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