Precision CNC Metal Spinning of Stainless Steel Dome Covers for High-End Industrial Screening Equipment

Precision CNC Metal Spinning of Stainless Steel Dome Covers for High-End Industrial Screening Equipment

1. Industry Background

The industrial screening equipment sector requires exceptional dimensional accuracy, sealing integrity, and premium surface finish for critical components. The customer is a leading Singapore-based screening equipment manufacturer and a global leader in material classification systems used in mining, chemical processing, and bulk material handling industries.

The key requirement was a custom stainless steel spun dome cover, serving as the upper sealing and protective enclosure of the screening machine. This component must provide:

• Ultra-high dimensional precision for perfect assembly fit
  
• Seamless, weld-free construction
  
• Mirror-quality surface finish
  
• Long-term reliability in harsh industrial environments
  

Previously, the customer used stamped and welded assemblies, which resulted in:

• Visible weld seams
  
• Curvature deviation up to ±0.5 mm
  
• Poor sealing performance causing material leakage
  
• Rough surface finish affecting product positioning in the premium market
  

To resolve these issues, the customer required a precision CNC metal spinning solution with seamless forming and superior dimensional control.

2. Customer Selected Solution

Custom CNC metal spun AISI 304 stainless steel dome cover

Technical Specifications

• Outer diameter: Ø680 mm
  
• Height: 180 mm
  
• Geometry: Smooth hemispherical dome profile
  
• Mounting holes: 12 evenly distributed flange holes
  

Wall Thickness

• Main wall thickness: 3.0 ± 0.1 mm
  
• Reinforced mounting flange thickness: 4.5 mm
  

Material Properties

• Material: AISI 304 Stainless Steel (EN 1.4301 / ASTM A240)
  
• Tensile strength: ≥ 520 MPa
  
• Yield strength: ≥ 205 MPa
  
• Excellent corrosion resistance and mechanical strength
  

Surface Finish

• Mirror polished finish
  
• Surface roughness: Ra ≤ 0.3 μm
  
• Completely free of weld marks, scratches, or defects
  

3. Core Manufacturing Process

3.1 Raw Material Selection and Pre-Processing

• ASTM A240 certified stainless steel sheets with thickness tolerance ±0.05 mm
  
• Ultrasonic inspection ensuring defect-free material structure
  
• CNC laser cutting with precision ±0.03 mm
  
• Edge chamfering (R1.2 mm) for stress control
  
• Stress-relief annealing at 300°C to eliminate residual stresses
  

This ensures dimensional stability during spinning.

3.2 Precision CNC Metal Spinning Process (Key Technology)

Manufactured using a high-precision dual-roller CNC metal spinning machine, featuring:

• Servo-controlled positioning accuracy: ±0.005 mm
  
• Real-time pressure feedback system
  
• Laser distance measurement for dynamic correction
  
• CAD/CAM programmed tool path optimization
  

Proprietary Three-Stage Progressive Metal Spinning Process:

Stage 1: 25% reduction – primary dome formation
Stage 2: 20% reduction – curvature refinement and wall thickness control
Stage 3: 10% reduction – final precision shaping

Process benefits:

• Seamless, weld-free construction
  
• Curvature deviation ≤ 0.1 mm
  
• Wall thickness variation ≤ 0.05 mm
  

Temperature controlled between 25–35°C to prevent dimensional distortion.

3.3 Precision Machining and Flange Processing

• Custom precision fixtures (±0.01 mm positioning accuracy)
  
• 5-axis CNC machining for mounting hole processing
  
• Hole tolerance: ±0.03 mm
  
• Hole position tolerance: ±0.05 mm
  
• Edge finishing with axial runout ≤ 0.04 mm
  

Ensures perfect sealing fit.

3.4 Mirror Surface Finishing Process

Three-stage polishing process:

Stage 1: Diamond abrasive grinding (800 grit)
Stage 2: Aluminum oxide polishing (1200 grit)
Stage 3: Fine mirror polishing (2000 grit)

Final surface roughness:

Ra ≤ 0.3 μm (mirror finish)

Followed by:

• Ultrasonic cleaning
  
• Passivation treatment
  
• Enhanced corrosion resistance
  
• Long-term surface stability
  

3.5 Quality Control and Testing

Inspection methods include:

• CMM dimensional inspection of 16 critical dimensions
  
• Tolerance control ≤ ±0.08 mm
  
• Air pressure sealing test at 0.4 MPa (zero leakage)
  
• 240-hour salt spray corrosion test
  
• 100% visual inspection before delivery
  

4. Our Core Advantages

Ultra-High Precision Metal Spinning

• Dimensional tolerance: ±0.08 mm
  
• Curvature accuracy ≤ 0.1 mm
  
• Exceeds industry standards
  

Seamless One-Piece Construction

Compared with welded assemblies:

• Eliminates weld defects
  
• Improves structural integrity
  
• Enhances sealing performance
  

Premium Mirror Surface Finish

Mirror polishing and passivation provide:

• Ra ≤ 0.3 μm surface finish
  
• Superior corrosion resistance
  
• Premium aesthetic quality
  

International Project Execution Capability

• Dedicated engineering communication team
  
• Sample validation and batch traceability
  
• Production yield rate: 99.9%
  
• Lead time reduced by 15% compared to industry average
  

5. Quality Validation Results

Dimensional Accuracy

Assembly gap:

≤ 0.1 mm

100% installation compatibility achieved.

Surface Quality Validation

Customer confirmed:

• Seamless mirror finish
  
• Superior appearance compared to competitors
  

No corrosion or defects after long-term use.

Performance Validation

After 12 months continuous operation:

• No deformation
  
• No leakage
  
• No structural failure
  

Fully suitable for harsh mining and industrial environments.

Compliance Certification

• ISO 9001 certified manufacturing process
  
• Meets international industrial equipment standards
  
• Approved for global supply chain integration
  

6. Customer Problems Successfully Solved

Precision and Fit Issues

Improved assembly compatibility:

from 85% → 100%

Eliminated material leakage.

Surface Quality Issues

Achieved seamless mirror finish.

Enhanced customer's premium product positioning.

Reliability Issues

Seamless metal spinning eliminated weld failure risks.

Extended maintenance intervals by 3×.

Global Supply and Delivery Requirements

Established long-term partnership with repeat production orders.