Ultrasonics – at the heart of medical device automation
06 April 2016
The Medical Device industry demands quality, consistency, cleanliness and traceability in all aspects of component production.
These stringent requirements extend to the joining technologies that are often a key element of automation and assembly processes. The benefits of cleanliness, process consistency and controllability of the ultrasonic process are generally well understood, however the flexibility in the ultrasonic process application has been a significant driver in the uptake of the technology within the automated assembly systems used by the Medical Device sector. Examples of this flexibility can be seen in Telsonic’s “Cut’n’Seal” and “SONIQTWIST” techniques.
Many items used within a medical environment including dressings, filter membranes, cleansing pads and gown labels, all require concise sealed edges to ensure product integrity. Additionally, products that come into contact with skin must be comfortable to wear and free from frayed or ragged edges which could cause irritation.
Telsonic’s “Cut’n’Seal” process is used for shape cutting of any product, where collated layers of non-woven, woven man-made textiles, laminates or single layers that may be prone to fraying, require a joined and smooth edge. The process is also used where flexible textile layers are required to be joined to thin rigid substrates, in applications such as wound care, respiratory filter products or face masks.
The process has additional benefits including no consumables and none of the environmental issues associated with recycling or the disposal of chemicals, which can be the case with certain adhesives. The “Cut’n’Seal” process can easily be integrated within a wide range of automation concepts from pre-production proof of principal systems to fully validated high volume production lines.
The principles of Cut’n’Seal can be extended to enable the process to perform a welding operation immediately following the cutting process. One example of this principle is the production of specialist medical consumable filters. Operating within a fully automated system, the filter media is fed from a reel into a machine which also presents and aligns the plastic moulded filter frames. Telsonic’s ultrasonic technology is then used to initially cut the filter membrane from the reel of material, before welding it to the plastic moulding. This concept eliminates the need for pre-cutting and collating filter membranes for subsequent presentation to a separate assembly and welding machine. This two-stage concept can also be used in a semi-automatic configuration if required, for lower volume products.
Putting a twist on ultrasonic welding
Thin films and membranes, which often have a typical thickness of only 50µm, are used to create a hermetic air tight seal on medical pots, devices, containers and drug delivery systems. It is essential therefore that any process used to weld the delicate film or membrane media does not induce any defects or damage.
The vertical amplitudes produced across the face of an ultrasonic sonotrode, when using conventional linear ultrasonic welding techniques, may result in perforation of delicate membranes due to the diaphragm effect. This problem is effectively eliminated using the trademark SONIQTWIST process.
Telsonic’s SONIQTWIST produces radial amplitude in a circumferential manner at the perimeter of the seal, with the torsional amplitude diminishing to almost zero at the centre of the membrane or film. SONIQTWIST does not stretch the membrane during welding and does not cause a diaphragm effect or induce perforation of the film. The SONIQTWIST technique therefore effectively eliminates the risk of perforation, when welding polymer based foils, films and membranes. The technique has the advantage of speed, with complete weld cycles being achieved in less than one second. The unique characteristics of SONIQTWIST also enables multiple membranes, in close proximity to one another, to be processed without causing any previously welded membrane to become dislodged or lose its hermetic seal.
The characteristics of SONIQTWIST make it the ideal process for a wide range of welding and forming operations in a variety of materials, including plastics, ceramic and aluminium. The process also minimises particle production and size, supporting good automated manufacturing practice requirements in the medical device manufacturing sector. The benefits of SONIQTWIST can also be applied to welding operations on housings which contain delicate electronic devices which must not be damaged or affected during welding. The process is not limited to circular parts, with rectangular and non-symmetrical shaped components capable of being welded, sealed and joined using this technique
Telsonic engineers have designed the SONIQTWIST welding head such that it can be easily retrofitted to a standard bench top machine for low volume or proof of principal scenarios. The head can also be mounted to pneumatic actuator modules or servo operated actuators, enabling incorporation within a fully automated assembly machine. The SONIQTWIST configuration can also be used in multi-head applications.
Telsonic ultrasonic modules and systems offer many levels of choice for end users, machine builders and system integrators within the medical device sector. The company’s range of ultrasonic modules is designed to be “automation friendly” allowing easy integration within stand alone systems and sophisticated production lines. Telsonic UK offer a comprehensive range of ultrasonic modules and systems for a variety of plastic and metal welding, cutting, sealing, cut’n’seal, food cutting and cleaning applications within a wide range of industries.
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