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‘First’ composite axes are lighter and more dynamic

23 August, 2013

The German motion technology specialist Schunk claims to have produced the first standard linear motor axes to be made of reinforced carbon composites (RCCs). It says the rigid modules are about 58% lighter than comparable aluminium modules, and deliver more dynamic movements with rapid accelerations.

According to Schunk, the LCx linear modules will set a new benchmark for high-precision, high-speed movement of Z or Y axes in assembly operations.

The composite construction is claimed to bring other advantages. For example, the high modulus of elasticity gives the axes superior bending and torsional stiffness. Good internal damping reduces vibration and ensures high dynamic stiffness. And because the thermal expansion of the composite material is minimal, the axes remain precise even if they heat up during operation.

The carbon axes come in two versions. One (called LCN) has a simple X profile and can reach a rated force of 200N and a maximum driving force of 500N.

The other (called LCM) is designed for moderate loads and is equipped with a wide double X profile. It can achieve a rated force of 400N and a maximum driving force of 1,000N.

For both versions, the maximum acceleration is 40m/s2, the maximum speed is 4m/s, and the maximum useful stroke is 1,200mm. The modules can be used horizontally or vertically, and offer the choice of either a static profile with a moving slide, or a static motor with a moving profile.

The lightweight linear modules are based on Schunk’s high-speed LDx modules. The use of servo-electric linear motor drives results in high dynamics and good repeat accuracies. The driving force is transmitted directly to the slide by precision drive elements, without needing mechanical power transmission components. Precision-cut steel guide rails increase accuracy further.

Schunk claims that its composite linear axes are the first of their type

The LCx axes are fitted with absolute-value transducers to provide a repeat accuracy of 0.01mm per axis. The modules are claimed to pay for themselves rapidly in dynamic joining and placing operations because of their short cycle times, and high precision and stability. Because there are almost no parts to wear, maintenance costs and unplanned downtime are said to be negligible. The axes do not need end or reference sensors, reducing the investment and programming costs and number of cables required.

The powerful servomotors allow lower-power axes than usual to be used in many applications or, in vertical applications, greater masses to be moved. Because the motor, measuring system and linear guidance are integrated into the axis profile or slide, the compact modules need little space.

The axes are controlled by Rexroth IndraDrive controllers as standard. Siemens Sinamics S120 drives are available as an option.

The LDx modules support Profibus, Sercos III, Profinet IO, EtherNet/IP and EtherCat, and can be integrated quickly and easily with higher-level controllers.

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