Laser Welding Suits Precision-Welding Processes

Laser Lines has explained the key advantages of laser welding. Nylon welding processes are split into two categories: low-energy-density, and high-energy-density processes. Low-energy-density processes are those such as traditional arc and resistance welding technologies that rely on heat conduction through the material from a surface point to provide melting. High-energy-density processes using lasers create a heating filament, known as the keyhole, which penetrates the depth and offers 2D line heating, causing a highly efficient heat transfer into the weld joint.

The key advantages of laser welding are a small heat-affected zone (HAZ), accurate control of heat input, and the ability to direct the beam precisely to the weld point. This means reduced thermal distortion, the ability to weld close to heat-sensitive parts, and precision welding capabilities. Major applications for sub-kilowatt lasers are in precision-welding and heat-sensitive welding processes, such as hermetic sealing, because the typical focused beam diameter of 100 microns localises temperature rises around the weld to fractions of an inch. These stainless-steel coupons were welded using the Firestar f400 laser. The 0.9mm (0.036in) thick stainless steel was fixtured with the ends tightly aligned to create a butt-type weld.

Because most laser-welding processes do not use filler wire, but instead rely on the molten material to create the weld joint, part fit-up for a laser weld must be free of any gaps or voids in order to achieve strong, consistent joints. As with conventional welding processes, creating initial spot welds at intervals along the joint helps to prevent material separation during the actual weld pass. Full weld penetration through the stainless steel was achieved using 400W of power at a weld speed of 1.9m/min (75in/min).

Beam delivery for this application was accomplished using a 63.5mm (2.5in) positive meniscus lens, which produced a 100-micron (0.004in) spot and 1.8mm (0.07in) depth of focus. During welding, argon shield gas at a flow rate of 1.0 SCFM prevents the molten weld pool from reacting with the surrounding atmosphere. At this material thickness and weld speed, there is no difference between argon and helium assist. When welding thicker stainless material at higher speeds, helium shielding provides deeper weld penetration due to its higher ionisation potential and smaller weld plume.

Switch Range Suits Safety Applications

Moeller Electric T rotary switches and P switch disconnectors are suitable for use as main, maintenance and emergency-stop switches that can be locked in the off position with up to three padlocks. Moeller Electric T rotary switches and P switch disconnectors are available in ten different basic switch types with several mounting forms and both standard and customised contact configurations. This makes them a compact, convenient, dependable and cost-effective solution for virtually any application involving uninterrupted currents of up to 315A.

Both ranges are available in versions with 400/415V AC23A ratings from 6.5 to 132kW and with uninterrupted current ratings from 20 to 315A. They are suitable for use as main, maintenance and emergency-stop switches rated to IEC/EN 60204 and IEC/EN 60947 and can be locked in the off position with up to three padlocks. They are available in their own enclosures or for mounting in control cabinets, either on the door or rear of the panel with a cover interlock. The T range is also available as motor load switches for changeover, multispeed, reversing and star-delta switches.

T0 switches can be supplied with up to 22 contacts and 12 switching positions and are suitable for many different switching and control functions, such as on/off, hand/auto, changeover, step, coding and instrument selector. Compact TM switches are designed to save space but also to be particularly easy to install and wire. They have an AC23A rating of 3kW and an uninterrupted rating of 10A. Moeller Electric supplies a full range of enclosures for use with its rotary switches and switch-disconnectors.

These enclosures are available in insulated and stainless steel versions with ingress protection ratings up to IP65 and in sheet steel with ingress protection ratings up to IP55, making them suitable for use in the food industry. ATEX-compliant insulated enclosed versions of T rotary and P switch disconnectors are available up to 100A. All types and ratings are approved for use in dust areas, zone 22 and category 3 and all are approved for device group II.