| RF welding is a basic technology, and the | | | | pressure, current and voltage and their |
| basic devices necessary to affect such a weld | | | | profiles. |
| have not changed since the inception of the | | | | |
| process. Today, as in 1942, we need a | | | | When modern material handling systems are |
| generator to provide RF, a transmission line | | | | used in conjunction with these devices, high |
| to transfer power, a press to apply force and | | | | speed automatic production systems can be |
| an electrode in the desired geometric pattern | | | | built. Many hundreds of such systems are in |
| to be welded. | | | | use throughout the U.S. These systems |
| | | | manufacture a wide variety of products for |
| The terms "Radio Frequency (RF) Welding or | | | | the automotive, stationary products, and |
| Sealing" are often used interchangeably with | | | | medical industries. |
| "High Frequency (HF) or dielectric welding or | | | | |
| sealing." When matter is brought into contact | | | | The continuing stream of new RF responsive |
| with an electromagnetic field, some portion | | | | materials being brought to the market further |
| of the electromagnetic field will go through | | | | impact the industry. In addition, additives |
| a change of energy state. As a result, it | | | | and RF responsive adhesives are continually |
| will be converted to heat and dissipated | | | | being developed for specialized applications. |
| within the contacted matter. The degree to | | | | It is now possible to bond materials that in |
| which this con-version will occur, or the | | | | the past were considered unsuitable for the |
| efficiency of this conversion of energy state | | | | RF process. These changes are opening up a |
| is dependent on the atomic and molecular | | | | new range of products that can now be |
| structure of the matter, the frequency of the | | | | manufactured by this time proven technology. |
| electromagnetic field, and the field | | | | This will have a great effect in the medical |
| potential (Volt-age/cm). The term dielectric | | | | industry, as it tries to eliminate the use of |
| heating correctly describes this phenomenon | | | | vinyl. |
| at any frequency while RF or HF heating | | | | |
| describes the process over the lim-ited | | | | Both electron beam and laser welding, when |
| frequency range from 1 to 200 megacycles/sec | | | | initially discovered, were thought to be |
| (megahertz/sec). | | | | possible replacement technologies. However, |
| | | | these technologies have been found to be more |
| The area where most of the technological | | | | applicable for spot or seam welding of metals |
| changes have taken place is in the components | | | | or other rigid materials where welding times |
| from which the individual devices are | | | | are measured in minutes and hours. In RF |
| constructed. Solid state components have | | | | welded products, welding times are measured |
| replaced mercury vapor rectifier tubes. | | | | in seconds or fractions thereof. Guideline |
| Digital timers have replaced industrial | | | | believes the likelihood of these becoming |
| timers. Programmable Logic Controllers (PLC) | | | | competing technologies is very low. In |
| have replaced relay logic. | | | | Guideline's opinion there is nothing on the |
| | | | horizon that will replace RF welding in the |
| When a PLC is used with linear and optical | | | | next 5 to 10 years. Its place will be as |
| encodes, precise control can be achieved over | | | | secure as it is today, not only as the |
| the various functions that determine the | | | | economically preferred way to weld certain |
| specific characteristics of the weld. Using | | | | materials, but in many cases the only |
| these types of devices it is possible to | | | | feasible method. |
| monitor and control functions of time, | | | | |