Furnace Surveying With 'In-Process Survey Systems' - the Experience So Far

Furnace temperature surveys demanded by quality-assurance systems are time-consuming and disruptive to production when conducted by conventional means. To minimize these disruptions, in-process survey systems with in-built data transmitters are finding increasing use in heat treatment furnace applications for temperature surveying in real time. This paper looks at the types of furnace these systems can be used in and how the system can be set up to survey directly from the product basket or the hearth of the furnace We look at how the use of RF telemetry from inside the furnace, combined with specialized software has enabled enables the user to carry out surveys with the least amount of intervention by the technician. The paper also examines the experience of users who originally surveyed their furnaces using the traditional 'trailing thermocouple' method, but switched to survey systems that could be charged to the furnace as a normal load, saving downtime and in some cases, expense on costly thermocouples. The correct selection of thermocouple type and diameter is also examined and trial results are examined which show the optimum size and type was selected. Finally we look to the future, and how surveying systems in continuous heat treating processes may be used to spot trends in furnace conditions which may lead to reject product, and alert the user before rejects occur.