Rapid complex tool setting
Renishaw's automatic tool setting and tool breakage detection systems recently installed at Hewland Engineering Ltd, are proving to be highly successful in raising productivity of transmission part manufacture for motor sport vehicles worldwide. Hewland has also used the Renishaw QC10 ballbar to provide the quality assurance requested by customers, by guaranteeing the performance of its machines.
Hewland Engineering Ltd is a world-class supplier to the motor sports industry, with such success and reputation that founder Mike Hewland has been hailed as ‘the father of modern motor racing transmission'. Hewland has a list of competition successes in every form of motor sport, its extensive customer list including such marques as Alfa Romeo, Ferrari, Honda, Lola, Mercedes Prodrive and Subaru.
However, it is not enough that Hewland Engineering maintains its reputation for design superiority, supreme product quality and reliability. It must also stay competitive in a world market. Hewland operates an impressively modern and spotlessly clean transmission manufacturing plant at White Waltham, Maidenhead. Elimination of arduous, time-consuming manual work.
Manual tool setting and inspection for breakages is a skilled and labour intensive business at the best of times, so any opportunity to eliminate it, if taken, will quickly pay dividends. Dave Radley, Hewland's operations director, heard the fully automated NC1 could make significant time savings, identify tool breakage without any chance of further component damage and guarantee a consistent process.
Mr Radley first saw the NC1 laser system when it was launched at the previous MACH exhibition, and was sufficiently impressed to have it installed on a busy twin-pallet Matsuura VMC. The most valuable aspect of the non-contact NC1 system is its ability to check the diameter and length of each of these delicate tools totally free from any operator involvement. With cycle times per load as short as 35 – 45 minutes, and with the company running a two-shift system, the time saved with the automated system is considerable.
Tool breakage detection
"Added to this", says Mr Radley: "The automatic checks for tool breakage at rapid feed rates and the ability to check each facet of a multi-faceted tool, has helped bring significant reductions in the need for rework, and has also helped to further raise the already high levels of quality assurance". In this application, the transmitter and receiver unit have been located diagonally across the table so they don't obstruct easy changeover of the pallets.
Typical components include clutch rings machined from steel forgings - eight-up at each setting, with thousands produced each year. Only four tools are needed at each setting: 1) a two-balloon-type roughing cutter; 2) an 8 mm diameter end mill; 3) a form cutter; and 4) an engraving tool. The components produced on this machine are built into the company's ‘Classic' range of gearboxes which have been in continuous production since the 1960s, through to modern ‘off the shelf' and bespoke gearboxes for single seater cars, World Rally cars and Le Mans cars. Further productivity and quality improvements on a wide range of applications.
Such was the success of the first installation that a second system was quickly put into operation on a Daewoo Mynx vertical machining centre employing a number of different small and delicate tools. This machine is used for producing a variety of high precision details on different components including some intricate cam tracks on selector barrels.
Other work involves using some very distinctive cutting tools, such as a form tool with a radius face, for features on the ends of transmission half shafts. The entire profile of the cutter must be checked to ensure the component accuracy, rather than just length and diameter, which is only possible with the Renishaw NC1. The machine uses special Renishaw software routines to achieve this, a process that would be extremely difficult if it had to be carried out manually.
With components being wet-machined, the unique MicroHole™ protection system comes in for particular praise, providing a stream of air through the beam apertures to protect them from coolant and swarf, without affecting accuracy. To prevent coolant drips from triggering the beam, Renishaw has developed its own ‘drip rejection' software and Mr Radley was happy to confirm it is very effective.
Hewland was using another CNC machine, 20 years old, that suffered from a significant amount of backlash in one axis. They had been quoted £5000 to replace machine components likely to cause the backlash, but took this opportunity to run a trial test with the Renishaw QC10 ballbar.
The QC10 ballbar continuously, and very accurately, measures the radius of a circle described by the machine in 2 of its axes. Once this test has been performed, which takes a matter of minutes, the software that controls the test also analyses and diagnoses the results. Analysis is given of 21 different machine variables, with suggestions of corrective action. The whole procedure, including initial set-up, takes about 10 minutes of machine time.
Continuously testing with the QC10 ballbar
When a test was run on Hewland's machine, the ballbar software identified the exact amount of backlash, along with the axis and direction of travel. The appropriate entry on the machine's axis compensation register was amended by this value, which immediately corrected the errors caused by backlash.
With the success on the first machine Ken Wallace, Quality Manager, decided to buy a ballbar system, which is used right across Hewland's machine shop to qualify the wide variety of machines. Ken adds "A major customer required us to provide traceable proof of our quality assurance, Renishaw's QC10 ballbar gave the guarantees they sought on the machine's performance."