Linear Guide vs Linear Rail

The two terms are used loosely, and that is how the wrong part gets ordered. In this catalogue a linear guide is the assembled system — block plus rail — while a rail is the profile the block runs on, and a block is the carriage that carries the load. When someone asks for “a linear guide”, the first question is whether they mean the block, the rail, or the pair.

The three parts, plainly

The confusion matters because the block and the rail are separate part numbers with separate lead times. An enquiry that says “HG25” without saying which of the three is being asked for will come back with a question, which costs a round trip.

When the pair has to be ordered together

Up to accuracy P and preload ZA the block and the rail are interchangeable: a block can be bought for an existing rail, or a rail for existing blocks. SP and UP accuracy and ZB preload are lapped as a pair, so the two are ordered together and cannot be separated afterwards. That is the single most important thing to know when replacing a worn part on a precision machine: if the old guide is SP, a new block alone will not restore the grade.

What “linear guide” means in a search

In search results and supplier catalogues, “linear guide” usually refers to the assembled system, “linear rail” to the profile, and “linear bearing block” to the carriage. The same product family appears under all three names, which is why one page cannot rank for all of them. Here the block index is on linear guide blocks and the rail index on linear guide rails; the replacement lookup at /replace/ takes a model and tells you which part it is.

How to ask for a quote without a round trip

For a block: model, quantity, accuracy grade, preload. For a rail: size, length and hole count, or the stroke and the number of holes. For a set: both, plus the note that it is a matched set. If the machine is already running and the part is a replacement, send the model off the old block and the length of the old rail and the rest follows.

Where to go next

Blocks by family: HGH20CA, HGW25CC, HGL30CA, MGN12. Rails: HGR20, HGR25. Technical: rail length, selection, replacement lookup.

The names in the catalogue

The printed catalogue uses "linear guideway" for the assembled product and "rail" for the profile, with the block called a "slider" or "block". Suppliers mix the three freely, and search engines index all of them, which is why the same family appears under several names. What matters when ordering is not the name but the three fields: the model (block), the length and hole count (rail), and whether the two are interchangeable or a matched set.

A “linear guide” in a quotation line usually means the pair, because that is what a machine needs to move. A maintenance order is different: it is usually one block, sometimes one rail, and occasionally the pair when the old one was SP grade. Ask which case applies before pricing, because the supply rule changes with it.

Four ordering errors that cost a week

Ordering a block without the accuracy and preload, so it comes back as a question rather than a price. Ordering a rail by length only, without the hole count, so the holes are placed to the nearest standard and not to the machine. Ordering an SP replacement block on its own, which cannot restore the grade because the pair was lapped together. And ordering a “set” without saying so, which arrives as two parts with two lead times and no matching record. Each of these is avoided by one line of detail in the enquiry.

A quick way to tell what a quotation is for: if it lists a length in millimetres, it is a rail; if it lists accuracy and preload, it is a block; if it lists all of them, it is a set. Any quotation missing one of those three groups is incomplete, whatever the part is called.

The same rule applies to a maintenance kit: a “guide” supplied as a set arrives matched, while a “guide” ordered as two lines may arrive unmatched and will need checking before it is fitted. Write “matched set” on the order when that is what the machine needs, and write the rail length on the same line.

FAQ