DPM (Direct Part Marking) is a new direct marking technology. In this method the barcode is embedded directly on products, materials and subassemblies. This technology is preferred by NASA to mark spacecraft parts. DPM is often used within civil industry and nowadays is being implemented in a variety of processing and logistics companies. DPM technology has become popular for three main reasons:

DPM technology is used to mark components and subassemblies within aircraft, automotive, armament, electronic, petrochemical, pharmaceutical and medical industry, train transport and others. Direct part marking (DPM) is used in many fields. It is implemented in manufacturing enterprises and logistics where it supports management and goods traffic control. DPM marking implementation means:

• more efficient production management and goods traffic along with more efficient documentation of those processes
• more reliable quality and efficiency control along with goods traffic
• enhanced production and dispatch of goods
• close monitoring of marked object flow from production to withdrawal
• data integration and exchange between manufacturer, carrier and seller
  

DPM combines all benefits of automatic identification technology–eliminates human errors, supports efficient resource management, access to current information on assets. Contrary to the traditional labels it is durable (indestructible), resistant to harsh external conditions and allows to encode a large quantity of information (up to 3600 characters) on a very small area.

Benefits of direct marking (DPM):

• durability (with this technology the code is durable–cannot be erased, removed or faked)
• a large quantity of data can be encoded on a very small area (up to 3600 characters) (in  Europe for DPM marking method Datamatrix code is often used whereas in Japan it is QR code)
• two-dimensional barcode can be read at any angle
• it can be used on different materials (metal, plastics, glass)
• elimination of human and machine errors (even if broken, two-dimensional barcode is in 20% read correctly)
• easy object identification. While scanning the code, the user receives major information on the given object. The information concerns the producer, when and where the product was made, etc. You can appreciate the value of object identification as its durable marking allows you to track the whole history of a given object and avoid the theft (once the code was embedded it cannot be removed or changed)
• low operating costs (operation is cheaper than traditional labels)
• even materials of small size can be marked (like in case of electronic subassembly marking, Datamatrix code maintains its full functionality even if it is generated in a small size)
• improved work efficiency, as marking and object identification is fully automated
• production serialization option (implementing DPM system enables fast and automated data filing of all production)
• quick implementation of technology
• continuous flow and origin of marked objects as every object includes detailed information on its origin and production

• DPM code reading device (terminal, reader) transmit scanned information to the database. Modern DPM readers are universal devices – they read both codes in DPM technology, traditional labels and RFID
• marking device which can be applied to mark the material in any method. Depending on marking method such devices have different size and capabilities
• application for PC computer, integrates all data delivered by users and DPM code readers
• DPM code verifiers which check the correct codes in DPM technology

Direct marking combines several methods. Each of them has unusual benefits and requirements. You can choose marking method according to: type of material for marking, reading technology, implementation costs. There are intrusive and non-intrusive Direct Part Marking (DPM) methods. Intrusive method involves direct contact between marking device and surface which is being marked. Non-intrusive does not involve such contact.

This is intrusive method, also known as „Dot Peening”. In this method the code is grooved by using the hard head. Marking machine hits precisely on a material surface and with subsequent strikes it grooves the code on it.

Burning out method requires the use of laser. Laser beam is directed onto a marked surface which changes the color of the marked surface.

With the use of a laser the code can be put on by cutting, melting or evaporation method.

This intrusive method involves engraving a given character directly on a object’s surface which is usually metal.

• You can engrave alphanumeric characters, trade marks along with one-dimensional (1D) barcodes
• size of engraving devices is quite small, can be moved from one place to another
• low implementation costs
• minimum operating costs
• as devices can be manually or computer-controlled, they can be used at assembly line

• with this method two-dimensional barcodes cannot be put on a surface
• marking time of material is longer than laser marking
• this method cannot be used on any kind of surface

In this method special ink is precisely put on a marked surface.

Benefits:

• marking speed

• lower code durability (comparing to burning out and engraving) and operating costs for ink, nozzle or maintainance

This method requires specific matrix and chemical solutions.

Benefits:

• durability; can be used on a metal; any materials required for this method can be kept in a small box

Disadvantages:

• long operation time (you cannot mark a large quantity of objects in a short period of time)
• operating costs (for reagents)
• in this method, the barcode must be put on by human and it cannot be machine-made or automatic

The code on a given object must be checked with the use of a verifier.

These devices check barcode quality by:

• contrast
• point size
• print depth
• point quality
• horizontal and vertical moving of points in a code
• horizontal and vertical code extension
• code slanting
• percentage of code damage tolerance (code in ECC 200 symbology is fully legible even at 20% damage)

• Data Matrix codes put directly on a surface must comply with international standards. AIM (Association for Automatic Identification and Mobility) is an accreditation agency operating in Europe and the USA. JIS is an accreditation agency (equivalent of European AIM) operating in Japan, where QR Code is mainly used
• even surface on which the code is embedded
• relevant marking method is of major importance
• relevant lightning of the reading angle
• relevant scanner setting