What is direct part marking?

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Direct Part Marking (DPM) is the permanent marking of an item with a machine-readable barcode for tracking purposes. It is used in the aerospace industry, as well as in the manufacture of automobiles and electronics. DPM is useful for product management because it allows the same part to be tracked throughout its lifecycle. There are many methods of applying direct part marking, including dot systems, laser marking, electrochemical and inkjet engraving. Various direct part marking codes are also used.

Dot print marking uses a pin, known as a pen, to create indented dots on a metal surface. The pin is pneumatically or electromechanically driven into the metal by the marking machine. The stitch pattern created by stitch marking is a two-dimensional square of indentations that can be read by a machine to identify the part. When creating the code, factors such as spot size and depth are carefully controlled by calibrating the marking machine for consistency. Point marking is widely used in all industries because of its flexibility, ease of application and cost-effectiveness.

Other methods of direct part marking are used where appropriate. Electrochemical etching employs chemicals to etch the surface of a metal using a stencil. Inkjet marking uses quick-drying ink to mark painted surfaces where other types of identification may be difficult to read. Laser marking, less applied due to its higher cost, uses a laser beam to melt or alter a surface and produce marks.

Companies and government agencies that use direct part marking have found that two-dimensional codes are more effective for their purposes than the alphanumeric recordings that can also be produced through DPM. The most commonly used codes are Data Matrix™ and Quick Response Code, or QR Code®. While the Data Matrix™ tends to be used in the telecommunications and aerospace industries, the QR Code® is often used in the automotive industry.

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The Data Matrix™ code consists of a square of black and white dots or cells. The dot-peen technology will produce a set of indentations in a square, appearing as both positive and negative space. Data Matrix™ codes can be up to 300 micrometers wide, although they can be read, allowing them to be used on very small electronics.

QR Code®, like Data Matrix™, is a two-dimensional square code consisting of black and white areas. QR Codes® have the advantage of containing more alphanumeric characters than Data Matrix™, but they are also considered the less secure of the two. For this reason, government agencies and industries that require high security prefer to use Data Matrix™.

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