Raw saw-cut tube ends present sharp, irregular burrs that often score tooling surfaces and disrupt subsequent assembly steps. When untrimmed tubes enter mandrels, collets, or end-forming dies, residual metallic flash wedges between close-tolerance interfaces. This article examines how mechanical facing and chamfering on a Bora Pipe Chamfering Machine removes these defects before they cause premature wear or part rejection.
Surface Scoring Mechanisms from Saw-Cut Flash
Saw blades displace metal during cut-off, leaving jagged burrs on both the inside and outside diameters. As the tube advances into a Griffin CNC Tube Bending Machine, the outside burr acts as a micro-cutting edge against the wiper die or pressure die. This localized friction produces deep scoring marks on the tube wall and accelerates abrasive wear on the tool steel. Inside burrs create similar interference when passing over mandrel balls, causing erratic drag forces that disrupt the tension balance required during rotary draw bending.
Mechanics of Controlled Chamfering
A dedicated chamfering unit applies a consistent angle and land to the tube edge, removing the sharp corner entirely. By shearing the residual burr cleanly, the operation eliminates the stress risers that interfere with axial feeding. Machining a controlled 30-degree or 45-degree bevel ensures the tube enters downstream tooling guides without catching or shaving material off the internal diameter.
Assembly Clearance and Sealing Requirements
Beyond protecting machine tooling, edge preparation dictates whether a tube will seat correctly in fittings or weld joints. Unchecked burrs occupy physical clearance inside slip-on connectors, preventing full insertion depth and compromising weld penetration or mechanical seal integrity. Facing the tube end squares the cross-section relative to the centerline, providing a uniform reference plane for subsequent welding or end-forming operations.
Inspection and Process Verification
To verify edge quality on the shop floor, operators must check both the root face thickness and the bevel angle using optical comparators or specialized gauges. Excessive feed rates during chamfering can produce chatter marks or secondary burrs, while worn inserts leave a smeared edge that still catches on close-fitting mandrels. Regular inspection of the cutting inserts ensures consistent dimensional output across high-volume production batches.
Frequently asked questions
Why do saw-cut burrs damage tube bending tooling?
Raw burrs act as abrasive cutting edges that score wiper dies, pressure dies, and mandrel balls, accelerating wear and causing surface defects on the bend.
What angle is standard for tube chamfering before assembly?
A 30-degree or 45-degree bevel is typical, depending on whether the tube is destined for a mechanical fitting, slip joint, or subsequent welding process.