The Effect of Surface Treatment on Stainless Steel on Marking Quality

Pre-treatment of the stainless steel surface is a key step in laser marking, directly affecting the clarity and durability of the markings.By analyzing core factors such as the degree of cleanliness, surface roughness, and surface treatments, and combining this with practical experience, they help users grasp the practical techniques for improving marking quality.

Why is pre-processing so important to the quality of the marking?

We all know that stainless steel looks smooth, but in fact it can have oil, rust or even tiny scratches on the surface.These "invisible problems" can cause the laser to produce blurry or broken lines, or even cause the ink to fall off.For example, it's like writing on an oily piece of glass.

The result of insufficient cleanliness.

If the surface is oily or dusty, the laser energy will be absorbed unevenly.If a customer complains that the pattern on a part has turned gray, it's probably because the oil wasn't completely removed during pretreatment.The first step is to soak the object in an alkaline cleaning agent, and then to use an ultrasonic cleaning device to remove the grime from the nooks and crannies.

The secret of surface roughness.

Too smooth a surface would have given the laser no "foothold" to work with.An old-timer who has done comparative experiments says that if you lightly sand with 800-grit sandpaper before applying the label, the sharpness of the edge is increased by more than 30 %.But be careful not to overpolish--too much roughness will cause the laser to scatter, with the opposite effect of what you intended.

Three techniques for pre-processing.

A trick for removing the oxidized layer chemically.

When you come across stainless steel plates with a black oxide coating on them, don't rush to put them on the machine.Dip it in a diluted nitric acid solution for two minutes (remember to wear gloves!), rinse, and immediately dry with a hair dryer.The surface of the glass after this treatment is as smooth as the screen of a new phone, which makes it much easier to engrave.

Hidden effects of temperature control

Because of the low temperatures in the factory during winter, the panels can easily become damp after being treated.Once I saw workers put a board on the machine to be engraved right after it had been cleaned, and the moisture on the board caused the laser to engrave it at different depths.Now we stipulate that after pre-processing, the product must be dried in a 25 ° C environment for 10 minutes. The problem hasn't appeared again.

Saving money by choosing tools.

Don't be superstitious about imported grinding discs! A common nylon brush used with a 2000-rpm grinder can completely achieve industrial-level requirements.Last week, I was helping a friend test a factory, and we were able to save half the cost of materials by using locally made products. The quality of the labels and the test results were just as good, and the boss was so pleased that he added a chicken leg to the menu on the spot.

Guidelines for avoiding pitfalls.

If the marking becomes yellowed, it is 80 % likely that it has not been neutralized after acid washing.There is a simple test for this: Use a piece of pH paper to touch the surface of the product. If the result is neutral, then it's fine.Customers also complain that the signs rust easily, but this is because the passivation layer was damaged during the pretreatment process.It is suggested that after the paint is dry, it be wiped with alcohol to remove dust and form a temporary protective coating.

To sum up, pre-processing may seem to add to the number of steps in the process, but it actually saves time.I've seen too many people jump right into the main work without warming up, and it ends up taking them more time to get back on track.If you get the foundation right, the rest will follow naturally.