Telsonic Keep Ultrasonics Safe and Sound

Just like any other manufacturing process, ultrasonic welding has to conform to the dynamic guidelines laid down by the Health and Safety Executive with regard to safety guarding and noise emission. As a proactive and responsible supplier, Telsonic has developed a range of machine and acoustic guarding concepts for their ultrasonic systems, which not only meet current health and safety regulations, but allow easy and quick access for operators and maintenance personnel.

Guarding fulfils a dual role

In its simplest form, ultrasonic welding is carried out by an operator manipulating a hand held unit around the various welding positions on a component. Using the technology in this configuration usually requires little in the way of operator protection, other than perhaps the provision of acoustic ear defenders in certain cases. Providing the system is used in line with the manufacturer’s instructions, the main focus from a health and safety perspective is likely to be operator ergonomics.

However, instances where operators interact with process controlled, powered machinery can pose potentially greater risks if safety guarding is not configured correctly. In many applications, particularly for the automotive and medical device industries, there is a requirement to automate the welding process for productivity, validation and traceability purposes. In these cases relevant operator guarding will be required, however if designed and configured correctly the guarding fulfils a dual role, providing a physical barrier between the operator and the moving parts of the machine and also suppressing noise which may be generated by the ultrasonic welding process.

Light Guards

Light guards in the loading area are a popular and effective choice of guarding where fast ergonomic cycles are required of the operator within the load/unload sequence, especially in industries such as automotive. This ‘open’ aspect of the machine does however allow any unsuppressed noise to emit from the light guarded aperture. In these applications, ear defenders and machine isolation are obvious options within the overall environment of background noise and the application generated noise levels

Welding on the quiet

As an ultrasonic process we might be surprised to find noise is actually an issue. In fact, if a correctly tuned ultrasonic welding system is operated in air, without product contact, it is inaudible to the ear. It is only when the process comes into contact with the materials to be joined that a lower frequency and thus audible noise is generated. The level of noise generated is greatly influenced by the type of material and to some extent, by the shape of the part being processed.
It is also important to point out that ultrasonic welding systems not properly set up or maintained, will generate higher levels of noise than those which are properly tuned and well maintained. This also applies to component fixtures and any other equipment which may be attached to the fixtures in the immediate vicinity of the welding nest. If any of these items are loose they will vibrate in “sympathy” with the welding transmission. The varying levels of noise produced from different products and applications require different levels of acoustic suppression. Telsonic’s guarding concepts for ultrasonic welding systems fall into several different categories, from simple local barriers to sophisticated, all encompassing acoustic enclosures. Special applications, which are required to comply with clean-room and GAMP environments can also be accommodated using appropriate guarding designs and materials.

Many applications on small to medium sized components, in the higher welding frequency range (35kHz) and of lower energy/peak power delivery, are carried out using Telsonic’s range of stand-alone ultrasonic welding systems. For this type of system Telsonic offer simple, manually operated local guarding, with a pull down door or sliding drawer table, used in conjunction with guard interlocked two hand start or auto-start routines. This provides both a physical barrier between the operator and the part whilst often providing adequate levels of acoustic suppression.

When simple noise barriers, ear defenders or machine isolation are not practical solutions within an assembly or shop floor area, then the decision on how best to provide a cost effective solution to guarding, whilst adhering to the HSE noise directive noise assessment formula, becomes more complex.
At the lower common European Ultrasonic weld frequency (20kHz) and with larger applications, a full enclosure around the welding system is normally more desirable to support noise suppression and Telsonic offer a choice of enclosure concepts. Where the noise appraisal is perceived to be less of an issue, enclosures built using an aluminium extrusion framework and polycarbonate infill panels will usually provide an adequate level of noise suppression, whilst offering excellent safety for the user. In addition, features such as automatic opening of the door or sliding table at the end of the welding cycle provide tangible benefits for the operator, helping to reduce the unload and load times. This guarding style can be further enhanced with full infill panels with sound suppressing laminates.

For more demanding applications where greater consideration needs to be given to noise suppression, Telsonic offer full acoustic guarding enclosures mounted on their own work stands. These are fabricated from sheet steel, powder coated and are fully lined with a special polymer cellular laminate to provide excellent noise suppression. These systems also incorporate an automatic rise and fall door with a safety strip, which fully seals the cabinet against noise leakage during the welding cycle. This, operator unload and load door, is integrated within a larger, fully interlocked maintenance door, providing easy access to the welding system and its associated sonotrode and fixtures. Machine Isolator, emergency stop and reset controls are located on the machine front panel.

With a track record spanning over 40 years, Telsonic has been involved in the integration of ultrasonic technology into thousands of production systems. The unrivaled knowledge and experience gained during this time enables Telsonic’s engineers to provide not just the ultrasonic welding system, but the guarding and acoustic solution tailored to match the application.