Metal Casting Technologies : MCT DEC 2017 (4TH QRT)
METAL Casting Technologies 4th Quarter 2017 17 a foundry’s entire operation, and many state and local governments and universities offer audit programs. Industry trade groups also offer audits specific to the metal casting industry. The creation of a successful EMS for a foundry typically involves the following stages: l A foundry energy audit l Identification of energy-saving opportunities l Evaluation of energy-saving opportunities l Prioritisation of foundry projects l Implementation of an energy management programme as an inclusive part of the foundry’s overall management system As part of improved energy management, the leading energy demand management systems will enable foundries to: l Manage energy usage from all types of equipment (not just furnaces) to reduce costly demand spikes without negatively affecting production. l Take advantage of dynamic pricing for electricity. The system monitors meters and receives pricing data from utility providers in real time, automatically adjusting power demand to take advantage of lower rates or to minimise charges during rate spikes. l Participate reliably and safely in the latest demand response programmes that pay energy users for reducing their energy use – including those that require a real time, system-to- system response. Software solutions Over half of the energy used during the actual casting process is not used for the final casting itself, but for gating and risering systems, which are necessary to route metal to and into the cavities that later contain the final castings. These systems also provide material to the casting during the solidification process, counteracting the volume difference between the liquid and solid state of the metal and thereby eliminating shrinkage defects. It is here that casting process simulation can also help to maximise energy efficiency, enabling foundry engineers to design optimum gating and riser systems before the first casting is poured. This achieves energy savings in two ways – firstly through minimisation of the required amount of material, and secondly through the related reduction in energy use for the melting process. “Technological developments such as simulation software are already providing a major positive influence in sustainability efforts,” says Waupaca’s Esch. “Such software is allowing metal casters to efficiently pour moulds and optimize their mould metal yields which has a significant effect on reducing energy use by minimising remelt.” Simulation can also boost energy efficiency and lower carbon dioxide emissions by reducing the process and cycle times for high production castings. It can optimise the heat-up process and temperature distribution of permanent moulds, and determine the pattern layout with the maximum numbers of parts. It also lowers energy consumption by reducing the amount of moulding material required, improving shakeout conditions, and eliminating cleaning and rework, Significant indirect energy savings are achieved by reducing or eliminating trial and error runs prior to the final production run. Breathing easy In addition to recycling and energy use, emissions to air are another key environmental concern for foundries. The foundry process generates dusts, acidifying compounds, products of incomplete combustion and volatile organic compounds (VOCs). Dust is a major issue, since it is generated in all process steps, in varying types and compositions. Emitted from metal melting, sand moulding and casting and finishing, it may contain metal and metal oxides. Foundries were one of the first industries to use emission control systems to capture aerial contaminants and boost environmental protection. Such systems typically fall into one of two categories: l Source capture This should always be the primary means for capturing casting emissions, involving fixed capture hoods or Many of the most practical advances in melting technologies that hold potential for energy reduction centre on retrofit improvements for existing furnaces. These include oxygen- enriched fuel combustion, preheating of charge, molten metal delivery, and waste heat recovery. Much of the heat in melting operations is lost to the atmosphere. When this waste energy is re-used, it can reduce a foundry’s energy costs by up to 20%, as well as lowering emissions. Waste heat recovery devices (such as recuperators, regenerators and shaft/stack melters) simply transfer thermal energy from the high-temperature effluent stream to a lower temperature input stream (make-up air or metal charge). Waste heat conversion methods, such as absorption refrigeration, thermoelectrics and thermionics, use elevated flue gas temperatures to drive energy conversion devices. Options for heat recovery The most common uses for waste heat in the metal casting industry are preheating charge material and preheating combustion air. Another good use for recovered heat is space heating, especially in colder climates, where space heating bills can contribute as much as half of the total energy bill in the winter. At a Waupaca foundry in the United States, for example, a recovery loop added to a cupola melting system ensures waste heat from the plant is put to good secondary use. Since installation, the loop has provided 70% of the energy required to heat the plant over a typical winter, increasing the temperature of a water/glycol solution flowing through a network of coils within the facility’s air makeup units. The loop also provides all the energy for the plant’s hot water needs. “This kind of system makes environmental and economic sense,” says Waupaca’s Esch. “The energy savings mean it has paid for itself after two years. It has also reduced carbon dioxide emissions by 4,600 tonnes a year.” Some metal casters have found more innovative ways of recycling heat energy. One US-based metal caster, for example, has installed a system for using waste heat to evaporate wastewater. The facility was spending over $20,000 annually disposing of 48,000 gallons of wastewater. By using exhaust gases from a reverberatory furnace to evaporate the water, the foundry was able to slash its waste disposal costs. Enhanced energy management Rising energy costs and increasingly stringent environmental legislation mean energy management is now an ongoing concern in every foundry. The successful implementation of an energy management system (EMS) invariably relies on a collective effort from foundry personnel, starting with top management. Since the primary business goal is financial savings, managers must understand economic principles and run their departments as if they were standalone businesses. For progressive foundries, energy management is a cost reduction strategy that can have an immediate impact on profitability. It is also a risk protection strategy that insures foundries against future energy rate increases and regulatory effects. Based on a typical 4% operating profit, it takes a foundry $1 million in new sales to generate $40,000 of operating profit. It is far easier to save $40,000 in energy costs than find $1 million in new and profitable sales. Successful energy management demands a holistic, comprehensive programme. Energy consultants can evaluate FEATURE 16 www.metals.rala.com.au Reusing waste energy in a foundry can reduce energy costs by up to 20% and also lower emissions. A key environmental concern for foundries, emissions to air from the casting process can include dusts, acidifying compounds, products of incomplete combustion and volatile organic compounds. FEATURE Beckwith Macbro Resin Coated Sands Contact : Rob Dalla Via 30 Devon Road Devon Meadows, Melbourne Telephone: +61 3 5995 4244 Mobile: 0417 332 723 Fax: +61 3 5995 5030 E-mail: firstname.lastname@example.org Website: www.beckwithmacbro.com.au All grades of resin coated sand used for shell molding and shell cores for ferrous and non-ferrous applications PRODUCTS n Range of resin strengths from 1.0% to 5.0%. n Silica, Zircon, Chromite coated sands or blended mixes. n Coated Sands of different AFS typically from 50-90 AFS. n Thermal Reclaimed Coated Sands. n Frac Sand. SERVICES n Full technical and trouble shooting service. n On-site shell core and shell molding facility to evaluate the product applications. n Laboratory facility to ensure product quality. FORSALESHELLCOREMACHINESSHELLMOULDMACHINES A climatic system module from Infuser installed at a foundry.
MCT MAR 2018 (1ST QRT)