Transformation of the Modern Foundry
The foundry industry has been in a state of transformation for over 2,600 years. From simple shapes carved into stone, to topologically optimized and additive manufacture-facilitated creations, the evolution of metalcasting is easily witnessed. Whether this change has principally come about by man, method, material or market can be debated ad infinitum. Many futurists build their foundations on active fault lines, but the foundry industry likely faces a significant downturn. With the gradual shift from internal combustion engine personal vehicles to semi- or fully-autonomous electric vehicles, competing in these shrinking markets will likely require agile and novel foundry solutions.
My introduction into the world of metalcasting was facilitated by a police officer (my father), a telephone company lineman and a machine tool salesman (the fathers of my two friends and partners in our new casting enterprise). Surprisingly, the three men had the accumulation of over 100 years of permanent mold casting experience while never directly employed in the metalcasting industry. The journey was sparked by the desire to acquire additional toy soldiers and while we could have attempted to badger our parents to buy commercially-produced injected plastic versions, this was summer, and the Christmas holiday was months away. Our fathers offered a solution that would yield an almost endless supply of figures and other objects: we could cast them! This solution was made even more inviting by the realization that the castings would be produced using free or exceptionally low cost recycled waste materials gathered from other local industries and service providers: automobile service stations, roofers, offset print shops and the neighborhood plumber.
While our training was abbreviated by our mentors’ individual work schedules and our impatience to start our new enterprise, the process steps closely echo the ones we consider today:
Safety and Personal Protective Equipment: The metalcasting apparatus was equipped with a mechanical interlock to prevent release of liquid metal if the mold was not closed and secured. Horseplay was expressly forbidden. Long pants and leather gloves were to be worn when handling hot castings. Hands were to be thoroughly washed with soap and water after casting and before eating or drinking.
Site Selection: Our “foundry” location required concrete patios with good ventilation. The area was to be free of clutter and combustible materials, wood, paper and especially gasoline (despite the manufacturer’s claim that run off channels would prevent spilled liquid metal from damaging the area).
Job Training and Work Instructions: A combination of written and verbal instruction provided by our metalcasting mentors, “job” instructions were to be followed without exception unless approved by the management (fathers). This would haunt us later.
Supply Chain Management and Sustainability: Our activities would mirror modern beneficial reuse and recycling practice, as charge materials consisted wholly of discarded waste products.
Gating and Venting: The function of the mold “plumbing” system was explained and its impact on the quality of the casting was demonstrated using various scrap castings. All molds featured “previously approved gating systems;” venting or gating alterations would be made only with approval of the management.
Tooling Maintenance: Molds were inspected prior to each cast for nicks or other obstructions that would interfere with proper closing and result in a runout. Tooling would be refurbished only under direct supervision by the management.
Metallurgy: The basics of alloying were demonstrated by comparing the relative plasticity and hardness of various forms of lead and it’s why linotype was coveted by scrap market competitors, identified as bullet casters. A formal understanding of the unique solidification characteristics was provided years later during phase diagram lectures by Dr. Carl Loper Jr. (Fig. 1).
Process Control: Periodic removal of dross (slag), accurate placement of the pouring basin in relation to the pouring spout and maintaining a continuous pouring stream were identified as key process parameters. Casting release from the mold could be enhanced by a light dusting of talcum powder or the application of acetylene soot from an antique miner’s lamp. When the latter method was allowed by management, the reaction between water and calcium carbide was demonstrated.
Casting Finishing: The hazards of ingesting lead dust were well known by management, flash and gating were to be removed by shears or by cutting. Under “no” circumstances were sanding or grinding allowed.
Inspection: All castings were visually inspected for short pours, cold shuts, misruns, dross defects. Defective castings could be salvaged or returned to the melt center.
Our casting operation lasted only a few weeks until it was terminated by management for grievous violations of safety, work instructions, environmental regulations and an ill-advised attempt to conceal property damage.
We had elected to move our casting operation indoors due to a sudden and heavy rain (Violation 1). We resumed casting operations in a basement laundry room with a linoleum tiled floor with limited ventilation (Violation 2). My friend’s younger sibling was allowed to join our operation in order to buy his silence (Violation 3).
The sibling had not participated in any of the training by management and was dependent on our group to provide proper guidance (Violation 4). In our haste to resume casting operations, we neglected to dry or remove excess grease from our charge material (Violation 5). The younger sibling dropped instead of slowly adding charge material into the molten bath. The resulting splash and spatter damaged portions of the floor tile and resulted in a burn on the hand of the younger sibling (Violations 6 and 7).
While we attempted to conceal the damaged floor by installing a spare tile, the new unweathered tile shown like a beacon (Violation 8). While we properly administered first aid to my friend’s sibling and created the proper cover story, we neglected to address the distinctive odor created by the heated service station grease and grime. Despite our attempts to conceal our indiscretions, our enterprise was terminated immediately. Not by OSHA, but by another powerful governing body, the DAD. Punishment meted out by the DAD (our fathers) was severe and irreversible. Molds, casting apparatus and finished castings were confiscated and likely destroyed. A harsh punishment, but the brief experience provided long-lasting lessons that paralleled future learnings.
Educating Future Metalcasters
Frequent business travel would result in questions about the corporate logo clothing I wore. The words “foundry” and “castings” produced puzzled looks generated by the relative anonymity of our industry and its products.
Metalcasting was included in vocational-based toys and playsets produced by AC Gilbert and other manufacturers from the late 1920s to the late 1960s (Figs. 2-3). Fundamentals of metalcasting were often taught in middle and high schools as part of their industrial vocational or art education curricula (Fig. 4). Fine art subjects were frequently cast using the lost wax or investment casting process using pewter, silver or gold. Iron or aluminum castings, including “tribute” copies of a popular, manual transmission shifter handle, were cast by enterprising students in the late 1960s and early 1970s. Many metalcasting programs disappeared as insurance costs rose and other education programs vied for shrinking budgets.
The formation of the Foundry Educational Foundation (FEF) and its governing board organized a fundraising campaign to provide financial support for the increasingly technical industry. Since 1947, approximately 100 schools have rotated in and out of the network to provide financial support to metallurgical engineers, material scientists and other academic interests to support the current and future needs of the metalcasting industry and its supporters.
Foundry managers have recently recognized the value of early exposure to metalcasting in the form of live demonstrations in classrooms (Foundry-in-a-Box) or as a part of National Manufacturing Day activities. The benefits realized by these activities may not manifest immediately on a foundry’s ledger, but instead create the initial spark for a young man or woman not predisposed to metalcasting. While outwardly simple, several real-world lessons can be incorporated in this type of scaled demonstration.
In his 2012 Hoyt Lecture, Eugene Muratore delivered a passionate plea for continued education and encouraged attendees to drink deeply at the fountains of knowledge. There can be no question that access to information has improved at nearly an exponential rate. Prior to the 1980s and the formation of the publicly accessed internet, technical information resided predominantly in print form or on film (microfiche) in personal, internal corporate, collegiate or trade association libraries, including the comprehensive AFS library, where AFS Transactions and other technical articles were stored in paper form and copies were provided to members who requested them by mail or facsimile (fax). Through the mid-2000s, the AFS library collection was scanned and digitized. In 2017, the current online library was launched and made a benefit of AFS membership with free downloads, eliminating the need to purchase each article. More importantly, the information is accessible 24/365 on a variety of connected devices even in the most remote areas.
Participation in onsite and in-person AFS Technical Committee work provides access to technical content and OEM subject matter experts. As many OEMs have closed or downsized their own captive foundry operations, casting process familiarity is likewise declining. While many foundries took on the challenge to provide basic foundry education in the mid-1990s and continue to today, the AFS Institute began converting many classroom lecture courses to online courses in 2015. The AFS e-learning program was launched in 2017, which currently stands at 110 modules. In 2020, virtual classroom courses were launched during the COVID-19 pandemic. The continued promotion of both basic and advanced metalcasting instruction is of paramount importance to the continued growth of the foundry industry.
The Third Industrial Revolution—Industry 3.0
In the late 1970s and early 1980s, ideas and concepts frequently outpaced the capability of the available technology (Fig. 5). Progress was stymied by computational speed and the availability and cost of data storage capacity. Early integration of computer technology was largely devoted to accounting functions and simple data analysis. As we approached the end of the decade and into the 1990s, computer technology rapidly evolved to the point where several applications including research, machine control, simulation and engineering could be realized.
Efficiency in any form of manufacturing requires process steps to be carried out in a specific order with great precision and capable of adjustments according to changing raw materials and manufacturing conditions (i.e., temperature, humidity, etc.). In the past, a human brain provided the interface between instrumentation and the mechanical devices being controlled through levers, buttons, dials and valves. Efficient or effective control depended on the speed at which the human operator became competent at analyzing process inputs and correctly performing the necessary and timely actions or adjustments. Replacing the human interface between instrumentation and the control mechanisms would progress slowly. In the early 1700s, the distinctive patterns of knitting machines were controlled by paper punch cards that created the on/off functions of the loom’s elements.
Machinery control was further advanced by the invention of electromechanical relay by Joseph Henry in 1835. Some of the earliest applications in the foundry were likely molding machines, mullers and melting system controls. Rapid development of faster, smaller and survivable processors facilitated the creation of the Programable Logic Controller (PLC). In the late 1970s and early 1980s, PLCs were generally a direct relay logic replacement. As processors evolved from 8-bit and 16-bit to the 32-bit processors we have today, the programming instruction capabilities have evolved to where we are only limited by the imagination of the engineer.
Example of Control Technology—Core Sand System
In batch mixing operations, the specific recipe drives the overall batch composition. The specific recipe selection can be driven by data passed from the core machine PLC system to the batch mixing PLC, or it can be driven by RFID, or Bar/QR codes unique to the tooling or part number being manufactured. Each component addition can be compensated for variance in the raw sand batch weight (Fig. 6).
During typical batch processing, the specific recipe is read or determined, providing batch size, sand composition (single or multiple sand types), dry additives, binders and ratios, and all associated batch addition sequencing or timing. Once the recipe is known and the system is prompted to produce sand, the PLC will control all logic to produce quality/repeatable sand. If there are issues, the system will stop and alarm the condition on the human-machine interface (HMI). All critical batch data is displayed and saved/archived into a database.
In addition, seasonal temperature changes are experienced by foundries worldwide that can result in swings as great as 40 degrees Centigrade to core sand temperature in foundries. Consistent temperature control of sand in the core process is critical for optimal performance. The problem is compounded by systems that run intermittently or are otherwise disrupted, resulting in over-heating or over-cooling of the sand and directly affecting binder reactions. Today, we have the technology to maintain sand temperature to ± 1C (1.8F) by using a plate heat exchanger. Raw sand is on one side of the plate and tempered water circulating within 2C (3.6F) of the desired sand temperature on the on the other side. With sufficient residence time, sand arrives at the desired temperature.
Many foundry coremaking operations require specialty sand additives to mitigate core-specific defects (veining, penetration, distortion, etc.). Today these additives are added via a loss-in-weight feeder with controls for both flow rate and total addition to ensure the sand additive is precisely and repeatably added to the mixer (Fig. 7).
The liquid chemicals used in resin-bonded core or molding processes are metered via mass flowmeters into the mixer (Fig. 8). The mass flow technology compensates for chemical viscosity changes, pump wear, filter restrictions, and any other outside variable impacting the chemical flow. Mass flow provides absolute accuracy and repeatability of the chemical additions.
Casting Process Simulation
Prior to 1970, gating and riser design was the result of empirical information gained through experimentation and the application of thermodynamic principles. University research in the 1970s and 1980s, resulted in 2D and 3D models used to calculate the freezing order of different casting sections. The incorporation of computational fluid dynamics, thermal transformation data and heat transfer calculations allowed the simulation of mold filling, mold and casting distortion and mechanical property prediction, which resulted in the introduction of commercial solidification software programs in the late 1980s (Fig. 9).
Acceptance of the “Black Box” simulation results were initially hampered by the computational speed of available computer systems. Foundry managers frequently challenged that samples could be cast and analyzed in a fraction of the time required for the simulation, which, depending on complexity could take days or weeks to complete. Today’s systems can deliver results well within a day to even hours, resulting in a paradigm shift where simulation is used as an initial feasibility versus a problem solution tool. Today’s simulation tools are continuously improved by actual casting validation by universities and foundries using real-time X-ray and thermal scanning techniques. By incorporating user-defined variables and multiple simulations, optimization of the gating system can be realized to find the best solution.
Casting Design Optimization
Rising fuel efficiency and emissions standards are driving a strong demand for lighter components at all car and truck OEMs. To be accurate, all casting markets have seen greater emphasis on lighter weight designs. While steel weldments, forged or cast aluminum materials are frequently specified, ductile iron has great potential to meet weight reduction goals through design optimization using Finite Element Analysis (FEA) coupled with casting process and engineering simulation tools, acceptable functionality can be established before producing the actual casting.
Environmental Challenges & Regulation
In the decades preceding 1970, industrial pollution may have been considered an acceptable consequence of a strong industrial economy. The age of common law regulation for dealing with environmental problems was coming to an end. A noteworthy event would coincide with my first metalcasting enterprise, the June 22, 1969 Cuyahoga River Fire.
The fire was not the first or most costly in terms of property damage or loss of life, but it signaled the public’s recognition of growing concerns. Incidents like this culminated in the National Environmental Policy Act (NEPA), signed into law on January 22, 1970, and the formation of the Environmental Protection Agency (EPA) on December 2, 1970. The decade that followed signaled the dawning of environmental challenges for all industries, including metalcasting. What followed was the initiation of the modern environmental regulatory structure with the creation of the Clean Air Act, Clean Water Act, definition of hazardous waste and others to address past and potential environmental problems.
The 1990s introduced and expanded the idea of implementing an Environmental Management System (EMS) to identify how organizations (foundries) most impacted the environment and to define a process to control those impacts via operational controls and continuous improvements. This afforded a systematic approach to conducting actions that went beyond basic compliance.
As we entered the 2000s, “sustainability” became more mainstream. The present-day desire for sustainability action and a flow of sustainability information expected by stakeholders has become common and ever expanding. It is now expected that sustainability information be provided that was inconceivable or considered confidential not that many years ago. Metalcasters are good at working hard in anonymity; this historical approach may no longer be appropriate given the expectations of internal and external stakeholders.
Metalcasters should develop and implement monitoring, measurement and information tracking systems to convey this information—not only on request, but proactively to build appreciation of metalcasting’s important role in society with the public, potential job seekers, regulators and potential customers. Developing and publishing an organizational corporate sustainability report can serve multiple functions in this area and create a baseline reference that can be used to support many stakeholder requests. The historical evolution observed in the environmental field will continue. The metalcasting industry should expect more and tighter environmental regulation, increased stakeholder pressure (including social media and citizen science activists), and future challenges in addressing costs related to energy consumption, carbon emissions and material supply.
The metalcasting industry will continue to transform; however, any metalcasting organization conducting their business exactly as done 10, 20 or 30 years ago must realize that there is “a trap waiting to be sprung.” Each organization needs to anticipate these changes and set objectives and targets to evolve their environmental, health and safety performance. These may be modest at first, but the work to effect improvements and communicate proactively with communities and stakeholders can no longer wait.