Basics
Understand DPM read-rate risk from mark method, surface finish, lighting angle, mounting distance and production movement.
Direct answer
DPM barcode reading is difficult because code contrast depends on marking method, surface finish, lighting angle, camera distance and part movement. A reader should be tested with real marked parts and target read-rate conditions before selection.
DPM barcode reading is difficult because code contrast depends on marking method, surface finish, lighting angle, camera distance and part movement. A reader should be tested against real marked parts and target read rate.
Dot-peen, laser and etched marks can change appearance across batches. A reader that decodes one clean sample may fail when glare, shallow marks or curved surfaces enter production.
Provide real marked samples or photos, module size, material finish, read distance, speed, expected read rate and no-read handling before selecting a fixed reader.
Direct part marks can be laser etched, dot-peened, inked or molded into metal, plastic, glass or ceramic. The reader must handle lower contrast than many printed labels.
A code may disappear under flat light and become readable under low-angle or directional light. This is why DPM testing should include real parts, not only code size.
A production reader must decode repeatedly across surface variation, speed and mounting tolerances. A single successful bench read is not enough for line acceptance.
How to test before buying
Run weak, glossy, curved and borderline marks at production speed. Confirm the lighting angle, reader distance, decode settings and no-read output before treating one successful decode as acceptance.
Decision checks
Usually higher contrast and easier to decode.
Lower contrast and stronger surface dependence.
Use repeat read-rate checks, not a single photo.
Decision table
| Factor | Practical rule | RFQ impact |
|---|---|---|
| Printed label | Usually higher contrast and easier to decode. | Confirm label size, speed and distance. |
| DPM code | Lower contrast and stronger surface dependence. | Send real marked samples and material finish. |
| Acceptance | Use repeat read-rate checks, not a single photo. | Define target read rate and line speed. |
Application proof
DPM marks often fail because mark depth, surface finish and lighting angle change the apparent code contrast.
Wide moving material needs even illumination, encoder synchronization and enough line rate to avoid missing small defects.
Reflective metal surfaces can hide scratches and burrs unless the lighting geometry is matched to the defect direction and part movement.
Common mistakes
Factory handoff
The factory route review starts by checking whether the image can be made stable with lighting and fixture control. Then the camera, lens, reader or 3D sensor route is sized against speed, resolution, interface and installation constraints.
If you already have a Keyence, Cognex, Basler, OPT, LMI, Hikrobot or barcode-reader reference, include it as a reference model. Deyi Vision uses it to understand the application class; final selection still depends on real samples and production limits.
Guide to RFQ
Use the guide to frame the question, then send the details so engineering can recommend a route.
Request engineering RFQGuide FAQ
DPM means direct part mark. The barcode or 2D code is marked directly on the product surface instead of being printed on a separate label.
They often have lower contrast and are affected by material finish, lighting angle, mark depth, reflection and mounting distance.
Send marked part samples or photos, code type, code size, material, line speed, mounting distance, angle limits and target read rate.
