There are four primary weld methods available in ultrasonic plastic welding:
Weld by Time
Welding by time is an open loop process.
When welding by time, the welder will turn on for a set amount of time in seconds. The welder will be active for that amount of time no matter what is happening within the given weld cycle. This is called an open loop process because no feedback from the weld during the cycle is considered as the welder works. This is not a dynamic process meaning that there is no consideration for variation in parts from cycle to cycle. Sometimes this is the only process available but it can work well if parts are consistent and sufficient testing of welded parts has been done.
Weld By Position or Weld By Absolute Distance
Welding by position or absolute distance forces the welder to continue welding until the sonotrode (ultrasonic horn) has reached a set distance. This is also a closed loop welding process in that the welder will continue to fire the sonics until the set distance is reach or the welder times out.
Weld By Energy
Welding by energy is a closed loop where units are watt seconds (joules). When a welder is set to weld by energy, the ultrasonics continue to fire until the set amount of joules have been put into the part. The amount of joules is a function of the force and power applied to the part over the time the part is welded. This is a closed loop system because each part can have a unique path to achieving the same amount of weld. For example the weld collapse distance or time may be different from part to part but the energy achieved in each part will be the same.
Weld By Distance
Weld by distance is by far the most effective and consistent way to weld parts. In this weld method, an ideal weld distance is determined by the part geometry during the design phase. The welder actuates and once triggered, it continues to weld until a certain weld distance has been achieved. Unlike weld by absolute distance, weld by distance allows for slight variation in initial part height and warpage because it welds relative to the location of the trigger.
Contact Trinetics Group at 321-622-8584 to see which primary ultrasonic weld method of is right for your product or machine.