When you think of respiratory and surgical masks, which are currently
produced predominantly in Asia, ultrasonics is probably not the first thing
that springs to mind. Yet ultrasonic welding plays an important roll in
making these products. As an experienced technology provider for mask
production equipment, Weber Ultrasonics AG now manufactures respiratory and
surgical masks in Germany. This is made possible by the fast and active
support of other companies as well as the huge dedication of its own
employees.
Efforts to stem the spread of Covid-19 make one problem of globalisation
clear: the dependency on low-cost manufacturing countries for personal
protective equipment (PPE). That is why, in addition to protective clothing
and gloves, breathing protection and surgical masks have been in short
supply in Germany and other European countries since the global spread of
the corona virus Sars CoV-2. ‘Since the Sars pandemic in 2002/2003, we have
been producing equipment for the manufacture of different protective masks
made of nonwovens based on thermoplastic synthetics. The equipment is
primarily supplied to customers in Asia,’ reports Christian Unser, Chief
Sales Officer at Weber Ultrasonics AG. It includes components such as
generators, boosters, converters and sonotrodes as well as complete systems
for welding, laminating, cutting and embossing with ultrasound. Producing
masks itself was never an issue for the component and plant manufacturer
based in Karlsbad (Germany) – until the start of March 2020.
Entering into production of FFP respiratory masks
What triggered it was an enquiry from a mechanical engineering customer who
was unable to get filter domes for its special ventilated respiratory masks
in FFP2 protection class as a result of the export restrictions in place
for these products in virtually all countries. ‘Together with the customer,
we developed a plant design for producing the three-dimensional filter
elements in a very short time. The customer immediately placed an order for
three machines,’ explains Christian Unser. In parallel with this
development, Weber Ultrasonics converted the design into a standard machine
for the production of complete breathing protection masks. The first
process step of deep-drawing the masks represented a challenge. This takes
place through hot-forming, which requires a suitable tool as well as
special heating elements and corresponding control units. In order to be
able to produce corresponding prototypes quickly, Christian Unser turned to
a market player that also works in this segment and spontaneously provided a
heating element and control unit. The Head of Design at Weber Ultrasonics
obtained a second one from his former employer. The necessary tool was made
by a neighbouring model maker and long-standing partner of the company
practically overnight. ‘It really is great how different companies have
offered spontaneous support and cooperation,’ comments the Chief Sales
Officer.
60 respiratory masks per hour with one machine
The production of the breathing protection masks takes place with this
standard machine in a multi-stage process. In the first step, an open-pored
fibrebond as stabiliser, a layer of meltblown nonwoven as particle filter
and a layer of spun-bond are shaped through hot-forming. The edges of the
masks are then joined in an ultrasonic welding process. To do this, an
ultrasonic converter converts the electrical signal produced by the
generator into mechanical oscillation. This is transferred via a booster
and a customised welding tool, the sonotrode, onto the surface to be joined.
The frictional heat this generates causes the nonwoven materials to melt
specifically at the edges, where they form a permanent bond without
distorting. At the same time, the reliable, energy-efficient and productive
joining technology ensures a soft and skin-friendly surface. After the
masks are then punched out mechanically, tapes are attached for fastening
them.
The production capacity of the compact standard plant with a single tool is
around 60 breathing protection masks per hour. The aim is to achieve
protection class FFP3 for the masks produced according to the current
standards and to perform an accelerated inspection of corona virus pandemic
breathing protection masks for Germany.
Virtual start-up with real twin for surgical masks
Weber Ultrasonics has also experienced increased demand for production
equipment for surgical masks. The company’s solutions in this segment so
far enable the production of 200 masks per minute. ‘For this application we
are currently working all-out to set up a testing plant at our premises
that will use a newly developed procedure for continuous ultrasonic welding.
This will enable us to increase production capacity to 400, maybe even 600
masks per minute,’ explains Christian Unser. This machine combines the
steps of folding the fabric, integrating the nose wire, vertical and
horizontal welding, welding on an elastic band and separating.
One reason for the fast implementation of this system in the factory in
Karlsbad is the current travel restrictions. ‘We now need to put the plants
into operation virtually at our customers’ premises and to do this it is
important that we have the same performance here,’ says Christian Unser.
‘This also has the positive effect that we can push forward developments
directly on the plant, perform tests for customers and above all produce
surgical masks in large quantities ourselves.’
The respiratory mask after deep-drawing and welding of the edges with
ultrasound.
Photo: Weber_mask production_Final Mask
For the respiratory masks produced according to the standards for
protection class FFP3, an accelerated inspection of corona virus pandemic
breathing protection masks for Germany will be carried out.
Photo:
Weber_Maskenproduktion_Welding2
In order to be able to start the production of the respirator masks
quickly, different other companies supplied equipment for the deep-drawing
process of the nonwovens.
Image source: Weber Ultrasonics AG
