Lost wax to lost foam: reflections on past, present and future.
The above title was chosen with careful thought, and this lecture was written with a concerted effort to not bore you with anecdotes, but reflections on a lifetime blessed with friends and unusual experiences. The great challenge of this effort has been the sorting out of highlights of a 55-year great experience with great people - an experience that will continue. Foundry persons, by the very nature of the demands of their daily exertions - motivation, creativity, ingenuity and integrity of performance - are truly an unusual group. Yes, I'm proud to be a foundryman.
In 1972, only 25 years ago, I was privileged to author and edit the Metalcaster's Reference and Guide. Our primary goal was to produce a compendium of useful data and information related to metalcasting that would not become obsolete. As a matter of fact, the slogan for announcing the marketing of this APS publication was "everything you wanted to know about metalcasting and did not know where to find it." The preface of this volume expanded on the writings of Bruce Simpson, National Engineering Co., in his 1969 book, History of the Metalcasting Industry, in which he made a truly interesting observation: "The metalcasting industry has a glamorous and thrilling past, but one seldom used even by foundrymen in capturing the imagination of the public. It is hoped that this book will give foundries data upon which to build programs of public interest."
In that same hope, we have included an abbreviated "Timeline of Casting Technology," excerpted from the comprehensive one published in modern casting's 1996 Buyers Reference Issue (November). Compiled by AFS staff, it provides an overview of key technological events that have changed the course of our industry. Too often, great efforts are expended for comparatively short and immediate use, then only remain as an archival reference. It is our hope that you will treasure and frequently reference this work.
Where We've Been
Throughout the years, I have received many honors in the form of recognition, along with invitations to contribute to various publications. Although these invitations can be declined and must be of an extra curricular involvement (in addition to the normal work day), the challenge of contributing from a vast treasure of experience has been ample reason for accepting some of the assignments. One of the most recent was a collaboration with Martha Goodway, Curator of the Smithsonian Institute, Washington, DC in writing the chapter on the "History of Metalcasting" for the American Society of Metals Vol. 15. She dealt with the very early and ancient metalcasting, while I wrote the chapter adapting a great deal of the aforementioned Simpson material, as well as updating the chapter to present day technology.
With ongoing archeological expeditions and the world's thirst for historical artifacts, we continue to find evidence of superior metalcasting examples now dating back almost six millenia. Among the artifacts presently on exhibit at the Smithsonian Institute is a bronze investment casting of a door knocker [ILLUSTRATION FOR FIGURE 1 OMITTED]. While we have no way of knowing what the as-cast quality was or how much hand tooling was done, as one example of lost wax castings of the past, the quality of this casting is excellent. Its full length from top to bottom is 38 in. This is circa 465 B.C., and has been identified as being cast for a Chinese emperor.
In the preface for the 1972 Metalcaster's Reference and Guide, I wrote, "our industry has moved more rapidly in the past 25 years than in the preceding 3500. With the impending transition to such major accomplishments as the metric system, greater environmental awareness and constant technological advances, it is too much to hope that this first edition will be free of errors or without important omissions." This statement, made 25 years ago, was quite prophetic in some respects. Although we are the world's only major country that still has not "metricated," the advent of OSHA and EPA, and the fantastic costs to our industry for compliance or litigation, environmental awareness has certainly become a major element in our manufacturing processes. As for technological advances, there continues to be a constant acceleration in the years since World War II.
Right Place, Right Time
As we prepare to discuss the present state of our industry, there is a saying "Timing is of the Essence," and we pause to reflect on the importance and personal interpretation of this phrase. In my lifetime, which includes 55 years of continuous service to the metalcasting industry, I have seen the U.S. involved in four wars, and watched our industry advance to become a producer of net shape and near net shape castings. We believe that the impetus for this advance of technology began with the introduction of the Croning Process (better known to our industry as the shell or shell mold process). Prior to the introduction of the shell process, the foundry industry relied primarily on green sand for molding, and conventional core oil for its baked cores.
While I was the metallurgist for the Buffalo Pipe and Foundry Company in 1949, I was fortunate to meet Frank Less, Technical Marketing Director of the Durez Co., which was then engaged in a race with the Monsanto Co. to patent the phenol formaldehyde compound necessary for use with the shell molding process. That day, I poured the first shell molds made in the U.S. They consisted of a series of house numbers from 0 to 9, mounted on a section of broken transite core plate and poured in aluminum bronze since the nonferrous division of the foundry was in production of a permanent mold aluminum bronze brash holder for U.S. Navy DC motors.
The success of shell molding as a viable casting production process was immediate. It provided the stimulus for binder manufacturers to transfer this technology into the development of the new binder compounds that appeared in rapid succession through the 1950s and 60s, giving our industry the flexibility of choice in using these systems for molds and cores. It was during the early 50s that the shell process was introduced as a unique coremaking process, heralded by its ability to produce a "shell" core instead of the previous solid, baked, oil bonded cores. Even today, after almost 50 years, the shell core process is a major element in a great amount of today's casting production - both ferrous and nonferrous. The era of shell molding and shell core development was a major chapter in my career, and Johannes Croning was himself awarded the AFS John A. Penton Gold Medal in 1957.
Parallel to binder development during this fabulous era of the 50s was the introduction of ductile iron (certainly one of the greatest metallurgical developments of the 20th century). The decade also saw the development and introduction of high-density molding and the accompanying advances in sand technology, offering maximum control of dimensional tolerances and improved casting surface quality.
The history of the development of ductile iron is well known and very well documented. The trials and tribulations endured by the pioneers of the process were recorded by an AFS series of interviews for the 25th anniversary of ductile iron's development. Here again, I was fortunate to be involved in much of the early development - the failures as well as the successes - plunging the magnesium as the nodulizing treatment, enjoying the fascinating personal discussions with Keith Millis and his co-inventor and colleague at International Nickel Company (INCO), Albert P. Gagnebin. Although the research and developmental work had been performed by INCO and the co-inventors, I feel that our metalcasting industry - the Steve Karsays, QIT Co.; Verne Pattersons, Foote Mineral Co.; Lyle Jenkins, Wagner Casting Co.; and many others, were responsible for proving the metallurgical accomplishments in actual casting performance.
The other major development of the 50s - high-density molding - also had its pioneers or, in a more accurate vernacular, gamblers. They were people who risked their reputable manufacturing names in an industry that had grown familiar (as well as complacent) with the compaction of clay-bonded sands with hand rammers, then pneumatic rammers and onto squeezers, jolt squeezers and jolt rollovers. Eminent sand technologists like Clyde Sanders, American Colloid Co.; Joe Shumacher, Hill & Griffith Co.; Bert Troy, National Engineering Co.; and Tom Barlow and Cliff Wenninger, International Mineral & Chemical Co., gave a lot of time, perseverance and patience assuring veteran foundrymen and molding superintendents that sand preparation would now have to conform to differing characteristics, especially lower moistures.
Similarly, we must not fail to mention the original research done in this period in the use of electronics by the world renowned sand technologist Gerhard Levelink and his colleague Julien Berg. In his AFS-funded research, Levelink unveiled his Water Explosion Theory, which today is no longer a theory, but an unfortunate reality in a great many of our casting facilities. The categorized burn-on/burn-in defect identified in 1973 by Levelink as the "hard mold defect" is responsible for a great deal of current casting rework and scrap. It was my privilege to meet with him and to arrange for this AFS-funded research in 1972, despite storms of protest over going abroad for an investigator. His use of the microphone within a mold to be poured and the use of the oscilloscope to record the explosions during pouring still stands alone as a tribute to ingenuity as well as to the transfer of technology.
Scrap and Rework
I have always found it disturbing to make a technical engineering visit to one of our member foundries at which claims are made of very low casting scrap percentages, only to find that the finishing room has literally become a sculpturing room, with excessive grinding of weld repairs or surface defects in order to camouflage discontinuities. As customer demands become more exacting, we must refocus our attention on the astronomical costs of rework. If only one were to review the inventory and purchases of supplies of the special tooling being used in our sculpturing operations, this alone should alert any manager to the situation that is at work like a creeping paralysis amongst many of our foundries. The JIT buzzword for delivery means little when casting flow is detoured for rework.
I hasten to comment at this point on the excellent Hoyt Lecturer in 1994 by my good friend of many years, CMI's John Jorstad. A main theme of his presentation was the aim for "zero scrap." This continues to be our target, but through the years of metalcasting as an art (and now with technological advances) married to a science, we are closer to his goal. But in reality, until our people develop a work ethic of pride in craftsmanship and accomplishment, we will continue our extensive and expensive rework. Contrary to Crosby's title "Quality is Free," we must acknowledge that this is not true. Casting quality obtained through rework is expensive and takes its toll on the margin of profit.
Necessitated by high-density molding machine requirements, sand testing has grown from its very basic approach of gauging physical properties to sophisticated and more meaningful online tests, such as the Mold Quality Indicator test. In addition, dependable and reliable tests have been developed for accurately defining the friability (brittle characteristics) of a molding sand. Here, it is interesting to note an instance where we have long known about an existing condition, without having a consistently effective solution. But now, through transfer of technology, we are capable of solving the problem instead of guessing at causes and using the T & E (trial and error) approach. In speaking of friable or brittle sands, a large number of our green sand foundries are plagued with this sand condition and fail to recognize it as a major contributor to casting surface defects. Interestingly, this condition also existed in sand systems without the sophisticated formulations of today's mixtures. During the 1938 Casting Congress, an audience member asked Harry Dietert to clarify a point from his presentation on sand friability. His response was most interesting: "A friable sand is a sand that has lost its cohesive and adhesive characteristics. It is a rotten sand."
Pioneers of sand testing - Harry Dietert; Clyde Sanders; H. Ries, Cornell Univ.; Douglas Williams, Ohio State Univ.; Alex Graham, H.W. Dietert Co.; Franz Hoffman, George Fischer Co.; and Dittmar Boenisch, Foundry Technical Institute, Germany, would be proud of the continuing efforts of our AFS technical committees' dedicated efforts in the interest of pursuing continued in-depth research of sand performance in casting production.
Eyes on the Future
The future of our industry is dependent upon the managers of our industry. Regardless of the castings being produced, or whether the facility employs 10 or 1000, commitments to adapting to change and to improving technology will, along with programs for people development, become a top priority and require formulae necessary for success rather than mere survival. Clyde Sanders issued the challenge in his Hoyt Lecture of 1973 when he asked: "management, are you ready?" Our good friend Hugh Sims bluntly stated how seriously we must reevaluate our educational system when, in his 1991 Hoyt Lecture, he presented his challenge: "help the eagles fly." As Sims said, "We all take pride in the past, but we live for the future."
We are an industry capable of meeting our customer's increasing quality demands. Rapid prototyping has materially shortened our tooling and pattern capabilities, and has also now proven to be the source of accuracy in unraveling complex casting geometries [ILLUSTRATION FOR FIGURE 2 OMITTED]. The combination of computer-aided design, rapid prototyping and solidification modeling is destined to bring our industry the respect and recognition that its craftsmanship and creativity have long deserved. With the technology's pioneering accomplishments, rapid prototyping successes have already saved thousands of hours and dollars in casting prototype development.
Progress is being made on other fronts. Emphasis on ladle metallurgy, increased knowledgability in the use of ceramic filters, continued study and research of metal flow, metal velocity and mold filling characteristics, as well as ladle design and refractory erosion studies, will contribute to the continued quest for improved casting quality.
Take, for example, bottom-pour ladles, which for years have used a circular orifice in the ladle nozzle. Continuing research into clean steel and the minimizing or elimination of the reoxidant inclusions, which create major quality problems in bottom-poured steel castings, has produced a radically changed orifice design in the nozzle [ILLUSTRATION FOR FIGURE 3 OMITTED]. This has materially changed the characteristic of the metal flow and reduced the reoxidation ("scum") defect as a major contributor of casting surface defects.
Research and analysis of sand performance (silica, nonsilica, new and reclaimed) and the properties responsible for contributing to casting quality problems must be on the forefront of continued, intensive study. In metallurgy and alloy development, we must continue to study the field performance of austempered ductile iron. We must endeavor to develop new alloys capable of handling the increased temperatures and operating pressures present in modern applications and demanded by industries that have developed the confidence to replace fabrications with castings.
The continually evolving use of lasers for welding is tomorrow's path for the development of cast weldments. We must continue to communicate with designers to inform them of the benefits of castings and the advantages of CAD/CAM and rapid prototyping for tooling and pattern development. Casting designers must be encouraged to explore the advantages of the casting processes that are no longer laboratory curiosities but now proven in production. The excellent castings produced with the lost foam [ILLUSTRATION FOR FIGURE 4 OMITTED] and the "V" processes, as well as the high-integrity and quality of today's permanent mold aluminum castings, contribute to technologies of the past that conform to the new demands imposed by an increasing environmental awareness. These methods are meeting customer demands for closer dimensional tolerances and the ever-increasing challenge to our industry for net shape and near net shape components.
Ongoing research and development to study improved machining possibilities, solidification characteristics of complex casting configuration and thinwalled casting design will continue well into the 21st century.
3200 B.C. - The oldest casting in existence, a copper frog, is cast in Mesopotamia.
1480 - Vannoccio Biringuccio (1480-1539), the first true foundryman and the "father of the foundry industry," is born. The founder of the Vatican, his De La Pirotechnia is the first written account of proper foundry practice.
1642 - America's first iron foundry (and second industrial plant), Saugus Iron Works, near Boston, pours the first American casting, the Saugus pot.
1776 - Foundrymen Charles Carroll, James Smith, George Taylor, James Wilson, George Ross, Philip Livingston and Stephen Hopkins sign the American Declaration of Independence.
1809 - Centrifugal casting is developed by A.G. Eckhardt of Soho, England.
1818 - First U.S. cast steel produced by the crucible process at historic Valley Forge Foundry.
1825 - Aluminum, the most abundant metal in the earth's crust, is isolated.
1845 - Open hearth furnace is developed.
1849 - A manually operated diecasting machine is patented to supply rapidly cast lead type for newspapers.
1863 - Metallography is developed by Henry C. Sorby, Sheffield, England, enabling foundrymen to polish, etch and microscopically examine metal surfaces for physical analysis.
1870 - Sandblasting is developed for large castings by R.E. Tilghman of Philadelphia.
1884 - First architectural application of aluminum, a 100-lb cast aluminum pyramid, is mounted on the tip of the Washington Monument.
1886 - Charles M. Hall, age 22, discovers a process of aluminum reduction through electrolysis. The invention replaced chemical reduction and lowered the metal's cost, modernizing the aluminum industry.
early 1900s - First patent for low pressure permanent mold casting process issued to England's E.H. Lake.
1905 - Diecasting machine is patented by H.H. Doehler.
1906 - First electric arc furnace is installed in U.S. at Holcomb Steel Co., Syracuse, NY.
1912 - First muller with individually mounted revolving mullers of varying weights is marketed by Peter L. Simpson.
1913 - First low-frequency electric induction furnace is installed in U.S. at Crucible Steel Casting Co.'s Lansdowne, PA, plant for special melting.
1919 - Saito and Hayashi introduce the spiral fluidity test.
1924 - Henry Ford sets "production record" of 1 million autos in 132 working days.
1930s - Spectrography is pioneered by Univ. of MI professors for metal analysis.
1930 - First high-frequency coreless electric induction furnace is installed at Lebanon Steel Foundry, Lebanon, PA.
1940 - Wood flour is introduced into foundry practice as a sand additive.
1940s - Inoculation of gray iron becomes common, as high quality cast irons replace scarce steel.
1947 - The shell process, developed by J. Croning to produce mortar and artillery shells for the Germans during World War II, is discovered by U.S. officials and made public. Ten years later, he receives an AFS Gold Medal for his invention.
late 1940s - Thermal sand reclamation is applied to core sands and, to a limited degree, clay-bonded sands.
1949 - A U.S. patent on ductile iron, a cast iron with a fully spheroidal graphite structure, is granted to K.D. Millis, A.P. Gagnebin and N.B. Pilling.
early 1950s - -Experimentation in high pressure molding begins, as foundrymen begin to increase the air pressure in air squeeze molding machines to increase mold hardness (density). At the same time, molding machine manufacturers increase the size of their squeeze cylinders.
1950s - The pneumatic scrubber is developed to reclaim clay-bonded sands. Several wet reclamation systems are also in operation.
1952 - Sodium-silicate/C[O.sub.2] system is introduced.
1953 - Hotbox system of making and curing cores in one operation is developed, eliminating the need for dielectric drying ovens.
1958 - H.F. Shroyer obtains a patent for the full mold process, forerunner of the lost foam casting process.
1960 - Furan hotbox binders in use for core production.
1960s - Compactibility and methylene blue clay tests are developed for green sand control.
1965 - Cast metal matrix composites are first poured at International Nickel Co., Sterling Forest, NY, by Pradeep Rohatgi.
late-1960s - Scanning electron microscope (SEM) is invented in England.
late 1960s - Thermal analysis begins to be used in iron foundries for the rapid determination of carbon equivalent and phosphorous contents, making it possible to study the transformation of an alloy during cooling.
1968 - The coldbox process (a phenolic urethane/amine gassed binder system) is introduced by L. Toriello and J. Robins for high production coremaking.
1971 - The vacuum-forming or V-Process molding method of using unbonded sand with the use of a vacuum is developed in Japan.
1971 - Counter-gravity (vacuum) casting process is developed by Hitchiner Mfg., Milford, NH.
1971 - Rheocasting is developed at Massachusetts Institute of Technology.
1971 - U.S. Congress passes Occupational Safety and Health Act (OSHA) and Clean Air Act.
1972 - First production austempered ductile iron (ADI) component, designed and engineered by Tecumseh, is produced by Wagner Castings Co.
1973 - First foundry argon oxygen decarburization (AOD) unit installed at ESCO Corp.
1974 - Fiat introduces the in-mold process for ductile iron treatment.
1976 - Foote Mineral Co. and BCIRA (U.K.) develop compacted graphite iron.
1981 - High production lost foam casting of intake manifolds begins at General Motors' Massena, NY, plant.
1982 - Warmbox binder system is introduced.
1988 - Rapid prototyping and CAD/CAM technologies combine in a breakthrough to shorten tooling development time.
1988 - Ford adapts Cosworth process precision sand casting process for high production.
1993 - First foundry application of a plasma ladle refiner (melting and refining in one vessel) occurs at Maynard Steel Casting Co., Milwaukee.
1994 - Use of low-expansion sand for lost foam is patented by Brunswick Corp., Lake Forest, IL, to enable precision casting of large components.
1995 - Babcock and Wilcox, Barberton, OH, patents a lost foam-vacuum casting process to produce stainless steel castings with low carbon content.
1996 - Cast metal matrix composites (brake rotors) are used for the first time in a production model automobile, the Lotus Elise.
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|Title Annotation:||metal castings industry|
|Comment:||Lost wax to lost foam: reflections on past, present and future.(metal castings industry)|
|Author:||Kotzin, Ezra L.|
|Date:||Jul 1, 1997|
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