Selection Guides

DPM Barcode Reading Guide

Plan direct part mark code reading by material, mark type, contrast, lighting angle and reader mounting conditions.

DPM barcode reading test bench with fixed reader low angle light and metal parts with direct part marks

Direct answer

DPM Barcode Reading Guide

DPM barcode reading should be planned from the marked part, not only the code type. Material finish, mark method, depth, contrast, curvature, lighting angle, exposure and mounting distance decide whether a direct part mark can read reliably.

Where this matters

Start with the inspection condition.

For DPM codes, the reader and lighting must be tested with real marked parts. Screenshots or ideal printed codes are not enough for a production quote.

Why projects fail

Confirm the limits that change hardware.

Surface finish changes read-rate.

RFQ preparation

Send enough context for a real review.

Mounting angle and exposure are part of selection.

What engineering should check

What this page should help teams decide.

DPM codes need lighting matched to the mark.
Surface finish changes read-rate.
Mounting angle and exposure are part of selection.

Related Deyi routes

Product families commonly involved.

Practical note

DPM difficulty comes from surface physics.

Laser engraving, dot peen, etching, stamping and molding create different contrast behavior. A mark that looks visible to the eye may fail under the reader if surface reflection or shallow depth hides the module pattern.

Practical note

Lighting angle is part of the reader selection.

Dark-field, coaxial, dome, multi-angle or low-angle bar lighting can produce very different results on the same mark. DPM selection should include light tests, not only reader datasheets.

Practical note

Mounting and exposure control read-rate.

Working distance, angle, depth of field, exposure time and part movement determine whether the mark is sharp enough. For moving lines, trigger timing and vibration should be reviewed before model lock.

Practical note

Acceptance should include no-read and false-read behavior.

A DPM project should define target read-rate, allowed no-read handling, image saving for failures and whether damaged or borderline marks must still read. Without this, the quote cannot be tested objectively.

How to test before buying

Use this guide as a pre-RFQ decision filter, not as a part-number shortcut.

Machine vision selection is usually stable when the project starts from the inspection condition instead of a catalog model. Before requesting a quote, define what must be detected or measured, how the part moves, what surface behavior affects contrast and which factory constraint cannot change.

Use this guide to translate the requirement into testable inputs: sample images, target tolerance, line speed, field of view, working distance, mounting envelope and the current failure mode. That gives the factory enough evidence to map the request to camera, lighting, optics, reader or 3D routes.

Decision checks

Three checks before locking the route.

Laser etched metal

Often needs angle control to separate mark contrast from reflective metal.

Dot peen mark

Needs lighting that reveals dot depth and shape without glare.

Molded plastic mark

May need low-angle or diffuse lighting depending on relief and gloss.

Decision table

Use these data points to turn the concept into an RFQ-ready decision.

Factor	Practical rule	RFQ impact
Laser etched metal	Often needs angle control to separate mark contrast from reflective metal.	Send real parts and surface finish notes.
Dot peen mark	Needs lighting that reveals dot depth and shape without glare.	Send dot size, material and read-rate target.
Molded plastic mark	May need low-angle or diffuse lighting depending on relief and gloss.	Send multiple batches if surface varies.
Curved or small parts	Depth of field and mounting angle become critical.	Send part geometry and available mounting space.
High-speed line	Exposure, trigger and reject timing must be tested at production speed.	Send speed range and no-read output requirement.

Application proof

Related delivery routes that make this selection decision concrete.

View all cases

Direct part mark code reading review for metal parts with camera and lighting

Metal and surface inspection

Direct Part Mark Code Reading on Metal Parts

DPM marks often fail because mark depth, surface finish and lighting angle change the apparent code contrast.

Packaging inspection

Packaging Label and Barcode Traceability

Labels and codes move quickly, vary in position and must be verified without slowing the packaging line.

Automotive parts inspection

Automotive Metal Surface Defect Inspection

Reflective metal surfaces can hide scratches and burrs unless the lighting geometry is matched to the defect direction and part movement.

Common mistakes

Problems that slow down selection.

Selecting by model number before the inspection target is measurable.
Treating lighting as an accessory instead of the main contrast-control tool.
Ignoring fixture stability, part variation and operator maintenance workflow.

Factory handoff

What Deyi Vision reviews after receiving the project details.

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

Have a real part, sample image or production constraint?

Use the guide to frame the question, then send the details so engineering can recommend a route.

Request engineering RFQ

Guide FAQ

Questions related to dpm barcode reading guide.

Ask engineering

What is DPM barcode reading?

DPM reading means reading direct part marks such as laser-etched, dot-peen, stamped, engraved or molded codes directly on the product surface.

Why is DPM harder than printed barcode reading?

DPM marks depend on surface texture, mark depth, reflection and lighting angle, while printed labels usually have stronger contrast and flatter geometry.

What should I send for a DPM reader recommendation?

Send real marked parts, material finish, mark type, code size, line speed, working distance, mounting limits, read-rate target and no-read workflow.