Spinning and Auxiliary Forming to Produce a Ventilation Duct Section with Reinforced Flange

From welded assembly before to single-piece controlled forming now

 

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

The approach created:

• Long production cycles
• Welding distortions affecting roundness
• Inconsistent flange geometry
• High labor costs
• Increased part weight

The requirement was clear: Reduce welding. Stabilize geometry. Improve production efficiency. Achieve 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 disc (blank) 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 starting 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 metal forming.