Preventing Roll-Over Burrs in Tube Inner Edge Deburring

Secondary roll-over burrs on the inner diameter of a tube form when the deburring media plastically deforms the edge rather than shearing or abrading the sharp micro-fracture left by the saw cut. When deburring soft materials like low-carbon steel or aluminum tubing on Boru Çapak Alma Makineleri (Yalın) equipment, excessive brush penetration depth or incorrect rotary filament speed folds the fine metal flash inward across the bore rather than removing it completely. This secondary burr restricts bore clearance, damages internal mandrel tooling during downstream bending, and creates inconsistent seating surfaces for secondary fitting operations.

Mechanics of Secondary Burr Formation on Tube ID Edges

Saw cutting generates a heavy primary burr directed along the axis of cut. During the subsequent inner edge deburring cycle, the deburring media applies a combination of radial and axial force against the inner diameter lip. If the shear resistance of the primary burr exceeds the yield strength of the softened edge material under high friction heat, the material displaces laterally. Instead of clean particle separation, the base of the burr undergoes local plastic deformation, flattening back down onto the interior wall of the tube.

This condition occurs frequently when abrasive filament brushes or rotary deburring heads operate with excessive axial engagement force. Rather than slicing through the burr root, individual wire tips slide over the lip under heavy compression, pushing the ductile material into the bore. On ductile materials such as copper or annealed stainless steel, this action forms a thin, continuous rollover collar that adheres tightly to the inside wall. This is one of the first things we check when a customer reports persistent interior burrs despite increasing deburring cycle times on a Yalın machine.

Adjusting Wire Filament Engagement and Spindle Speed

Correcting secondary rollover requires balancing rotational velocity and radial filament pressure against the tube end. High spindle speeds combined with light axial contact generate clean abrasive cutting, whereas low speeds and heavy engagement shift the process from cutting to smearing.

• Filament trim length: Shorter, stiffer filaments provide higher mechanical aggression for heavy cut burrs, but require strict limit stops to prevent force spikes that fold ductile material.
• Wire diameter selection: Finer wire diameters (0.20 mm to 0.30 mm) flex around the internal edge contour, severing fine flash without transferring high axial loads into the bore wall.
• Rotational speed: Higher peripheral wire speeds increase the effective stiffness of the dynamic brush, allowing the tips to shear burrs cleanly rather than deflecting and pushing metal back into the inner tube diameter.

When setting up deburring parameters on Yalın deburring units, tool penetration depth into the tube ID must be restricted to the minimum distance required to break the sharp internal corner. Over-penetration forces the sides of the brush wire against the internal diameter, generating frictional heating that increases ductility at the lip and promotes material folding.

Feed Rate and Axial Dwell Time Verification

Axial feed force controls how fast the deburring tool contacts the tube face. A rapid axial advance slams the deburring head onto the raw saw-cut edge, bending the primary burr inward before the rotating elements can shear it. The axial advance must transition to a controlled working feed rate prior to physical contact with the tube.

Dwell time at full engagement also influences rollover behavior. Extended dwell periods under constant compression generate localized heat buildup on thin-wall tubing. As the edge temperature rises, the tensile strength of the burr decreases, making it far more likely to fold over into the inner diameter instead of fracturing off clean. Dwell time must be set just long enough for full circumference coverage—typically a fraction of a second—before the head retracts smoothly.

Inspection Parameters for Clean Edge Breaks

Verifying a clean inner edge break requires evaluating both visual appearance and tactile feel along the internal circumference. A simple visual inspection from the end of the tube may conceal a rolled-over burr that lies flat against the interior wall.

To verify edge quality on the shop floor:

1. Perform a mechanical feeler gauge or plug gauge test by passing an inspection mandrel sized to 98% of the nominal tube inner diameter through the deburred end. Any resistance indicates localized rollover or inward wall deformation.
2. Examine the internal edge break under 10x optical magnification. A correct deburring pass shows a uniform chamfer or radius without a dark shadow line at the interface where a folded burr presses against the ID surface.
3. Check the temperature of the tube end immediately following processing. Excessive surface heating indicates friction smearing rather than effective chip and burr removal.

Providing exact part specs helps determine the correct brush or tool setup. When requesting a process recommendation or quote, provide your tube material grade, outer diameter, wall thickness, and required production volume.