When Norbar Torque Tools, the world’s leading torque specialist, conducted a gear quality project at its Banbury plant, the company chose a Stark Zero Point system from Roemheld to achieve the desired improvements in quality and repeatability, while also reducing set-up times.
Norbar had invested in two new Gleason machines and was looking to reduce wasted time through all aspects of the gear shaping process: from starting with an accurate gear blank, through to fitting to an accurate fixture mounted to an accurate base plate. In particular, Norbar was keen to get away from having to clock and adjust every fixture and gear part shaped.
The company had used Roemheld zero point mounting technology before on different machines, so was aware of its capabilities. After consulting with Roemheld on the project, Norbar purchased Stark zero point mounting plates for both machines. To increase accuracy whilst reducing loading times, the new machines utilised drawbar automatic clamping. All fixtues were then fitted with the Stark zero point nipples allowing fixturing to fit straight onto the base plate with no adjustment required. Norbar also introduced a colour code system on the Stark zero point bases to indicate the best loading position for each fixture to minimise runout. This allowed fixtures to be mounted with a 10-15micron accuracy and repeatability within 5 microns.
Norbar also reduced first- off quality check down time by introducing as much in-process checking as possible. This led to the company being able to produce almost four times as many components than with the previous setup .
In addition, Norbar asked Reomheld to supply adaptor plates to mimic the old machines so the company can still use the original fixturing. These too were fitted with the Stark zero point nipples for the required accuracy and repeatability. These improvements have resulted in excess capacity on the machines in anticipation of Norbar’s planned future expansion.
Tim Bloor, Design Engineer at Norbar UK, who headed up the project, said: “My aim was to minimise setup times with the introduction of two new gear shapers. We were raising the bar in terms of the expected quality and accuracy of geared parts coming off these machines. The Stark plates have provided a solid foundation for mounting all gear shaping fixturing and we have a high level of confidence the fixturing we fit to the Stark base plates will be accurate so subsequent clocking of the fixture and component will just be a simple confirmation of its accuracy and consistency. It is early days but we have seen a big improvement in gear quality and consistency, much quicker run times and greatly reduced setup times. So the expenditure was well worth it for the long term.“
The introduction of this new technique of using drawbolts and fixturing together was a major culture change for the setters and operators as it was so different from the old style of fitting and adjusting fixtures and clamping components. As a result, Norbar has made good use of Roemheld’s ongoing technical support to help them maximise the technology‘s potential for accuracy and repeatability.
Norbar Torque Tools Ltd started in 1942 as North Bar Tool Co and was the first company in Britain to commercially manufacture a torque wrench. The initial demand was driven by the need to accurately tighten the gasket-less cylinder head of the Rolls Royce Merlin engine. Bill Brodey and his partner Ernest Thornitt obtained a license from Britain's war-time Government to begin manufacture of torque wrenches and Norbar was born. Since then, Norbar has continued to invest in the very latest design, manufacturing and quality control technology to achieve the highest level of innovation and precision in the field of torque control equipment.
The company has remained family-owned and now has a turnover in excess of £25m and employs over 240 people in its Norbar factory in addition to offices in America, Australia, China, Singapore, New Zealand and India. Demand for its products is such that the company has now outgrown its UK manufacturing plant in Banbury and is planning a phased move to a new factory in the town that will triple its manufacturing space.
Norbar manufactures torque wrenches from 0.3 N.m up to 1500 N.m and gear boxes up to 300,000 N.m in capacity. As well as the gear shaping machines, the company uses a wide array of machines and processes with some machines capable of running 24 hours a day. The majority of finished products are both assembled and calibrated within the Banbury plant to maintain accuracy and quality. It also operates a UKAS accredited torque calibration lab that can provide an independant torque calibration service.
Norbar are committed to expanding the engineering to order and manufacturing to order bespoke part of the business, which has always formed a key role within the company’s success: both in the UK and the lucrative export market. The company‘s ability to design solutions to order has resulted in the development of numerous special products including a sub-sea gearbox manufactured entirely out of aluminium to comply with tight weight restrictions. The move to the new factory will also include the setting up of a production realisation department dedicated to developing new products and customer solutions.
Tim Bloor said: “With this factory expansion we will be increasing our machining capacity and will be looking to make the machining process as LEAN as practical. This could well involve using the Stark system for other processes away from the gear shaping where they have proved to be so successful. “
For more information on Stark zero point mounting, contact Roemheld on 01462 459052.