Lewco Inc. manufactured and delivered a vacuum-assisted composite curing oven to a United States military base. The enhanced-duty oven, which has a maximum temperature of 500°F, is used to cure vacuum-bagged composite aircraft parts.
The vacuum-assisted composite curing (VACC) process involves drawing a vacuum on composite layups in vacuum bags, or tooling, while cured in an oven. Lewco supports this process by equipping composite curing ovens with a vacuum pump, part-monitoring thermocouple jacks, vacuum ports and transducer ports. This oven is equipped with 12 vacuum ports, 12 vacuum transducer ports and 16 type J thermocouple jacks. The vacuum ports are equally spaced down both sides of the oven and connected to a common header pipe. The header pipe includes an isolation valve for each side and another one at the main connection to the source. Each port includes a high-temperature quick disconnect fitting on the interior. The thermocouples are divided into two eight-port jack panels located on each side of the oven. All the jacks are wired directly to the control panel for continuous monitoring and recording.
The batch oven includes a top-mounted heater box with a 700,000 BTU direct-fired natural gas burner and a 30,000 cfm high-efficiency circulation fan that provides uniform heat throughout the workspace. A variable speed drive is included on the exhaust fan for controlled cooling cycles and shorter purge time. The airflow of the oven is designed to meet strict temperature uniformity requirements.
Oven controls include a programmable logic controller (PLC) with a touchscreen human machine interface (HMI) that includes Lewco’s composite curing program. A Eurotherm Nanodac temperature controller and redundant high-limit controller provide precise temperature control and over-temperature protection.