How to Choose THK Linear Guides, Ball Screws, and Actuators

THK is a brand of linear motion components: parts that guide, support, and move loads in a straight line within a machine. At MR, we distribute them for maintenance workshops, machine builders, and plants working with automation. The starting point is always understanding the function of the part within the equipment.

The most frequently requested product types are linear guides, ball screws, and linear actuators. There are also orders for bearings for rotary tables, assembled motion units, and accessories such as bellows or lubricators. Each type solves a different problem, although they often work together on the same axis.

For a quote, it's best to have the identification engraved on the part or on the equipment plate. If the brand is erased, the main measurements and a clear photo are enough. With that, we quote the corresponding reference and respond promptly.

A linear guide has two parts: the rail, which is bolted to the structure, and the carriage or block, which runs on it with rolling elements that recirculate inside. They are used in machining centers, cutting machines, measuring equipment, Cartesian robots, and positioning tables. Their job is to move the load with low friction and no lateral play.

When choosing a guide, consider the rail width, carriage type, and load directions. A flanged carriage is mounted from above or below, while a non-flanged one requires less space. If the machine experiences shocks or strong moments, a longer carriage or two carriages per rail is recommended.

When replacing a carriage, it's also important to know if the original rail is still in good condition. A new carriage on a worn rail tends to last little and work noisily. Therefore, when requesting a quote, tell us if you need the rail, the carriage, or the complete assembly, and the rail length you use.

A ball screw transforms motor rotation into linear displacement. Between the screw and the nut, balls circulate that reduce friction compared to a common trapezoidal screw. It is used in feed axes of machine tools, electric presses, robots, and positioning tables.

There are two main manufacturing methods: rolled screws, where the thread is formed by deformation, and ground screws, where it is finished with a grinding wheel. Rolled screws are used in transport and general positioning. Ground screws are chosen when the axis needs to repeat the position with high accuracy, as in a CNC machine.

The key data for a screw are the nominal diameter, lead, total length, and the shape of the ends that support the bearings. The nut type also matters: flanged or cylindrical, single or preloaded. With that information, or with the part identification, we quote the corresponding THK screw.

A linear actuator combines the guide, the drive mechanism, and the support structure in a single body. The motor is mounted on it, and the assembly is ready to move a load between two positions or along its entire stroke. It is used in assembly lines, packaging, dosing, and testing equipment.

The internal mechanism can be a ball screw or a toothed belt. The screw provides more force and better repeatability; the belt allows long strokes and faster movements with light loads. The choice depends on what matters most in your application: precision, speed, or travel length.

To quote an actuator, it's helpful to provide the useful stroke, the load it moves, the mounting orientation, and the motor to be coupled. If you are replacing an existing one, the plate identification simplifies everything. With that data, we quote the appropriate THK actuator.

In addition to linear motion, THK offers bearings designed for high-rigidity rotation. Crossed roller bearings, for example, arrange rollers in alternating directions and support radial, axial, and tilting loads simultaneously. That's why they are found in rotary tables, robot joints, and heads.

In tight spaces, needle bearings are also used, which have long, thin rollers. They support radial loads with a very thin section, allowing compact axes. They are common in cam mechanisms, followers, and pivots within automatic machines.

To quote this type of bearing, we need the inner diameter, outer diameter, and width, or the identification engraved on the ring. It also helps to know how it is mounted and what loads it receives. With that, we quote the bearing that corresponds to your equipment.

A linear system lasts longer when protected and well lubricated. Bellows and rail covers prevent chips, dust, or coolant from entering the rolling zone. Carriage seals perform the same function at the entry of the rolling elements.

Lubrication can be manual, with a grease gun, or automatic, with lubricators that dose continuously. In dirty environments or on axes that work many hours per shift, automatic lubrication reduces downtime. The grease must be compatible with the seals and the axis speed.

If upon inspecting an axis you find play, noise, or marks on the rail, it's best to check the entire assembly before replacing a single part. Send us photos of the rail, carriage, and work area along with measurements. With that, we quote the necessary spare parts and accessories.

To quote any THK product, write to us via WhatsApp or email. Ideally, send the identification engraved on the part or on the equipment plate. If you don't have it, send the main measurements and a clear photo.

It also helps to provide the quantity, the machine where it is mounted, and whether it's a replacement or new equipment. If you have the identification from another brand, send it anyway: we review the measurements and quote the corresponding THK option.

MR has been working since 1945 in Buenos Aires, Argentina, with components for industry. Write to us with the code, measurement, or a photo, and we will respond promptly with your quote.