Stainless steel is one of the most widely used metals across several industries. Prized primarily due to its corrosion resistance, stainless steel comes in different grades and variants according to the ratio of chromium and molybdenum mixed into the steel alloy material.

In addition to its distinct corrosion resistance, stainless steel also has a measure of resistance against acid attack. It is a durable and versatile material that has a visual appeal due to its characteristic lustre and can stand up to most steam cleaning and sterilisation treatments.

With a broad base of application, such as construction, healthcare, and food service, laser etching stainless steel has become an equally sought-out service. The process is fast, cheap, and highly accurate, which does not only produces high-quality output but retains the anti-corrosive properties of the metal.

Laser etching stainless steel medical instruments

Laser marking stainless steel and the medical industry

 

The medical industry is a particularly heavy user of stainless steel because of the industry’s strict requirement for materials that will not produce or transmit biological and chemical contaminants. Surgical tools made of this metal can withstand repeated cycles of sterilisation by autoclave and the oxidative effect of several sterilising chemicals. Stainless steel prosthetics, such as hip bone replacements and cranial plates, can be made of alloys especially designed to resist mechanical wear and biological reactions.

Lasers are also the technology of choice of the medical industry to comply with the FDA’s mandate to mark all medical tools and devices with a unique device identifier (UDI). This requirement creates a system of traceability and liability for all medical devices, where each product can be traced and identified to its manufacturer. Having such a system compels medical device manufacturers to be accountable for the quality of their products in case of a product recall.

Although there are different requirements in the marking of medical devices made of stainless steel according to their applications, they will most often need to be able to resist chemical and heat degradation. Lasers fulfil these requirements on top of remaining clear and legible despite repeated abrasion and mechanical stress. Laser technology is a particularly accurate and can recreate incredibly small alphanumeric characters, logos, barcodes, and QR codes with superior clarity.

Medical devices, in particular, should not have deep etches, as these become perfect breeding grounds for bacteria. For this reason, annealing stainless steel is an especially appropriate process as it merely changing the colour of the metal through a chemical reaction without consuming any of the material. Thus, the surface of the material remains as smooth as it was before the engraving process.

Stainless steel engraving and the automotive industry

The automotive industry is another industry that benefits from the use of laser technology to comply with traceability standards. Every vehicle – whether it’s a car, bus, motorcycle, farm machinery, or construction equipment – needs to be marked with a Vehicle Identification Number (VIN) once it leaves the manufacturing facility. The VIN is a 17-character serial number that is commonly marked at various components of the vehicle such as the chassis and the engines. Moreover, automotive manufacturers regularly make their own marks on their parts, whether to serve their own tracking system or simply to provide branding.

Laser machines have been used for years by automotive manufacturers for their ability to produce tamper-proof and easily identifiable marks. It’s also a fast procedure that will fit right into any manufacturing process without slowing it down – a 17-character VIN can be laser marked in only about 4 seconds. Being a non-contact method, automotive parts do not need to be clamped down before marking, avoiding secondary damage. Compared to a more traditional method such as dot-peen marking, the part to be marked using lasers do not undergo any unnecessary stress. Without the need to use fixtures or clamps, laser etching stainless steel also has unequalled flexibility in terms of marking newly designed and modified automotive parts.

In such a large-scale level of production such as those found in the automotive industry and the manufacture of engineering parts, the reliability of the machines is invaluable. As an almost entirely automated process, stainless steel produces accurate results with a consistent quality all the time. Since the marking of parts is commonly a step done towards the end of the manufacturing process, an error in this step that results in a part being scrapped will be exceptionally costly and disruptive.

Integration of a laser solution into the existing manufacturing process is made particularly easy with out-of-the-box turnkey solutions. Modern laser etching equipment has been designed to be easy to learn and use. Designs need not be made on any proprietary software, as most laser marking applications can import files created from the most common design software. Marking with dynamic data, such as part numbers and batch numbers, is well within the standard capabilities of most laser applications.

Steel engraved applications

Outside of the medical and automotive industries, laser marking of stainless steel has been used for the accurate and permanent marking of cutlery, signages, and jewelry. Aside from its rapid turnaround being optimal for high-volume production, lasers also provide an unmatched level of design freedom. Characters as small as 2pt and even photo-realistic designs can be quickly and accurately reproduced on signage, personalised gifts and trinkets.

 

CO2 and Fiber laser machines

There are two options for laser technology that can be used to engrave stainless steel: CO2 and fiber. CO2 machines, being the older technology, generally involves less capital cost to buy and install. However, this lower capital expense can eventually be offset by maintenance and parts replacement costs.

CO2 systems are particularly sensitive equipment that requires frequent adjustment and realignment. Moreover, CO2 lasers are not readily compatible with cutting and engraving of reflective materials, including stainless steel. Without any pre-treatment, CO2 systems will only recoil off of a metal surface. Laser etching stainless steel using a CO2 machine often involves coating the metal part with a specialist paint, which the laser then “burns” off.

On the other hand, fiber systems have become the standard technology for metal engraving. Merely varying the wattage output of a fiber laser allows it to create different markings and engravings with varying depths. A fiber machine is also very accurate – with diameters as low as 0.1mm, fiber lasers can create incredibly detailed designs. Best of all, fiber machines do not require pre-treatment to etch stainless steel.

The major drawback of using fiber laser systems is that the purchase price of the equipment is much higher. However, the systems make up for this by being incredibly robust. They generally require less maintenance and have fewer moving parts that need to be periodically replaced. A fiber laser also finishes the same amount of work faster – the output of 2 or 3 CO2 machines can be reproduced by a single fiber laser system. In terms of electrical efficiency, fiber lasers are clearly the winner, using only about a third of the power to produce the same amount of work as a CO2 laser.

Depending on the material you are working with, and the throughput you require, either a CO2 or a fiber laser can be the most effective marking solution for you. Each one has its strengths and drawbacks, and the appropriate selection of technology is the first step towards the successful implementation of a marking system.

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