Modern Manufacturing Processes or Equipment - Research Paper Example

Modern Manufacturing Processes or Equipment – Laser Cutting al Affiliation Modern Manufacturing Processes or Equipment – Laser Cutting Introduction: Basic Description of Laser Cutting Laser cutting is a fairly new technology – a technology in which the strength of electromagnetic radiation (laser) is applied in the cutting of materials of different strengths. The laser cutting as a technology is particularly used to hasten production-line processes (Borade, 2012). Dahotre and Harimkar (2008) define laser cutting as a two dimensional process of machining in which the removal of the material is obtained by directing a strong laser beam on the workpiece. The heat produced by the laser beam consequently vaporizes or melts the workpiece throughout the depth or thickness of the material thereby developing a cutting front. The molten material is removed from the cutting front through a pressurized gas jet (Dahotre and Harimkar, 2008). The pressurized assist gas also facilitates material removal through chemical reaction such as by oxidizing the material. The process of material cutting proceeds through the cutting front movement across the plane of the material. The motion of either the work piece and/or focused beam relative to each other executes the process. It is important to note that laser cutting is a repeatable, reliable, and high-speed technique that can be applied to materials of various thicknesses and types to generate very clean-cuts with narrow widths. The process is specifically suited as a semi or fully automated cutting process for high production volumes. Initially, the industrial application of laser cutting involved the cutting of slots in die boards using a 200W laser. Today, laser machines are able to cut a wide variety of metallic materials including superalloys, brass, aluminum, steels, and copper, and nonmetallic materials such as quartz, rubber, cloth, wood, plastic, and ceramic (Dahotre and Harimkar, 2008). Borade (2012) states that the laser cutting process entails laser beam emission when stimulated by a lasing material (radio frequency or a gas). The stimulation is effected when the lasing material is exposed to electrical charges an enclosure. Once the stimulation of laser material occurs, the beam is reflected and bounced off from a partial mirror. The beam is permitted to gather sufficient energy and strength before being released as a jet of monochromatic consistent light. The light further goes through the lens, and is focused to form an intense beam that is less than 0.0125 of an inch in diameter. The width of the beam can be adjusted based on the material to be cut. The width can be as small as 0.004 inches. The surface material’s point of contact is generally marked with the assistance of a pierce. The power pulsed laser beam is pointed toward this point and along the material depending on the requirements. There are various methods used in laser cutting and they include: melt and blow; vaporization, thermal stress cracking; melt, blow and burn; burningscribing; and cold cutting (Borade, 2012). Figure 1 below shows the basic configuration of a laser cutting machine Fig1: Basic configuration of laser cutting machine Courtesy of Kai Chen The laser cutting approaches are based on the contact between the laser beam and the workpiece, and function of assist gas in the process of material removal. The main approaches used to cut the materials using laser include: fusion cutting, controlled fracture technique, reactive fusion cutting, and evaporative laser cutting. The choice of the suitable method and the operation condition relies on the workpiece thickness, type of laser used, and thermo-physical features of the material. Evaporative laser cutting is generally used in cutting wood, paper, and cloth. On the other hand, fusion cutting is used in the cutting of nonferrous materials like aluminum and titanium. Reactive fusion cutting is used in the cutting of stainless steel, titanium, and mild steel. Controlled fracture cutting is used in the cutting of alumina and other types of ceramics (Dahotre and Harimkar, 2008). Current State of the Art Recently, the WEC Laser division of WEC Group purchased the state-of-art Adige LT8 Tube Laser Cutting machine from BLM Group. The tube laser is known for its user-friendliness and highest flexibility, extreme precision and top quality laser cutting, on a tube with a bar weight of up to 35kg/m and a diameter range between 12 and 220 mm. It is equipped with a tilting head which permits, on all the sections (special and open profiles included), 3D cut processing. The cutting head possess 3D tilting axes semi-bevels and bevels which simplify welding/fitting operations of medium to large thickness tubes. With this state-of-the-art tube laser machine, WEC Laser can provide laser cutting of box, tube, and the most open profiles such as channel and angle with a RotoLas ability that enables laser box section cutting and laser tube cutting up to a maximum envelope of 414mm, 12mm thick, and 3m long (WEC Laser, 2011). The tube laser cutting machine is capable of cutting profiles and tubes with large wall thicknesses and diameters without the need to sacrifice productivity regardless of their complexity (WEC Laser, 2011). Radian Laser Systems have developed state-of-the-art laser cutting machines. The IPG Ytterbium fiber lasers, for example, operate at a wavelength of 1070nm and are perfect for machining, laser cutting, and marking of metals. The multi-kilowatt effective power, wide operating power range, small spot size, power stability, excellent beam quality, and the operating wavelength are some of beneficial qualities that fiber lasers come with for the majority of their applications. Fiber lasers have a “very wide dynamic operating power range, and the beam focus and position remain constant, even when the laser power is changed, allowing consistent processing results every time” (Radian Laser Systems, 2010, par 3). Furthermore, various spot sizes can be attained by changing the configuration of the optics. These characteristics enable the end user to select a proper power density for cutting a wide range of wall thicknesses and materials (Radian Laser Systems, 2010). The small spot size and high mode quality of the fiber lasers with the optimized pulses facilitate the cutting of complicated features in thin materials. This mode of cutting results in minimal HAZ and slag, which are very essential to most micro-machining applications. The high power density linked with fiber lasers’ small spot sizes imply faster cutting with superior edge quality. Pulse cutting with fiber lasers has been used in cutting silicon wafers for solar panels, stencil cutting, and cutting cardiovascular stents. The high power multimode lasers are generally used for the cutting of heavy plates and thin sheets of various materials. Common applications of the high power multimode lasers include cutting riveting holes in titanium and aluminum alloys for aerospace application, 3-D cutting of automotive body parts like high temperature steels and hydroform tubes, and cutting thick plates in steel shipbuilding and industries (Radian Laser Systems, 2010). Radian’s innovative metal marking, cutting, and machining lasers use IPG’s state-of-the-art optical fiber lasers bring economic performance and superior reliability in comparison with conventional, high power CO2 CW laser cutting processes, and the total ownership cost is minimized by up to 80 percent over the life of the product. All the fiber lasers in Radian use IPG Photonic pulsed fiber optic laser modules that symbolize state-of-the-art technologies in high performance industrial lasers. The main advantage of the Radian laser systems is based on their reduced operating costs and improved reliability (Radian Laser Systems, 2010). Safety Issues Some maintenance and safety issues have to be taken into consideration when using lasers. First, safety issues entail awareness that when an individual is working with some materials like PVC, toxic gases are released in the cutting process. Common solutions to quality and safety issues entail the installation of masking devices and air flowing handling equipment. It is important to note that the newest generation of lasers requires little maintenance because they are developed with sealed systems. The usual failure points in the laser system are generally the external optics, particularly when they are not maintained properly. Periodic cleaning should be part of the regular maintenance to avoid the failure of the laser optics (Preco, Inc., 2011). As stated earlier, there are several safety issues linked with the utilization of lasers in materials processing applications. The chief hazards linked with lasers include light exposure, fume production, and electrical shock. Majority of the lasers function with the discharge of high voltage. There is a greater risk of electric shock in the enclosure of the laser. To make sure that there are no accidental contacts with the high voltage, shorting systems and interlocks must be used. Laser light creates a significant safety risk both to humans and physical materials. Most of the industrial lasers are Type 4 which is very dangerous when in contact with any part of the human body. The light beam, for example, can cause total blindness if directed to the eye. It may lead to destruction of the front of the eye or retinal burning. It is, therefore, highly advised that one avoids skin and eye exposure to scattered and directed radiation. It is highly advised that the laser beam be completely enclosed in order to protect personnel (BOC, 2010). Figure 2 below roughly shows the intensity of light produced by the laser beam during cutting. Fig 2. Intensity of laser beam Courtesy of http://www.stainlesssteel.me Operators of the laser cutting machines should be provided with viewing screens that contain interlocked shutters. The high power laser beam should not come into contact with the skin because it can lead to severe burns. The utilization of large volumes of assist gases presents safety risks which need to be addressed. Furthermore, cutting or welding fumes can pose a hazard to personnel as they can cause suffocation, or irritation to the skin. Laser processing of polymeric or plastic materials is recognized as a significant hazard. It is worth noting that workers should recognize the hazards of the processes, and the means to control or avoid the risks must be applied in all cases. The implementation of safe working practices and safety training will assist in the reduction of these risks (BOC, 2010). Advantages and Disadvantages of Laser Cutting Advantages of Laser Cutting There are many advantages of using laser-cutting as a technique over the traditional machining techniques. Laser cutting entails a noncontact process. It is not necessary to clamp the workpiece or centre it on precise fixtures like in traditional machining. Correct positioning of the workpiece on an X-Y table with a definite direction of the cut can be easily gotten during the laser cutting process which facilitates the machining of flexible and flimsy materials (Dahotre and Harimkar, 2008). Since laser cutting is a noncontact process, there are no mechanical forces and tool wear that could destroy delicate workpieces. The absence of mechanical forces implies the use of less sophisticated fixtures for keeping the workpiece in place (Kannatey-Asibu, 2009). Automation of laser cutting is easier compared to the automation of conventional machining methods. Majority of the laser-cutting processes are controlled by Computer Numerical Controls (CNC) which facilitates the precise control of the process over the cut dimensions and higher cutting speeds. The process of laser cutting is faster compared to the conventional methods. For instance, the usual speed for cutting a 4 mm thick carbon steel with a laser (1,250 W CO2) is 3m/min (Dahotre and Harimkar, 2008). Figure 3 below shows a CNC controlled laser cutting machine. Fig 3. CNC laser cutter machine Courtesy of http://www.cuttingtoolssite.com Laser cutting produces precise and fine cut dimensions to an extent that the process can be utilized for profile and fine cutting. It can be done with a very narrow kerf width, approximately 0.1mm. The quality of cuts made in laser cutting process is high unlike it is with the conventional machining methods. The material is heated and melted by laser in a localized fashion. In combination with melt elimination in the process of cutting, laser cutting technique minimizes thermal stresses and heat-affected zones (Dahotre and Harimkar, 2008). Thus, there is minimal damage to the base material. This makes laser cutting suitable for burnable and heat sensitive materials. There is also minimal distortion and stress (Kannatey-Asibu, 2009). Also, the process of laser cutting is flexible. Furthermore, laser cutting can be utilized in various materials ranging from non-metallic to ferrous and nonferrous materials (Dahotre and Harimkar, 2008). Disadvantages of Laser Cutting Process The laser cutting process has several disadvantages. Initially, the process of laser cutting was limited to the cutting of thin materials (materials less than a few millimeters in thickness). This is, however, not the case today, thanks to technological developments. One of the main disadvantages of laser cutting is that highly conductive and reflective materials like silver and gold cannot be cut using the laser technique. The rapid quenching and melting linked with the process lead to the development of a hard edge in the cut piece for hardenable materials. Additionally, it is restricted to cutting through the materials. Therefore, blind pockets, holes, or slots are difficult to cut in precision using laser. Yet again, the laser cutting system capital cost is relatively high compared to the cost of conventional machines. It is approximately two orders of magnitude higher than the oxy-fuel system. Another disadvantage of the technology is that the processing of particular materials like polymers can lead in the generation of toxic exhaust fumes (Kannatey-Asibu, 2009). The efficiency and consumption of power of laser machines depend on the type of laser utilized for cutting and the type of cut to be made. Laser cutting entails high power consumption compared with the rest of the technologies utilized in cutting. Laser cutting of plastic materials can be very costly because plastics release fumes when exposed to heat. Because of this, the whole setup has to be assembled in a room which is well ventilated. The set-up of such a room can be very expensive. As stated before, the fumes emitted during the process of cutting can be very toxic and fatal to personnel in the company. The rate of production is not constant when laser cutting is utilized. It highly relies on the laser used for cutting, the type of material, and the thickness of the workpiece. Carelessness in adjusting laser temperature and distance can lead to the burning of some materials. Human involvement is generally required in case of repairs and test runs. When the worker comes into contact with the laser beam by mistake, he or she can suffer serious burns (Sonkushre, 2012). Future Trends in Laser Cutting Laser cutting is currently used as a graphic art medium although still in its infancy. Despite the fact that it has been used effectively in a number of companies in the last twenty years, the laser technology is now starting to find more uses in other markets. Some of the new areas of application of laser cutting relate to stationary products, direct mailings, insert ads, and party accessories. In the words of Hrukty (2009, par 2), the technology is no longer “a high-priced novelty medium reserved for limited quantities and high-end applications”. In the last several years, one of the fasted growing applications of laser cutting has been in packaging. The laser cut surfaces have unique qualities and add elegance to cosmetic and food packaging that would be hard to accomplish using other means (Hrukty, 2009). In the fashion industry, jewelry makers and fashion designers have adopted the technology and use it to develop new and unique designs. Fashion purists may hate the ideology of lasers and machines creating their clothes. However, the practice is gaining popularity within the fashion industry. Though laser-cut clothes may not fill up the stores anytime soon, it is only a matter of time before the designers start to integrate more machines in their design processes (Hines, 2011). Cut openings can have a delicate visual quality and provide a faint peek at the product or permit the consumers to sample the scented products. The tangible quality of the cut paper can also develop an additional degree of interest. In the field of packaging, which is highly competitive, laser cutting has offered the manufacturers a novel tool with which they can differentiate their products. Lower equipment costs, higher volume capabilities, and increased demand indicate that there are lasers in the future for the many finishing shops (Hrukty, 2009). Conclusion The use of laser technology in industries is a relatively new phenomenon. The technology currently is applied in various fields including medicine, production, aesthetics and machining, the list continuously growing. Laser cutting as a mechanical process has grown in use over the years. Although the initial cost of purchasing laser cutting machines is significantly high, its benefits far outweigh its disadvantages considering the quality and speed of machining among others. The laser cutting technology is bound to grow in use in several fields as currently witnessed in packaging and fashion. References BOC (2010). Laser processes. Retrieved from http://www.boconline.co.uk/health/process_safety/processes_safety/laser_processes.asp Borade, G. (2012). Laser cutting process: How does laser cutting work. Retrieved from http://www.buzzle.com/articles/laser-cutting-process-how-does-laser-cutting-work.html Dahotre, N. B. & Harimkar, S. P. (2008). Laser fabrication and machining of materials. New York, NY: Springer. Hines, M. (2011, July 14). 15 laser-cut fashion finds: From computerized swimsuits to casual cut-out clothing. Retrieved from http://www.trendhunter.com/slideshow/laser-cut-fashion-finds Hrutky, T. (2009, May-June). Trends in laser cutting applications. Retrieved from http://www.fsea.com/article.asp?ID=112 Kannatey-Asibu, E. (2009). Principles of laser materials processing. Hoboken, NJ: John Wiley & Sons. Preco, Inc. (2011). Laser basics for die cutting fabricators. Retrieved from http://www.precoinc.com/multi/articles/laserbasics/page3/ Radian Laser Systems (2010). Technology. Retrieved from http://www.radianlaser.com/newsite/technology.html Sonkushre, P. K. (2012, January 30). Advantages and disadvantages of laser cutting. Retrieved from http://www.buzzle.com/articles/advantages-and-disadvantages-of-laser-cutting.html WEC Laser. (2011). 3D laser cutting capability! Retrieved from http://www.laser-eng.com/Laser-Tube-Cutting-flyer-WEC-Laser.pdf Read More