How to Choose the Best Marking Technology

Each marking technology has its benefits and drawbacks. Between dot peening, inkjet printing, laser marking, and printed labels, the right solution is not always obvious. The key to choosing the best technology is to understand your marking requirements. This can be done by asking yourself the following questions.

What is the part’s material and shape? Which type of identifier do you want? Do you have traceability requirements? How will the part be positioned during marking? What is the available marking time? Will the markings go through post treatments?

Before we help you answer these questions, let’s first go over each technology.

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Overview of the Technologies

Laser Marking Technology

• Can mark any material
• Can mark curved surfaces
• Permanent marks
• Marking in movement (on the fly) is possible
• Can compensate part positioning variations
• High-speed marking
• High resolution and high contrast
• Markings can maintain their readability through most post processes
• No consumables
• Non-contact process (low maintenance)

Cons

• High initial investment

Laser marking is the most versatile technology, using the energy of a laser beam to create high-quality markings directly on a part surface. Different types of lasers generate different wavelengths that are used for different materials. Typically, fiber lasers are used with metals while CO2 lasers are used with organic materials.

Also, there are multiple laser processes that offer different benefits. Laser etching is faster, laser engraving is more resistant, and laser annealing preserves the material’s corrosion resistance (ideal for stainless steel and chrome-plated parts).

Dot Peen Marking 

Pros

• Permanent marks
• Markings can remain readable through some coatings
• Good at marking metal surfaces
• Low CAPEX

Cons

• May damage soft materials like plastics
• Cannot mark curved surfaces
• Limited part positioning tolerance
• Not aesthetic enough for logos and graphics
• Low contrast affects readability
• No marking in movement (on the fly)
• Slow marking process
• High maintenance

Dot peening is a mechanical process that hits part surfaces with a stylus to indent them. The resulting markings can be felt by the touch and have almost no contrast.

Manufacturers often hesitate between dot peening and laser marking because both technologies generate permanent markings. Those who want to minimize their initial investment typically choose dot peening, while those who have higher quality requirements choose laser marking.

Inkjet Printing

Pros

• Marking in movement (on the fly) is possible
• Fast marking method
• Can mark any type of material
• Low initial investment

Cons

• Cannot mark curved surfaces
• Not aesthetic enough for logos and graphics
• Not permanent
• High recurring costs
• High maintenance

Inkjet printing applies high-quality ink on surfaces using a spraying nozzle. These systems are cost effective at first but come with recurring costs: ink needs to be replenished on a regular basis. The nozzle also needs to be cleaned to prevent the marking quality from degrading.

Printed Labels

Pros

• Can apply labels on curved surfaces (when done manually)
• Fast marking process
• Can be applied to any type of material
• Can maintain traceability through heat treatments
• High resolution and high contrast
• Low initial investment
• Marking in movement (on the fly) is possible 

• Not permanent
• Recurring consumable costs
• High cost of specialized labels (heat resistant, etc.)
• Medium/high maintenance

​Labelling is a marking technique that uses printed labels or tags that are sticked directly on the surface of the material. The surface needs to be as clean as possible before applying the label. The process is not considered permanent because labels can fall off, especially if the surface was dirty prior to applying the label.

Considerations for Choosing a Marking Technology

1. Part Material & Geometry

The actual parts to be marked should be your starting point when choosing a technology. You need to make sure that it can address the parts’ physical properties.

To do this, marking experts will ask you about the surface shape, metal alloy, part temperature, part size, number of cavities, and so on. These are all factors that will influence your choice of a marking system.

For example, all marking methods can create markings on a flat surface. But curved surfaces present a challenge that only laser marking systems or printed labels (when applied manually) can address. 

Also, all marking technologies can be used to mark metals, but plastics are more challenging. For example, pneumatic dot peen systems are meant for hard materials and will damage plastic surfaces. If you choose dot peen marking for plastics, you need to opt for an electromechanical system since it has a lower force of impact.

2. Type of Identifier

Do you want to mark QR codes, data matrix codes, alphanumerical serial numbers, graphics, or logos? Your type of identifier will affect your choice of technology.

For example, if you need to mark logos or graphics, dot peen systems and inkjet printers are not a good solution because they do not create aesthetic results.

2D codes and alphanumerical serial numbers can be created by any type of marking system. However, if you are marking identifiers that must be read by inline machines with cameras, not all technologies are a good choice. Keep reading to learn more.

3. Readability Rate & Permanence

If marking for traceability, you need to consider how well your identifiers can be read by barcode readers or scanners.

Codes created by inkjet printing or dot peening are harder to read because of their variable or low contrast. These systems don’t always do well with inline reading. Ink is typically used for man-readable marks and its contrast is affected by the part finish. For dot peening, special lighting conditions are required to compensate for the low contrast. 

If you need permanent marks, the best technologies are dot peening and laser marking, since the marks are directly engraved into the part. They are referred to as direct part marking technologies. 

Printed labels and inkjet printing are not considered permanent. Printed labels can fall off, and inkjet printing can be affected by chemical aggression, solvents, or mechanical abrasion.

4. Part’s Position During Marking

The part’s position during marking can limit your choice of a marking system. For this reason, marking experts will ask you if you plan to perform marking using conveyors, robots, or manual workstations. They will also ask for information such as the conveyor speed and the part positioning error.

Here are some examples where the part’s position is crucial for your choice of technology.

If you need to mark on the fly, dot peening is not an option since these systems need a perpendicular, physical contact to perform the marking.

If the part positioning error is too large, vision systems can be directly connected to laser marking systems to communicate positioning variations, allowing the laser to make the necessary adjustments.

5. Available Marking & Cycle Time

To integrate marking equipment directly in a production line, you need to make sure it can keep up with the cycle time and production volume. You can ask yourself questions like, “What is my current process cycle time between two parts?” and “What is the available marking time?”

This will help you choose the right automation equipment, and potentially eliminate marking technologies that can’t keep up.

Here is an example.

If you only have a few seconds to perform the marking operation, you should probably opt for laser marking, printed labels, or inkjet printing. Dot peen marking is a slower technology that can’t keep up with short cycle times.

The marking time itself is not everything; you need to account for the total cycle time. This could include robot movements for bringing pieces in and out, table rotations, fixing parts onto fixtures, and so on.

Some machines can create cycle time by performing the marking operation in hidden time. An example is the rotary laser marking machine. While one part is loaded onto the rotary table, another one is marked on the other side. This means you can deduct the robot’s or operator’s loading time from the total cycle time. Those become operations done in “hidden time” during the marking operation.

Automation features can help you meet your production goals, which is why you should take the time to explain your entire process when discussing with marking experts.

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6. Post Processes & Complete Traceability

With current traceability regulations, an increasing number of manufacturers need to implement the marking operation at that start of production. This is used to track products throughout the supply chain—from the beginning to the end of their lifecycle. Complete traceability helps fight product counterfeiting, minimize the size of recalls, and control quality.

These regulations create marking challenges that were nonexistent before and force manufacturers to switch technologies.

Parts marked early in a manufacturing process may go through post treatments such as sandblasting, shotblasting, powder coating, e-coating, or heat treating. 

Post treatments can remove identifiers, make them unreadable, or drastically reduce their readability. If this is the case, you need a technology that ensures readability through the part’s lifecycle.

For this reason, printed labels and inkjet printing are falling out of popularity in several applications. Both types of marks are removed by most post treatments and should not be used to implement complete traceability. One exception is printed labels, which can resist heat treatments by using expensive high-tech papers and plastics.

Dot peen systems maintain traceability through some post treatments (such as coatings) by creating deep markings, but the resulting low mark quality leads to poor readability.

When it comes to post process resistance, the best solution is laser marking. There are laser etching and laser engraving processes that maintain traceability through powder coating, e-coating, heat treating, and shotblasting.

Conclusion

When the time comes to choose a technology, keep in mind there is no one-size-fits-all marking solution. We hope that the considerations provided in this article helped you find a solution.

You can use the overview provided at the beginning to quickly see if a tech applies to your situation.

And when in doubt, ask an expert.

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