Newall linear encoder technology has replaced traditional glass scales on a CNC lathe at GETRAG FORD Transmissions' Halewood plant to great effect. Previously experiencing approximately one glass scale failure every two months, the replacement Newall SHG-TT incremental linear encoder with TTL output has performed for 12 months without a single cause for concern.
The GETRAG FORD Transmissions Halewood plant on Merseyside produces around half a million transmissions every year, including its MT82 six-speed gearbox, for Ford Transit, Fiesta and Fusion models. The showcase facility receives regular praise for its efficiency and last year was voted 'Best Engineering Plant in Britain' by Cranfield University and Works Management magazine. With these facts in mind it is no wonder there is very little tolerance for product failures. So when an EMAG USC lathe started to exhibit repeated failure due to glass scale problems associated with alignment or contamination issues, the company turned to WYKO, a specialist supplier of power transmission equipment, to provide an integrated solution. The company recommended replacing the scales with an SHG-TT inductive linear encoder from Newall Measurement Systems.
Such is WYKO's transmissions expertise, that the company has a branch of its Integrated Supply Division on site at Halewood, as it does at many other Ford sites, including Dagenham and Southampton. This strategic advantage means WYKO is best placed to advise GETRAG FORD Transmissions which solution will best fit the manufacturing process in question.
“Because we are on site at Halewood we can respond to customer demands in a fast and accurate manner,” says John Kay, WYKO's regional business development manager (motion control). “Upgrading machine tools is a regular type of project we undertake. This occurs typically because of obsolete spare parts or regular machine failures, to the point where it is no longer cost effective to perform repeated repairs. Downtime at plants such as Halewood is not tolerated. If a machine isn't producing parts, it's not making money.”
Mr Kay says that the EMAG USC inclined bed lathe at GETRAG FORD Transmissions was demonstrating frequent problems attributable its glass scale linear encoder. “The amount of vibration present in the operation was creating alignment difficulties,” he explains. “Add to this the ingress of contamination from the presence of grinding dust and swarf, and it was fair to say the glass scale was not coping very well with the hostile manufacturing environment.”
WYKO began its search for a replacement that would eliminate the problems being experienced. “We found that the level of protection from contamination offered by the SHG linear encoder from Newall, combined with its innovative mounting method, made it the clear favourite,” he says.
Traditionally, machine tools have relied on linear encoders that use glass scales to provide measurement data. Unfortunately, these suffer problems related to reliability and accuracy, particularly where harsh environments are encountered. Newall Measurement Systems, world leaders in the design and manufacture of inductive linear encoders, have developed solid state devices which use Digital Signal Processors (DSPs) and high speed analogue to digital convertors (ADCs) to provide rapid, accurate and repeatable positioning information.
Newall's SHG range of linear encoders is capable of achieving an accuracy of +/-3 microns. It is also sealed to IP67 and resistant to severe shock, vibration and RFI, making it ideally suited to the application at Halewood. The SHG can deliver real-time feedback at traverse speeds of up to 20m/s. As with all Newall inductive linear encoders, it is impervious to contamination and requires no maintenance. A comprehensive measuring length range is offered, giving travels ranging from 50 to 10,004mm.
Installed approximately 12 months ago, the SHG, which is linked directly to the machine's Siemens CNC, has helped the EMAG machine achieve faultless reliability despite the hostile production environment. In fact such has been the success of the project that other opportunities for retrofits are in the pipeline at GETRAG FORD Transmissions, again replacing glass scale technology with a history of failures. “The project has passed off extremely well,” confirms Mr Kay. “If the original glass scales had still been on the machine I am confident we would have witnessed it being changed six times in the past 12 months. Yet with the SHG there have been no problems whatsoever. We are now actively encouraging our customers to look at Newall encoder technology as reliability is simply superior.”
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