Lasting impressions

With increasing numbers of manufacturers asked by customers to provide traceability, part marking is becoming more commonplace at machine shops up and down the country. Part of the dilemma for production engineers, however, is which marking technology to deploy? Popular options include laser marking, pin stamping, electro-chemical etching and ink jet printing, as well as engraving on the machine tool. Deciding factors range from permanency requirements and material composition, through to ease-of-use and production environment compatibility. According to Rofin-Baasel (01327 701100), the flexibility of the laser, combined with its capability to mark a diverse range of metals, has seen the technology become the process of choice in the Formula One sector, where race cars have, on average, some 3,500 individual components that are subject to a process of continuous improvement. Add to this the fact that teams typically have three cars and you have around 10,000 individual components that need to be managed at any given time. Image:F1 teams are using small data matrix technology Rofin says that laser marking has become the preferred solution for Formula One teams, as it is able to produce permanent 'readable' codes on virtually all materials, without compromising the structural integrity of the component. Because laser is able to produce either round or square matrix elements, and can mark codes as small as 1 by 1 mm, Rofin has installed several of its PowerLine E-10 end-pumped vanadate laser sources at a number of Formula One facilities. The high beam quality produces a small focused spot and this, combined with short pulse lengths, produces high quality matrix codes. With the leading suppliers of laser marking systems keen to capture market share, the pace of machine development in recent years has heightened. Image:Trumpf's TruMark technology is "affordable" Fimark (01932 245226), for example, has introduced the Larovi 6-axis laser system for marking and etching complex shapes and forms. The Larovi integrates laser, robot and 3D scanning to deliver 6-axis processing that enables the end user to wrap legends, codes and images around intricate components. The system can accommodate components measuring up to 250 by 250 by 250 mm, with a maximum weight capacity of 20 kg, while the robot has a speed of 4 m/s. The Larovi also has real part location, compared to theoretical location, which allows the laser to readjust for each individual component and gives consistent positional accuracy. At UK laser marking machine manufacturer Electrox (01462 472400), one of the latest innovations is a through-the-lens (TTL) system, developed for the high accuracy marking of small item arrays loaded in a jig. The company says that customers can achieve rapid set-up, minimise waste and increase throughput. In operation, the TTL camera first verifies 'part present/not present'. If 'not present', the camera moves to the next position in the jig. On 'part present', the camera software compares the image with a reference image and initiates X, Y and rotational offsets in the mark file to compensate for any small positional inaccuracies and variations in the orientation of the part in the jig. One particular application is high value titanium and stainless steel cross-head screws for surgical implants, where the marked area may be as small as 2 mm² and the cross may be at any angle in the jig. Image:Addison Electrical hails ITC's engraving tools Although the ability to provide effective marking and traceability services as part of a component manufacturing 'package' is enticing for potential customers, many machine shops view marking as an additional capital outlay that is unmatched by added value. For this reason, some laser marking system suppliers are introducing entry-level technology. The new TruMark 3010 diode-pumped solid state laser, with a wavelength of 1064 nm, for example, provides Trumpf's (0844 482 0188) established laser marking technology at an affordable price. Thanks to new Navigator software, even inexperienced users can perform laser marking. Using the intuitive menu navigation, operators simply select the material and the desired marking process. The laser subsequently creates a test matrix, from which the user selects the one that achieves the best result. The Navigator software then determines the optimal laser settings for marking, such as pulse frequency, pulse power or scanner speed. While laser technologies have understandably captured the most column inches in recent years, many other forms of marking have also evolved in order to retain their appeal, such as the new Micromark re-circulating spray system from EFD (01582 666334), which helps manufacturers eliminate the maintenance and downtime associated with conventional ink marking systems. EFD says that conventional marking systems include felt pads that can become contaminated with debris and spray valves that clog from heavy ink pigments. EFD's 781RC system negates these problems by using a re-circulating pump to keep pigments in suspension and a short burst of air after each cycle to clear residue in the nozzle. Identifying new markets is integral to the success of many non-laser marking systems. Technifor (01926 884422), for instance, is already witnessing ample interest in its recently introduced XF530p micro-percussion marking system – a portable model capable of attaining 0.4 mm depth. Whether used on cylindrical or smooth surfaces, it can be applied to the part, without the need for additional pre-tensioning equipment or supplementary positioning. The XF530p can mark pipelines (mining, oil and gas), lifting/hoisting equipment (pallet trucks, forklift trucks), off-road vehicles and naval constructions. Another alternative to laser marking that remains popular is engraving using a machine tool, largely because the component can remain on the machine and be completed in a single set-up. By default, cutting tools for engraving operations need to be small, but strong. Take a new series of engraving end mills from LMT Fette (02476 369700), for instance. Developed using FEA, Fette Micro Cutters have a highly stable neck geometry that reduces the likelihood of breakage. Optimised transition points in the design effectively halve the influence of cutting forces on the tool by shifting the weakest point to an area of lower impact. One company using engraving cutters to great effect is Addison Electrical Ltd, a manufacturer of electrical control panels located in Banff, near Inverness. Here, the company has recently taken to engraving, using a 6 mm diameter cutting tool with 0.75 mm flat from ITC (01827 304500) to produce legends on stainless steel control panels that are machined on a CNC router. "In recent years, we've trialled many engraving tools, but ITC's cutter has been the best by far," says director Kenneth Addison. "The tool has excellent swarf evacuation and, with a longer flat, the ITC cutter has extended tool life way beyond anything we've used previously. Cutter breakages have also been eliminated." Resourceful outsourcing To fulfil the requirements of companies that cannot justify the purchase of laser marking systems, ES Technology (01865 821818) now offers an enhanced sub-contract laser marking service. Thanks to recent investment, the Oxfordshire-based company can now boast a combination of seven different YAG and CO2 lasers operating full time, while major contracts from the medical and motorsport sectors have also led to an increase in staff. On medical device components in particular, it is essential that any graduations marked on thumbwheels, control knobs or dials are accurate in their positioning and radial pitch. Here, ES Technology has developed a robust solution for the radial positioning of components on circumferential marking applications. The use of zero-backlash planetary gearboxes to rotate and index components under the laser during marking ensures that all graduations are produced with an accuracy of ±0.05 mm. First published in Machinery September 2009