Rectangle Ferrite Rod for ERW Tube Mill

Rectangle Ferrite Rod is a rectangular ferrite core used inside the impeder of ERW tube mills and HF welding machines. It helps concentrate magnetic flux and increase the impedance of the internal current path, directing more high-frequency welding current toward the tube edges.

A common rectangular ferrite rod specification is 45 mm × 20 mm, while the length can be customized according to the impeder design.

What Does a Rectangle Ferrite Rod Do?

In an ERW tube mill, high-frequency current needs to concentrate at the two edges of the steel strip to create the heat required for welding.

The ferrite rod is installed inside the tube near the welding point.

Its main job is simple:

HF Welding → Ferrite Rod → Controls Magnetic Flux → Reduces Unwanted Internal Current → Improves Welding Efficiency

The ferrite core helps guide the magnetic field and increases the impedance of the internal current path, so more useful current is concentrated around the welding edges.

Where Is It Used?

Rectangle ferrite rods are mainly used in:

• ✅ERW Tube Mills

• ✅HF / HFI Tube Welding Lines

• ✅Steel Pipe Mills

• ✅Stainless Steel Tube Mills

• ✅High-Frequency Welding Machines

• ✅Impeder Assemblies

They are normally installed inside the impeder, directly in the tube before or around the welding point.

Rectangle Ferrite Rod vs. Round Ferrite Rod

The biggest difference is shape and installation, not basic function.

⚡Important: A rectangular ferrite rod is not automatically better than a round ferrite rod. The correct type depends on the tube size, impeder design and welding conditions.

How to Choose the Right Ferrite Rod?

Before ordering a Rectangle Ferrite Rod, check these key parameters:

For replacement orders, the most useful information is usually:

Tube OD + Wall Thickness + Existing Ferrite Size + Photo

Ferrite Rod vs. Impeder

These two terms are sometimes confused.

🧲Ferrite Rod = Magnetic Core

📏Impeder = Complete Ferrite Assembly

The ferrite rod is the magnetic component inside the impeder. The complete impeder normally includes the ferrite core, protective structure, support and cooling arrangement.

So, if a customer asks for a ferrite rod, they usually need the core itself rather than the complete impeder assembly.

Ferrite Rod Cooling

Ferrite rods work close to the high-frequency welding area, where temperatures can become high.

A properly designed water-cooled impeder helps remove heat and maintain stable ferrite performance.

💧Good cooling is important for:

• Stable welding performance
• Longer ferrite service life
• Reduced thermal damage
• Continuous tube production

The actual cooling requirements depend on the tube mill, welding power, production speed and impeder design.

Rectangle Ferrite Rod FAQ📌

1. What is a Rectangle Ferrite Rod?

A Rectangle Ferrite Rod is a rectangular soft ferrite core used inside the impeder of an ERW tube mill. It helps concentrate magnetic flux and control the high-frequency current path during tube welding.

2. What is the common size of a Rectangle Ferrite Rod?

A commonly used size is 45 × 20 mm, referring to 45 mm width × 20 mm height. The length can be customized according to the impeder design and tube mill requirements.

3. Where is a Rectangle Ferrite Rod used?

It is mainly used in ERW tube mills, HF/HFI welding lines, steel pipe mills and stainless steel tube mills. The ferrite rod is installed inside the impeder near the welding area.

4. What is the difference between a Rectangle Ferrite Rod and a Round Ferrite Rod?

The main difference is the cross-sectional shape. A rectangular ferrite rod has flat sides, while a round ferrite rod has a circular cross-section. Both perform the same basic function, but the suitable type depends on the impeder design.

5. Is the ferrite rod the same as an impeder?

No. The ferrite rod is the magnetic core, while the impeder is the complete assembly that holds and protects the ferrite core and normally includes a cooling arrangement.

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