The final step in most finishing processes involves curing the coating. "Curing" generally refers to the chemical changes a coating material undergoes to develop a tough polymeric finish. This process allows a coating to resist attack by various chemical, environmental or mechanical agents.
Baking enamels and conventional powder coatings require an oven to heat the coated parts to a temperature range that will initiate and complete the chemical reactions involved in curing. More often than not, the parts represent a vast array of sizes, shapes and mass, all of which place different demands on the heating source. The curing oven must have the thermal output and sophistication of control to accommodate these differences.
Fortunately, oven manufacturers have continued to develop and optimize oven engineering and heat source technology. Many of today's designs also incorporate recirculation and abatement technologies to meet legislated emissions regulations.
As a result, the finishing technologist has an assortment of options to consider when choosing a curing system. The needs of the finishing system may call for a something as simple as a basic gas convection oven or may dictate something as sophisticated as a combination infrared/convection system with real-time feedback loops that adjust oven settings based on part temperature responses.
The following oven roundup presents some of the latest in curing technology to help you select the right system for all your finishing needs.
Curing/Baking OvensACE Equipment Co.
Bench, batch and walk-in curing/baking ovens from this company can be supplied either assembled or unassembled. Many options are available, including floor-type, cart-style and burner-box configurations. Benefits include dependable operation, proven design, low operation and maintenance cost, and ease of operation. Call (800) 255-1241 or (216) 267-6366, or visit www.armaturecoil.com.
Batch OvensBenko Products Inc.
Each batch oven in the product line is designed around the heating requirements of the application. Electrically or steam heated or gas-fired, each oven offers uniform heating capabilities up to 800°F (427°C), precise temperature control and any airflow pattern. Rugged, all-welded carbon steel construction ensures durability. Call (440) 934-2180 or visit www.benkoproducts.com.
Modular Curing OvenBlue M
The MicroBatch automated curing oven system integrates a cluster of MicroBatch systems within a small footprint and can be configured with variable quantities of chambers to match customized process profiles, throughput and low level work-in-progress (WIP) objectives. The robotic and control systems are designed to ensure seamless integration into any production line with computer integrated manufacturing (CIM). The MicroBatch Series supports continuous in-line curing and small lot sizes by handling magazines and custom designed baskets. Loading and unloading of oven chambers can be fully automated to eliminate operator assistance and diminish human error, while semiautomatic operation can facilitate reduced operator requirements in assuring complete process cycles. Automation needs are field upgradeable. Call (570) 326-1770 or visit www.bluem.com.
Combination Dryers, OvensC.A. Litzler Co. Inc.
Systems from this company combine both infrared and convection, or radio frequency and convection, in a single unit. Combination dryers and ovens have independent temperature controls for the convection, infrared or radio frequency (RF). Thermodry combination dryers and Thermocure combination ovens use a combination of infrared and convection to solve the challenges of drying and curing. Combination convection and radio frequency dryers are offered in four main combinations: RF preheat, RF boost, RF finish, and full RF/convection. Each combination offers benefits to improve the drying process. Call (216) 267-8020 or visit www.calitzler.com.
Specialty Ovens and Conveyor SystemsCasso-Solar Corp.
These systems can be used to dry and cure liquid and powder coatings, as well as adhesives, on metal, wood or plastic parts. Conveyors can be custom spindle, indexing, flat-belt or overhead. Specialty fixturing can be designed to hold or mask the product. The oven systems can use long-, medium- or short-wavelength infrared, electric or gas, in combination with convection where desired. Call (800) 988-4455 or visit www.casso solar.com.
Catalytic Infrared OvensCatalytic Industrial Systems
This company's paint drying infrared oven line includes dry-off, powder gel/ramp and cure ovens. Other models include continuous and batch convection cure ovens, combination systems, infrared retrofits and portable cure units. Long-wave catalytic infrared ovens are designed to reduce curing times of waterborne, powder and most other coatings. Call (800) 835-0557 or visit www.catalyticirovens.com.
Reflow OvensConceptronic, a div. of CVD Equipment Corp.
Features of the Ultra High Production System include Windows NT 4.0 graphic interface software; 14 vertical heating zones (14 top and 14 bottom heaters); a 180" (457 cm) long heat chamber with 137.2" (348 cm) of total linear impingement; and a 45" (114 cm) wide, uniform processing area. The high zone recirculation rate allows the Apollo to handle product loads up to 200 lb (90.7 kg). With a built-in air/nitrogen atmosphere capabilty, the oven includes a four-zone, 72" (183 cm) long enclosed Genesis cooling section. Call (631) 981-7081 or visit www.conceptronic.com.
Truck-In/Walk-In OvenDespatch Industries
The TA Series truck-in/walk-in oven is designed for industrial process versatility and dependability. The company's design, manufacturing, quality and innovation reportedly ensures industrial ruggedness, excellent process control, and dependable operation. Typical applications for the TA Series include aging, bonding, curing, drying, finish baking and burn-in. Call (800) 828-9903 or (888) 337-7282, or visit www.despatch.com.
Infrared Modular OvensFostoria Industries
This company has designed infrared modular sections that incorporate a custom high-density refractory board composed of aluminum silicate and other non-organic binders. These reflector boards are especially useful in higher-watt-density applications, such as curing powder coatings, and are self-cleaning in many operations. High-density boards are capable of withstanding up to 100 W per square inch and also act as a generator of medium wavelength infrared. The ovens can also combine drying and preheating cycles into a single process when necessary, giving manufacturers the option of a complete powder cure system using only electric infrared. This greatly reduces the system footprint and cost. Call (800) 495-4525 or visit www.fostoriaindustries.com.
Electric Conveyor OvenGrieve Corp.
No. 823 is an electrically heated, 1,000°F (538°C) belt conveyor oven being used for drying water-based glue on stainless steel mesh. Workspace dimensions measure 36" wide by 15" high x 15' deep. Incoloy-sheathed tubular heating elements provide 160 kW, and a 7,800 cfm, 5-hp blower provides vertical-downward airflow to the workload. Call (847) 546-8225 or visit www.grievecorp.com.
Ovens, DryersHix Corp., Thermatrol Div.
Thermatrol electric, gas or propane conveyor ovens utilize infrared heaters, infra-air or combination IR/convection heating to meet specific process needs. Features include inline integral coolers, the ability to interface with external PLCs and integration with robotic operations. The IR heat panels provide uniform curing and/or drying over the entire process. Recirculating hot air using high-velocity air knives breaks up moisture barriers and drives solvents away from the substrate. Call (800) 835-0606 or visit www.ovens-dryers.com.
Electric Infrared OvenIntek Corp.
Electric infrared heating elements and heater modules are suited for use in process ovens for applications up to 1,000ºF (538ºC). The heater design includes an aluminized steel cabinet to serve as a structural member in the construction of the oven. The heater does not have any moving parts, and the self-contained insulation provides operating efficiency. Call (636) 584-8500 or visit www.intekcorp.com.
Custom Dry-Off, Curing OvensKMI Systems Inc.
This company offers a selection of custom engineered dry-off or curing ovens that can be engineered for specific space requirements, including roof and floor mounting or elevated designs. KMI uses a modular design of interlocking oven panels containing non-settling, non-combustible, non-asbestos type industrial insulation rated for 500°F (260°C). Panels are supported by a substantial structural steel framework designed to prevent uncontrolled expansion from repeated heat-up and cool-down cycles. Batch type, infrared and combination IR/convection ovens can be specified as a single component upgrade or replacement or can be incorporated into a complete paint/coating system. Call (815) 459-5225 or visit www.kmisystemsinc.com.
Custom Ovens, DryersLanly Co.
Designed to use specific combinations of radiant and air-impingement systems, custom ovens and dryers ensure product uniformity and maximize production. The ovens and dryers range in size from high volume to small batch or lab prototype. Call (216) 731-1115 or visit www.lanly.com.
Class-A Walk-In OvensLewco Inc.
Heat-Pro by Lewco Inc. recently supplied a leading company in the formulation, sale and application of protective and functional coatings for clear plastics and glass with two electrically heated ovens. Each of these ovens, to be used for curing coated parts, required a work space of 6' x 14' x 7' high with an operating temperature of 500°F (260°C). Because these ovens would be curing coatings containing solvents, an NFPA Class-A oven design was required. Dual air flow was used in the design. The 180 kW required for the oven was wired into five standard 36 kW banks. The use of 36 kW banks allows 60 A wiring (with 480 V, three-phase power) to be used within the guidelines of the National Electric Code. Call (419) 625-4014 or visit www.lewcoinc.com.
Vertical Tower OvenRadiant Energy Systems Inc.
This company's vertical tower drying and curing oven incorporates medium-wavelength infrared Type QF heaters. The panel heater delivers radiant heat across the full area of its face. The medium-wavelength energy generated by the system is absorbed readily by water and most products, allowing high drying efficiencies. Hot air is recirculated to enhance drying and save energy. The combination of infrared and air improves drying efficiency by breaking the boundary layer and removing water vapor from the heater area. Call (800) 486-7786 or visit www.radiantenergy.com.
Vertical CuringThermal Product Solutions
The Ultima system can be configured for the continuous inline curing of components in carriers, strips, magazines, baskets or other transport mediums. The oven is designed to ensure good thermal performance with a small, automated equipment footprint. It can be used as a standalone system or integrated into existing equipment. Process flexibility is achieved through nine separate curing chambers with independent controllers for temperature, airflow and exhaust for effluent gases. Internal active cooling provides reduced process time and product exits the oven at less than 122°F (50°C). Call (570) 326-1770 or visit www.thermalproductsolutions.com.
Custom Industrial OvensTherma-Tron-X (TTX) Inc.
This company's industrial ovens for paint curing feature high-efficiency convection, infrared or combination configurations using electric, oil, steam or gas heat sources. Designs include custom monorail, power-and-free, square transfer and batch with aluminized steel interiors and exteriors and semi-rigid, non-settling mineral wool insulation. All systems include PLC controls, powerful air seals and bottom entry (where possible) for accuracy and reliability. Call (920) 743-6568 or visit www.therma-tron-x.com.
Uniform DryersWenger Manufacturing Inc.
The Cascade dryer has a multi-deck, continuous batch, vertical design that permits quick product changeover, good moisture control and high energy efficiencies. The system's design also reduces floor space, maintenance and cleaning demands. It can be equipped with an integral cooler section with internal ducting, recirculation fans and heat zones. Call (816) 891-9272 or visit www.wenger.com.
Infrared OvensWisconsin Infrared Systems
This company offers a range of infrared equipment in many sizes and configurations. Infrared technology allows faster heating than convection ovens, decreasing oven floor-space requirements by 75 to 90 percent. Heating can be provided by either gas catalytic or electric infrared, in long, medium or short wave, combined with convection as necessary. Call (262) 642-4200 or visit www.wisinfrared.com.
Industrial OvensWisconsin Oven
This company offers a range of industrial ovens, including continuous models that are custom-designed. A gas-fired drive-shaft tempering oven can achieve a uniformity of +/-2°F at 450°F (232°C). The parts are conveyed through the oven on a custom-designed part holder riding on a two-chain conveyor. Other equipment can be used for metal finishing, preheating, solder reflow, composite curing, drying, aging, sterilizing and shrink-fitting. Equipment can be heated by gas (direct and indirect), electric and steam with temperature ratings to 1,400ºF (760ºC). Call (262) 642-3938 or visit www.wisoven.com.
Circular Tray DryerWyssmont Co.
The Model K-10 Turbo-Dryer is used to remove the bound water of hydration from a specialty chemical at a rate of approximately 100 lb/hr. Gentle handling allows continuous drying of low-density product without requiring a dust collector. The dryer yields uniform product due to its positive retention time and close temperature control. Call (201) 947-4600 or visit www.wyssmont.com.
Editor's note: The oven information in this article was compiled from press releases and is not intended to be a comprehensive overview of all curing ovens. Additional new product information can be found in the "Products" section of this issue, as well as online at www.paintandpowder.com.