Thermocouple innovation shortens autoclave setup for stringers/frames

ATK Aerospace Structures (Clearfield, Utah) produces, among other structures, carbon fiber/epoxy stringers and frames for an aircraft application that demands high-rate production. Until recently, one of ATK’s production cycle challenges was in preparing the parts for the autoclave. ATK process engineer Nate Lodder says it could take one-and-a-half to two hours to attach and document the required thermocouple channels.

The composite structures, for an unidentified customer, require two to five thermocouples per part, with anywhere from 20 to 60 parts per cure. ATK identified this process through its LEAN initiatives as an opportunity to significantly reduce cycle time. The thermocouple system in use was proving to be a significant bottleneck in meeting the goal to produce more parts per autoclave each month.

In August 2011, ATK began to trial an alternate thermocouple system from TE Wire & Cable LLC (Saddle Brook, N.J.) called AccuConnect. A multi-circuit thermocouple extension harness, AccuConnect consists of a multi-circuit threaded connector (male or female) coupled with a customer-specified number of thermocouple wires (type J or K). The other end of the AccuConnect harness terminates with a customer-selected individual thermocouple connector or a multi-circuit connector.

“We selected an AccuConnect system with six channels in one connection and gold plating on all connectors. This dramatically reduced the number of connections needed vs. the previous system of one channel per thermocouple,” Lodder says. “Implementing the AccuConnect system reduced the overall thermocouple setup time to just 20 minutes.” In conjunction with its use of AccuConnect, ATK has developed a barcode system that enables the company to quickly scan and document thermocouple layout.

The simplified documentation is not trivial. When one channel was represented by one thermocouple, ATK had to use specialized layout software to ensure that connections were associated with the appropriate parts and structures.

Since August, Lodder says, “ATK has run the AccuConnect thermocouples through more than 80 cure cycles in three different autoclaves.” He reports that signals have been accurate and problem-free and expects that ATK will expand Accu-Connect use to its other autoclaves.

Orbital ATK Aerospace Structures