Inner Scarfing Knife: A Key Tool for ERW Pipe Welding

In ERW (Electric Resistance Welded) pipe production, burr removal is an important process after welding. During high-frequency welding, excess metal may form along the weld seam on both the inside and outside surfaces of the pipe.

An Inner Burr Removal Knife is designed to remove excess weld metal from the inner surface of the pipe. It helps improve the internal surface condition and provides a cleaner finish for further processing or final pipe applications.

AIS Machinery supplies inner burr removal knives and related tooling for ERW tube mill production lines.

1. What Is an Inner Burr Removal Knife?

An Inner Burr Removal Knife, also called an internal scarfing tool, is a cutting tool used to remove excess welding burr from the inside of an ERW steel pipe.

During the high-frequency welding process, the edges of the steel strip are heated and pressed together to form a welded pipe. This process produces excess metal along the weld seam, which is known as welding burr or weld bead.

The inner burr removal knife is installed inside the pipe, near the welding section. As the pipe moves forward continuously, the knife cuts away the excess metal along the internal weld seam.

The purpose is to reduce the internal weld bead and achieve a smoother inner pipe surface.

2. Main Functions of an Inner Burr Removal Knife

The inner burr removal knife plays an important role in the ERW tube manufacturing process.

Its main functions include:

• ✔️Removing internal welding burr: Cuts away excess metal formed during the high-frequency welding process.
  
• ✔️Improving inner surface quality: Helps create a cleaner and smoother internal weld area.
  
• ✔️Supporting further processing: Reduces unwanted internal weld projections that may affect subsequent pipe processing or applications.
  
• ✔️Maintaining consistent production: A suitable knife and correct installation help achieve stable burr removal during continuous pipe production.
  

The knife dimensions, shape and cutting edge should be selected according to the pipe specifications and production requirements.

3. Inner Burr Removal Knife vs. Outer Burr Removal Tool

Some customers may confuse inner burr removal knives with outer burr removal tools. Although both are used to remove excess welding metal, they are designed for different positions and applications.

The main difference is where they work.

⚙️Inner Burr Removal Knife:

The knife works inside the pipe to remove excess metal from the internal weld seam. Its design and dimensions must suit the pipe's internal space and production requirements.

⚙️Outer Burr Removal Tool:

The external burr removal tool is installed outside the pipe. It removes excess metal from the outer weld seam. Depending on the tooling design, external burr removal systems may use replaceable cutting inserts or other cutting arrangements.

Both tools serve the same general purpose of removing excess weld metal, but they cannot directly replace each other.

4. How to Choose the Right Inner Burr Removal Knife?

Choosing the correct inner burr removal knife is important for achieving suitable cutting results and stable production.

Before requesting a quotation, customers are recommended to provide the following information:

• Pipe outside diameter (OD)
  
• Pipe wall thickness
  
• Inner burr removal knife dimensions or technical drawing
  
• Photos of the existing knife, if available
  
• Required quantity
  

Different pipe sizes and tooling designs may require different knife dimensions. Therefore, providing a drawing or clear sample photos is helpful for confirming the correct product.

If you are unsure about the exact knife type, you can also send us photos of your existing tooling. Our team can help check the product details before quotation.

5. Inner and Outer Burr Removal Knives Supplier – AIS Machinery

AIS Machinery supplies both inner burr removal knives and outer burr removal tools for ERW tube mill production lines. Whether you need internal or external burr removal tooling, we can provide suitable products according to your requirements.

Different pipe sizes and tube mill configurations may require different knife dimensions and designs. To help us identify the correct product and provide an accurate quotation, please send us your technical drawings, existing knife model or clear product photos.

Contact AIS Machinery to discuss your requirements and get a quotation for inner or outer burr removal knives.