Direct Part Marking (DPM) is the process used to mark information on the surface of industrial parts.
But what exactly is it? And what are the different direct part marking methods?
Here is everything you need to know!
What is direct part marking in the industry?
Direct part marking is a set of techniques used in the industrial sector to identify or inscribe data on your products : serial numbers, manufacturing dates, bar codes, Datamatrix codes, logos.
The objective? To guarantee the traceability of manufactured products throughout the supply chain and their life cycle.
An industrial laser engraver uses a laser beam to interact with the material and create a permanent marking. This chemical reaction can produce different effects depending on the surface condition, the material of the part, the type of laser used and the marking parameters selected.
Compared to mechanical technologies (dot peen marking machines and scribing), laser marking is less deep.
There are several types of laser sources to mark different types of materials:
Laser technology offers many benefits for part identification:
However, laser technology can have some limits for DPM:
Dot peen marking machines use a mechanical engraving technique that deforms the material of a part into an indentation to mark it with very little breakage (no heat, no chips because the material is pushed back and therefore no change in weight).
The part identification is done thanks to a vibrating stylus whose tip strikes the surface of your part via a pneumatic or electromagnetic mechanism. This tip oscillates at a high frequency, between 1 to 300 times per second.
The stylus moves over a marking area of variable size, depending on the type of industrial engraver being used.
This technology was invented by our experts at Gravotech (Technifor) almost 40 years ago and is now used worldwide! Some of our dot peen marking machines have been running continuously on production lines for decades...
Pneumatic dot peen marking uses compressed air. Like a small jackhammer, the tip of the stylus strikes the workpiece and is brought back to its initial position by a spring. The oscillation frequency is very high, between 150 to 300 Hertz (150 to 300 impacts per second). This makes it a very fast direct marking method.
Electromagnetic dot peen marking machines uses a powerful electromagnet that is electronically controlled. With each electrical impulse, the tip of the stylus is propelled violently toward the part to create a sharp, deep impact, then returns to its initial position thanks to a spring. The impact frequency can vary between 1 to 40 Hertz (1 to 40 strokes per second) depending on the desired effect.Discover our dot peen machines
Dot peen marking is the most widely used technique for direct part marking (DPM):
Dot peen is the most common solution to mark industrial parts, but it also has some limits:
Scribing industrial engravers use a carbide or diamond tip to create a continuous, clean, and aesthetic marking. The tip glides over and scratches the part leaving a permanent, deep and clearly legible mark.
Scribing is a part identification solution dedicated to metal: it can be used on a wide variety of metal parts such as aluminum, brass, and copper, as well as hard materials such as steel and stainless steel.
Scribing part marking systems also offer another important advantage: by remaining in continuous contact with the parts, the part identification process is much quieter than dot peen, which strikes the parts. Scribing is therefore recommended for materials that resonate, such as sheet metal and hollow parts.
Scribing has many advantages for industrial direct part marking:
Scribing has few disadvantages for DPM needs, but there are two to consider:
Integrated laser system to mark and engrave on all metals.
Integrated laser system for high quality marking on plastics and metals.
Integrated laser system for high quality and cold marking on plastics and precious metals.
Integrated laser system to mark organic materials.
Label marking involves printing information on a label and then sticking it onto a part.
This identification solution is best suited to temporary marking or identifying parts that are not visible to the end customer, such as those inside a vehicle.
Historically used to identify plastic parts, this method is tending to disappear in favour of permanent marking techniques that are more compatible with today's safety, quality control and classification requirements.
The benefits of this type of marking for direct marking on parts:
The limits of marking by label:
Inkjet marking consists of using an inkjet print head to directly mark the part.
Less efficient and reliable than other identification solutions, this marking is the least used in the industrial field.
It is rather recommended for the marking of cardboard and food packaging.
The benefits of inkjet marking for DPM:
The limits of inkjet marking for direct part marking:
Stamp marking is a simple, manual part marking system. A metal tool is used to stamp a character (letters, numbers, etc.) onto metal, plastic or cardboard parts. It is also possible to find lever-operated stamping machines which make marking easier.
Its speed of execution, depth of marking and low cost are undeniable advantages. However, the wear and tear of the dies is more important and this manual identification solution excludes any notion of uniformity and compliance with marking standards.
N.B.: There are some automatic stamp machines that allow incremental marking, but their complexity and low output do not make them an ideal choice for companies.
The benefits of stamp marking
The limits of stamp marking
Designed to mark metal parts of varying sizes and shapes, electrochemical marking consists of transferring a pattern on a stencil onto a given part. Depending on the stencil, the part identification is more or less rapid.
In practice, the stencil is printed with a thermal printer and soaked in an electrolyte before being placed on the part. The hand-held marking head, connected to a generator, is then applied to the stencil in a back-and-forth motion, delivering a low current. This current, in combination with the stencil and the electrolyte, leaves a high-contrast black mark on the part.
The benefits of electrochemical marking
The limits of electrochemical marking
An engraving pen is a hand-held industrial engraver device for quick marking of parts of various sizes.
Depending on the market, this direct part marking machine either digs into the material with its rotating diamond tip, or taps and deforms the surface of the workpiece (successive dot peen) with a carbide tip.
Space-saving and geared more towards companies customizing objects, this marking is used in industry to mark tools or equipment.
The engraving pen is available in pneumatic or electric versions. It is a simple, low-cost machine.
The benefits of marking with an engraving pen:
The limits of marking with an engraving pen: