Car seats today are far more than a place to sit and often incorporate safety-critical elements such as airbags and seat belt buckles. It is therefore vital to ensure that these are correctly installed and for this reason Johnson Controls International is relying upon Crane Electronics' TorqueStar Opta torque data collectors with CheckStar rotary transducers to audit the assembly processes used on threaded fasteners. Moreover, Johnson Controls has to store detailed records in case its customer, Toyota, requests data relating to the seats it installs in the Avensis and Corolla models.

Johnson Controls International is an established user of torque measuring and auditing equipment from Crane Electronics and was offered the latest TorqueStar Opta by Crane as soon as it was available. Although the engineers at Johnson Controls were impressed with the instrument's capability, they were obliged to investigate other products available on the market.

Mathew Winter, the Maintenance and Facilities Co-ordinator, explains why the Crane solution was felt to be superior:

"The storage capacity on the TorqueStar Opta is sufficient to hold the data for a full five days' worth of readings. On the nearest competitive product, there is only enough space for one day's data. Furthermore, if you were to start the second day's rounds without downloading the first day's data, the records would simply be overwritten, with no prior warning. To lose data like this is simply unacceptable, and even with the best will in the world, people are not at their best at 6.00 a.m. when we do the tool rounds. Losing data would be a genuine risk that we are not prepared to take."

Besides its substantial memory capacity, the TorqueStar Opta offers other advantages. For example, with our workload increased battery life means that the instrument can last for five days without having to be recharged, and the on-board software makes it easier to modify the tool rounds if, for example, the production line is rearranged or new tools are added.

A further benefit stems from the TorqueStar Opta's graphical display that enables the operator to view trends as soon as a reading has been taken. This means potential problems are identified immediately, without the data having to be downloaded from the instrument first.

At its Burton-on-Trent factory, Johnson Controls is now using two TorqueStar Optas and four CheckStar in-line transducers with measurement ranges of 2.5-25Nm and 7.5-75Nm. While the safety-critical components are assembled with conventional threaded fasteners and electronically controlled tools, other components are fastened with self-tapping screws and pneumatic drivers. Every electric and pneumatic driver used on the line is audited on a daily basis, and click wrenches are audited at six-monthly intervals. Needless to say, the TorqueStar Optas and CheckStar transducers take all of this in their stride, and the instruments' UTA identification technology means that each transducer is automatically identified and recorded for each torque reading, with no need to rely on an operator to record anything manually.

After each tool round, the operator uses Crane's Opta Comms package to download the data to SPC Lite running on a PC. Should Toyota ever request it, data can be provided for every threaded fastener on a seat manufactured on a given date or as part of a given batch.

Mathew Winter is very pleased with the performance of the instruments and is also grateful for the support he receives from Crane Electronics: "We have not had any problems since the new instruments were brought in and our experience with Crane in the past has been very positive. If ever we have an issue, someone either visits us or they give detailed advice over the telephone. All in all, we are very satisfied with Crane Electronics and their products."