When a Langevin-type ultrasonic transducer fails — whether in a Branson welder, Telsonic system, or any other brand — the root cause is often a cracked, delaminated, or depolarized piezoelectric ceramic ring. Replacing the ceramics, rather than the entire converter assembly, can restore full function at a fraction of the cost of a new transducer.

Sino Sonics manufactures PZT-4 and PZT-8 piezoelectric ceramic rings from Φ10 mm to Φ70 mm in stock standard sizes, with custom OD / ID / thickness available. Every piece is individually tested and supplied with a performance report. Material grade is military-grade (high-density, poreless), the same class used in our own converter assemblies.

Why Piezo Ceramics Fail in Ultrasonic Transducers

Ultrasonic transducers run ceramic stacks under high cyclic mechanical stress. Common failure modes include:

• Thermal depolarization — operating above the Curie point (typically 320 °C for PZT-8) irreversibly reduces piezoelectric activity
• Mechanical cracking — from over-tightening the center bolt, impact, or thermal shock
• Delamination — adhesive or silver electrode layer separation, often visible as discoloration
• Fatigue

  Tip: For high-duty welding transducers like Branson 900/803/8700/922 or Telsonic MPI/SG, choose PZT-8.

  — gradual reduction in coupling efficiency over high-duty-cycle service

In all these cases, the metal mass blocks and booster are typically undamaged. Replacing only the ceramic stack — and re-torquing the assembly — is a viable and economical repair path.

PZT-4 vs. PZT-8 — Which Material for Your Transducer?

Property	PZT-4 (PZT-42 / PZT-43)	PZT-8 (PZT-82)
Mechanical quality factor Qm	700–1000	≥ 1800
Planar coupling Kp	55–60%	—
Thickness coupling Kt / Kr	—	≥ 46%
Dielectric loss tg δ	Higher	< 0.3%
Temperatura de Curie	~330 °C	320 °C
Typical use	Cleaning transducers, sensors, mid-power welding	High-power continuous welding, industrial welding

Not sure which grade your original ceramic is? Branson welding transducers generally use PZT-8-class hard piezoelectric material. Telsonic systems also predominantly use hard PZT for their welding converters. If you have the original part number, send it to us and we will match the material.

Stock Size Cross-Reference — Piezo Ceramic Rings

The table below lists common Langevin transducer ceramic ring sizes found in Branson, Telsonic, and equivalent systems. These are standard sizes we carry in stock.

Outer Diameter	ID / Thickness (examples)	Typical Transducer Application
Φ20 mm	Various	Small 40 kHz cleaning transducers, compact welding
Φ25 mm	Various	35 kHz welding converters (Telsonic SG-35, equivalents)
Φ30 mm	Various	30 kHz, compact 20 kHz converters
Φ32–Φ35 mm	Various	20 kHz / 35 kHz mid-power welding (most common stacking size)
Φ40 mm	Various	Standard 20 kHz industrial welding converters (Branson 900 / 803 class)
Φ50 mm	Various	High-power 20 kHz converters (Branson 922 / CJ-20, Telsonic MPI class)
Φ55 mm	Various	Heavy-duty 20 kHz and 15 kHz converters
Φ60 mm	Various	Large-area 15 kHz / 20 kHz welding, power-dense systems
Custom Φ10–Φ90 mm	Per spec	Any non-standard transducer, including angled / curved

Full dimensional stock list: sinosonics.com/piezoceramic/piezoceramic-ring-stcok-size/

Note: Branson and Telsonic part numbers are cited for cross-reference purposes only. Sino Sonics is not affiliated with either company. Our ceramics are manufactured to standard piezoelectric dimensions and are not original OEM parts.

Matching Ceramics to Your Transducer — What to Measure

To order the correct replacement ceramic ring, you need three measurements from the existing (failed) ceramic or from the transducer drawing:

1. Outer diameter (OD) — measured across the flat face
2. Inner diameter (ID) — the center bore (for the clamping bolt)
3. Thickness — the dimension along the polarization axis (height of the ring)

Optional but helpful: resonant frequency of the transducer (20 kHz, 35 kHz, 40 kHz, etc.) and number of ceramic rings in the stack (typically 2–4 for Langevin converters).

Send these measurements to [email protected] and we will confirm the matching stock size or quote a custom ceramic to your drawing.

Why Source Ceramics from Sino Sonics

Military-Grade Material

Our PZT-4 and PZT-8 ceramics are manufactured using a high-pressure, high-temperature sintering process that produces a poreless, high-density microstructure. Lower-cost commodity ceramics often have internal voids that act as stress concentrators, leading to premature cracking under cyclic ultrasonic loading.

100% Individual Testing

Every ceramic ring is tested individually before shipment. We provide a performance report (resonant impedance, capacitance, mechanical quality factor) for each batch, which allows you to verify the ceramic before assembling it into the transducer stack.

OEM Transducer Assembly Supply

If you build or repair ultrasonic transducers, we can supply matched ceramic pairs or full stacks with consistent characteristics — important because ceramics in a Langevin stack should be matched in capacitance to balance the load. Matched sets are available on request.

Custom Geometry

Standard rings cover most Branson and Telsonic stack geometries. For unusual sizes — including angled face rings for focused transducers or non-circular cross-sections — custom manufacturing is available. OD / ID / thickness specified to your drawing. MOQ 500 pieces per specification.

Competitive Unit Price

Φ32–35 mm rings (the most common Langevin stack size) are stocked at $4.00 each (list $5.00). Larger sizes scale accordingly. Buying ceramics for transducer repair is substantially cheaper than a new complete transducer assembly, even factoring in labor.

Frequently Asked Questions

How do I know if the ceramics are the failed component vs. the rest of the transducer?

Use an LCR meter or impedance analyzer to measure the capacitance and resonant frequency of the disassembled ceramic stack. A cracked ceramic will show abnormal capacitance or a split resonance peak. A depolarized ceramic will show near-zero piezoelectric response. If you have an impedance analyzer (we also sell the PV520A), you can sweep the transducer before and after reassembly to confirm recovery.

Do I need to re-polarize the ceramics after assembling the transducer?

No. Our ceramics are shipped fully polarized. The polarization axis aligns with the thickness direction. During assembly, maintain correct polarity orientation (all ceramics in a stack must be oriented the same way relative to the clamping bolt axis).

What silver electrode coating is used?

Standard silver (Ag) electrode. Gold (Au) electrode is available for custom orders where higher corrosion resistance is required.

Can you supply the full Langevin transducer rebuild kit — ceramics, electrodes, insulating washers, center bolt?

Yes. We can supply a rebuild kit including matched ceramics, copper electrode shims, PTFE insulating washers, and stainless steel center bolt sized to your transducer spec. Contact us with the transducer model or dimensions.

What is the delivery time for stock sizes?

Standard stock ring sizes ship within 10 business days. Custom sizes add 2–3 weeks production.

Request Pricing

Browse the full product range →

Send us OD × ID × thickness (in mm), material grade (PZT-4 or PZT-8), and quantity. We will respond with pricing and availability within one business day.

*See also: All Ultrasonic Transducers · Ultrasonic Homogenizers*