German precision gas oven parts manufacturing case: zero tolerance CNC machining and customized brass screw solutions

Project requirements

The customer needs to customize two key accessories:

 

1. Customized brass screws: The head needs to be drilled with a micro hole with a diameter of 0.45mm for precise control of gas flow.
2. Precision CNC parts: Contains two high-precision holes (diameters 5.5mm and 17.5mm), requiring zero tolerance to ensure stable operation of the oven combustion system.

Product technical specifications and core challenges

Zero tolerance CNC parts (combustion valve assembly)

Key parameters:

• Diameter of hole 1: 5.5mm (±0mm tolerance)
• Diameter of hole 2: 17.5mm (±0mm tolerance)

Function: Control the gas and air mixing ratio, which directly affects the combustion efficiency and safety.

Custom brass screws (gas flow regulator)

Key parameters:

• Material: high-strength brass (corrosion-resistant, high-temperature resistant)
• Micropores in the head: diameter 0.45mm (±0mm tolerance)

Function: Accurately adjust the gas flow rate to ensure flame stability.

Core Challenges of the Project

Technical Barriers to Zero Tolerance Manufacturing

Difficulty of Micro-hole Processing:

• The 0.45mm hole diameter of the brass screw is close to the limit drilling size, which can easily lead to drill bit breakage or hole diameter deviation.
• Solution: Use Swiss precision drilling machine with customized tungsten steel drill bit for progressive processing in stages.

Double-hole coaxiality and tolerance control:

• The 5.5mm and 17.5mm holes of CNC parts need to be absolutely coaxial and tolerance-free, and traditional processing is easily affected by thermal deformation.
• Solution: Constant temperature processing of five-axis CNC machine tools, with real-time laser measurement feedback system.

Material stability:

• Brass is prone to burrs when drilling, and CNC aluminum parts need to avoid cutting stress deformation.
• Solution: Add electrolytic polishing process to brass parts, and use stress release heat treatment for CNC parts.

Precision parts manufacturing process

Brass screw manufacturing process

Material pretreatment: H62 brass rods are selected and annealed to improve ductility.

Precision drilling:

• Use 0.45mm ultra-fine drill bit, speed 20,000 RPM, with micro-lubrication technology.
• Replace the drill bit after every 10 pieces to ensure the consistency of hole diameter.

Post-processing: Electrolytic polishing to remove burrs, 100% go and no-go gauge inspection.

CNC parts processing technology

Equipment and programming:

• Five-axis DMG MORI CNC machine tool, CAM programming reserves 0.02mm margin.

Stage processing:

• Rough processing: Remove 90% of the margin and cool for 24 hours to release stress.
• Fine processing: Hole processing is completed in a constant temperature workshop (20℃±1℃), and real-time laser calibration is performed.

Quality inspection:

• The three-coordinate measuring machine (CMM) fully inspects the aperture and position, and the data is archived and traceable.