Better wear

As the global credit crunch bites even harder the need to cut manufacturing costs becomes more important by the day, and operators are looking at maintenance as a possible target to making savings.

The field of linear motion now offers a range of products and services specifically designed to reduce the amount of attention required by parts and machinery over their operational lifetime — particularly those that must operate within a demanding environment and face frequent wash-downs or extremes of temperature.

Meanwhile, on the operational side, software has arrived with the ability to streamline performance to optimise production by simulating motion trajectories and possible errors.

On the product side, cable carrier system provider

has developed a lubricant-free toothed belt drive, specifically for the low-cost sector to fast-position small loads of up to 15kg. The company's new linear unit, called the DryLin ZLW-0630 Basic, is compact, small and lightweight, and aims to provide an alternative to leadscrew drives or pneumatic cylinders.

A 500mm stroke version weighs only 800g and is designed to be both maintenance and corrosion free. The stroke length is variable up to a maximum of 1,000mm. The device's guide profile and the carriage plate are made of anodised aluminium with a low deadweight to ensure low mass inertia.

The housings on the ends of the belt drive are made of a special impact-resistant plastic material, 'igumid G', while parts of the drive system and the sprockets are manufactured from tribo-optimised igus polymers. To ensure the belt runs smoothly, the glass fibre reinforced system is made of neoprene, allowing extremely quiet low-vibration running. There is also an option to include plastic plain bearings so that the toothed belt shaft can be used under water without the risk of corrosion.

The entire system has been created with the twin aims of being both simple and versatile, hence the fact that the flat and robust linear units can be assembled easily in a number of different ways. Captive nuts allow installation from three or two sides, as well as the attachment of sensors and initiators for positioning. There are also plain bores in the end blocks for individually cut threads for screw attachment at the narrow ends.

'The big difference with our belt drives is that they use dry running bearings in order to be totally maintenance free,' said Matt Aldridge, director of bearings at igus. 'Other designs use ball bearings, which must be greased,' he said. 'This is problematic in an environment such as in packaging, where the belts must be regularly washed down. We have therefore designed out lubricants and seals, which have one disadvantage —they can fail. Our designs are also better suited to dirty and dusty environments as there is no grease to become contaminated.'

Such feature make igus' products well suited to the food industry, another area where there are frequent wash-downs. However, their low-cost structure means they also have some interesting niche applications, such as being used for microphone positioning in football grounds.

'The drives have replaced the rope and pulley system,' said Aldridge. 'We are also in the position of taking our first order for use in aircraft seats, where they have attracted interest owing to their low weight.'

Elsewhere,

has created a range of actuation solutions to improve the efficiency of solar panels, which are frequently located in areas suffering from extreme heat and cold as well as dust or sand. Its LA series actuators are designed for use in solar tracking systems, which orientate a solar panel or concentrate a solar reflector or lens towards the sun.

The technologies are designed to resist dusty and wet conditions, and have the ability to raise energy output by as much as 40 per cent. A key feature of their robust design is the incorporation of non-corrosive housings and tubes that are tested to withstand rapid changes in temperature.

Another approach to the problem is the streamlining of the motion process.

has designed new Motion Designer software to provide an easy-to-use graphical user interface for generating and analysing motion trajectories and also improving the performance of complex motion profiles. The software greatly simplifies trajectory programming and reduces development time where an exact motion profile, simulating a dynamic environment or real-world conditions, needs to be generated. Applications requiring optimum performance can also benefit with detailed motion analysis tools and iterative learning control algorithms that reduce following error and cycle times over multiple runs.

Although aimed at test and development applications for motion and movement measuring components such as inertial sensors, gyros, accelerometers and tracking systems, the software could also be of interest in areas where increased performance and optimised production throughput is required. Motion Designer software can generate or import trajectories as position, velocity, acceleration and time-profile points, before downloading them as AeroBASIC PVT commands to the motion controller.

To run and evaluate the results, a number of waveform tools are available. These may be combined as building blocks before conversion to AeroBASIC commands. If a real-motion trajectory can be measured, the software is able to interpret and convert it to actual PVT commands for rotary or linear motion simulation. A number of input file formats are supported including Excel, CSV and Matlab, and Motion Designer can also handle partial trajectory information such as position versus time or acceleration versus time and calculate the other state variables.

The software has been developed to save time and simplify programming. previously the task would typically be carried out using high-level program development requiring hours of code generation and debugging. Features also include the ability to overlap multiple trajectory runs to see precisely how program changes modify motion and influence performance.

With the introduction of these new systems and software to streamline operations and reduce maintenance, it should be possible to cut costs and raise output with relative ease.