High-frequency welding (HF Welding) is the core process of an ERW tube mill. The performance of the HF welder directly affects weld quality, production speed, power consumption, and overall operating cost.

Today, the most common HF welder technologies include Silicon (Si), IGBT, and the latest Silicon Carbide (SiC) solutions. Understanding their differences helps tube manufacturers choose the right equipment for long-term production.

Where Is the HF Welder Used in an ERW Tube Mill? 📍

Typical process:

Uncoiler → Strip Accumulator → Forming Mill → HF Welder → Squeeze Rolls → Cooling → Sizing Mill → Flying Saw → Run-out Table

The HF welder is installed after the forming section and before sizing.

Its function is to provide stable high-frequency energy for continuous welding.

How Does an HF Welder Work? ⚡

The working principle is based on high-frequency resistance welding.

Step 1️⃣ Power Conversion

Industrial AC power is first rectified into DC.

Then the inverter converts the DC into high-frequency AC (typically 100–500 kHz, depending on tube size and application).

Step 2️⃣ High-Frequency Energy Transfer

The high-frequency current is transferred to the tube through:

• 🌀 Induction Coil (Induction Welding)
• ⚡ Contact Tips (Contact Welding)

The magnetic field causes current to concentrate at the strip edges due to the skin effect and proximity effect.

Step 3️⃣ Edge Heating

Only the two strip edges are heated very quickly.

The rest of the tube remains relatively cool, improving efficiency and reducing heat distortion.

Step 4️⃣ Pressure Welding

The squeeze rolls apply pressure immediately after heating.

The heated edges are forged together to produce a continuous, high-strength weld.

Excess material (inside and outside burr) is removed by scarfing tools.

Main Components of an HF Welder 🔧

A complete HF welding system usually includes:

• ⚡ Rectifier Unit
• 🔄 Inverter Cabinet
• 💻 PLC Control System & HMI
• ❄️ Water Cooling System
• 🌀 Induction Coil or Contact Assembly
• 🧲 Impeder
• 🔌 Output Transformer (depending on system design)
• 🛡️ Protection & Monitoring System

Each component works together to ensure stable frequency, precise power output, and reliable operation.

Common HF Welder Technologies

Today, the three most common solid-state HF welder technologies are Si, IGBT, and SiC. Each offers different advantages depending on production requirements and budget.

🟢 Silicon (Si) HF Welder

Advantages

• 💰 Lower initial investment
• ✔ Mature and proven technology
• 🔧 Suitable for basic production

Limitations

• ⚡ Higher power consumption
• 📦 Larger equipment size
• 📉 Lower efficiency than newer technologies

🔵 IGBT HF Welder (Most Popular)

Advantages

• ⚡ High conversion efficiency
• 💡 Lower energy consumption
• 🛠 Reliable and easy to maintain
• ⭐ Excellent balance of performance and cost

Limitations

• 💲 Higher investment than Si systems
• 🚀 Efficiency is slightly lower than the latest SiC technology

🟠 SiC HF Welder (Latest Technology)

Advantages

• 🚀 Highest energy efficiency
• ⚡ Faster switching speed
• ❄ Lower heat generation
• 📦 More compact design
• 💰 Lower long-term operating cost

Limitations

• 💲 Higher initial investment
• 🏭 Best suited for high-speed or large-capacity production lines

Si vs IGBT vs SiC HF Welder

How to Choose the Right HF Welder? 🤔

Choosing an HF welder depends on several production requirements.

1. Tube Size Range 📏

Larger diameter and thicker wall tubes require higher output power.

Power selection should always match your production range.

2. Production Speed 🚄

Higher production speed requires faster and more stable power output.

Modern IGBT and SiC systems provide better performance for high-speed lines.

3. Material Type 🏗️

Different materials require different welding characteristics.

For example:

• Carbon Steel
• Stainless Steel
• High-strength Steel

The HF power supply should match the welding requirements of the material.

4. Energy Consumption 💡

If electricity cost is an important concern, choosing a high-efficiency system can significantly reduce long-term operating costs.

Although SiC equipment has a higher initial investment, it can deliver noticeable energy savings over years of production.

5. Future Expansion 📈

If production capacity may increase in the future, selecting a welder with some power reserve helps avoid equipment upgrades later.

Why Choose AIS HF Welder?🔍

AIS Machinery provides complete HF welding solutions for ERW tube mills, combining reliable equipment, fast delivery, and professional technical support.

✅ Advanced HF Technology

We offer IGBT and the latest SiC solid-state HF welders to meet different production capacities, tube specifications, and energy-saving requirements.

✅ Complete HF Welding System

We can supply the complete HF welding package, including:

• ⚡ HF Welder
• 🧲 Impeder
• 🌀 Induction Coil / Contact Assembly
• ❄️ Water Cooling System
• 🔧 Output Transformer
• 💻 PLC & HMI Control System
• 📦 Complete Spare Parts

Everything is designed to work together for stable and reliable production.

✅ Factory Testing Before Delivery

Every HF welder is fully tested before shipment to ensure stable performance.

We provide:

• ✔ Factory Acceptance Test (FAT)
• ✔ Performance Testing
• ✔ Test Report
• ✔ Complete Inspection Records

This helps customers install and commission the equipment with confidence.

✅ Short Delivery Time

Thanks to our standardized production and stocked core components, we can provide short delivery times for many HF welder models, helping customers reduce project lead time.

Customer Success Stories 🌍

AIS HF welding systems have been exported to Saudi Arabia, Egypt, and many other countries, supporting customers in a wide range of ERW tube and pipe production projects.

Our customers value us for:

• ✔ Stable welding performance
• ✔ Complete HF systems and spare parts supply
• ✔ Reliable quality inspection before shipment
• ✔ Fast delivery and responsive after-sales support
• ✔ Professional technical assistance throughout the project

Whether you need a new HF welder, a complete welding system, or replacement spare parts, AIS Machinery can provide a reliable solution tailored to your production requirements.