Traditional ultrasonic plastic welding “modes” use computerized measurements associated with each weld to control weld consistency by focusing on a single parameter or a limit most critical to part quality such as downforce, distance/collapse depth, time, or energy. For typical rigid, plastic parts, these weld modes help ensure high repeatability and quality for welding, insertion, staking and swaging operations.
However, controlling weld quality with single-parameter welding has made choosing a weld mode much more difficult when assembling plastic parts that:
Are compressible or contain compressible elements.
Are inserted into substrates that vary in hardness or structural consistency.
Contain or are installed over sensitive metal or electronic components that could be damaged by pressure, vibration, or heat during ultrasonic welding essential for product assembly.
To ensure consistent assembly quality with such “hard-to-handle” or variable parts, electronics manufacturers and others have had to augment single-parameter weld-modes with additional information. Generally, this is done by adding a measuring device external to the welder that provides a data point or signal that allows for changes in the critical weld parameter.
The practice of adding external measurement devices and associated input/output (I/O) to an ultrasonic welder is not uncommon. However, it does add time, complexity, and expense to the process, particularly for mass-produced parts, and adds a new wrinkle to the customer/technical support relationship.
Engineers in the ultrasonic-welding industry thought the added trouble of adding sensors raised some questions: What would it take to build a welder that would not need external measuring devices? How could this be done? What kind of hardware, software or weld modes would it take?
A group at Emerson sought out the answers. Building on the latest Branson ultrasonic plastic welding machine, the team developed a patent-pending “dynamic mode” and introduced it on the Elite Precision+ version of the GSX-E1 welding machine.
The new mode takes advantage of several key GSX-E1 features, including an advanced electromechanical weld actuator, new ultrasonic welding algorithms, high-speed data communications and a big boost in computing power. Its upgraded software supports more robust automation and faster actuator response when interfacing with PLCs and gives users more flexibility in developing and deleting application-specific welding recipes.
The improvements let the new dynamic mode overcome the limitations of single-parameter weld mode controls. It can monitor, recalculate, and adjust several weld parameters such as force, weld energy, velocity, and distance in real time. This enables optimization of weld performance in terms of a user-specified target value such as part compression, positioning, or pull strength. In essence, the new mode gives users greater versatility and more consistent welding results that match a design profile rather than just a single parameter.
To use a welder equipped with dynamic mode, operators select the single-parameter weld mode that provides the best application results to date. Then, they enter two application-specific “scores,” which act as limits for dynamic mode activity. The first is a material “density” score that characterizes the hardness or resistance of the material that is to receive the welded, staked, or inserted part. Low density scores equate to harder, more resistant materials. The second, the “reactivity” score, affects the reaction time needed to get the desired density setting.
In operation, dynamic mode monitors each weld cycle, using the density and reactivity limits to adjust and improve the cycle in response to specific part-to-part variabilities throughout the production run.
Read more: New Ultrasonic Welder Mode Uses Real-time Adjustments to Improve Welds
