A New Level of RF Welding Consistency for Medical Manufacturers
Solid State RF generators provide better process control and consistency
The RF Welding Machine Challenge
When sealing complex medical pouches, blood bags, urinary bags and similar products, high consistency and repeatability is required. However, this isn’t the case with most RF sealing systems using standard oscillator tube RF generators. Their low frequency and harmonics don’t allow efficient power coupling; tending to dissipate power, only transferring 30-70% of total power to the load (sealing dies). Aside from the basic inefficiency of the equipment, users also experience excessive down time mainly due to arcs and constant tuning of parameters and system components due to product and die changeovers on the same equipment.
ONEX RF Automation, Duarte, CA, specializes in the design and manufacture of manual and automated RF sealing systems for medical device, automotive and other manufacturing industries. Known for its focused solutions, ONEX RF looks outside the box to develop innovative and sound solutions for process challenges such as this one.
Onik Bogosyan, president of ONEX RF Automation, explains that to improve RF sealing system efficiency, coupling methods needed a technology upgrade. “Instead of typical loading to the heat source, (which constantly created arcs due to the sensitive product nature) we looked at a unique patented solution that uses solid state generator and direct coupling technology. This is similar to high end amplifier tuning as used to obtain maximum audio wattage for quality sound,” he says. “By direct coupling we were sure we would be able to transfer our amplified signal to the source with minimum loss in transaction and precisely control the power at the load in two sealing cycles.”
The concept of direct coupling allows the RF generator to transfer power direct to the load and with the servo controlled Auto Tuner system monitor the reflective power and constantly adjust the load impedance to achieve 99% efficiency. The system runs more efficiently and consistently, while sealing the product to achieve maximum desired quality. The goal was to consistently deliver a more reliable and controllable process.
Moving to Solid State RF Welding
ONEX RF turned to their expertise in solid state technology. Their patented solid state generator technology immediately eliminated the arcing, down time, maintenance and operator safety issues, since it removed the use of oscillator tube. This in turn, eliminated the issue of RF power degradation, producing high quality seals with consistency and repeatability previously unknown in the RF welding industry.
“The solid state RF generator provides a consistent 27.12MHz high frequency signal, which is efficiently is tuned to the load using auto tuner system in addition to consistency the generator power is set via analogue signal from a PLC/PC based control system” Bogosyan says. “The solid state RF generator and auto tuner provide consistent seal with minimal power loss. The analog signal allows the power to be set and maintained precisely throughout the seal cycle, and be quickly changed to perform a different seal cycle. Based on our experience the system uses 50% less power than RF welders based on oscillator tube technology.”
“We tested this technology on a complex application sealing a sensitive medical product,” he adds. “The material was 0.009” thick and required very precise power control to prevent arcing or over-melting, in addition to the shape and size of the product, it had a valve port and a very small 0.032” diameter tubing welded onto the pouch. Initially, we’d done power calculations based on tube style generator which came to 2.3KW power for the parameter seal and 800W to weld the tubing. But, when we tested the dies using a conventional RF generator, we could not control the power efficiently and saw high variations, arcing and material burn. When we switched to solid state generator solid state technology, we were able to achieve excellent results from the first attempt and the system utilized 50% less power compared with Tube style generator.”
Bogosyan points out that having the output power controlled by an analog signal is essential sealing medical bags or pouches with multiple port seals or component assemblies. “In many similar applications where we sealed newly introduce medical materials we were able to tune and control the RF power precisely and perform film seal with less power and without use of external source of heat suggested by the film manufacturers, resulting in a high quality seal without burns or arcs, which would have been impossible using tube style RF generators,” he says.
ONEX RF Sealers come with solid state generator US patented solid state technology that use crystal oscillator instead of vacuum tubes. ONEX RF systems come in different platforms, RF-Shuttle X2, RF- Roto M1, RF-Star M2 and RF-Galaxy inline automated systems. The solid state generators used in ONEX systems are very small and fit in 19” rack mount industrial cabinets and don’t require large floor space. ONEX RF systems allow easy and fast setup of process parameters stored in the PLC/PC based control system, accessed via touch-screen menus. ONEX RF systems offer bar code reader option that reads barcodes on the dies and sets the system parameters instantly. This reduces set-up time from hours to minutes.
Because solid state generator technology is far less sensitive to complex material formulations, it allows ONEX RF to easily provide medical users a way to expand the envelope regarding their end products. The technology is easily customized for highly application specific manual or automated systems. “We have accomplished applications that were virtually impossible to seal by creating RF welding fields,” Bogosyan says. “Crystal oscillator technology easily adapts to applications that couldn't be successfully done using other systems.”
Expanding RF Welding Markets
ONEX RF systems are easily validated for all medical applications, specifically RF sealing process parameters set for each and every product. ONEX RF sealers use solid built platform and are great fit for medical and other industrial applications. “Operators can be easily trained on ONEX RF-solid state generator systems in a day,” he says. “Any manufacturer that needs optimal RF welding/sealing at half the energy and maintenance cost will benefit using ONEX RF systems, including automotive, packaging, military, office supply, recreational, flooring, air structure, pool liners and more.”
ONEX RF-solid state generator technology allows customers to achieve results far beyond standard tube style RF sealing machines resulting in higher quality products and repeatable processes. “This is a revolutionary process that has been proven with many systems already in the field,” Bogosyan says.