MULTICELL Heaters Power Hot Expander Forms For Titanium Parts

Problem:

Forming titanium aircraft parts required a two-step process: mechanical forming at room temperature and thermal-conditioning in a furnace. The recent increase in demand for titanium parts has created a demand for faster cycle times.

Solution:

A new hot forming hydraulic expander permits simultaneous forming and thermal conditioning of titanium aircraft engine casings. By using Watlow^® multicell heaters and ceramic insulation to keep temperature profiles uniform along the part, the expander can maintain tighter control of the part's physical dimensions.

Three MULTICELL heaters, operating at 1350°F (730°C), slip-fit into holes bored into each of the hot expander's dies. A closed loop electronic control system monitors signals from thermocouples in the three zones. This is a departure from previous hot expanders which provided heat via a single wound filament located near the center of the part. By applying heat to three zones along a part instead of one, distortion due to varying rates of thermal contraction is kept to a minimum.