The production of medical technology products such as implants, instruments, and devices is subject to very strict requirements – even in part cleaning. Ultrasound is an indispensable process in this regard. It ensures that the required cleanliness is achieved stably, efficiently, and sustainably during both intermediate and final cleaning.
Ultrasound and medical technology – this combination initially associates with imaging diagnostics. However, ultrasound can do much more in this area. Sound with frequencies above the human hearing range has established itself as an economical and sustainable standard process in wet-chemical cleaning applications in the manufacture and preparation of medical technology products such as instruments, implants, and other devices. It can be used for components made from various materials such as stainless steel, titanium, cobalt-chromium alloys, ceramics, and plastics.
Optimally adaptable to the task

For the very different cleaning tasks in medical technology, Weber Ultrasonics develops demand-oriented generators and oscillation systems in collaboration with cleaning system manufacturers and users, designed as rod, plate, and immersion oscillators with different frequencies. This includes single-frequency solutions as well as dual and multifrequency ultrasound systems in a frequency spectrum of 25 to 132 kHz. They enable the construction of space-saving cleaning systems tailored to the workpieces and cleaning requirements.
The development of vacuum-tight single, dual, and multifrequency immersion oscillators opens up the use of ultrasonic cleaning even in full vacuum cleaning systems. For high purity applications, where particularly high demands are placed on component cleanliness and cleaning equipment, immersion and plate oscillators are available in corresponding designs. They meet the requirements of hygiene class 4 according to DIN 11866 with a surface roughness of < 0.35 µm.
Reliable and damage-free cleaning of stents

Heinz Schade, managing director of the company of the same name, also relies on the wide range of highly effective ultrasonic components. The company, founded in 1999 and based in Reutlingen, develops and produces machines for balloon and catheter manufacturing as well as stent processing, which are distributed worldwide. Additionally, software that is optimally tailored to the various machines allows for the seamless documentation and traceability of processes required in medical technology.
This helps ensure that the strict requirements of the MDR regarding process and product safety as well as quality management are met.
A focus of the equipment portfolio is on manufacturing steps for stent production that follow laser cutting, such as electropolishing, heat treatment, etching, and ultrasonic cleaning. The company has been manufacturing the tanks for the cleaning systems in-house for about 20 years. This allows them to be adapted to the various products or the specific requirements of each customer. 'Through our own manufacturing, we were then looking for a supplier for the ultrasonic components. With Weber Ultrasonics, we found a partner who has convinced us to this day with competent advice and uncomplicated collaboration,' reports Heinz Schade.

To ensure the quality and safety of the products, stents are usually cleaned between the various processes. A final cleaning is then performed before packaging, which is usually carried out in a clean room. 'In doing so, increasingly higher requirements for surface cleanliness must be met. At the same time, it must be ensured that no damage occurs to the sensitive stents during cleaning,' he specifies the requirements.
Essential parameters for this are the frequency of the ultrasound and the power in watts per liter of bath volume. For a uniformly stable result, a homogeneous sound field must also be generated in the bath. 'The ultrasonic solutions from Weber Ultrasonics are ideal for these tasks. The power can be very precisely adjusted by controlling the generator, and the sound emission occurs consistently and reliably. We have had no problems with the ultrasonic systems so far,' adds Heinz Schade.
Particulate and film-chemical contaminants are removed

Its cleaning effect is unleashed in a liquid bath through the physical effect of cavitation: The electrical signals generated by an ultrasonic generator are transmitted into the liquid by oscillation elements. The sound pressure is characterized by a change between underpressure and overpressure. In the underpressure phases, microscopically small cavities form, which collapse (implode) in the subsequent overpressure phase.
Shock waves with significant energy are generated, which 'blast off' particulate and film-chemical contaminations. At the same time, microcurrents are created in the liquid that wash away detached contaminants. These effects enable the removal of contaminants not only from surfaces but also from complex geometries, cavities, holes, and structures.
For critical surfaces in combination with pressure change processes

For components such as additively manufactured implants with an open-pore sponge structure or combined porous and polished surfaces, as well as components with very fine capillaries, ultrasound can be combined with pressure change processes. In these vacuum flood cleaning processes, alternating underpressure and overpressure as well as cavitation effects are generated by regularly repeating pressure changes. Cleaning and rinsing media thus reach areas that would otherwise only be partially or not at all accessible.
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