Electrically Heated Conveyor Ovens Designed for Hydrogen Embrittlement Relief

Feb 16, 2007

Wisconsin Oven designed and manufactured two Electrically Heated Conveyor ovens to perform hydrogen embrittlement relief on locking wheel lugs at a maximum production rate of 1,600 pounds of parts per hour for each oven. Each oven has a 4’2” wide x 31’ long x 9” high heating chamber and a 500°F maximum operating temperature.

The equipment is constructed with 4” thick tongue and groove panel assemblies and aluminized steel interior and ductwork. Three (3) access doors were provided on one side of each oven. The ovens are located side by side in the customer’s facility and were designed to accomodate a width restriction of 13’ total for both ovens.

The heating system features incoloy sheathed elements, each oven is rated at 144 kW with SCR power control. The recirculation system provides bottom-up airflow that utilized a special duct design to ensure all the supply air passes through the very dense load of parts. The recirculation blowers utilized high pressure to also aid in forcing air through the densely loaded parts; each oven was rated for 30,000 CFM at 30 HP.

The uniformity tests were performed with three (3) thermocouple points; each buried between two (2) baskets of parts three (3) baskets wide with 90 pounds of parts per basket. The ovens achieved +9°F / -5°F uniformity at a set point temperature of 400°F for 9 hours.

The conveyor features a 1/2” x 1” high carbon steel heavy duty flat wire belt with friction style herringbone slide bed, chain driven gear reducer with shear pin torque limiting. The conveyor also featured closed loop speed control of conveyor speed which utilized a Honeywell UDC 2500 controller (conveyor speed was displayed and could be adjusted from UDC controller), pulse counter, and analog converter to monitor and maintain the speed of the conveyor as necessary (if unable to maintain the acceptable pre-set speed range, an alarm would sound to alert the customer). The exit end of each conveyor features a proximity switch to stop the conveyor and sound an alarm if the part baskets reach the end of the conveyor, as well as a light stack with three (3) different colors assigned to particular alarms. Three conveyor E-stops were also provided on each oven.

The UL labeled and certified NEMA 12 control enclosure for each oven was installed on the side of one (1) oven. Each includes an Allen Bradley Powerflex 4 variable frequency drive and main power fused disconnect switch. The controls featured IEC style push buttons, and pilot lights. The temperature was controlled by Honeywell UDC 2500 temperature controllers and over temperature protection was also provided by UDC 2500 controllers. One control panel featured a Honeywell EZ Trend digital recorder which monitored the control thermocouple and two hard-mounted monitoring thermocouples of both ovens. An automatic shutdown feature was also included on each oven. For more information on our Conveyor Ovens click here to visit our website.