Since 1979, Georgia Oven Co. has been developing custom thermal devices, ovens and furnaces for customers in a variety of industries including plastics, textiles, medical, electronics and pharmaceutical. Today the company exclusively produces vacuum and atmospheric ovens for a myriad of applications.
John Starnes, electrical designer for Georgia Oven Co., says the company is constantly seeking to integrate new technologies into their oven systems for companies that cannot use the industry standard or require heavily automated production type units.
One such application brought the company to Watlow, via Atlanta-based distributor Star Electric Inc. Georgia Oven Co.'s customer uses a large multiple heating zone atmospheric oven to bake polyimide on stainless steel coils that make hard drive suspensions. The thermal system needed to effectively control 32 zones of temperature. Each zone required a limit and needed to communicate to a Programmable Logic Controller (PLC) and a Human Machine Interface (HMI).
The controller also needed to work with quartz glass panel heaters. The control scheme had to be capable of easily changing failed system components without altering or shutting down the other operating zones.
Watlow's EZ-ZONE® ST achieved all of these operational objectives. The package included the temperature controller, high limit, shutdown contactor, heat sink and solid state relay (SSR). Thirty two EZ-ZONE ST units were easily bussed together into the PLC. With the use of Modbus®, Watlow was able to set the temperature to all the zones by using a PLC.
By having the set-point retransmit through Modbus®, Watlow could also individualize high limit problems and controller errors on the HMI from each of the EZ-ZONE units. The use of a multi-loop controller would not have solved the need for individuality amongst the zones in the event of a controller failure. The EZ-ZONE ST breaks out each zone, which allows the user to isolate them or quickly swap them out. In addition, multi-loop controllers do not offer a high limit safety shutdown.
Starnes says the initial order of two ovens utilizing EZ-ZONE ST have streamlined communications and reduced panel space for their customer, among many other benefits.
"EZ-ZONE ST units are simple to integrate, smaller and increase the ovens' efficiency. These are meaningful benefits for our customer, who has come to expect innovation from us," Starnes says.