How to Specify Custom Fasteners for OEM Projects
The drawings, tolerances, materials, and validation details that help OEM teams move faster on custom hardware.
Custom fasteners often bridge the gap where standard catalogue parts fail to meet unique spatial constraints, load profiles, or harsh environmental exposures. However, imprecise engineering specs can lead to lengthy quote iterations and production delays.
Critical Details to Include in 2D Drawings
- Thread Class & Fit: Call out standard thread classes (e.g., Metric 6g/6H or UN 2A/2B) and specify whether dimensions apply before or after plating.
- Under-Head Fillet Radius: A sharp transition from shank to head creates stress concentration. Always specify the minimum radius.
- Surface Finish (Ra): Indicate allowable roughness on sealing surfaces, bearing faces, and non-critical shank areas.
- Drive & Recess Geometry: Specify drive standard (Torx, Hex, Socket, Spline) and depth limits.
Mertra’s application engineering team provides free Design for Manufacturability (DFM) reviews to help customers reduce tooling costs and lead times before launching production runs.