The practice of Direct Part Marking (DPM) is used across many industries to identify an array of end use items. This process, also referred to as machine-readable identification, is prevalent in the automotive and aerospace industries for marking alphanumeric and 2D DataMatrix codes on individual parts and assemblies.

Manufacturers can use DPM to track parts throughout the manufacturing process and supply chain. It is ideal for locating parts for service or recall and can assist in liability and warranty resolution.

The three main elements in DPM are encoding, marking and verifying. Encoding is the rendering of a string of data into a pattern of dark and light cells that includes data, padding and error correction bytes to then be used by the marking device. Marking is the imprinting of content directly on your part with the appropriate technology for the substrate. Verification is the act of confirming code accuracy and quality. This is most commonly performed immediately following product imprinting at the marking station

Marking Methods

Laser Marking

Laser technology is a popular solution for providing permanent codes on parts. Laser marking systems apply clear, high-quality codes in a wide range of production environments. Marks are applied using heat instead of ink, so lasers are often considered to be faster, cleaner and require less maintenance than other coding systems. Laser marking systems can generate high quality marks including linear and 2D codes, optical characters, and alphanumeric messages on a range of substrates. Variations in specified wavelength, marking head and chosen lens will result in different marking effects on a given substrate.

Continuous Ink Jet Marking

CIJ printing provides non-contact coding on a wide variety of products. With CIJ technology, a stream of ink drops is delivered to the print target via a printhead. The ink jet comes out of the printhead through a nozzle and an ultrasonic signal breaks the ink jet into tiny drops. These individual ink drops then separate from the stream and receive a charge that determines their vertical flight to form the characters printed on the product. CIJ printers deliver legible printing on nearly any surface, smooth or irregular, and can apply codes on the side, top, bottom or even the inside of a product. They are ideal for convex, concave, irregular, as well as very small or hard-to-reach surfaces where a non-contact printing method would work well.

Dot Peen Marking

Two other marking types common in the automotive and aerospace industries are dot peening and electrochemical etching. In dot peen marking, an indenting pin is used to create an indentation for each dot in the DataMatrix code. The contrast needed for accurate verification comes from the light that reflects differently on the indentations and the surface of the product. In some cases, one code dot is represented by four indentations that are positioned very close together, resulting in larger code dots that appear to be almost square in formation

Electrochemical Etching Marking

Electrochemical etching removes layers of material via electrolysis. This chemical etching process takes an image on a stencil and transfers it to an electrically conductive product by the action of electrolyte and electricity. The chemical etch marking process has the advantage of being easy-to-use and inexpensive, while still giving a high-quality mark. This process offers a high resolution black “oxide” or “etch” mark and it is suitable for both soft and fully-hardened metals.