A German manufacturer of high-end surveying instruments was developing a new theodolite model with improved angular accuracy. The design required a flanged bushing that would support the vertical axis rotation while maintaining precise alignment between the optical path and the angle encoder. The bushing needed to provide low-friction rotation with minimal backlash over years of field use.
The Challenge
The client's instrument design required a flanged bushing with the following specifications:
Inner diameter: 8mm with ±0.01mm tolerance
Outer diameter: 12mm with ±0.015mm tolerance
Flange diameter: 16mm
Flange perpendicularity: ≤0.02mm
Material: 303 stainless steel
Surface finish: Ra 0.4μm on inner bore
Quantity: 500 pieces for initial production
The client had previously sourced from a European supplier but experienced inconsistent bore diameters that affected encoder readings. They needed a manufacturer with tighter process control and consistent quality.
Our Solution
Tingfeng Hardware reviewed the 3D model and performance requirements. We proposed manufacturing the flanged bushing from 303 stainless steel on our CNC turning equipment. The one-piece flange and bushing design was produced in a single setup, ensuring perpendicularity between the flange face and the bore. Key process steps included:
Precision CNC turning of the bore to ±0.01mm tolerance
Flange facing to achieve ≤0.02mm perpendicularity
Passivation per ASTM A967 for corrosion protection
100% bore diameter measurement on all parts
Surface roughness verification on sample parts
We produced the 500 bushings in 10 days, with each part inspected for bore diameter and flange perpendicularity.
Outcome
The bushings fitted precisely into the instrument housing and provided smooth, consistent rotation. The encoder readings remained stable across the full rotation range. The client has since ordered bushings for two additional instrument models.