From welded assembly to single-piece controlled forming

The Challenge

A manufacturer of industrial ventilation systems was producing cylindrical duct sections by:

• Rolling sheet metal
• Welding longitudinal seams
• Welding separate flange rings
• Drilling connection holes in secondary operations

This approach created:

• Long production cycles
• Welding distortions affecting roundness
• Inconsistent flange geometry
• Higher labour costs
• Increased part weight

The requirement was clear:
Reduce welding. Stabilise geometry. Improve production efficiency.s final shape while maintaining full control over material flow, temperature and forming forces.

The DENN Solution

DENN re-engineered the part using controlled spinning and auxiliary forming operations on NTR and RB machines.

Instead of assembling multiple components, the duct section is formed from a flat stainless steel disk into a single-piece cylindrical body.

The process integrates:

• Spinning to form the cylindrical geometry
• Controlled wall thickness reduction
• 90° flanging with reinforced edge
• Integrated rib formation for structural stiffness
• Final drilling operation for assembly

All operations performed in a stable, repeatable cycle.

No welded flange ring.
No distortion from heat input.
No geometry correction required.

The Result

The transformation delivered measurable impact:

• Single-piece component instead of welded assembly
• Improved roundness and dimensional stability
• Reinforced flange with reduced overall weight
• Faster production cycles
• Significant cost reduction compared to traditional fabrication

In addition, reinforced flanges increased structural rigidity while allowing thinner base material — improving airflow efficiency and reducing material consumption.

Why It Matters

In ventilation systems, geometry directly affects airflow performance and installation precision.

By eliminating welding and controlling material flow through rotational forming, the manufacturer achieved:

Stable output.
Lighter parts.
Higher productivity.

At DENN, we simplify complexity —
replacing multi-step fabrication with controlled deformation.