According to Ambrell, a cap to container seal is made with the aid of a laminated disc composed of a wax layer, aluminum layer and a polyethylene (PE) layer. The aluminum layer acts as a susceptor, heating to about 125 to 150 degrees C in the electromagnetic field produced by the induction coil. It then heats up the wax and PE layer sufficiently to produce a hermetic seal between the cap and container. Heating time is less than a second in this high-speed, low energy consuming automated process.
Sealing caps on food containers and medications are pretty much taken for granted, but imagine the health and safety dangers, as well as the nasty molds, consumers would be subject to if these caps weren't properly sealed. The most extended induction application in this industry is the high-speed hermetic sealing in tamperproof packages, cap sealing and aseptic packaging. This technique guarantees the integrity of the seal, as well as the preservation of the product for longer periods of time.
Benefits of induction heating include:
- Rapid, efficient heating,
- Precise, repeatable heating,
- No flame.
One of the major benefits of induction heating is its energy efficiency. "Reduced energy usage in the manufacturing process is a win-win for developing a competitive advantage," says Mark Davis, Inside Sales Manager of Eldec Induction LLC. "Going green in manufacturing is more than a philosophy, a strategy, or a responsibility. It just makes good ‘cents' to reduce and conserve. Induction hardening or heating releases less internal residual stresses as a result of the lowest possible energy input - measured in kilowatt seconds - and, therefore, only a small fraction compared to the total mass that has to be quenched during the final heat treatment. The lowest possible energy input and resulting reduced energy consumption translates directly into improved environmental benefits."
Induction heating is an environmentally friendly alternative to traditional heating methods, such as blowtorches, oil baths, ovens and hot plates. These expensive methods produce smoke, fumes and oil waste, and are hazardous to personal safety and working environments.
But there are dangers associated with the induction method of heating. Fortunately, the 2014 edition of the National Fire Protection Association's NFPA 70: National Electric Code addresses these concerns with specific guidelines for warning labels, signs and equipment marking.
Warning labels or signs that read, "Danger - High Voltage - Keep Out" shall be attached to the equipment and be plainly visible where persons might come in contact with energized parts when doors are opened or closed, or when panels are removed from compartments containing 150 volts, AC or DC.
Figure 1: Lockout labels indicate that equipment has been disabled for maintenance or some other reason
In addition, a nameplate must be affixed to the heating equipment, providing the manufacturer's name, model identification and the following input data: line volts, frequency, number of phases, maximum current, full load kilovolt-amperes (kVAs) and full load power factor. Additional data is permitted.
Incorporating best safety practices involving induction heating can be accomplished with advice from suppliers who uses induction heating techniques for new product development, process evaluation and troubleshooting. Consultants work primarily with operators and line forepersons who are responsible for day-to day-equipment operations. Best practices include using lockout devices when servicing equipment.
Signs and labels should be used in facilities to warn workers about the dangers of working with induction heating on power supplies and coils that utilize high voltage. Another recommendation is the use of personal protective equipment (PPE) associated with working with induction heating. All equipment should utilize light guards or similar protective devices to prevent both contact with the coil and moving mechanical assemblies that might harm the operator during automatic operations.
Induction heating is also used for all types of:
- Forging and melting;
- Heat treating;
- Semiconductor and optical fiber applications.New technology, even green technology, poses potential hazards to the modern workforce. Ensure that your number one assets - your workers - are well informed of workplace dangers with aid from safety signs, labels and PPE indicators throughout your entire heating induction system.
About the Author
Jack Rubinger is a public relations specialist with Graphic Products where he contributes to industrial blogs, publications, and social media worldwide that provide visual communication solutions for the industrial workforce. www.GraphicProducts.com