A curing oven is defined as a thermal processing piece of equipment that causes a chemical reaction in a product with the use of heat. Curing ovens are utilized to harden products made from rubber, plastics, and various types of metals, and are almost exclusively used in the manufacturing industry. However, curing ovens come in many varieties, and there are numerous applications within the realm of manufacturing that require their use.
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Advantages to Curing Ovens
UV curing has quite a few advantages. UV-curable inks, adhesives, and coatings serve as a beneficial alternative to materials that are solvent-based. As opposed to solvent evaporation, which creates environmental pollutants and can reduce the thickness of the coating by up to 50 percent, UV curing involves no solvents, and thus no loss of volume or thickness in the coating. In turn, UV curing grants higher productivity, reduced turnaround time, less waste, less consumption of energy, and less emission of pollutants.
Other benefits of UV curing include improvement in the physical properties of adhesives, coatings, and inks, reduced work-in-process, drastically reduced setup and cleanup labor, and less necessary floor space.
Design of Curing Ovens
Curing ovens are usually built with steel insulated panels, steel frames, and include a heating element. Curing ovens can be powered by either electricity or by natural gas, and can often be custom-designed to meet the requirements of a specific application. In addition to customization, there are specialized curing methods that fortify certain materials, such as carbon fiber material and paint.
Materials Used for Curing Ovens
Powder coating is one example of the many types of processes carried out by a curing oven. The process of powder coating involves using static electricity to apply a powdered thermoplastic resin to a surface. The powdered resin gels and forms a protective layer around the surface of a product upon exposure to the curing oven’s heat. Numerous industries use this method of curing in order to enhance the appearance of their products, such as aerospace, marine, automotive, and furniture.
Aesthetic purposes aside, various industries also utilize curing ovens to dry, preheat, and cure specific parts and components of a product. Curing ovens are used for the curing of rubber, also known as vulcanization, which involves strengthening rubber products using chemicals and heat. Other processes which can be carried out by curing ovens include temperature testing, baking, sintering, and metal finishing.
Curing ovens deal with a wide variety of materials. Although the properties of these materials vary, they all react nearly the exact same way to the curing process. For example, resin materials, with the help of added heat and sometimes chemical additives, are strengthened during curing due to the process catalyzing the cross-linking of the resin’s polymer chains. Metal materials are prone to oxidation, or the degradation of surfaces due to prolonged exposure to oxygen. Heat curing the metal can not only help prevent oxidation, but also improve the metal’s durability and strength. If manufacturers need to cure metal in environments where oxidation must be avoided, there are specially designed vacuum ovens available that will enable manufacturers to cure metal under a strictly controlled atmospheric and chemical environment.
Methods used for the Curing Oven
A curative method that has been recently discovered and is becoming more widely utilized is curing by way of exposure to ultraviolet radiation. UV curing was originally introduced in the 1960’s, and became quickly adopted by a multitude of industries such as metal, glass, and plastic decorating, converting, electronics, telecommunications, automotive, and graphic arts.
Over the next 50 years, UV curing has grown into a multi-billion dollar worldwide industry. The UV curing process uses a photochemical reaction. In other words, UV curing uses light instead of heat. The desired material is mixed with a small percentage of photo-initiators before being exposed to ultraviolet light. The material—whether it is an adhesive, a coating, or an ink—hardens within a matter of seconds.
Applications for Curing Ovens
Today, UV curing technology has evolved to the point where manufacturers are now able to apply it to three-dimensional components. Examples include:
- Fiberglass Composite Parts
- Electric Motor Housings
- Golf Balls
- Contoured Wood Products
- Automotive Lighting Assemblies
- Plastic Molded Parts Such as Mobile Phone Cases
UV curing of 3-D parts is not without its challenges, however. UV curing is a “line of sight” process, meaning that every part of a given surface must be exposed to the UV radiation in order for the curing to be successful. “Shadow” areas, or any part of the object’s surface which is hidden, will not be cured. Fortunately, hybrid thermal and UV coatings are being developed that will assist manufacturers in achieving a thorough cure.