Iron Alloy

Iron alloys can be described as alloys which have iron as the principal component. Iron is used as a constituent in majority of the commercial alloys. For example, iron is the major component of wrought and cast iron and wrought and cast steel. Iron can also be alloyed with manganese, silicon, vanadium, chromium, molybdenum, niobium, selenium, titanium, phosphorus, or other elements for commercial applications. Some iron alloys are also used as addition agents in the process of steel-making. There are special-purpose iron alloys which demonstrate superior characteristics, like - magnetic properties, electrical resistance, thermal expansion, corrosion resistance, and heat resistance, etc.

Iron Alloy Castings

Iron castings are produced by molding iron alloys or molten iron. Gray iron is possibly one of the oldest worked metals used for casting. The metal is also one of the most abundant and least expensive materials.

Gray iron was the original cast iron, though it has recently been replaced in various applications by other iron-carbon alloys which have higher tensile strength. Ductile iron, as the name suggests, has high ductility than traditional iron materials, such as gray iron. These materials incline to be brittle and are prone to fracture under high tensile stress.

Iron is cast as like any other metal. It is poured into a mold and extracted after cools down. There are various types of casting methods, through which iron can be molded; some of these methods include shell molding, green sand molding, and centrifugal molding. The procedure through which the iron is caste can affect the mechanical properties of the metal, especially in regard to its cooling rate. Iron castings are used in a wide array of applications, including:

·         Automotive

·         Appliance

·         Agriculture

·         Machinery industries

Cast iron components are also used for pump housings, engine blocks, electrical boxes, decorative castings, and more.

Related pages

·         Steel Alloy

·         Grey Iron

·         Ductile Iron

Cast Iron Alloy

The term Cast Iron can be described as a large family of ferrous alloy. These alloys contain 2-4% carbon, along with silicon, manganese. Cast irons are manufactured and produced in specified shapes for processing by machining, heat treating, or assembly. Sometimes, to meet specific requirement it can be forged or rolled. Casts iron are produced by melting pig iron and then combining it with steel or scrap iron.

Normally, cast iron contains silicon up to 3%. Though this composition may vary while making special compositions, such as:

·         Silal: Silicon up to 6%

·         Duriron: Silicon up to 12%

One can purchase cast iron in several commercial grades, such as gray iron, chilled iron, mottled iron, white iron, malleable iron, ductile iron, spheroidal graphite iron, nodular iron, and austenitic cast iron.

Production Process

Cast iron is produced by melting pig iron. Often, this melting is done along with scrap steel and scrap iron. It also involves a several steps which lead to the removal of undesirable elements (phosphorus and sulfur).

·         The main objective of this processing is to reduce carbon and silicon content to the desired levels. Then, the addition of other elements to the melt takes place.

·         A small blast furnace known as a cupola is used to melt iron.

·         After melting is complete, the molten iron is removed from the forehearth of the blast furnace.

·         The final form is made by casting.

During solidification, the major proportion of the carbon precipitates in the form of graphite or cementite. When solidification is just complete, the precipitated phase is embedded in a matrix of austenite that has an equilibrium carbon concentration of about 2 wt%. On further cooling, the carbon concentration of the austenite decreases as more cementite or graphite precipitates from solid solution. For conventional cast irons, the austenite then decomposes into pearlite at the eutectoid temperature. However, in grey cast irons, if the cooling rate through the eutectoid temperature is sufficiently slow, then a completely ferritic matrix is obtained with the excess carbon being deposited on the already existing graphite.

Types of Cast Irons

Given below is a list of different types of cast irons and their properties:

·         White Cast Iron: White cast iron is hard to be machined as it's tough and brittle.

·         Grey Cast Iron: Due to the presence of microstructure of graphite in transformed-austenite and cementite matrix, grey cast irons are softer.

·         Spheroidal Graphite Cast Iron: The chemical composition of the cast iron is similar to that of the grey cast iron but with 0.05 wt% of magnesium.

·         Ductile Cast Iron: One of the most popular alloys used in casting. It has variety of applications including automobile components, industrial machinery, wind turbine electrical energy generation, valves, air conditioning machinery, lawn and garden equipment and agricultural products.

·         Spheroidal Graphite Cast Iron: Spheroidal graphite cast iron is known for its excellent toughness and has many applications, e.g. crankshafts.

Cast Iron Alloy Castings

Cast iron alloys have found wide usage in casting applications for their characteristics, such as strength, good strength to weigh ratio, economical price, and availability in abundance, capability to produce complex geometries. The cast iron castings are used in a multitude of applications, such as automotive, agriculture, appliance, and more.

Advantages in Casting:

·         A family of materials which is capable to meet a variety of engineering and manufacturing application requirements (the "family", includes - gray iron, ductile iron, compacted graphite iron, malleable iron, and white iron).

·         Capability of casting with inserts of other materials.

·         Capability to manufacture and design highly complex geometries and sections in various sizes.

·         Possibility to cast intricate shapes as well as very thin to very thick section sizes.

·         Good strength to weight ratio.

·         Generally economical than competing materials and relatively low cost per unit of strength than other materials.

·         Superior damping capacity, especially in Gray Irons.

·         Capability of redesigning and combining two or more parts from other materials into a single casting, thereby reducing assembly time and cost.

·         Different types of casting processes for low, medium or high production.

·         Variety of iron castings can be used without heat treatment (as cast) however, in case if required, they can be heat treated to enhance the overall properties or specific properties such as surface hardness.

Ferrous Alloys

Ferrous alloys are iron based alloys which have found extensive usage in wide range of industries because of its flexibility to meet strength, toughness, and impact of diverse industrial applications. This flexibility depends on the heat treatment processes and methods, which modifies the final micro-structure. Examples of ferrous alloys include carbon steels, stainless steels, alloy steels, tool steels, cast steel, cast iron, maraging steel, and specialty or proprietary iron-based alloys.

These days, many alloy manufacturers are trying to meet the compositional standards of the Unified Numbering System (UNS). Unified Numbering System (UNS), jointly developed by American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE), offers an overall designation system for thousands of metals and alloys in commercial use.

In UNS, metals and alloys are assigned a lettered prefix followed by a five-digit number. For example, carbon steels and alloy steels are categorized under the UNS G category and carry designations, such as UNS G10950.

Other Specifications for Ferrous Metals and Alloys

·         AISI-SAE

·         European Norm (EN)

·         Casting grades

·         U.S. Military specifications (MIL-SPEC)

Types of Ferrous Alloys

There are different types of ferrous alloys available in the market, which include – carbon steels, alloy steel, stainless steel, cast iron, cast steel alloy grades, cast iron alloy and iron alloy. Brief descriptions of these ferrous alloys are given below:

·         Carbon steels are ferrous alloys which contain carbon and small levels of other alloying elements, such as manganese or aluminum.

·         Alloy steels contain low to high levels of elements such as chromium, molybdenum, vanadium and nickel.

·         Stainless steels are highly corrosion resistant, ferrous alloys which contain chromium and/or nickel additions.

·         Cast iron, a ferrous alloy, contains high amounts of carbon. Ductile iron, gray iron and white cast iron grades are different cast iron types.

·         Cast steel alloy grades are made by pouring molten iron into a mold.

·         Cast Iron Alloy and Iron Alloy are 2 major ferrous alloys used in most industrial applications.

Material suppliers provide ferrous metals and alloys in many shapes and forms:

·         Semi-finished stock shapes are used for part fabrication. They are also suitable as feedstock for casting, forging, spinning and other forming processes.

·         Common stock shapes include bars, rods, tubes, plates, strips, shims, spheres, foil, wire, billets, slabs, and blooms.

·         Materials are also available as ingots, powders, fillers, and reinforcements.

Ferrous Alloys Casting

Companies often specialize in casting of ferrous alloys due to the requirement of specialized equipment for melting and pouring ferrous materials. Casting of ferrous materials is typically achieved through means of shell casting, sand casting, or to a lesser extent investment casting.

In ferrous casting, the most commonly used metal materials are cast iron alloys and iron alloys that include grey iron casting, ductile iron casting and steel iron casting.

Buying Tips

Before choosing ferrous metals and alloys for specific usages, a buyer must analyze the followings:

·         Dimensions: Outer diameter (OD), inner diameter (ID) overall length, and overall thickness are important dimensions.

·         Production processes: Most materials are cast, wrought, extruded, forged, cold-finished, hot-rolled, or formed by compacting powdered metals or alloys. Electric arc furnaces are used to produce very clean metals and alloys with fewer inclusions and lower variability.

·         Features: For improved weldability and the corrosion resistance Low carbon steels are used. For compressive strength, cold-worked steels are suitable.

Semi-Solid Metal Casting to Reduce Costs

Semi-solid metal casting (SSM) is a virtually net shape production process which gives manufacturers and users of copper alloy parts a substitute and, in several cases, an economical way to manufacture bulk quantities of parts with superior component quality compared to conventional pressure die casting technique.

The capability to apply SSM casting or die-casting with metal in a semi-solid state is an outcome of the successful evolution of a high temperature nickel-base alloy die system. This high temperature nickel based alloy die system prolongs the die life in die casting metals and alloys with high melting temperatures. As the process requires easily available cold chamber horizontal die casting machines as the casting unit; it has the potential for far-flung applications and uses by existing casting professionals equipped with such machines and technology.

Semi-solid metal casting is made with metal at a temperature between the temperatures of liquid and solid state, with the fraction solid being in the range of 30-65 percent approximately. The semi-solid billet holds its form and shape and is suitable for loading into the shot sleeve of a traditional die casting machine. For the semi-solid metal to have adequately low viscosity, the structure at the working temperature should comprise of a globular primary solid state surrounded by the liquid state. The technical and economical feasibility of the Semi-solid metal casting process are ascertained, to a great degree, by the approach used to develop the starting stock with the necessary precursor structure.

Advantages of Semi-Solid Metal Casting
As an advanced casting technique, SSM casting offers huge potential in saving costs, energy, and material, and in reducing the environmental impact of casting. The advantages are -

• Virtually net shape processing
• Reduced thermal fatigue heat, reduced mold or die wear, and reduced solidification shrinkage as a result of the reduced feedstock temperature.
• Lower shear strengths of semi-solid slurries that are related with lower forming forces than fitting operations for solid metal
• Potential for superior tolerance control because of the inherently tight process temperature control related with SSM casting and reduced thermal cycling of dies
• Finer, more consistent, micro structures resulting in higher mechanical performance
• Control of viscosity, which may result in less turbulent mold and die filling that, minimizes the gas entrainment, shrinkage, porosity, hot tearing, and other solidification shortcomings
• Superior material utilization in making small components because of the productivity and accurate introduction of metal into the forming dies
• As alternative for sand casting, SSM cast parts production gets rid of the environmental costs and troubles of reclaiming and disposing of lead-contaminated sands
• Increased casting speed compared to liquid processing due to lower thermal demands on the dies
• Allows for the lead content of red brasses to be highly reduced and, combined with a semi-solid charge, should enable alloys usually prone to hot tearing to be die cast

Best Foundry Practices

The metal casting industry has been, and continues to be, an integral component of the industrial backbone of several nations across the world. The industry provides employment to a large number of people and supplies huge amount of castings thereby impacting almost every other industrial and commercial sector. The metal casting industry is also an important recycler of metal scrap, a major energy user, and an important pollution prevention partner in many countries.

Good foundry practices address critical technology deployment requirements that will help foundries in saving costs and increasing profits. These practices help in reducing the energy consumption and environmental impact of the metal casting industry and improve its competitiveness.

Given below are some of the good practices that can be adopted for cost savings and increase in profits:

Energy Saving Practices
By adopting following measures and practices, foundries can make big cost savings –

Set variable frequency drives on motors
Getting rid of voltage imbalances helps in reducing losses from vibrations, mechanical stresses, torque pulsations and overheating.

Switch off equipment and lighting when not in use
Specifically place a start-up and shut-down procedures to control energy usage spikes.

Install high efficiency lighting
Using fluorescent lighting with magnetic ballasts instead of older ballasts is always cost-effective. Install targeted lighting at inspection points rather than less efficient ceiling lights.

Cut down the compressed air pressure set point by 10 percent
Maintaining excess air system pressure is very expensive. Set points can be cut down with proper maintenance of system and continual repair of air system leaks.

Upgrade motor drive belts
Using energy efficient cog belts instead of drive belts help in reducing energy requirements. Cogged belts can function on existing v-belt pulleys, but at lower temperatures.

Adopt superior melting practices
Specific recommendations may vary depending on the type of melting system used by the foundry. Furnace manufacturers can be of great help in helping to identify good melting practices for energy savings. The use of preheated air/oxygen and optimized burner designs has found to be good for gas-fired furnaces.

Improved compressed air practices 
Compressor should be properly sized, it should not smaller or over-sized. Use air storage systems to limit idling of compressors. Reduce leaks at valves, couplings and pipe joints.

Short cycle heat treatment
Majority of the heat treatment practices followed by foundries are overly conservative and waste energy. High efficiency furnaces and furnace linings are usually cost saving.

Low Cost Technology Practices
By adopting following measures and practices in various technical domains, foundries can save costs –

Melting
Melt cold, pour hot, pour fast – This will reduce the consumption of melting energy to minimum, while at the same time improves the quality of melt and reduces disfunctioning. It is usually much economical in the long run to completely preheat ladles than to melt hot and admit high temperature drops during the transfer of metal.

Molding
Upgrade the sand testing quality assurance – good control of sand systems ensure superior mold quality and reduction in scrap. Make consistent use of sand supplier testing capabilities. In several cases, improved molding practices can help reduce the biggest single contribution to casting scrap.

Scrap Reduction
Improved reporting and analysis of scrap – The single effective way to reduce scrap is to identify the scrap and its root causes in a proper manner. Lack of attention to detail in reporting of scrap may badly affect the bottom line; for instance, it is crucial to identify ‘sand’ or ‘slag’ as the causes of scrap instead of simply grouping them together as 'dirt'.

Lighting
Good housekeeping & lighting results in improved quality – A little extra KW of energy use, specifically in inspection areas, actually results in money savings. Good housekeeping leads to pride among workers and improved quality of products.

Data Collection
Decisions should be based on sound data collection - Make sure that the data, which you have collected has sufficient gage R&R; it is useless to collect data if you are not going to use it. Employees will be much more accurate and efficient collection of data if they know how that data is going to be used.

Training
Training helps in enhancing the skills and productivity of employees – Make use of all internal and external training resources to improve the work skills of your employees. If production employees are better trained they are found to be better problem solvers.

Profitability
Superior costing & pricing systems – This is essentially a challenge especially in the jobbing foundry, but is essential to ensure the long term success of an organization.

Metal Piles at China Ports indicating sluggish growth

A reddish-gray mountain range is springing up across China’s eastern seaboard, casting a shadow over the nation’s economy.

The mountains are iron ore, a crucial import which’s a lifeline to the world’s largest steel producer, and their size has become a telling, even if imperfect, signal of the Chinese economy’s sharp, sudden sputter.

Iron ore stockpiles at Chinese ports this week reached an all-time high of around 120 million tons, a senior analyst for Beijing’s Umetal.com told China Real Time on Thursday. The high supply level is not a good indicator: It suggests steelmakers aren’t in a hurry to produce, signaling a weak appetite across the industry that is heavily dependent on China’s all-important real-estate sector.

It’s not just iron ore.  China is the world’s largest buyer of just about every industrial commodity, so an economic slowdown since April in the world’s second largest economy is a reason for concern in global trade.

Coal stockpiles this week also reached a 2012 peak, rising 40% compared to a year earlier at 8.7 million tons, according to analysts at a research agency affiliated with the National Development and Reform Commission. High stock levels also extend to agricultural commodities, with the state-backed China National Grain and Oils Information Center warning last week that “recent soybean arrivals at ports have been on the higher side.”

As far as iron ore is concerned, however, the rising port stock levels aren’t necessarily a harbinger of doom, said Zhang Jiabin, research director for Beijing-based steel consultancy Umetal.com. While higher inventories normally point to slower downstream demand, Zhang said it would be too simplistic to say consumption is going down. “The ore stock level has been fairly steady this year, and although there has been some output reduction among smaller steel mills, there have not been large-scale production cuts,” he said.

Iron ore spot prices began to increase in the last week of May after sliding 9% from mid-April, signaling that steel makers have resumed bargain hunting.

Still, if ore inventory consumption is measured and compared in terms of how many days’ port stocks can last, it’s clear the industry is languishing. Stock levels surveyed in a sample of 50 smaller mills over the last 2 weeks have remained around 29.9 days-of-use, Macquarie Commodities said in a report published Wednesday. In comparison, mills were holding about 20-28 days’ worth of stocks last year, Macquarie said.

Steelmakers are also facing more problems obtaining bank loans. “It’s an open secret that banks are now more restrictive toward loans for steel mills and fluctuating prices have reduced the ability of trading houses to use imported steel as collateral,” Zhang said.

In some cases, analysts have already started projecting that rising quayside supply will dent China’s import appetite. Macquarie estimated that refined copper imports in May could fall 25 percent from April as Chinese consumers opt to run down high levels of domestic stocks. Copper stocks are estimated to have risen sharply this year to around 1 million tons. Iron ore imports have shrunken for 2 successive months.

Bouts of high port inventories don’t always tell the story of a slowdown that’s here to stay. China’s steel mills have been known to pause buying as a collective tactic to secure cheaper ore prices. But if the freighters calling at Chinese ports need any early indication of what’s going on, they need look no further than the record high right at their offloading berths.

Europe steel body asks EU to safeguard imports of metal scrap

Eurofer has asked Commission to watch and act on trade barriers

* Recyclers, scrap traders are worried by increasing protectionism

* About 30 countries including Ukraine, Russia restrict exports

LONDON, June 7 (Reuters) - Europe's steel industry association Eurofer has asked the EU's executive Commission to monitor and possibly act against nations outside the bloc which restrict exports of raw materials such as scrap, saying such barriers are unfair.

"We have recently sent a letter to the Commission saying that they should monitor those countries that are restricting exports of scrap and other raw materials and then possibly put some measures against this," Eurofer's Axel Eggert told Reuters.

"We want to have a level playing field because this is harming our industry."

Eggert did not name countries which were retaining scrap for their own use but an economist at the Organisation for Economic Cooperation and Development (OECD) said about 30 countries restrict the scrap exports.

Some of these include Ukraine, Russia, Vietnam, Venezuela and Argentina, said Barbara Fliess, senior economist in the Trade and Agriculture Directorate of the OECD.

Eggert said Eurofer, which says it represents 100 % of EU steel production, has not suggested any particular measures and has not asked for any restrictions of scrap exports from the bloc.

"That would be difficult under current EU law and it's not in our policy to ask for this kind of restrictions," he said.

He said that there had been calls from other European organizations to keep the EU's raw materials and scrap metal for its own use.

"There are discussions within the EU institutions, and they are not coming from Eurofer, to attain a close loop in Europe which includes raw materials and scrap."

Fears of Protectionism
Members of the Bureau of International Recycling (BIR) said last week that European steelmakers, including some top manufacturers, were pressuring the EU Commission to impose export restrictions on steel scrap from the EU to help preserve their domestic raw material stocks.

The head of Italy's steel industry body Federacciai, Antonio Gozzi, also told a news conference earlier this week that the association is considering requesting to put duties on exports of scrap steel from Europe, on which the local industry depends for about 60 % of supplies.

Members of BIR, which groups scrap and recycling businesses around the world, described the issue of export restrictions as alarming, very dangerous and unnecessary.

"There is enough scrap in Europe for domestic steelmakers," Tom Bird of Dutch company Van Dalen Recycling said during a recycling conference last week.

The BIR non-ferrous metals board also expressed concern over the visible growth in protectionist moves. To fight this trend it has commissioned a study, initially focused on aluminum and copper scrap consumption in the various countries and its flows around the world.

New Livonia recycling plant pays cash for metal, electronics

LIVONIA, Mich. (WJBK) -

Every day it's a surprise to see what shows up at Advanced Recycling on Merriman.  The recycling plant that specializes in metal and plastic recycling, opened for business in mid-May.  According to its owner Michael Bassirpour they're the first metal recycling facility in Livonia.

"We buy metal from industrial accounts, manufacturing companies, local residents trying to clean up their garages, basements.  We take electronics, all different types of metal bearing material.  Everything gets recycled at our facility.  We have a zero landfill policy."

We found one person dropping off scrap metal from Orin Jewelry in Garden City.  He got about $10 for some old light fixtures.

People also came by with old electronics and all kinds of other items.  Some walked away with thousands of dollars.  Everything that ends up at Advanced Recycling is shredded, melted down and reused, keeping toxic chemicals out of the environment.

People actually recycle some pretty surprising things like a beat up, old snowmobile.  It's staying out of a landfill and its owner got $50.

"We thumbprint the customers.  We have a photo I. D.  There's a picture of every single transaction.  We're not the police, but we do our best to ensure we don't buy anything stolen."

Advanced Recycling is open 6 days a week.  They say they pay some of the best prices in town.

Boliden Expands WEEE Recycling Capacity in Sweden

Swedish metals company, Boliden (STO:BOL) has officially opened a SEK 1.3 billion ($181 million) new expansion of its electronics recycling facility at the Ronnskar copper smelting plant, with a capacity of 120,000 tonnes per year.

According to company announcement the increased use of electronic products, shorter product lifecycles and stricter legislation governing electronic waste, means that the worldwide availability of electronic scrap is increasing.

Boliden officials said the expansion project was started in 2010 and the smelting of electronic material in the new facilities began in January this year.

If we believe metals specialist, its Ronnskar is one of the world's most efficient copper smelters in the recycling of copper and precious metals from electronic scrap.

The smelter is an integrated metallurgical complex that Boliden said extracts high-purity metals at low cost and with good environmental performance.

The company added that the investment is in line with its view of metals' eco-cycle in a sustainable society, and is helping to ensure that more electronic scrap is recycled, rather than being sent to landfills.

"A growing share of the metal production will originate from recycling. With this project Boliden combines high environmental performance with good business returns," explained Lennart Evrell, president and CEO of Boliden.

Things Looking Good for the New Scrap-Metal Plant in Riverton

RIVERTON – A new scrap-metal recycling plant has started processing test samples and plans to ramp up its production capacity in the coming months.

S.I.C. Recycling Inc., a subsidiary of Assumption-based Sloan Implement Co., started the plant just south of Interstate 72 earlier this year. The project got funding of more than $900,000 in financial incentives from the state.

“Things have been going great,” general manager Brady Bird said. “We haven’t had any significant hiccups.”

The plant will eventually process scrap metals which don’t contain iron, such as copper-aluminum radiators and copper wiring, and may expand to other items including old computers and other electronic waste, Bird said.

“The typical process is to run a couple loads to get an understanding for how the machinery’s working, and then you make some tweaks,” Bird said.

S.I.C. already has hired office workers, manufacturing personnel, a maintenance supervisor and “a handful of operators,” he said.

While S.I.C. isn’t hiring at present, the company always accepts applications and anticipates more openings in the coming few months.

According to officials, they expect the operation to generate 25 new jobs, but Bird said the final number will depend on several economic factors.

“It’s all based on what’s going on in the scrap industry and the commodity market,” Bird said. “If construction picks back up and the market is hot, then we’ve got significantly more volume coming through than we would otherwise.”

As per Village President Bob Todd, the new business will be a boon for Riverton.

“We’re excited and ready to get them going,” Todd said.

Besides generating jobs and property tax revenue, local officials hope S.I.C. will also result in business growth around the I-72 interchange at Overpass Road, he said. That area was annexed as part of the process of bringing S.I.C. to town.

A full-service truck stop or a motel will be good fit for the area, Todd said.

The plant also may lead to lower electricity bills for residents.

The village’s peak demand for energy is currently at night, meaning customers pay more for the power they use when they get home from work, Todd said.

Once the plant reaches its full capacity, the amount of energy it uses should shift peak demand – and the accompanying higher rates – to the daytime hours, he said.

Novel Casting Process Could Change the Way Complex Metal Parts Are Made

A Georgia Tech research team has developed a novel technology which could transform how industry designs and casts complex, expensive metal parts. This new casting technique makes possible faster prototype development times, as well as more efficient and cost-effective manufacturing processes after a part moves to mass production.

Suman Das, a professor in the George W. Woodruff School of Mechanical Engineering, has developed an all-digital approach which allows a part to be created directly from its computer-aided design (CAD). The project, sponsored by the Defense Advanced Research Projects Agency (DARPA), has received $4.65 million in funding.

Suman Das displays a ceramic mold produced directly from digital designs using large area maskless photopolymerization (LAMP) technology. In his right hand, he holds a single-crystal superalloy turbine airfoil which was cast using a ceramic mold of the kind he holds in his left hand. 

"We have developed a proof-of-concept system that is already turning out complex metal parts, and which fundamentally transforms the way that very high-value castings are made," said Das, who directs the Direct Digital Manufacturing Laboratory in Georgia Tech's Manufacturing Research Center (MaRC). "We're confident that our approach can reduce costs by at least 25 % and reduce the number of unusable waste parts by more than 90 %, while eliminating 100 % of the tooling."

The approach being used by Das and his team focuses on a technique called investment casting, also known as lost-wax casting. In this method, which dates back thousands of years, molten metal is poured into an expendable ceramic mold to form a part.

The mold is made by creating a wax replica of the part to be cast, surrounding or "investing" the replica with a ceramic slurry, and then drying the slurry and hardening it to form the mold. The wax is then melted out – or lost – to produce a mold cavity into which metal can be poured and solidified to create the casting.

Investment casting method is used to design precision parts across a wide range of industries including aerospace, energy, biomedical and electronics. Das's current efforts are focused on parts used in aircraft engines. He is working with turbine-engine airfoils – complex parts used in jet engines – in collaboration with the University of Michigan and PCC Airfoils.

Today, Das explained, majority of the precision metal castings are designed on computers, using computer-aided design software. But the next step – creating the ceramic mold with which the part is cast – presently involves a sequence of 6 major operations requiring expensive precision-machined dies and hundreds of tooling pieces.

"The result is a costly process which normally produces many defective molds and waste parts before a useable prototype is achieved," Das said. "This trial-and-error development phase often requires severl months to cast a part that is accurate enough to enter the next stage, which involves testing and evaluation."

By contrast, Das's approach involves a device that builds ceramic molds directly from a CAD design, completing the task much faster and producing far fewer unusable parts. Called Large Area Maskless Photopolymerization (LAMP), this high-resolution digital process accretes the mold layer by layer by projecting bitmaps of ultraviolet light onto a mixture of photosensitive resin and ceramic particles, and then selectively curing the mixture to a solid.

The technique places one 100-micron layer on top of another until the structure is complete. After the mold is formed, the cured resin is removed through binder burnout and the remaining ceramic is sintered in a furnace. The result is a fully ceramic structure into which molten metal – such as nickel-based super alloys or titanium-based alloys – are poured, forming a highly accurate casting.

"The LAMP process reduces the time required to turn a CAD design into a test-worthy part from a year to about a week," Das said. "We eliminate the scrap and the tooling, and each digitally manufactured mold is identical to the others."

A prototype LAMP alpha machine is at present building six typical turbine-engine airfoil molds in six hours. Das predicts that a larger beta machine – currently in construction at Georgia Tech and scheduled for installation at a PCC Airfoils facility in Ohio in 2012 – will produce 100 molds at a time in about 24 hours.

Though the present work focuses on turbine-engine airfoils, Das believes the LAMP technique will be effective in the production of several types of intricate metal parts. He envisions a scenario in which companies could send out part designs to digital foundries and receive test castings within a smaller period, much as integrated-circuit designers send CAD plans to chip foundries today.

Moreover, he said, direct digital manufacturing enabled by LAMP should allow designers to  produce increasingly sophisticated pieces capable of achieving greater efficiency in jet engines and other systems.

"This process can produce parts of a complexity which designers could only dream of before," he said. "The digital technique takes advantage of high-resolution optics and precision motion systems to achieve extremely sharp, small features – on the order of 100 microns."

Das also noted that the new process not only creates testable prototypes but could also be used in the actual manufacturing procedures. That would allow more rapid production of complex metal parts, in both low and high volumes, at lower costs in a wide range of industries.

"When you can produce desired volumes in a short period without tooling," he said, "you have gone beyond rapid prototyping to true rapid manufacturing."

Pittsburg State Organised Metal Casting Training

Pittsburg State University conducted its 12th annual Investment Casting Institute's Industry Certification Course.

This year 30 people signed up for the training, coming from parts of the world.

Investment casting is used to produce precision parts for various of industries from auto manufacturing to orthopedic implants.

Today the students used the PSU foundry to pour molten metal into forms they create.

"This particular training is for people in industry, they are already process engineers, casting engineers, product development engineers, people who develop the particular process," says Russ Rosmait, the Director of the Investment Casting Training Center.

"Whatever we can pull from here, the actual practical approaches to making the castings and put that into simulations, that is what is going to help the customer out in the end," says participant Steve Sikorski.

PSU's metal casting certificate program is one of just 25 in the U.S. accredited by the Educational Foundation.