Trials of an alternative thermocouple sheath have delivered significant cost and time savings for a components manufacturer which caters for some of the world’s leading automotive industry operations. In tests carried out at its plant in Aurangabadin India; High Technology Transmission Systems Pvt Ltd found that thermocouple assemblies supplied by Morgan’s Molten Metal Systems business outlasted even their manufacturer’s estimated operational life, far out-performing the existing solutions available to the company.
High Technology Transmission Systems (HTTS) is part of the Endurance Group, a global force in aluminium castings for the automotive sector with 19 plants across India, Italy and Germany. A high-performance die casting (HPDC) operation, HTTS produces cast aluminium clutch assemblies and other cast components.
The company approached Morgan looking for improved performance for the thermocouple assemblies used for the continuous measurement of the temperatures in its holding furnaces. HTTS has been using two different types of assemblies, both of which had inherent shortcomings. One is an L-shaped CI tube which lasts an average of seven to eight days. Although a low-cost option, this type of assembly requires a protective coating, which represents additional work, while the subsequent chance of metal contamination, which is very high, could compromise the quality of the end casting.
The second product being used is silicon nitride (SS316) which, although it has a recommended operational life of nine months, carries a high purchase cost and has considerably lower impact resistance, making it very vulnerable to breakage during the aluminium pouring process.
The trial involved Morgan’s innovative Blue Lightning thermocouple sheath supplied as a complete pyrometer assembly, which was installed in a 500kg furnace for a four-month period. The recommended life of the Blue Lightning is 42 to 48 days, but at the end of the 122-day trial, the sheath was still fully functional and capable of continuing in operation.
HTTS maintenance manager Sambhaji Bachkar, who oversaw the trial, says: “The thermocouple assembly performed well throughout the trial, maintaining and controlling the temperature in the holding furnace. When we removed it from the furnace, it was still in good condition, with no signs of deterioration.”
Robustly designed for extended service life, the Blue Lightning delivered a number of benefits for HTTS, as Ramdas Chitalkar, Technology Manager at Morgan Advanced Materials explains: “Apart from the extended life of the product, it proved to be a cost-effective solution in a number of other ways. There was no need for any additional coating, which requires time and manpower, so changeover time is reduced, and there is no danger of metal contamination, which has an impact on the end quality of the casting, so the risk of rejects is minimised.”
Blue Lightning Thermocouple Sheaths are available with either a ½in BSP pipe, ¾ in NPT pipe or without a pipe as a straight ceramic sheath for higher-temperature copper applications. The pipe versions are also available as a complete pyrometer assembly to help speed up installation and reduce installation costs.
The assemblies are specifically designed to provide a quick and technician-free change out of the existing pyrometer. Design features include; non-wetting chemistry for ease of cleaning, low dross build-up and elimination of metal contamination. Highly conductive, they deliver rapid response times, reduced fuel usage and good thermal shock resistance. The assemblies can be used in applications which require either a fixed or a floating pyrometer.