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Design excellence for thermoplastic nebulizer

TWI worked with Member company and health technology specialist Philips Avent to conduct a feasibility assessment of welding individual component parts of a new nebulizer device.

Many of the individual component parts to be welded had complex curvature, so assessment was needed before manufacturing could begin. The combined efforts of TWI and Philips Avent led to a nebulizer being available for children and adults needing respiratory treatment.

The Innospire Go is an award-winning portable mesh nebulizer, with a simple two-piece design and a detachable mouthpiece making the device simple to use, clean, and maintain. It is particularly relevant for children who find older systems more difficult to use, and won an ‘iF’ Design Excellence Award from iF World Design Guide and is now in full production.

As many of the nebulizer’s individual component parts have a technically challenging complex curvature, the team carried out a feasibility study to assess the best method for joining. TWI identified ultrasonic welding as the most appropriate method as it produces high quality joints rapidly in a range of materials and joint configurations. It is a relatively mature process which is commercially accessible, meaning development and production costs should be lower.

TWI assisted with the design and manufacture of the aluminium sonotrodes and nests - components that are responsible for introducing the workpiece to the 20kHz ultrasound energy. TWI also validated the welding process for two different thermoplastic material types (Grilamid TR90 and Noryl HN731A) on the four weld joints, with ultrasonic welding trials conducted on 100 pairs of each material supplied by Philips Avent, using a range of machine settings.

On completion of these trials, the team assessed a number of the welds by manual testing and visual inspection, and found that the robustness of the device was acceptable. TWI provided a summary of the work, which included the feasibility of ultrasonic welding each joint, and suggestions for process improvements.

For more information, please email contactus@twi.co.uk.

Avatar Scott Andrews Principal Project Leader, Polymer and Composite Services

Scott is currently working as a principal project leader in the novel polymer technologies section at TWI. Scott has been involved in plastics welding research for over 20 years. His primary role is to lead and deliver research projects relating to plastics welding, typically providing plastics welding consultancy for medical and automotive products (in particular joint design for welding), proof of welding feasibility, plastics welding troubleshooting, welding machine specification and validation for entering production.

In addition, Scott manages the day-to-day running of TWI’s Plastics Welder Training and Examinations business, and is currently a CSWIP approved Plastics Welding Examiner.

Scott’s areas of expertise covers all plastics welding processes - in particular ultrasonic welding, plastics welding equipment, analysis of plastic welds, plastic materials - including high-temperature thermoplastics as well as wood welding and wood polymer composite welding. Scott has successfully led many small to large polymer welding projects for a variety of applications, across a number of industry sectors (medical, automotive, power, aerospace, oil and gas, construction).

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