Conveyor ovens are a type of low or high temperature thermal process equipment used in a variety of industrial and laboratory settings. A conveyor oven can be configured as a single or multi-zoned oven. The number of zones is determined by the requirements of the manufacturing process. A multi-zoned oven lets an operator set up different temperature profiles in each zone; therefore, allowing parts to be precisely heat impinged. The equipment is sized according to the largest substrate that is going to be processed.
Conveyor ovens are versatile and convey small to large parts with varying duration heating times and varying production flows. Conveyor ovens can be used in the following applications and more:
- Curing of paints
- Drying of water or any other type of liquid
- Heat treating
- Sand core drying
- Powder paint curing
- Composite Curing
- Stress relieving of various substrates
- Adhesive and gel curing
Conveyor ovens are commonly used in the following industries:
- Heat Exchanger Process Equipment
- Heat treating
- Carbon fiber
- 3D Printing
- Heat Exchangers Process Equipment
- Heat treating
- Carbon fiber
- 3D Printing
Conveyor ovens use several different conveyor mediums to convey a part through the heated, and if needed, cooling tunnel. Flat wire mesh belt, chain, balance weave, mono-rail, walking beam, and roller conveyors are a small sampling of conveyor mediums available. The selection of a certain type of conveyor largely depends on the part configuration, weight and the desired process that occurs inside the oven. In many cases the conveyor system is a continuously running mass transfer system. However, additional flexibility can be created with indexing conveyor systems or by splitting the conveyor and transferring the part from one conveyor to the next.
Traditional ovens are constructed with tongue and groove insulated panels. The panels are insulated according to the highest temperature setting with access to the interior via side-mounted access doors. The panels can come in a variety of thicknesses from two to eight inches. The exterior and interior skin of the oven are both the same. Whether they are aluminized steel or stainless, the skin thickness is typically 20-gauge sheet metal. The panels slide into each other approximately every three feet, creating a seam between every panel.
The interior of a traditional oven requires a large amount of ductwork to transfer the heated air from supply ductwork to a part through nozzles. The theory is to have the velocity inside the supply ductwork at approximately half the speed of the nozzle velocity, creating a back pressure inside the ductwork. Once the entire ductwork is pressurized, the air protruding out of the nozzles throughout the oven is equal. This is needed to have a uniform air flow in the entire interior of the oven.
A conveyor oven can be heated with electric elements, and direct or indirect gas fired burner systems. Electric heating elements are tubular coils that carry current across them and use radiant heat to increase air temperature. Direct gas fired burners systems fire the flame inside the ductwork. Indirect gas fired burner systems fire the flame inside a burner tube also using radiant heat to increase air temperature.
Efficiency and Innovation for Conveyor Ovens
Horizon Performance Technologies LLC’s (Horizon) Cyclone Ovens™ provide consistent temperature control as well as significantly lowering operating costs (up to 75%) with the highest efficiency ovens in the manufacturing industry. Customized features are available throughout the mechanical and electrical systems to provide our customers with sustainable smart technology for today’s manufacturing needs.
Horizon’s Cyclone Technology™ improves heat transfer to the parts resulting in shorter process times. This, along with reducing the amount of interior ductwork, allows us to build smaller ovens saving floor space.
The exterior of the conveyor oven has been redesigned into 3/16 thick plate welded tight wall sections to retain more heat verses a traditional panel designed oven. The welded tight wall sections contain no open seams, which eliminates leakage points for heat and any contaminants in the atmosphere of the oven interior. The plate construction is 500% thicker compared to traditional conveyor ovens tongue and groove insulated panels.
This design meets NFPA guidelines for oven design and fulfills the explosion proof criteria. Thicker and heavier non-settling rockwool industrial grade insulation is used in the walls to reduce heat loss and is cool to the touch for operator safety. The smaller oven design and construction of the exterior walls also shortens heat-up times and reduces gas usage in the oven.
The interior construction of Horizon’s conveyor oven is fabricated with 18-gauge aluminized or stainless-steel sheet metal. The interior is 11% thicker than traditional conveyor ovens and acts as a radiant heat shield that reflects warmth to the part. This enhances part temperature uniformity, leading to higher quality results at the lowest cost possible.
The Cyclone Oven™ features high volume airflow with low pressure. The main difference between a traditional conveyor oven versus a cyclone conveyor oven is airflow. Instead of air being pushed into bulky supply ductwork then through air nozzles into the interior of the oven, the air is emitted directly from a recirculation fan into the interior of the oven. The return ductwork of the cyclone conveyor oven brings recirculation air through the burner flame and back to the air recirculation fan. The air then travels back into the oven interior creating convection. Below is a diagram showing the airflow in a cyclone conveyor oven.
One major component that increases electricity usage are the motors that power the recirculation fans in a conveyor oven. Traditional conveyor ovens require more recirculation fan horsepower (HP) to create equal pressure throughout the oven. As an example, traditional ovens operating a fan at 18,000 cubic feet per minute (CFM) will require approximately 2 ½ to 3 inch of static pressure in order to provide 4,000 feet per minute (FPM) at each nozzle. This requires a twenty to twenty-five HP motor. Horizon’s Cyclone Oven™ highest velocity airflow is 1,800 FPM. To achieve the same 18,000 CFM will require only ¾ inch to 1 inch of static pressure. This requires only a five HP motor. This is a savings of 75-80% in HP and ultimately kilowatts (kW) resulting in significant operating savings over the lifetime of the equipment.
Horizon has the expertise to help a customer develop the entire process for custom applications. Part testing can be conducted at Horizon’s technology Lab. Our technology lab consists of an industrial sized cyclone conveyor oven which allows Horizon technicians to simulate the temperature profiles for customer parts. We use a datapaq connected to the part via thermocouple wire to record data. The resulting data provides the design criteria for the airflow and British Thermal Unit (BTU) requirements for the oven.
Performance of Conveyor Ovens
Horizon Cyclone Oven™ design provides airflow directly in the interior of the oven resulting in better temperature uniformity. The technology does not require high velocity nozzles which allows more total airflow than traditional ovens.
The Cyclone Technology™ average velocity of the air past the part is three to six times higher than traditional ovens which allows us to decrease the oven footprint. This results in quicker heat up time and faster part heat transfer. The temperature curves below compare a traditional oven to a Cyclone Oven™ design. The Cyclone Oven™ shows more time at temperature than a traditional oven. This product uniformity assures highest possible part quality.
- The exterior wall sections are constructed of 3/16” plate and welded solid tight with no open seams.
- Non-settling Rockwell 4lb industrial grade insulation is used with ranges from 3 to 6-inch thickness for operating temperatures up to 1200 ⁰F (649 ⁰C).
- The internal walls and ductwork of the conveyor oven are 18 GA aluminized or stainless-steel sheet metal.
- The robust construction allows operators to walk on the roof with no need for extra support.
- Maxon, Eclipse, or Midco natural gas or propane fired burners.
- Indeeco tubular heating elements.
- Burners or heaters are accessed from floor level through maintenance plugs.
- PLC with PanelView HMI – allows adjustment of fan speed. Also, specific recipes can be developed and programmed, such as recipes for light, medium, and heavy parts.
The cyclone conveyor ovens assembled in our factory are fully tested prior to ship. A temperature profile is created via a datapak and confirms all critical design parameters are met.
Conveyor Oven Construction and Features:
- Access Ladders
- Product Baskets
- Thermal Oxidizer
- Roof safety Railings
- Thermal Oxidizer with Heat recovery
- Air Cooling Chambers
- Water Cooling Chambers
- Cooling chambers with chillers
- Filter systems
- Fresh Air preheat systems
- PLC controls