Co2 laser machines produce laser marking on stainless steel by using a pre-treatment process, a metal marking compound is sprayed onto the surface, this is allowed to dry naturally or can be heated to speed up the process, the laser beam is then passed over the surface bonding the compound to the metal resulting in a permanent mark. Compounds are available in a variety of forms including tapes, aerosol sprays and pastes we use pastes which is sprayed onto the metal using an airbrush to produce an even coating ensuring correct bonding to the surface. Once laser marking is complete the excess compound is wiped or washed off the surface with water.
Due to the high intensity of the laser, materials such as stainless steel, titanium and most other metals can be marked directly. The high pulse power of the laser in combination with a very small laser spot diameter with this method, logos, text, serial numbers and other information can be laser marked onto the material. The surface of the material is marked a few microns into the metal and its colour is changed producing a high contrast black to dark grey mark on most metals. Stainless steel is the most popular metal used for laser marking. There are many advantages to laser marking stainless steel. Firstly stainless steel is incredibly durable and available in different grades for durability, 304 is the standard grade but 316 has a better chemical resistance and is less effected by chlorides such as salt and is therefore considered superior, making it the ideal metal choice for laser marking.
We can mark detailed markings onto the surface of metal with the certainty that the metal can withstand the rigours of the marking process. The medical industry uses stainless steel and titanium for numerous products, such as surgical equipment, specialist tools, furniture and worktops. Manufacturing mark their products with identification numbers, barcodes or serial numbers to ensure that they meet a strict level traceability. This ensures that every item is accounted for and can be traced to its original manufacturing source. Many other industries use stainless steel for its anti-corrosion properties such as the automotive, domestic appliance and catering industries. The other benefit of laser marking stainless steel is the speed and efficiency of the marking process. Depending on the type of laser machine used, complex graphics and high detail can be marked onto stainless steel in seconds. Also the robustness of the metal ensures that the marking remains clear and legible. Manufacturing companies mark products to allow them to maintain a high level of traceability without compromising on manufacturing speed.
In contrast to printing marking your products with laser enables you to create a permanent mark, which will remain on the product even under demanding conditions for example marine environments and for medical products that have to be sterilised in an autoclave for sterilisation this uses heat to kill bacterial and spores by pressurised steam for many cycles. We have marked medical products that have been tested in an autoclave and this has not faded the marking at all. Additionally, the laser machine offers non-contact functionality, which requires no consumables to operate. As a result, Co2 laser marking machines are more environmentally friendly than their inkjet counterparts. Anodised metals can also be laser marked, so the first stage of the process is to remove the coating by passing the laser over the surface with maximum intensity, this removes all traces of the anodised coating, then the compound is sprayed onto the surface and the laser passed over again to mark the surface. Titanium can be marked by a Co2 laser without the need for application of a compound, the molybdenum content in the titanium causes the laser beam to react and produce the marking.
Rotary marking is where a cylindrical product is turned in a rotary device, which is fitted into the bed of the laser machine. It is programmed to turn exactly in time with the laser beam passing over the surface of the product producing high detail along the side. The product must be symmetrical but some curvature is tolerable although it can affect the dimensions of the area that can be marked.