Direct Part Marking (DPM) Explained
While 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.
