L&L Special Furnace Co., Inc. has delivered a second car bottom furnace used for curing complex ceramic composites, silicon carbide plates and military-grade armaments. The cycles require extremely slow heat-up and cool-down curves, which are critical for the end product.

The curing process is reportedly achieved by heating the parts slowly to drive off moisture without affecting part integrity. Some of the heating and cooling curves are as slow as 2°C per hour up to 1,010°C. Temperature uniformity is critical for this process, and both ambient and load temperature must maintain ± 10°F throughout the cycle. Two 18-in.-diameter air-cooled fans provide temperature uniformity of ± 5.5°C throughout the thermal cycle, along with 12 separate SSR power controls with digital biasing for balancing any temperature gradients as required.

The parts are loaded onto the furnace car bottom, and load weights can exceed 10,000 lbs. The furnace car bottom can be accessed from both sides and has an electric drive motor that moves the car in and out of the furnace on railroad rails. A series of high-density castable piers allow for forklift or overhead loading.

The door is attached to the car bottom and is clamped in place when the furnace is closed. The furnace is controlled by a Watlow F5 program control with multiple programs, along with computer communications and a Honeywell over-temperature system with manual reset. The furnace has an effective work area of 76 wide x 48 high 120 in. deep, which allows for many different parts and load configurations to be processed in each thermal cycle.

All L&L furnaces can reportedly be configured with various options and tailored to meet specific thermal needs. The company also offers furnaces equipped with pyrometry packages to meet ASM2750E and soon-to-be-certified MedaCred guidelines. Options include a variety of control and recorder configurations. A three-day, all-inclusive startup service is included with each system within the continental U.S. and Canada. International startup and training service is available by factory quote. 

For additional information, visit www.llfurnace.com.