Life sciences company MilliporeSigma recently turned to Emerson when heat sealing and ultrasonic welding failed to successfully seal a filter membrane to its plastic housing for a microfiltration device planned to assist in bioscience research.
MilliporeSigma supplies microfiltration membranes for bioscience research, as well as for use in the manufacture of high-tech medical devices requiring advanced filtration. A medical manufacturer chose one of MilliporeSigma’s microfiltration membranes for use in its new microfiltration device.
During testing, the medical manufacturer was unable to seal the MilliporeSigma membrane successfully to its plastic housing. MilliporeSigma’s delicate filter membranes must be sealed flawlessly to a plastic housing to filter out potential microscopic contaminants, and chemical and biological constituents. The manufacturer tried heat sealing and ultrasonic welding, but both damaged the 125μm-thick PVDF filtration membrane, which had 0.2μm pores. Emerson used the Tg – Glass Transition differential between materials as an advantage by melting and flowing the lower Tg filter housing material into the PVDF membrane’s pores, creating a hermetic mechanical bond.
To further complicate the challenge, the manufacturer anticipated producing 1 million products per year. This target meant the seal also needed to withstand the demands of high-volume production.
MilliporeSigma needed to optimize the tooling and assembly process and solve their customer’s problem. Engineers evaluated the equipment, materials characteristics, and welding specifications that were being used unsuccessfully to create the required seal.
To solve the problem, engineers used Branson ultrasonic technology and designed custom-tailored process parameters using Patented Amplitude Profiling that produced the desired results while protecting the delicate membrane from damage. Tool and horn assembly using FEA (finite element analysis) also maximized the effectiveness of high-frequency (40 kHz) ultrasonic welding, precisely matching weld specifications to the properties of the materials being bonded.
Prototype testing using the reconfigured horn fixture and new weld specifications delivered the intended results for MilliporeSigma and its customer. The device manufacturer could count on a consistent, repeatable, 360° hermetic seal that would withstand the demands of high-volume production and a shortened cycle time, which also lowered overall production costs.
The Emerson engineering team understood the science and art needed to weld a microfiltration membrane to a plastic housing. Branson’s high-frequency ultrasonic welding and custom-tailored tool and horn assembly solution helped them overcome the challenge of sealing the membrane properly to a medical device. These design features helped expedite the launch of a new air filtration product.
Because Branson ultrasonic technology produces strong, repeatable, seams and joints, withstands sterilization processes, and eliminates the need for solvents or glues, it not only addresses medical nonwoven and device manufacturing problems but does so while reducing the risks and sources of potential contamination. Cleanroom manufacturing requirements can be met with data monitoring and storage capabilities needed to meet stringent regulatory requirements.
Ultrasonic assembly can be applied in a range of frequencies and with varying levels of downforce, to bond even delicate nonwoven materials and filter media in consumer and personal care products, baby diapers and training pants, mattress pads, seat cushions, and covers, household mops, and cleaning products, and disposable vacuum and filter bags.