What are the quality standards for polished hardware parts?

The quality standards for polished hardware parts mainly include surface roughness, control of appearance defects, dimensional accuracy, cleanliness, and corrosion resistance. Different industries and applications have specific and detailed requirements.

Surface Roughness (Ra value)
Surface roughness is the core indicator for measuring polishing quality, commonly expressed as Ra (arithmetic mean deviation), with units in micrometers (μm). Requirements vary significantly depending on the application:

High-precision fields (e.g., optics, medical): Ra ≤ 0.01–0.05μm, approaching a mirror finish.

Precision hardware parts: Ra ≤ 0.4–0.8μm, commonly found in electronic and automotive components.

General decorative parts: Ra ≤ 3.2μm, suitable for everyday hardware, food carts, and other common products.

 Appearance Defect Control The polished surface must be free of defects that affect aesthetics or function. Common standards include:

Not allowed: Deformation, wavy lines, sanding marks, pitting, cracks, over-polishing, uneven gloss.

Area-based inspection

A-side (Front view): Most stringent; no visible defects within 10 seconds at a distance of 50cm from the light source and 30cm from the viewpoint.

B/C-side (Side/Back): Minor imperfections are permissible, but must not affect assembly or use.

Scratches and dents: No more than 3 scratches < 0.5mm wide and < 100mm long; no more than 2 dents ≤ 45mm in diameter.