Direct Part Marking (DPM) Explained

Posted April 4, 2016

DPM-Example-2While most barcodes you come across are printed on a label or paper-packaging of a product, in the manufacturing world and work-in-process applications many parts or components need to be marked with a barcode directly. Direct Part Marking is a process that  allows  users to mark a barcode directly on an item instead of printing the barcode on a label.

There are 3 main technologies available for DPM:  laser or chemical etching, dot peening  and ink jet printing. Each of these has specific  advantages  and disadvantages  in terms  of durability, cost and ease of reading.   The main advantages  of codes with  DPM technology are that  the code is permanently marked  on a surface and will  survive  for a long  time  (ideally  forever), regardless  of the  stress the part is passing  through during its’ life cycle. The main  reasons to choose codes with  DPM technology are:

  • Items that need to pass through harsh testing processes  (chemicals  agents, thermal cycles, oil, moisture, etc.)
  • Items that need to  be tracked  during  their  entire life cycle
  • Very small items (difficult to label)

DPM technology was first  adopted  mainly  by the automotive and general mechanical industries. Currently, the popularity of codes using  DPM technology has spread into  different sectors  including electronics, chemicals  and healthcare  industries.

Laser Marking

Laser Marking is currently the most  popular choice  used with  DPM technology. It is compatible with  a wide range of materials  and offers  several benefits: high  quality marking, high  throughput and no consumables.Laser Marking works  by creating a change of the material characteristics through the interaction with  a laser beam.

Depending on the laser type and power,  marking is obtained through the following methods:

Process Method Ideal Material
Ablation Removal of a surface layer PCB, Plated Metal
Engraving Removal of a material part in order to create a groove PCB, Glass, Metals
Color Change Melting or burning of the surface Plastic Wood
Annealing Surface oxidation Iron, Stainless Steel


Dot Peening

Dot peening  marking is created  by mechanical percussion, which actually punches  holes in the material, as shown below. The holes created by the mechanical percussion cause a different reflection/diffusion of the incident light on the surface to recreate  the dark and light elements  that  characterize a bar code.  Dot peening  is generally used with  metal parts  and it is very common in the automotive industry.

Ink Jet Printing

Ink jet  printing mark is created by directly spraying ink onto  the surface  of the part,  producing a pattern of spots.

The ink jet  method is generally compatible with  any substrate material, such as plastic, metal, glass, etc.   Since this  method is based on an ink deposit, the ink marking is less persistent than  other  methods and could be inappropriate for harsh production environments.

Scanning DPM Barcodes

DPM scanners are usually  equipped with  specialized illumination systems in order  to improve the readability of codes using  DPM technology. The object  surface can be reflective, shiny, polished, or be a contrasting rough surface. Depending on the marking technology used, the code can be more  or less visible  with  more  or less contrast when compared to the background.

DPM specific scanners are available in both handheld and fixed mount models to fit manual or automated applications.

For assistance finding the right DPM scanner to meet the specific needs or your marking type, contact us at Barcodes, Inc.

Filed under: Solutions
Tags: , , , , , , , , , ,