Smoothing the way for linear motion

New materials technology has resulted in the creation of wheels which run "virtually friction free" on the inside of aluminium profiles; providing stable support for the carriage plate in a new linear of linear motion units. The Herculane polymer technology, from Hepco, overcomes many of the problems associated with other polymers when subjected to loads, by exhibiting enhanced resistance to creep and flow. Performance is not sacrificed either as the units have the ability to run at operating speeds up to 6m/s and they have a load capacity up to 600N. all of this within a 60 51mm cross section. All this is achieved without the use of lubrication. Based on the results of regular customer feedback, Hepco has combined the new material and its strength in aluminium profile design with proven belt technology, creating a unit which, through the arrangement of the components, is effectively sealed against anything bigger than dust or sand particles, using the drive belt as the primary seal. Applications for the Profile Driven Unit (PDU) are envisioned in the print industry and similar automation requirements in the food and pharmaceutical sectors where cleanliness is an important consideration. The company is keen to point out that the PDU system, as it is compatible with both Hepco's and its competitor's profile systems, is an ideal replacement technology for ball-based systems which, it claims, cannot match the high speeds on offer. The internal carriage of the new systems is likened to a diamond in cross section with the top and bottom points cut off. Rectangular recesses are created within these faces in which the drive belt runs, both above and below the carriage. On each of the remaining angled faces a wheel assembly is mounted. With a total of eight wheels, four at each end, supporting the carriage within the confines of the profile. The external carriage plate is then secured, through the belt to the internal carriage, providing an external surface onto which other components can be mounted. This includes another PDU unit, creating an XY system. A choice of motors is on offer from the company, providing driving forces up to 280N; with a typical AC inverter motor delivering a linear force of 145N and speeds of up to 5m/s. The company provides a range of tubular flanges to ensure easy connection to most types and makes of motors and gear boxes. Drive shafts can be configured left, right or doubled. Integral end-of-stroke protection is available as standard and options available include holding brakes, positioning encoders and limit switches. The built in switch cam on the carriage plate can also be rotated to change sides.