Company insight
Pro-ball and Pro-wheel optics for flexible laser welding of foils
When it comes to the laser welding of foils with changing geometries in medical technologies, it is absolutely vital that the welding energy and pressure is applied dynamically. With its innovative technologies, ProByLas offers laser-focusing Pro-ball and Pro-wheel optics to achieve the perfect weld for two-dimensional or three-dimensional geometries.
F
or the welding of foils in medical technologies, radio-frequency (RF) or heat impulse welding are often applied, which are highly efficient for large series. For smaller quantities and changing geometries, the expense of part-specific electrodes respectively heating bars becomes more than somewhat unfavourable, leading to the need for other options. Laser welding can offer a viable alternative, as no specific tools are required. Only the welding contour in the motion control program needs to be changed.
Dynamic clamping
In addition to the energy of the laser beam for melting the polymers, the pressure in the weld seam is also crucial for strong bonding. The traditional
laid out accordingly for the pro-ball optics mounted on a robot.
The Pro-wheel optics is also based on an air bearing. It allows small tilts of the glass roller to compensate for uneven foils or the base underneath. With the Pro-wheel optics, wider welds can be produced, but primarily in one direction or curves with a large radius.
Ball (top) and roller optics (bottom) press the foils together with the freely rotating glass ball or roller and focus the laser at the same time.
approach of a fixed static clamping unit, which simultaneously presses the complete parts together, has limitations with large layouts as for example, with foils and textiles. For such applications, clamping the foils dynamically only at the current welding position makes more sense. This can be achieved using a rolling glass ball or glass roller that simultaneously focuses the laser beam on the weld seam and compresses the foils.
Flexible welding of different foil designs demonstrated on inflatable structures of TPU foils inside a Turnkey M.
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Specially designed optics With the special air bearing developed by ProByLas, the diameter of the glass ball has significantly been reduced to a standard diameter of 12mm and, in dedicated customer-specific modifications, even further down to a diameter of 3mm. With the pro-ball optics, any two- dimensional geometries in a plane are possible, with sharp curves or even corners. Also, three-dimensional layouts are feasible if the foils are cut out and
In the traditional laser welding process, the upper foil is transparent to the laser, and the lower layer is absorptive. With two transparent foils on either side of the absorptive one, also three-layer designs are possible, providing some more degree of freedom in the design, such as crossing fluidic channels or asymmetric designs of chambers for inflatable or stabilisation structures.
Clear-to-clear without additive With new types of lasers emitting at longer wavelengths, transparent foils can be welded to transparent foils. At longer wavelengths between 1,700–2,000nm, most polymers show a small intrinsic absorption of the laser light, allowing welding even without a colour additive. This is specially requested by medical fluid bag applications critical to any new additive brought into contact with the application.
At the MedtechLIVE tradeshow in Nuremberg, Germany to be held at the end of May, laser welding with pro-ball optics will be demonstrated by ProByLas on an inflatable cushion made of thermoplastic polyurethane (TPU) foils. ●
www.probylas.com Medical Device Developments /
www.nsmedicaldevices.com
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