Quality guide
Encoder Disc Incoming Inspection: What to Check
Inspect four groups — visual defects, dimensions/concentricity, graduations and optical parameters — and agree zone-based acceptance criteria with the supplier in writing before ordering. A single pinhole or broken line in the track zone can cause missed pulses.
One pinhole or broken line can make an encoder miss pulses or show a periodic error. Organize incoming inspection into four groups and agree acceptance criteria with your supplier before the order is placed.
| Group | Items | Common methods |
|---|---|---|
| Visual defects | Edge chips, cracks, scratches, pinholes, broken lines, adhesive residue, contamination | Stereo microscope, AOI |
| Dimensions | Outer diameter, bore, thickness, pattern-to-bore concentricity | Vision measuring machine, micrometer |
| Graduations | Line width, pitch, duty cycle, integrity, index position | Vision measuring machine, microscope, AOI |
| Optical parameters | Transmissive: optical density (OD) of opaque areas · Reflective: high/low reflectance | Transmission densitometer; spectrophotometer or reflectometer at the readhead wavelength |
Judge defects by zone
Defects inside the track zone hit the signal directly, so criteria there are strictest; the assembly zone outside the tracks can be relaxed. A typical rule: “no broken lines or line-crossing pinholes in the track zone”. Set exact sizes and counts from your readhead spot size and signal margin.
Sampling and records
- 100 % inspection on the first lot and on the first lot after any design change; move to an agreed sampling plan once stable.
- Ask for an inspection report with each delivery, with measured dimensions, concentricity and optical values.
- If you can, mount discs with your own readhead and record amplitude and phase over a revolution — it reflects real performance better than visual checks.
Packaging and handling
Pack discs with separators so they don’t rub; protect glass from drops; wear finger cots and touch only the outer edge and bore — never the track zone.
How ENC7 inspects
Before shipment every ENC7 disc goes through AOI for graduation integrity, pitch and surface defects; critical dimensions are verified on a vision measuring machine; transparent and opaque areas are tested for optical density. See Quality & certifications.