VIEWS: 25 PAGES: 49 POSTED ON: 3/13/2011
Energy and Environmental Issues in Manufacturing 3/3/09 Amie Ruhl Lyndon Wong Martin Koh Teo Qing Ren Yue Wei Chuan Topics Covered Casting Machining Lubricants and coolants Dry Machining Other Technology Case Study Casting Sales of $25 to $28 billion annually 2,480 metal casting facilities located throughout the United States Employing approximately 161,000 people Metal forming technique for 90% of all manufactured goods and for all machinery for manufacturing Casting: Energy Energy consumption estimated to be 200 and 250 trillion Btu Representing about 1% of all U.S. manufacturing energy use 55% of total energy costs can be attributed to melting Positive Actions $1.25 billion invested annually in pollution prevention technologies and in meeting environmental standards Uses scrap metal (for which it pays $1 billion annually) as 85% of its feedstock for ferrous castings U. S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), Industrial Technologies Program (ITP) Metal Casting Portfolio has funded research and development in cooperation with the metal casting industry to reduce its energy consumption and improve productivity Experimental technologies Electron Beam Melting Immersion Heater (High-Temperature Melting) Infrared Heating Microwave Melting Plasma Heating Solar Furnace Microwave Melting Originally developed by the DOE’s Y-12 National Security Complex for melting of uranium Conventional heating involves transferring of heat through the outer surface of the material to the interior Microwaves can penetrate the mass, enabling rapid transfer of high-intensity heat throughout the bulk Microwave Melting Microwave melting could cut melting cost by 30% Germany and Japan are taking a strong lead in the microwave technology applications Plasma Heating Plasmas are gaseous collections of electrically charged particles such as electrons and protons. As the ionized plasma flow hits the metal surface, it releases its energy melting the metal. The energy consumption rate is as low as 0.198 kWh/lb (of aluminum) compared to 0.345 kWh/lb (of aluminum) in induction melting. Plasma Heating Minimizes metal loss due to oxidation and contamination Dross rate of melting aluminum is lowered to less than 1% compared to the conventional 3 to 12%. Coolant Introduction to cutting fluids and lubricants Cutting fluid used in the following operations: Cutting Abrading Metal forming Introduction to cutting fluids and lubricants Benefits of metalworking fluids(coolants): Better surface finish Longer tool life Narrower tolerance of the work piece size Cleaner cutting zone Better resistance to corrosion Introduction to cutting fluids and lubricants Types of metalworking fluids: Straight metalworking oils Emulsifiable metalworking oils Synthetic metalworking fluids Semi-synthetic metalworking fluids Facts about coolants 1984 figures: Estimated 100 million gallons of metal working oil used per year in U.S Coolant consumption is estimated higher than 100 million gallons per year Cost of purchasing and disposal is about 48 billion a year. Health effects About 1 million workers are exposed to coolant in U.S Chlorinated paraffin transformed to dioxin Mist droplets can cause cancers, breathing problems and respiratory illness Non water miscible fluids usually cause skin disorders Health effects cont. In addition: Health effects cont. Bacteria and fungi can grow in cutting fluids Responsible for most of the health problems What is Dry Machining? Dry Machining refers to machining with no fluids Motivation: total manufacturing cost Motivation Disposal issues Permits Ecological compatibility Dry Machining Today Currently possible for some materials and operations Nickel Milling Steel Turning Aluminium Drilling Decreasing Difficulty Cutting Fluids Cool Lubricate Dry Machining Options Alternative Generate Alternative cooling less heat Lubrication Alternate Cooling Chilled air or Carbon dioxide Liquid Nitrogen Alternate Cooling: Cold air gun Alternate Cooling: Cold air gun Valve Vortex generation chamber Generate Less Heat Tool Geometry - Use of positive rake edges to reduce temperature - Chip grooves to break chips Process change - Higher speeds Generate less Heat: Positive Rake edges Positive rake with chip moving down top face of tool bit Generate Less Heat Inserts with positive rake edges - Chip groove to break chips into smaller sizes Alternative Lubrication Minimum quantity lubrication (MQL) Lubricious coatings Alternative Lubrication MQL MQL involves lubricating the workpiece with a very fine mist of coolant The coolants used are usually synthetic esters and fatty alcohols Alternative Lubrication MQL Characteristic of Minimum Quantity Fluids Synthetic Esters Fatty Alcohols -Chemically modified vegetable oils -Long chained alcohols from mineral oils -Biodegradable -Poor lubrication properties -Good lubrication properties -Better heat removal due to evaporation -Good corrosion resistance latent heat -Vaporises with residuals -Little residuals Alternate Lubrication MQL Typical MQL system Alternate Lubrication: Lubricious coating Insulate tool from heat Lower friction for chip removal Coating usually achieved via Physical Vapor Deposition (PVD) Many possible coatings -TiAlN, TiCN, MoS2 -combinations Other Processes Includes: forming, joining and assembly, surface treatments, rapid prototyping and heat treating Concerns Increasing energy consumption Greenhouse gas emissions Must combined technical feasibility, cost effectiveness, & ecological benefits Clean Process Design & Process Modification- Assembly Isolate processes identified as hazardous Eliminates direct hazards Auxiliary systems required Process Modification Green Assembly Plants Run out of “easy fixes” such as scrap elimination, energy efficient machines and solvent elimination Manufactures responsible for where and how they get the material- supply chains End-of-life management Application of solid lubricants- Turning Boric Acid- feasible alternative to the conventional cutting fluids Reduces cutting forces and tool wear low coefficient of friction at the tool work piece interface with the formation of lubricating film Feed System: Boric Acid Government Incentives Renewable energy credits Tax incentives Energy Star Case Study: Ford Motor Company and Pollution Prevention Dry Machining at Visteon Indianapolis Steering Systems Plant Description of the Facility - 1.9 million square foot facility in Indianapolis, Indiana. - Operating since 1957 - Production of steering columns, gears, and automotive components. Primary production operations machining, heat treatment, and assembly of components. Description of the Opportunity Being Addressed Six thread grinding machines were being used to produce power steering carbon steel worm gears. These grinding machines required the use of cutting oil. Oil mist emissions generated by these machines required an air emissions permit (potential emissions of 18 tons per year) and the use of pollution control equipment. Description of the Improvement Six grinding machines were replaced with five whirl milling machines (no cutting oil.) The quality of the finished part was significantly improved to that produced by the old process. Chips are removed via a drag belt chip conveyor. Significant benefits of this improvement include: · No oil mist · No odor emissions · No requirement for pollution control equipment or an air emissions permit · No waste oil generation · 75% less chip waste · Chip waste is recyclable · Cutting tips are recyclable · No sludges to be landfilled · No dermatitis risk · Elimination of fire protection requirements · Plant recognition - Governor's Award for P2 Substance Addressed Reduction Obtained Cutting oil 100% Oil mist emissions 100% Odors 100% Sludge 100% SAVINGS REALIZED (OPERATIONAL) $650,000 / YEAR CAPITAL / OPERATIONS INVESTMENT: $2.6 MILLION PAYBACK: 3.5 YEARS ENVIRONMENTAL HIERARCHY LEVELS: Source reduction and waste stream elimination. Conclusion -Manufacturing processes contributes to pollution and harms the environment. -Existing processes and facilities must minimize flows and loads wherever possible, and nontoxic substances must be substituted for toxic substances wherever possible. - Cleaner and more advanced processes that does less harm to the environment are available and to be discovered. Questions?