Laser Removal of Nickel / Zinc / Chromium Plating

By comparing the laser removal of nickel, zinc, and chromium, three common metal coatings, the authors analyze the differences in laser parameters, removal efficiency, and surface damage, providing a reference for selecting coating removal technologies for use in industry.The company's data on key parameters such as laser power and scanning speed help its clients optimize their production processes.

Why compare the results of laser removal of different kinds of plating?

In the metalworking industry, stripping off metal plating is often needed to repair a part or to adjust its surface properties.Nickel, zinc, and chrome are the three most commonly used coatings, but their physical properties differ widely, and their hardness, melting point, and thermal conductivity all directly affect the efficiency and effectiveness of laser removal.We are trying to find out what the parameters should be when different coatings are used, and which coatings are easier to deal with.

Design and method.

Materials and equipment.

The researchers chose steel plates of uniform thickness, and coated them with 8 microns of nickel, 12 microns of zinc, and 5 microns of chromium.The laser used is a fiber pulse laser with a wavelength of 1064nm and a maximum power of 300W.In order to simulate actual conditions, the tests were run with different power levels (80-250 watts), scanning speeds (200-800 millimeters per second) and frequencies (20-100 kHz).

Evaluation indicators.

There are three major indicators: 1.

1. **Thoroughness of stripping** --Observing the residue of the coating under a microscope.

2. Substrate damage--measuring the surface roughness of the substrate after removal.

3. Efficiency comparison--time per unit area.

The results of the experiment.

Nickel plating: "tender loving care" is required.

Nickel has a high melting point (1455 ° C), but it conducts heat quickly. It was discovered that when the power was turned up above 180W it was easy to damage the substrate.The optimal parameters are 120W of power and 400mm / s speed, which can remove the coating cleanly while keeping the surface roughness of the substrate below 0.8μm.But if the speed drops below 300 millimeters per second, the surface of the medium will begin to yellow.

Zinc coating: the most convenient option.

Because zinc has a low melting point (419 ° C), it can be cut using a 80W low-power laser at a high speed of 600mm / s.But be careful! Zinc vapor easily contaminates the laser lens, so it is recommended that you stop every 5cm2 to clean.The actual test efficiency is the highest of the three, only 12 seconds per square centimeter.

Chromium plating: A tough nut to crack

Chromium is extremely hard (HV900), so the power must be raised to over 200W to be effective.But high power is prone to cause minute cracks, so the final compromise was a 220-watt laser with a scanning speed of 250 millimeters per second.However, the efficiency is low, and it takes three times as long to apply the same area as it does to apply a galvanized coating.

Practical suggestions.

1. Test on a small sample first. Don't be stingy with the scraps. The plating thickness may vary from batch to batch.

2. Chromium plating: Pulse mode is preferred--Continuous-wave plating is prone to overheating. Pulse plating can reduce the heat-affected zone.

3. **Protective equipment** --When handling galvanized materials, be sure to wear a gas mask and ensure that the ventilation is adequate.

Maintenance costs must also be factored in.

The rate of wear for the laser head lens is noticeably different: When the chromium plating is being used, the lens has to be replaced every eight hours, but the zinc plating can last 24 hours.If the factory has to process chromium pieces every day, it is recommended that you directly buy a machine with an automatic dust removal function. Although it is more expensive, it is more cost-effective in the long run.