

What a quotation covers

A quotation for a block states the model, the accuracy grade and the preload, the rail it fits, the rail length and the hole count, and the lead time for that combination. Nothing is quoted as a catalogue price, because the same block in Z0 and in ZB are different products with different preparation. If the enquiry arrives without the accuracy or the preload, we ask for it rather than assume: the wrong preload is not visible until the axis is running.

Series at a glance

The highest dynamic load in each family, and the accuracy and preload that come with it. The figures are the largest size we publish in that family, not a typical value for the family.

Models by series

HG series (HGH / HGW / HGL)

MGN miniature

MGW wide rail

FAQ

Tell us the model, the quantity and the rail length, and the quotation comes back with the accuracy, the preload and the lead time for that exact configuration. See the rail page for the rail side.