Temperature profiling systems are typically used to measure product temperature throughout the brazing cycle and consist of thermocouples attached to the aluminum product, conveying temperature information to a data logger, which travel together with the product, through the furnace to produce the thermal profile.
Built specifically for use in controlled atmosphere brazing (CAB) furnaces, where aluminum components for automobile cooling and air conditioning systems are brazed, the TS08 thermal barrier range addresses the problems that can occur with profiling systems traditionally used to monitor product temperatures in these furnaces. These problems include:
Fast deterioration of the high temperature cloth inside the thermal barrier due to hydrofluoric acid attack (caused by chemicals in the flux combining with moisture from inside the barrier). This cloth protects the microporous insulation and when worn through, will allow the thermocouples to directly abrade the insulation, widening the exit of the barrier and allowing more heat into the system. This will damage the data logger that the thermal barrier is meant to protect.
Out-gassing of oxygen from air inside the ‘hot box’ or thermal barrier into the nitrogen atmosphere of the furnace. This can affect the quality of the braze in the products surrounding the system.
These problems have been addressed by PhoenixTM in the design of the new TS08 ‘Hot Box’ thermal barrier:
All high temperature cloth exposed to the furnace atmosphere has been removed, and thermocouples exiting the barrier rest on a stainless steel casing rather than abrading any insulation.
Oxygen is removed from deep in the microporous insulation by heating the insulation in a high vacuum, then back filling with nitrogen. Further to this the thermal barrier is fitted with a nozzle which allows it to be purged with a low pressure nitrogen flow just prior to placing in a furnace.
The TS08 thermal barrier also features thermocouple separators to prevent thermocouples ‘bunching’ when the barrier is closed, and makes it easy to identify the individual thermocouples (see photo below). A major US auto manufacturer has been using the PhoenixTM TS08 thermal barrier in their furnaces for the last 18 months and reports that they have carried out around 2000 successful runs during this period.