SCARFING RING_PSR

About internal scarfing

Scarfing removes the weld bead that forms when steel strip is shaped into a tube and welded on a tube mill. Cutting the weld deposit is one of the last operations in tube production. Scarfing inserts in external holders remove the outside bead, and scarfing rings such as the PSR, mounted on an internal holder, remove the inside bead. Material is removed by pushing a non-rotating tool through the workpiece.

Classification

• Application range according to the ISO 513 classification: P20-P45 (steel) and M15-M40 (stainless steel).
• Grade T9335 is designed for ISO material groups P, M and S.

Usage guidance

• Select the ring by tube size. This ring covers tube diameters from 17 to 22 mm with a 6.8 mm working radius.
• Use a holder designed for PSR size 0 rings, and check that the ring is seated and clamped securely.
• T9335 is intended for medium cutting speeds and copes with both continuous and heavily interrupted cuts.
• Rings with a non-standard outside diameter or thickness can be supplied as modifications. Consult Dormer Pramet.

Cautions

• Cemented carbide is hard but brittle. Avoid impact or dropping, and check the cutting edge for chipping before mounting.
• The ring works close to the hot weld zone. Check edge wear regularly to keep the scarfed surface consistent.
• Wear eye protection when changing rings or handling chips, and avoid inhaling dust if carbide is ground.

The PSR0-5-R6,5:T9335 belongs to the Pramet PSR range of scarfing rings from Dormer Pramet, which is part of the manufacturer's heavy industry turning tools. Tube mills use scarfing rings to cut away the weld bead that forms on the inside of the tube when steel strip is formed and welded. The ring is mounted on an internal holder, and the tube is pushed past the non-rotating cutting edge, which leaves a clean, smooth bore.

This ring has a 10 mm outside diameter, a 6 mm inside (cutting) diameter and a 5 mm thickness. Together these give a 6.8 mm working radius for tube diameters from 17 to 22 mm. The ring has the same diameters and working radius as PSR0-R6,5 but is 5 mm thick instead of 4.5 mm.

Key features

• Grade T9335 uses a functionally graded (FGM) WC-Co substrate with medium grain size and relatively high cobalt content, which gives it very high strength.
• The MT-CVD coating has medium thickness and a special surface finish, with a black surface colour.
• The grade handles continuous and heavily interrupted cuts at medium cutting speeds and withstands very unfavourable machining conditions.
• The tough coated carbide is suited to the extreme heat of the weld zone, and the cutting edge geometry supports good tube surface quality and long tool life.
• The ring has a plain design without a chipbreaker.

Applications

• Removing the internal weld bead during the production of welded tubes and pipes.
• Steel tubes (ISO P20-P45) and stainless-steel tubes (ISO M15-M40).
• Small-diameter tubes from 17 to 22 mm.

The PSR0-5-R6,5:T9335 is a flat, circular cemented carbide ring with a central through-bore and parallel top and bottom faces. The cutting edge is the edge of the inside diameter, and the ring has no chipbreaker.

• Outside diameter (INSD): 10 mm
• Inside / cutting diameter (DCI): 6 mm
• Thickness (S): 5 mm
• Working radius (PRFRAD): 6.8 mm
• Surface: black MT-CVD coating

In use, the ring is set in the internal holder at the ring rotation angle β. The inclined inside edge then forms a cutting arc whose osculating circle has the working radius PRFRAD = DCI / (2 × sin β), so the edge follows the inner contour of the tube.

Choosing a size 0 PSR ring with 10 mm outside diameter

Before ordering, check that the size and grade you need are available in the Dormer Pramet range.

Choosing the grade

Working radius

The working radius of a scarfing ring is calculated as PRFRAD = DCI / (2 × sin β), where DCI is the inside diameter of the ring and β is the angle of ring rotation. For this ring, a DCI of 6 mm gives the published working radius of 6.8 mm.