Herrmann Ultrasonics: Improving ultrasonic assembly
Herrmann Ultrasonics’ HiQ Dialog medical device manufacturing system is designed to increase manufacturing efficiency through optimized cycle time, changeover and downtime — three factors that affect manufacturing efficiency.
HiQ Dialog has programmable stroke selection and a “SoftTouch” mode that reduces damage to sensitive joints by bringing a quick approach with a gentle touch to applications. It also features a quick-change system and a hinged tool-change cover that can quickly mount an ultrasonic stack in less than a minute.
The amount of force applied to a part during the weld cycle is a critical process parameter, according to Michael Lindsay, an applications engineer with Herrmann Ultrasonics. In many cases, it helps to vary the forces throughout the cycle, allowing for more precise control of the rate of collapse while compressing both halves of the welded assembly together. An optimized rate of collapse can affect the final outcome of the welded assembly, especially in areas such as weld strength and cosmetic appearance, Lindsay said in an email to MDO.
“With traditional pneumatically driven systems, there are limitations to varying the forces throughout the stroke of an air cylinder,” he added. “Our goal was to engineer a solution that has the capability of force-profiling throughout the weld, allowing you to refine the process for an optimized result.”
Herrmann Ultrasonics had to engineer a pneumatic drive system that could not only vary the forces, but also have an extremely fast reaction time so that there was no delay or lag when changing from one form to another. An ultrasonic weld cycle is often less than half a second. For example, when using three different weld forces, the system must be able to switch over to the next force exactly on time so that it reaches that next force before the end of the weld cycle. This requires extremely fast processing speeds, as well as a pneumatic valve system capable of keeping up with those speeds, Lindsay said.
The HiQ’ Dialog’s force profiling capability allows a medtech manufacturer to refine its weld parameters to a level that’s closer to the middle of the potential process window. This reduces the risk of a bad weld, creates a higher yield and may improve efficiency by reducing machine cycle time. The HiQ Dialog also has position control, allowing a manufacturer to set an intermediate start position so the cylinder does not have to travel all the way back to the fully retracted home position after each weld.
“Combine that feature with the ability to maximize the ‘free air’ travel speed to and from the part before and after the weld, and now you have the capability to significantly reduce your overall machine cycle time,” Lindsay said.
HiQ Dialog also uses DataRecorder software that records and archives all weld process values and process parameters. While the welder will store critical weld data and results internally, it overwrites old data after 300 welds in order to maintain hard drive space. The software streams this data to an external storage location where it can be stored indefinitely, and used for analysis, audits and reporting.
Many devices welded on the HiQ Dialog are used in surgical procedures where they come into direct contact with the patient. The company’s equipment is also used to weld applications that are directly implanted, such as injection ports, heart valves and pacemaker components.
“All of these applications are considered critical or high-risk for patient safety, and therefore a failed weld could potentially have dire consequences,” Lindsay said. “The advanced weld process control capability and onboard real-time quality monitoring features of the HiQ Dialog help ensure quality, repeatable welds, so surgeons don’t need to worry if a product will fail in the field.”