What Is Direct Part Marking, and Why Is It Important?

From the US military to NASA and the FDA, government agencies are making unique device identification (UDI) and, in some cases, specifically direct part marking (DPM), mandatory. In the private sector, many hospitals, medical offices and automotive manufacturers have been using DPM for quite some time. But what is direct part marking?

Similar to barcode and RFID, DPM is simply a method used to assign a unique identifier to an asset. While RFID and barcode technology are well-known solutions, there are applications where those simply aren’t possible or don’t make sense. Enter direct part marking.

What Is Direct Part Marking?

Direct part marking is exactly what it sounds like: a method for placing an identifying marker directly onto a part or item, for example by etching or laser-engraving a symbol into the surface of the item. DPM is a great option for tracking parts or assets in challenging or industrial environments where stick-on or otherwise attachable labels are likely to fall off, wear out, or be lost or damaged. Because of the capacity of some DPM symbologies like Data Matrix to encode a significant amount of data in extremely small (down to even 1/16” square) spaces, direct part marking is particularly useful for identifying parts that are too small to hold an RFID tag or label. In fact, one of the biggest benefits of DPM over RFID is that you can place a permanent, encoded mark onto just about anything.

“You can’t put a label on a jet engine blade. Once you start the engine up and the label gets heated, it’s gone,” explains Richard (Rick) Bissonnette, president of Strategic Systems and leader in the field of asset tracking.

DPM can survive such an environment because, unlike the stickers and tags used in barcode and RFID systems, direct part marks are embedded and, for all intents and purposes, permanent.

A direct part mark contains a code that represents information about the part or item it identifies. As mentioned earlier, the mark can be produced in several different ways, either during the manufacturing process or applied later by an end user, including laser etching, dot peen, and inkjet. The type of mark needed depends on factors such as the item’s size, shape, function and environment. DPM can be used on most materials, including plastic, metal, rubber and glass.

DPM vs RFID

For straight-up, high volume asset tracking, there’s no contest:  the benefits of RFID win over DPM, hands down. Still, each has its own set of limitations and strengths. A good solutions provider should be able to offer both, so that you can explore all of the options before deciding which is best for your application.

Some of the key influencing factors include the following:

• Cost
• Size of items
• Location of items
• Function of items
• Location and type of reader
• How you need to track items
• Long term vs short term

Direct part marking can be a less costly alternative to purchasing pricey RFID tags. Being able to produce some types of DPM symbologies at just a tenth of a cent each — compared to a dollar and up for durable RFID tags — makes DPM a more economical solution.

That said, if the parts are subject to dirt and grime, then a DPM scanner might not be able to locate the code. Unlike RFID readers, a DPM scanner needs to have a direct line-of-sight to the object in order to read it. Then again, direct part mark reading isn’t affected by proximity to materials like water and metal, which can interfere with RFID reads.

Which One Should You Choose?

Ultimately, whether you use RFID or DPM to identify certain types of assets may not be up to you, especially when industry and company standards require direct part marking. Many automotive companies, for example, already require DPM. “Direct part mark is better for the auto industry,” Rick explains. “The parts come to assembly already marked, so as companies receive parts they can scan them. Then, if they ever need to do a recall, they know by serial number every part in every car.”

If you decide that DPM is best for your application, remember two things:  it all comes down to the code and the reader. “First, you want to make sure your codes are cleanly produced to be as readable as possible,” Rick advises. “And second, you need to select the best possible reader for your application. The skill is to make sure you understand which technology will work best with the code and materials. Your reader has got to be aggressive enough to decode your marks in a timely fashion.”

Considering the skill level necessary to achieve DPM success, it is worthwhile to seek out a DPM-certified hardware vendor when purchasing your equipment. Strategic Systems is a DPM-certified company — one of just a handful of Zebra partners with that distinction.

Thinking About Implementing Direct Part Marking?

If you have any questions about DPM, we can help. Contact us now for general information, or to find out more about our DPM reader offering.