Tube Bending Tolerances: A Practical Guide for Exhausts & Assemblies

Overview

Tolerances determine whether an assembly fits the first time. This guide explains the real‑world factors behind bend angle accuracy, ovality, and springback for common materials used in exhaust systems.

Key Definitions

• Centerline Radius (CLR) and its impact on flow and packaging

• Ovality and wall thinning—what’s acceptable and how to control it

• Tangent length and stack‑up implications for welding and fixtures

Material & Geometry Considerations

Stainless 304/409 and mild steel behave differently during bending. Wall thickness, diameter, and CLR/D ratios influence springback and deformation. Designing with these in mind reduces rework.

Shop‑Floor Controls

Pre‑cut accuracy, mandrel selection, lubrication, and machine calibration are foundational. In‑process inspection—angle checks, go/no‑go gauges, and sample CMMs—keeps parts within spec.

Design for Assembly

Agreeing tolerances early with your manufacturer prevents late‑stage redesign. Provide DXF/STEP models, critical-to-quality features, and datum strategies to ensure repeatable fit.