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JRS Ensures That Land Rovers Are ‘Well Screwed Together’

May 2000
At Land Rover’s East Works in Solihull, where the body-in-white is prepared for the Range Rover, Freelander, Discovery and Defender vehicles, a Crane Electronics JRS (Joint Rate Simulator) is used to check the performance of the power tools. Around 120 tools are verified per day, with the more heavily used tools being inspected every day. Any tools that are starting to drift towards the torque tolerance limits or are deteriorating in any other way can therefore be adjusted or serviced before they cause a problem.

Prior to the JRS being introduced, Crane’s TorqueStar equipment was being used. However, the JRS allows a wider range of tools to be tested – including angle and impulse nut runners – and it enables mapped joint rate simulation to be carried out. This ensures that the JRS, which holds the mapped data in its on-board memory, precisely simulates the characteristics of the actual joint. During tool verification, measurements are made for speed, time, angle, torque and pulse count. These values are stored and compared against the historical data and tolerances so that trends or faults can be highlighted.

“Setting up the mapped torque database was very easy and didn’t take at all long”, states Des Farhey, the Calibration Monitor. He adds: “Crane have always been superb with training and back-up; operators here are changed frequently, so we suddenly find that we need Crane to train somebody else to use the JRS. They really have supported us extremely well throughout.”

Because the JRS is used to test the tools in situ, which avoids disrupting production, it is important that it can be manoeuvred into tight spaces on the assembly line. Thanks to its compact design and four large castors, the JRS can be brought to exactly where it is required, and the ‘dead man’s handle’ locks the wheels automatically so that there is no risk of it rolling away. The JRS is battery powered and each charge is sufficient to last for up to 2700 test cycles – more than enough for a week's use at Land Rover.

Although the data that is collected at Land Rover is not currently downloaded to a PC for further analysis, this is planned for the near future. “It does so much, it is efficient, and it is easy to use”, says Mr Farhey. “It has also proved to be 100% reliable, even in the factory environment where is inevitably gets the occasional knock as it is wheeled around from one station to the next.”

Quality assurance is a major issue for the automotive industry, so instruments that make the QA process easier, more efficient or more accurate are increasingly of interest. The JRS is one of the most versatile, accurate means of testing nut runners, pulse tools, torque wrenches and similar tools and, as such, is ideal for Land Rover’s needs.


Crane Checkstars And Torque Transducers Assure Range Rover Quality

When the new Range Rover was launched it was immediately recognised as a vehicle of superior quality. One parameter which is controlled as part of the quality assurance programme at Range Rover is the torque applied to every threaded fastener. On a modern automotive production line virtually every nut, bolt and screw is tightened using a powered wrench (or battery 'gun') which is set to cut out at a specified torque. Everything, from gas struts to air filter boxes, is fitted using one of these guns.

The Range Rover production line has almost 400 guns, each of which has a set torque level with upper and lower limits. Each gun has to be tested regularly and the equipment used for this was supplied by Crane Electronics, consisting of eight TorqueStar intelligent readouts, seventeen base-mounted torque transducers and two CheckStar rotary transducers.

Paul Pratt is the Conformance Engineer responsible for the torque equipment and he explains the routine: "Each week every gun on the line is checked. This has to be done during production, so we have the TorqueStar and transducers mounted on a trolley which can be taken down the line and wheeled from one zone to the next. Each gun is checked on the transducer five times and, if necessary, adjusted and rechecked. The guns are all uniquely identified and the TorqueStar knows what torque each gun should be set to, that information having been downloaded from a PC."

In addition to the TorqueStars and transducers used for routinely checking the assembly tools off-line, there are also two CheckStar torque transducers. These can be taken on to the production line and fitted in-line between the gun and the fastener to check the actual torque which is being applied. This has proved to be a useful means of troubleshooting, and the compactness of the CheckStars has meant that even relatively inaccessible items can be investigated.

Build quality is paramount for a flagship vehicle such as the Range Rover. In Paul Pratt's words: "We wanted the best that was available for torque measurement, and the Crane equipment gives us everything we could wish for.”