Ultrasonic Generators Explained: From Mains Power to Weld

Every ultrasonic welding, cutting or sealing system — from a hand welder to a fully automated line — is driven by an ultrasonic generator. It is the least visible part of the system and the most misunderstood. The horn gets the attention because it touches the part, but the generator decides how much energy reaches the joint, how stable the process is, and how well the ultrasonic system talks to the rest of your machine. This guide covers what a generator actually does, the control functions that matter, and how the Rinco range fits together.

What an ultrasonic generator does

At its core, the generator is a frequency convertor. It takes 50/60 Hz mains power and converts it into high-frequency electrical energy at the working frequency of the ultrasonic stack — typically 20 kHz, 35 kHz or 70 kHz. That electrical output drives the piezoelectric convertor, which turns it into mechanical vibration; the booster and horn then carry that vibration into the part.

A modern digital generator does considerably more than produce a fixed-frequency signal:

• Frequency tracking. The stack's resonant frequency is not fixed — it shifts as the horn warms up, as load changes during the weld, and as tooling ages. The generator continuously measures the stack's electrical behaviour and adjusts its output frequency to stay locked on resonance. Without tracking, output would sag mid-weld and the system would trip on overload whenever conditions drifted.
• Amplitude regulation. Weld quality depends on vibration amplitude at the horn face staying constant regardless of load. The generator holds the commanded amplitude by regulating drive voltage as the melt develops — and on digital models the amplitude setpoint is programmable, so different jobs can run different amplitudes on the same stack.
• Power and energy measurement. The generator measures delivered power throughout the weld. That signal is what enables energy-mode welding (stop the weld when a set energy has been delivered) and process monitoring against reference curves.
• Protection. Overload detection, frequency-window limits and error reporting protect the convertor and horn from damage when something goes wrong — a cracked horn or jammed part announces itself as a generator error rather than destroyed tooling.

Standalone generators vs OEM modules

Generators come in two basic formats, and choosing between them is mostly a question of who is building the machine.

Standalone generators are self-contained units with their own enclosure, user interface and connectors. They suit hand welding, retrofits, laboratory work and special-purpose machines where the generator sits beside the application. Rinco's standalone range spans simple manual operation through to full digital process control.

OEM generator modules such as the Rinco AGM and AGM PRO are designed to be built into someone else's machine — packaging lines, textile equipment, automated assembly cells. They are compact, rack- or plate-mountable, and controlled entirely through their interfaces rather than a front panel. For machine builders, this means the ultrasonic system becomes a component: the PLC commands start, amplitude and limits, and the module reports status, power and faults back. The AGM PRO extends the concept with more advanced integration and process control capability for demanding automation.

The Rinco generator range

All are matched to Rinco convertors and tooling, and Techspan supplies them in Australia alongside the stack components they drive. Exact feature sets, frequencies and power ratings per model are on the individual product pages — or ask us and we will match a model to your application directly.

Choosing a power rating

Generator power must cover the peak demand of your largest weld, with headroom. The demand side is set by weld area, material and joint design: small 35 kHz joints in amorphous plastics may need only a few hundred watts, while large 20 kHz welds in polypropylene or sealing applications across wide areas can call for several kilowatts. Three practical guidelines:

1. Match the generator to the stack frequency first. A generator drives one system frequency; a 35 kHz generator cannot run a 20 kHz stack.
2. Size for the peak, not the average. Power demand spikes as the melt initiates. A generator that meets the average but not the peak will overload intermittently — the most frustrating kind of fault to trace.
3. Headroom is cheap insurance. The generator only delivers what the load demands, so a higher rating costs nothing in running energy and keeps the door open for future tooling.

Installation basics

Generators are electronics, and they last longest when treated as such. Give the unit clean mains power and proper earthing; keep it out of hot, dusty corners of the cabinet and respect the cooling clearances so airflow is never starved. Route the high-frequency cable to the convertor away from sensitive signal wiring, use the specified cable and length rather than an improvised extension, and make sure connectors are done up firmly — an intermittent HF connection mimics half a dozen other faults and wastes hours of diagnosis. None of this is difficult, but it is the difference between a generator that runs for a decade and one that develops mystery errors in year two.

Integration and I/O

If the generator is going inside a machine, look at the interface before anything else. The essentials to check:

• Control inputs — start/stop of ultrasonics, amplitude setpoint selection or analogue amplitude command, and reset.
• Status outputs — ready, ultrasonics active, overload/error, and end-of-weld signals your PLC can act on.
• Process data — power and energy readouts for monitoring, quality gating and traceability, available on the digital models.
• Physical format — panel, rack or plate mounting, cooling clearances and cable routing to the convertor.

This is where the OEM modules earn their keep: they are designed around exactly this integration workflow, rather than adapting a front-panel instrument to remote control.

Generator health and the rest of the stack

Because the generator continuously measures the stack, it is also your best diagnostic tool. Rising idle power, frequency drifting toward a window limit, or increasingly frequent overloads are early signs of tooling trouble — a cracking horn, a fretted joint face, a failing convertor. Treat generator errors as information, not nuisance: they usually point at a mechanical cause further down the stack.

Talk to Techspan

Techspan is the authorised Rinco Ultrasonics distributor in Australia, supplying the full generator range — standalone, rack-mount and OEM modules — plus convertors, boosters and custom tooling, with local applications support. Whether you are specifying a single replacement generator or designing ultrasonics into a new machine, talk to us and we will spec it with you.