Posted to News on 1st Nov 2013, 00:00
Low friction positioning and transportation
Comprising a sliding carriage mounted on a rail, linear guides provide a means of positioning or transporting loads of many different types, including dovetail slides, ball type linear motion bearings and roller type linear motion bearings.
>Dovetail slides are simple designs, with a v-shaped carriage that locks into the linear base's corresponding groove. A greater force is required to move them than with other designs, and friction can be an issue, restriction speed and acceleration, but they offer high load capacities and good durability. In addition, they are inherently resistant to environmental contamination, are resistant to shock, and are capable of long travel.
>Rolling element linear motion systems include roller types and ball types. Each of these employ either recirculating or non-recirculating rolling elements, with recirculating types offering advantages of potentially unlimited stroke lengths. The rolling elements significantly reduce friction, so far less force is required to move the carriage. This enables more precise positioning and allows higher speeds and accelerations. There is also far less wear than with sliding types, so they will maintain accuracy over a much longer lifetime.
>Typical applications are found in a whole range of different industries, including medical equipment, packaging machinery, parts handling, machine tools, food and drink production, filling and coiling.
>In deciding on the best technology for a given application, engineers should look at considerations for running parallelism, repeatability and resolution. Lateral and moment load support capability must also be considered, and allowance must be made for thermal expansion. Alignment requirements, preload and frictional properties are also key.
>Franke Bearings offers a wide range of linear guides, including systems with O-arranged raceways, double row recirculating rollers, single row recirculating balls or linear tables and linear modules. All guide bodies are made from high-strength aluminium, and are as much as 65% lighter than steel guides. The aluminium roller guide is available as a double row rail with cassette and a pair of single rails with roller shoes.
>Franke linear guides employ specially processed raceways, which are integrated into the guide rails. The precision raceways ensure precise and silent running, even at high speeds. The rollers designed for high load ratings are set in the roller shoes at a 90° angle and rest on a four-point contact. This means that even high loads can be borne from all directions.
>The cassette of the roller guide combines an aluminium body with steel or stainless steel needle or ball bearing rollers. Special cover discs on the roller seal the bearing to the outside. Eight rollers in ball O-formation guarantee an equally high load capacity in all directions. The rollers are equipped with a groove, which is adjusted to the profile of the raceway.
>Thanks to this patented system of guided rollers, the rollers are guided laterally which guarantees smooth and silent running. It also allows high traverse speeds and accelerations.
>The cassette plate has mounting holes in accordance with industry standards. The slide resistance can be adjusted up and down individually using a setting screw on the side. Five standard sizes are available from size 12 to 45. In the UK, Franke stocks standard and stainless types in all sizes, and high temperature, high dynamic and lube-free types in certain sizes.
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