Austral
Brick, one of Australia's leading brick & tile manufacturers, recently engaged
the services of Linear Systems Australia to overcome a continuing failure problem
on a fully automated "De-Hacking" or brick stack & wrap machine.
The major causes of their problems were 2 ball screw transport axes mounted below the 2 main chain conveyor inputs which carry the end product into a robotic stacker. Continuous machine down time was being experienced by the company on their 3 year old "state of the art" machine in replacing these screws which were deteriorating because of environmental and misalignment issues. It was obvious on inspection by LSA that not enough initial application had been given to two critical aspects of ball screw operational parameters at design stage.
The first of these was appropriate protection of the ball screws from the normal environmental hazards of a brick plant. Brick dust and other small particulates are constantly falling off the product during in plant processes with no other path to take in this case but directly onto the ball screws mounted below these two major conveyors. In no time at all this matter mixes into the lubricant and becomes a very effective lapping paste quickly deteriorating both the screw surface as well as the internals of the ball nut.
The
secondary problem recognised by LSA was the lack of any external support rails
and guides to cope with any misalignment or deflection that might translate
into the ball screws as a radial load. Ball screws are designed to handle axial
or loads along the line of the screw and do not cope well with any radial or
loads at a right angle from the screw. These loads would normally be handled
by auxiliary linear rails or guides which were absent in this application.As the loads being transported by these ball screws were extremely minimal in comparison to their maximum performance capacity , Linear Systems Australia offered Austral Brick the option of a totally retro engineered system replacement which would seal off the ball screws from the harsh environment and include supporting rails to cope with all external deflective forces.
The decision in this instance was an evaluation of the cost of these two new systems and the benefits which they offered compared against the output losses incurred by continually interrupting machine productivity to replace ball screws and nuts in an extremely awkward location underneath the main body of the machine . In this case it wasn't a difficult decision for Austral to make as the new systems would offer uninterrupted service for many years by comparison and save the company man hours and machine down time losses that would more than compensate for the system costs.
Linear Systems Australia designed the retro units using an Ironcad 3D package. All machining and assembly was then carried out in the company's workshop and installed at site by Bellato Engineering at Austral Bricks' main Sydney plant. Ball screws , linear rails and bearings were supplied by Thomson (USA) and the exercise exemplifies the value of retro engineering solutions providing major benefits where automated applications are experiencing repetitive failures.
