Laser marking readability is commonly used in the manufacturing process to put serial numbers, model numbers, logos, technical specifications, and product identification codes on metal parts. Such markings allow manufacturers to identify their products, keep them traceable, and give customers important information. Yet a laser mark is of no use unless the information remains clear and readable.
It may happen that the final mark doesn’t look as one would expect; small letters can appear blurred, the lines might become too thin, the figures could be hard to make out, or the contrast might be inadequate. Such difficulties can arise even when the same laser marking machine is used on a number of different products.
The fact is that the quality of the laser marking readability depends on a number of factors other than the machine itself, such as design preparation, character size, the properties of the material, the surface condition, the laser settings, focusing, and the position of the workpiece.
Seven Design and Setup Factors to Check
1. Choosing the size of the characters and selecting the font
A basic check should be made of the size of the text which is in question. When the characters are very small, it becomes hard to read because the laser cannot clearly reproduce the necessary detail.
The choice of font is also very important; fonts with thin lines, decorative styles, and complex character shapes do not always offer the same level of readability as simpler ones. One should also take into account the spacing between letters and numbers.
For instance, when a serial number is engraved on a small metal part it is necessary to leave sufficient space between the characters so that each number can be recognised separately. If the characters are placed too near to one another, the marking will look crowded.
When choosing a character height and font, manufacturers should take into account the marking area available and the level of detail needed. It is useful to test the text actually produced in order to find out if the chosen design is still readable.
2. The arrangement of the layout and the spacing of the characters
A clear identification of the individual characters can still make the entire laser marking readability hard to understand due to bad design arrangement.
When information is placed too near to one another, the text is incorrectly aligned and there are overlapping design elements, readability decreases. This is especially important in the case of a product which has to show a number of details, for example a model number, a serial number, a manufacturer’s logo and technical information.
The digital layout must be prepared on the basis of the dimensions of the marking surface, with the important information properly separated and without including any decorative elements which would reduce the available space.
Before sending the design to the marking machine, manufacturers should also check the position of the logos, numbers, symbols, and codes.
3. The type of material and the surface finish
The final appearance depends directly on the type of material in question. Materials such as stainless steel, aluminium, titanium, brass and alloy steel will react differently to laser energy due to their composition and the characteristics of their surface.
The surface finish is also important; for example, a polished metal surface will show a different kind of marking compared to a brushed or coated one. With certain materials it is necessary to use settings which give greater contrast, whereas with others a different method of marking is needed.
For example, when using stainless steel marking it is necessary to use particular settings in order to obtain the desired contrast without producing an undesirable surface appearance.
Manufacturers ought to look at the actual material beforehand and check if the surface condition is appropriate for the design intended. In order to find out the required appearance it is useful to test various settings on a sample.
4. The settings for laser power, speed, and frequency
Another cause why laser marks may become difficult to read is incorrect machine settings, and the way in which energy interacts with the material is affected by laser power, marking speed, and frequency.
When the power is too low, the mark might be too light or not well defined; on the other hand, too much power can cause unnecessary material to be removed, lead to dark areas, or give an uneven finish. Likewise, a marking speed not appropriate for the material and the design can have an effect on the consistency of the result.
The frequency also has an effect on the laser marking readability process, especially when different materials and marking requirements are involved.
It would be wrong for manufacturers to suppose that a single set of settings will be suitable for all kinds of metal components; the settings must be altered in accordance with the material, the surface finish, the desired marking depth, and the required contrast.
5. The focus position and working distance
The place where the laser focuses can affect the quality of the marking; if the workpiece is not placed at the correct focal distance then the marking may suffer a loss of clarity and the fine details may become less well defined.
This is particularly apparent when dealing with small characters, thin lines, and detailed logos. If the focusing is incorrect the laser spot may become larger than desired, thus impacting the accuracy of the design.
The operator must make sure that the component is in the correct position and that the focus is adjusted in accordance with the machine’s requirements before marking starts.
When the surfaces of the products are uneven or curved, more care should be taken in positioning since the distance between the laser head and the workpiece can vary over the marking area.
6. The positioning of the workpiece together with its surface preparation
It is impossible to obtain consistent results even if the design is properly prepared and the right laser settings are used, provided that the workpiece is not correctly positioned.
When a component shifts while being processed, the marking may become misaligned or distorted; this is especially important in the case of marking a number of components in production batches.
Surface contamination can also have an effect on the final outcome. Oil, dust, residue and uneven coatings may affect the way in which the laser interacts with the material.
Before laser marking readability the workpiece, manufacturers must check it and should use appropriate fixtures or positioning devices to ensure that it remains stable. The surface should be prepared in accordance with the requirements of the material and the marking process.
7. Testing samples and inspecting the marks
It is important to carry out a final check before starting full production since the real laser marking readability result might be different from that shown in the digital design.
Manufacturers must use the material intended for use, the required surface finish, and the specified laser settings to test representative samples; this allows them to verify that small text, logos, lines, and identification codes are still readable. Manufacturers working with machine-readable identification codes can also refer to the GS1 guidelines on 2D barcode quality and verification to understand the factors that influence barcode readability and scanning performance.
Useful quality checks include:
- Checking how clear the letters, numbers, and symbols are.
- Checking that the characters are properly spaced and aligned.
- Checking the contrast and consistency of the markings.
- Looking for any incomplete characters or irregular marks.
- The barcodes and QR codes should be tested with the intended scanning equipment.
- Comparing the markings on the sample with the approved design.
They assist in spotting any issues before larger batches are processed.
The Role of the Opto Fiber Laser Marking Machine
The Opto fibre laser marking machine can be used in industrial metal marking applications where detailed text, numbers, logos, serial numbers, and other identification information are required.
The specifications given for it include a pulsed fiber laser source, a standard output power of 20W together with optional higher power options, and a wavelength of 1064 nm. The machine also has adjustable power settings and a maximum listed linear marking speed of 12,000 mm/s.
The minimum character height listed is 0.2 mm, the standard working area is 110 × 110 mm and larger sizes are available. These specifications are important for manufacturers if they need to assess character size, marking area and production requirements.
The machine is capable of carrying out marking, engraving, and texturing on materials that are compatible, such as stainless steel, aluminium, titanium, alloy steel, bronze, and copper.
Laser Marking Quality Compared with Common Marking Problems
Various marking problems may indicate different areas that require attention, and by identifying the particular issue that is visible the manufacturers can decide which one to check first.
Manufacturers can also review the common causes of inconsistent laser marking quality to identify other process-related issues that may affect the final result.
| Common marking problem | Possible factor to check | What to evaluate |
| Blurred characters | Focus position | Workpiece distance and laser focus |
| Very light markings | Laser parameters | Power, speed, and frequency |
| Crowded text | Design layout | Character size and spacing |
| Uneven contrast | Material and surface finish | Material compatibility and settings |
| Distorted markings | Workpiece positioning | Fixtures and component stability |
| Missing or incomplete lines | Design and settings | Artwork quality and marking parameters |
| Difficult-to-scan codes | Code design and marking quality | Dimensions, contrast, and scanning performance |
Final Thoughts
Laser marking readability become hard to read for a number of reasons, such as small character sizes, bad design spacing, surface finishes that are not compatible, incorrect laser settings, inappropriate focus positions, workpieces that are unstable, and a lack of adequate sample testing.
Before starting full production, manufacturers who are using laser marking on metal parts should check these factors. A fiber laser marking machine that is suitable will still need the proper design preparation and operating conditions if it is to produce readable and consistent results.
The Opto Fiber Laser Marking Machine includes features that enable detailed marking on compatible metals, and by comparing the machine’s capabilities with the seven design and setup factors manufacturers may be able to determine possible reasons for poor readability and enhance the consistency of their finished markings.
FAQs
1. What makes laser marks hard to read?
Laser marking readability may prove hard to read due to small characters, bad spacing, wrong laser settings, inappropriate focus positions, or uneven workpiece positioning.
2. Does the power of the laser have an effect on the readability of the markings?
Correct laser power can result in marks that are too faint, uneven, or too deep. The settings must correspond to the material and the desired marking appearance.
3. Does the type of material surface have an effect on the quality of laser marking?
Right, metal surfaces which have been polished, brushed, coated or left untreated may give different effects. Manufacturers should test the actual material before deciding on the final settings.
4. What effect does character size have on laser marking?
If the machine is unable to reproduce the necessary details, it may be difficult to read the small characters. Before production, attention should be paid to character height, the choice of font, and spacing.
5. What kind of machine is appropriate for carrying out detailed laser marking on metal?
The Opto Fiber Laser Marking Machine can be used for detailed laser marking readability on compatible metals such as stainless steel, aluminium, titanium, and alloy steel.
6. What is the importance of carrying out sample testing before starting laser marking production?
Testing with a sample allows manufacturers to assess readability, contrast, character spacing, alignment, and the quality of the laser marking readability on the real material prior to carrying out larger batches.
