The lost foam or expendable pattern-casting process is a relatively new process in commercial terms, but is gaining increased attention due to the environmental and technical benefits that are achievable for some types of casts. In the lost foam casting process, an expendable pattern is formed out of polystyrene foam. Patterns can be made manually, using automated systems or by molding those using a permanent die. Manual pattern making typically involves carving blocks and gluing sections together to build up the desired shape.
The finished pattern is a single piece (i. e. no cores) incorporating all necessary gating systems. Process details and organizational: Lost foam casting is a type of investment casting process which uses foam patterns as the investment. This technique takes advantage of the properties of foam to plainly and inexpensively form castings that would be complicated or impossible, using normal “cope and drag” techniques. Why foam casting? In the world of metal casting, there are only three non-captive aluminum lost foam job shops exist, where the traditional process called sand casting remains at the top.
But most of the companies could offer only with a lost foam facility. The manufacturers gives value-added castings, though the casting part might be initially more expensive, but the entire cost of the component, for the reason that of reduced or eliminated machining, less assembly and less of the other aspects, can make it more commercial for its customers. The green sand, permanent mold and die cast are lot of established processes but there is only handful of lost foam aluminum users.
Even though the fact that there are only a small number of lost foam job shops across the country, some of the Irish and American Foam Cast still have to compete in the entire metal casting market. Due to the higher tooling costs than traditional casting the customers disregard lost foam strictly. Initially customers might be turned away by costs, but comparing to those cast by traditional methods certain lost foam components can be less-expensive. When estimating lost foam, with a total-cost point of view from design to finished component, customers save on unavoidable expenses in sand casting.
Some of the customers were hesitant on utilizing lost foam because of its intricacies, when the Foam Cast drew in its first potential customers. But lost foam supplies the ability to design without interior while casting in geometry and features from the start. The lost foam can facilitate the staff to execute direct administration correctly over the casting process even with in the facility. Lost foam can also fabricate multiple parts to make one casting from thin to thick wall components independent of a riser. Advantages of Lost Foam Casting
• The lost foam casting can be used for precision castings of ferrous and non-ferrous metals independent of size. • Compared to sand casting fewer steps are involved in lost foam casting • In the foam casting system ‘Core making’ is eliminated. • Binders or other additives and related mixing processes are eliminated. • High dimensional accuracy can be achieved and thin sections can be cast (i. e. 3 mm). • There is lower capital investment. • The flasks used are less expensive and easier to use because they are in one piece. • The need for skilled labor is reduced.
• Multiple castings can be combined in one mould to increase pouring efficiency. • Lower operating costs can be achieved for appropriate castings. • Complex castings, particularly internal sections, which require high dimensional accuracy and have thin sections, can be produced very cost effectively in comparison with to conventional sand molding processes. • Fettling and machining is minimized due to high dimensional accuracy and the absence of parting lines or core fins. • The shakeout process is simplified and does not require the heavy machinery required for bonded sand systems.
• High levels of sand reuse are possible. As little as 1-2% of the sand is lost as a result of spills. Periodically a portion of sand may need to be removed or reclaimed to avoid the build-up of styrene. Advantageous Productivity Areas of Lost Foam Process in Industry: ? Reduce Production Costs – The lost Foam process provides opportunity to reduce the labor as well as the content of energy and make other efficiency improvements must be pursued. As the activity based cost accounting approaches do the Lean manufacturing, six sigma and other concepts to progress operating efficiencies need to be practiced.
Revolutionary technologies and process changes also should be investigated to achieve metal casting without the use of tooling. The industry should investigate the application and blending of statistical, shop floor layout, computer numerical control, and scheduling technologies to radically change the nature of EOQ’s, production release sizes, inventory levels, and delivery performance in metal casting plants. ? Reduce the Energy Content of Cast Products – In the lost foam system the energy consumption can be reduced by improving product quality – thereby decreasing the scrap and melting requirements.
The Improvements in equipment and process efficiencies can also save energy. The foam casting industry should build up a complete understanding of thermo physical behavior of alloys in melting, flow, and solidification as well as the capability to accurately simulate these behaviors. ? Waste Management – In the foam casting system, in order to enable increased reuse of foundry sand and other by-products and waste streams, more environmentally sound binders, and better emission treatment, the improvement in process are required.
These Process improvements will also help to reduce scrap and thereby waste in casting processes. ? Reduced Labor Content of Cast Products –the current foam casting practices must be investigated in order to identify opportunities to decrease the number of steps in the process, develop and implement no-touch casting processes, and execute advanced information and control technologies. ? High-Quality, High-Performance Engineered Cast Components –the techniques to progress quality, precision and performance will result in fewer customer returns.
The foam industry must develop an understanding of all process variation which affects the performance of castings in their applications; and develop process controls to ensure that variation is within allowable limits. Better performing products will also open new markets for metal castings. Tools are needed to capture digital, analog, or computer vision signals from all levels of the metal casting process to provide real time feedback about process status and to provide the ability to correct variances before they become product defects.
The current status of Metal Casting Industry: According to Donahue “There have been significant advances from the past two years in aluminum lost foam, and yet domestic growth is almost non-existent”. The development have been made possible not because of a large group of lost foam metal casters but because of individual metal casters. According to Donahue, this influx of capital has contributed to advances in eight key areas of aluminum lost foam casting: * New types of foam which resists the folding and creating voids;
* Improvement of the metal interface with sand by coatings; * Sand with low expansion rates that fill more quickly and completely; * More capable compaction systems; * reduced porosity through pressurized solidification; * Alloys that is more compatible with the filling process unique to lost foam; * modeling software; * gating advancements, such as hollow fiber sprues. Lean Manufacturing Lean Manufacturing is an operational strategy oriented achieving towards the shortest achievable cycle time by eliminating the waste.
Its key thrust is to increase the value-added work by eliminating waste and reducing incidental work. The procedure often decreases the time between a customer order and shipment, and it is designed to radically improve profitability, customer satisfaction, throughput time, and employee morale. The advantages are lower costs, higher quality, and shorter lead times. The term “lean manufacturing” is invented to represent half the human effort in the organization, half the manufacturing space, half the investment in tools, and half the engineering hours to develop a new product in half the time.
Jones and Mitchell (2006) as cited in Clive Atkinson & Dr Margaret Linehan suggests Four significant benefits that can be gained through the adoption of lean management to an organization. First, increased productivity with the same workers with the existing resource levels. Second, the Improvement of delivery of work within less time. Third, reduction of error or defects and improved quality. As a Fourth one, Improved Customer satisfaction derived from the improved staff morale and a stable workforce. The characteristics of lean processes are: 1. Single-piece production 2.
Repetitive order characteristics 3. Just-In-Time materials/pull scheduling 4. Short cycle times 5. Quick changeover 6. Continuous flow work cells 7. Collocated machines, equipment, tools and people 8. Compressed space 9. Multi-skilled employees 10. Flexible workforce 11. Empowered employees 12. High first-pass yields with major reductions in defects Lean Manufacturing integrates the use of Heijunka, level sequential flow, the heartbeat or pace of the production system, continuous flow manufacturing, cellular manufacturing, and pull production scheduling techniques such as Kanban.
The Lean module explores the 5 Principles: • Value: it deals with –What the customer is willing to pay for. • Value Stream: Actions which adds value to a product or process. • Flow: The continuous movement of product, favoring single-piece flow and work cells versus production lines. • Pull: Replacing only material that is used and eliminating excessive inventory. • Strive for Perfection: A relentless elimination of waste on a never-ending basis. Applying Kaizen as a Tool of Lean Manufacturing Technique: Kaizen Event: This is a quick-hit method for Lean process improvement.
This tool needs organizational learning and readiness for implementation and is a power tool to eliminate waste in the facilities of casting industry. . Tools: Kaizen Model Kaizen was created in Japan following World War II. The word Kaizen means “continuous improvement”. It comes from the Japanese words “kai” which means “change” or “to correct” and “Zen” which means “good”. The Mixed model, one piece flow manufacturing can become a reality only when setup can happen in seconds. In these days several companies are doing mixed model assembly.
Progressive automobile manufacturers use mixed model assembly methods to customize each vehicle as it comes down the line. The power of the approach presented in kaizen for quick change over is to help make it possible to do mixed modeling in production as well by making changeovers even faster. Kaizen is a system which involves every employee – from superior management to the cleaning crew. Everyone is encouraged to come up with small improvement suggestions on a regular basis. This is not a once a month or once a year activity, it is a continuous process.
These repeated small developments add up to major benefits. These will result in improved productivity, improved quality, better safety, faster delivery, lower costs, and better customer satisfaction. Above all of these benefits to the company, the employees working in Kaizen-based companies generally feels easier to work and more enjoyable resulting in higher employee moral and work satisfaction, and lower turn-over. With every employee looking for ways to make improvements, the expected results will be:
Reduces Waste: In particular areas such as inventory management, waiting times, transportation, and worker motion, employee skills, over production, excess quality and in processes kaizen model will reduces wastage. Improvement: it improves in space utilization, product quality, use of capital, communications, production capacity and in the maintenance of employee. Kaizen Offer: It provides immediate results in the organization. Instead of focusing on large, capital intensive improvements, Kaizen focuses on creative investments which solve continually more number of small problems.
Still the large and capital projects and major changes in that are needed; nevertheless kaizen improves the process of capital projects, the real power of kaizen is in the ongoing process of frequently making small improvements which develops the processes and reducing waste simultaneously. SMED SYSTEM: The other tool called SMED system is a process which makes possible to perform arrangement of equipment and changeover operations with in ten minutes, and is also used as an element of Total Productive Maintenance –TPM. Effects of 1. Forming of Implementation Team:
The production employees/executors and professional team members, having responsibilities in their own sectors, represent the best alternative for team members. The purpose in implementing the 5S techniques is to enlarge the effectiveness through the development of knowledge and skills of the workers, and their responsibility. By this technique workers become more dedicated to their work; they are capable to understand appropriately the given situation and can take the correct decisions. Hence the implementation team members must act as a machine, production, tool and design technologist.
2. Training: The maintenance employees have to perform changeover team and machine setup has to be introduced into and qualified in implementing new methods and the procedures introduced into changeover procedures minimum once a week. Clarifying all the misunderstandings, training is forecasted to be done per team and questions as well as giving clear directions to enable faster and easier tool exchange (SMED). 3. Survey and screening of the situation prior to the method implementation Every changeover detail are recorded in video and complete work activity sequence is written down.
Every move and every activity of the operator have to be recorded specifically, hence any unnecessary activity to attain even worse results. The same procedure recording should be done after implementing the method to establish the effectiveness in both applying the method and accomplishing the result (SMED). 4. Classification of Activity: In the classification of activity it is consists of the analysis of recorded material and the activities which can be divided into two groups: the internal and external ones.
External activities are all the set up activities which can be performed while machine is in operation; where as the Internal set up activities are the ones that can be performed only if the machine is not in operation. The Internal activities refer to the dismantling of used tool, to the mounting of new ones and ascertaining communication in line of machine tool (SMED). 5. Transforming internal activities into external activities: The Transformation of internal activities into external activities is much possible. It is the most proficient procedure ever for decreasing machine outage rates (SMED).
6. Improvement of internal activities minimization – Set the tools visually, at the hand of operator (5S) – Using the connectors that may be rapidly exchanged for all tool power sources (5S) – Possible Usage of as many locating pins for accurate tool positioning. (SMED) – Cranes with sliding transporters (SMED) – Using of cranes for heavy tools only (SMED) – Using of standard tools as possible (SMED) 7. Improvement of External activities: – Placing visual markings for easier and faster identification (5S) – Using check list to prevent unpredictable events in resources preparation (5S)
– “At hand” tool organization (5S) – Work place organization that decreases tool search time (5S) – Using appropriate tool preheating machine along with adequate device (SMED). 8. Forming and Standardization of the SMED procedures. 9. Saves quantification of savings reached by SMED. 10. CIP (Continuous Improvement Process) Applicability of Lean to Lost foam Industry: The five-step thought process for directing the implementation of lean techniques is easy to remember, but not easy to achieve: 1. By using the product family –the specification of value from the standpoint of the end customer.
2. Elimination of steps when necessary, that do not create value and identifying all the steps in the value stream for each product family. 3. Make the value-creating steps occur in tight sequence such that the product will flow smoothly toward the customer. 4. As flow is introduced, permit customers to pull value from the next upstream activity. 5. As value is specified, value streams are identified, wasted steps are removed, and flow and pull are introduced, begin the process again and continue it until a state of perfection is reached in which perfect value is created without any waste.
There are several approaches an organization must take to meet the desired goal. Here, are some outlined tips to ensure a continuous lean transformation. 1. Identifying the company’s cultural model: Culture answers the question of “how do we do things around here? ” and is actually the accumulation of leadership behaviors. Any organization which is serious about “becoming lean” needs to identify its cultural model and determine how to close the gap from the current cultural state to the ideal future cultural state.
Once the base of improvement action works to build new principles, values and behaviors into the organization, then the ideal culture aspired to and begin to work on organized progress toward that ideal state is to defined. In the end, the organization’s culture determines the ultimate success of any lean transformation. 2. A process improvement culture should be build: After identifying this model, a culture that practices process improvement should be build as part of daily life. Changing from a reactive culture to a process-improvement culture requires embracing an “opposite” approach.
3. Establishing a practice of leadership involvement The senior leadership committed to lean improvement only to drop off after the implementation gets started. Bringing leaders to the point where they recognize how to seek out waste before removing it drives the success of lean transformation. 4. Continually engage in rapid improvement events The most effective way a manager or manufacturing engineer learns how to apply lean tools and concepts is through participation in the initial week-long improvement event.
The next step is to establish a series of these events as you develop new processes and uncover additional areas of waste, which will help you incorporate lean into every aspect of the business. Effects of Improving Productivity in Lost Foam Industry: Metal Casting industries that apply Lean manufacturing principles can be seen improvements in the following areas: • Reduced Manufacturing Lead Time to less than 1 day • Improved Delivered Quality – The defect rate is reducing to Six SIGMA level which is 3 Parts Per Million • Improved Delivery Performance to 99+%
• Increased Inventory Turns to greater than 50 turns per year • Reduced conversion costs on materials to finished goods is to 25 – 40% which is less than mass producers • Reduced Manufacturing space to 35 – 50% which is less than mass producers • Reduces New product development rate to less than 6 months References: Clive Atkinson & Dr Margaret Linehan, An Analysis of Lean Management Procedures within Irish Motor Dealerships: International Journal of Buisnessand Management – Vol .
3, No. 11, Retrieved July 18, 2009, from http://ccsenet.org/journal/index. php/ijbm/article/viewFile/894/849 Dennis Sowards, Lean Thinking is not a Fad Diet, Retrieved July 18, 2009, from http://www. masetllc. com/news/pdfs/0306-1. pdf Lean management practices in the pharmaceutical industry Heiko Gebauer, Michael Kickuth, Thomas Friedli International Journal of Services and Operations Management 2009 – Vol. 5, No. 4 pp. 463 – 481 Kaizen, Retrieved July 18, 2009, from http://www. graphicproducts. com/tutorials/kaizen/kaizen-benefits. php Lost-foam casting, Retrieved July 18, 2009, from http://www.reference. com/browse/wiki/Lost-foam_casting Modern casting, Retrieved July 18, 2009, from http://goliath. ecnext. com/coms2/gi_0199-3666396/Finding-a-niche-with-lost. html Lost Foam Foundries find Energy-Saving Opportunities, Retrieved July 18, 2009, from http://www. foundrymag. com/feature/feature/67804/lost_foam_foundries_find_energysaving_opportunities Hobert E. Eppicch, Implementation ofMetal Casting Best Practices, Retrieved July 28, 2009, from , http://www1. eere. energy. gov/industry/metalcasting/pdfs/implementation_final. pdf
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