The transducer is the heart of an ultrasonic welding system — it converts electrical energy into the mechanical vibration that does the welding. Choosing the right 20 kHz ultrasonic transducer (or 15/35/40 kHz unit) decides weld depth, cycle time and tooling life. This guide explains the types, gives a frequency selection table, and shows how transducer, booster and horn must match.
Transducer Types
Welding transducers are sandwich (Langevin) designs: ceramic disc stacks preloaded between metal masses. The ceramics are the working part — we use PZT-4 class for high-power continuous duty and PZT-8 class where stability at elevated power matters.
| Parameter | Specification |
|---|---|
| Design | Sandwich piezoelectric, preloaded bolt stack |
| Frequencies | 15 / 20 / 35 / 40 kHz |
| Nominal power | 1,500 / 2,000 / 2,600 / 3,200 / 4,200 W |
| Ceramics | PZT-4 / PZT-8, matched sets |
| Interfaces | Standard 20 kHz mounting threads and flanges; brand interfaces on request |
| Matching | Tuned with our boosters and generators as a system |
Our production transducer for plastic welders: ultrasonic welding transducer. Driving generator: touch-screen ultrasonic generator.
Frequency Selection Guide
| Frequency | Amplitude Potential | Best For | Typical Parts |
|---|---|---|---|
| 15 kHz | Highest | Large parts, long weld seams, thick sections | Automotive large housings, pallets, degating thick gates |
| 20 kHz | High — the industry standard | General-purpose welding, metal welding, wire splicing | Most plastic housings, filters, caps, wire harnesses, battery tabs |
| 35 kHz | Moderate, precise | Small, delicate parts; minimal flash | Electronics, medical small parts, thin films |
| 40 kHz | Lower, very precise | Fine welding and food cutting | Films, packaging, ultrasonic cutting blades |
Deeper comparison of the two most common choices: 15kHz vs 20kHz ultrasonic welding explained.
Match Transducer + Booster + Horn as a System
The three elements form one resonant chain. Mixing a transducer with an off-gain booster or an untuned horn is the most common cause of unstable welds and cracked ceramics. When you order a transducer from us, we check it against your existing stack — or supply the matched booster and horn, tuned and measured together. Replacement and custom tooling: horn manufacturing and repair.
Signs Your Transducer Needs Replacement
- Weld quality drifts while generator output stays constant
- Generator reports over-temperature or resonance loss alarms
- Visible ceramic cracking or stud loosening at the stack
- Frequency reading has moved beyond the generator’s lock range
Recurring transducer failures usually point at a stack mismatch or horn problem — send us the old parts and the generator model, and we’ll diagnose before you buy anything.
FAQ
Can I use your transducer with my existing machine brand?
In most cases yes — we build to common mounting interfaces and match the electrical specification to your generator. Tell us the machine brand, model and frequency.
What is the real service life?
Years of production duty. Ceramics age slowly; the practical failure causes are mechanical (impact, overtightening, mismatched stacks), not end-of-life.
Do you sell transducer + booster + horn as one kit?
Yes — a matched, tuned kit with a measurement report is our recommended way to buy, especially for non-standard frequencies.
Order a Matched Stack
Send your machine model, frequency and application — we’ll recommend the transducer and matching booster, with a tuning report before shipment. Email jackm@mcsonic.com or call +86 189 3970 6772.