Molders form sand molds for use in the production of metal castings. This production method, known as sand casting, requires knowledge of the properties of metals and sand mixtures, pattern shapes, and pouring procedures. Implementing a two-part box called a flask, molders pack specially prepared sand mix around a pattern of the object that is to be cast. The pattern is then removed and molten metal is poured into the cavity where it solidifies and forms the casting. Approximately 157,000 molders and molding machine setters, operators, and tenders are employed in the metal and plastics industry in the United States.
Molder Career History
The origins of metal molding can be traced back thousands of years. King Solomon of Israel, who lived in the 10th century b.c., for example, is said to have placed two brass pillars at the entrance to his temple. These pillars would have been cast in molds before being erected. Also, copper and tin were cast into bronze as far back as 3000 b.c.
The industrial revolution in the 18th century changed the way metal molding was perceived. Before that time, molders were considered craft workers who primarily used molding techniques to produce wares such as jewelry and cookware. With the burgeoning of mass-production methods in factories, the work of the molder slowly became what it is today. Modern techniques and technologically advanced molding machines have made metal casting one of the fastest, most economical, and versatile ways to produce metal products.
However, because technology has introduced automation into the industry, molders’ responsibilities have narrowed. In some cases, molders are sharing job responsibilities with related skilled workers such as machinists, machine tool operators, numerical control tool programmers, and setup technicians.
Molder Job Description
Castings are molded substances that form the basic parts of all kinds of metal products, from heavy machinery to automobile engines to household appliances. More than a dozen types of metal molding and casting processes exist. The traditional, and still most common method of producing cast-to-shape pieces, is sand casting. Technological advancements in recent years, however, have made alternative casting methods such as evaporative, investment, and no-bake casting increasingly attractive because of their cost-effectiveness.
Sand molders, as they are also called, work in foundries that produce castings from iron, steel, and nonferrous metals (i.e., alloys containing no appreciable amounts of iron). Traditional, manual sand casting begins with the preparation of a mold, which the worker creates from specially treated sand. In the green sand molding method, the molder packs and rams a mixture of sand, clay, and chemicals around a pattern (a model of the object to be duplicated) in a molding box called a flask. Flasks are usually made in two parts, which are separated to allow removal of the pattern without damaging the mold cavity.
A mold is created by following a series of specific steps. After positioning the drag (lower) half of the pattern and flask, the molder sprays it with a parting agent and places reinforcing wire in the flask. Sand is sifted over the pattern and pressed into its contours. Then the molder shovels sand into the flask and packs it in place with hand ramming tools or a pneumatic hammer. With this completed, the molder positions the cope (top) half of the pattern and flask on the drag half and repeats the procedure.
The process of making a casting continues with the separation of the drag and cope and the removal of the pattern. The molder then cuts a hole in the mold through which the liquid metal will be poured. Next, the molder positions a core in the cavity left by the pattern (to produce a hollow casting), reassembles the flask, and pours molten metal into the mold. When the metal cools and solidifies, the casting is removed and the mold is cleaned. Many of the final steps involving cleaning and assembling molds are often performed by workers known as mold closers or finish molders.
Although a few foundries still construct molds using the traditional manual methods, most molds today are made by machines that pack and ram the sand mechanically. Machines make it possible to turn out large quantities of identical sand molds quickly, simply, and more cost efficiently. Workers who operate these machines are called machine molders or machine line molders, and it is their job to set up the machine, to control the pressure applied to the sand by working the pedals and levers, and to cut pouring spouts in the mold. In addition to this, machine molders assemble the flask and pattern on the machine table and fill the flask with the prepared sand mixture. The workers who operate the machines that pack the sand into the flask are called sand-slinger operators.
In the foundries that still use manual methods, hand molders compact the sand around the pattern with hand tools such as trowels and hand rammers and with power tools such as pneumatic rammers and squeeze plates. Molds for small castings, such as jewelry, are usually made on a workbench by bench molders, while those for large, bulky castings are made on the foundry floor by floor molders. Some molders are skilled in making many different kinds of molds; other molders specialize in only a few types.
Molder Career Requirements
If you are interested in becoming a molder, you should have some knowledge of mechanics, drafting, computers, and mathematics. Shop courses that teach the use of hand tools and introductory machining methods would also be beneficial. Many employers prefer to hire workers who have good communication skills as well as high school diplomas.
In addition to a high school education, many employers tend to favor applicants with satisfactory job experience of some sort, whether in molding or similar work. The two primary ways of becoming a molder are through an apprenticeship or an on-the-job training program.
A four-year apprenticeship program combines practical experience with more formal instruction. Apprentices work under the close supervision of experienced molders. At first they are given simple tasks such as shoveling sand. Gradually, apprentices are transferred to more difficult and challenging jobs, such as ramming molds, removing patterns, and setting cores. They also learn how to operate various molding machines and how to make complete molds.
Apprentices may work in various departments to gain a thorough knowledge of foundry methods and practices. They also receive at least 144 hours of classroom instruction per year in subjects such as shop mathematics, metallurgy, and shop drawing. Apprenticeship programs for molders are usually offered by an employer or through a union, although the number of apprenticeships has been declining in recent years.
In an on-the-job program, a prospective molder begins as a foundry helper and acquires a considerable amount of job experience simply by observing experienced molders at work and helping them as the opportunity arises. The value of the more formal apprenticeship is that the management of the foundry and the union know that the apprentices are preparing themselves for the job of molder, which often speeds up the process of becoming a journeyworker.
Students interested in becoming sand molders should enjoy working with tools and metals, have mathematical ability, and be able to follow instructions closely. Attention to detail and good work ethics are also needed in order to ensure the level of quality needed for this type of work. Physical strength and endurance are also required.
Exploring Molder Career
Prior to high school graduation, you could prepare for a job as a molder by applying for foundry work in the summer or on a part-time basis. You could use that opportunity to ask molders questions about their jobs and to become well acquainted with their responsibilities. Another opportunity for exploring the occupation involves contacting a trade organization, such as the American Foundry Society. This particular group is a technical association whose members are experienced foundry workers, patternmakers, technologists, and educators. Training courses are sponsored through the Cast Metals Institute and include a variety of subjects concerning the castings industry. College students might consider reading the group’s monthly publication, Modern Casting, which presents issues on current technology, a calendar of industry events, and other related news.
There are approximately 157,000 molders and molding machine setters, operators, and tenders employed in the metal and plastics industry in the United States.
Most foundries are small operations, with fewer than 2 50 workers. They are located in areas that have easy access to raw materials, most notably the Great Lakes states, the West Coast, and Alabama. There also tend to be more jobs in large industrial cities, such as Detroit, where foundries exist solely to supply parts for automobiles. However, some small production companies and factories are located in other areas and they continue to employ molders.
Sand casting is done in both job and production foundries. Job foundries generally specialize in producing specific, small parts that are then sent to production foundries, which produce larger items from such job foundry parts.
A state employment office is a good source to contact for openings in foundry work. You may also go directly to a foundry’s personnel office to fill out an application form. Because sand molding is often a job that is represented by a union, it is possible to find available openings through a local office of the representing union.
Sand molders who are skilled and have the necessary experience may become senior molders and work with different types of molding operations from beginning to end rather than repeating the same operation on one casting. Others may advance to supervisory positions, with the responsibility of managing a group of molders.
Molders who have worked in various foundry departments as part of their apprenticeships might be able to become a department supervisor or even advance to foundry superintendent. In order to qualify for these positions, they must have a thorough knowledge of various foundry jobs, skill in working with people, and a high level of initiative.
According to the U.S. Department of Labor, median hourly wages for molding, coremaking, and casting machine setters, operators, and tenders, metal and plastic, were $11.88 in 2004, or about $24,710 annually for full-time work. Most molders currently employed are experienced molders who have worked for many years. Starting salaries for new workers are considerably less than those of more experienced workers. Some molders are paid on an incentive basis, and they generally have higher earnings than other production workers. The U.S Department of Labor reports that in 2004 the lowest paid 10 percent earned $7.87 per hour or $16,360 annually while the highest paid 10 percent earned $19.16 per hour or $39,850. Benefits for molders depend upon the foundry or manufacturing company’s policies but generally include paid holidays and vacations as well as health care insurance packages.
Molders work indoors and with others. Responsibilities are performed mostly during the day and within a standard 40-hour workweek. Tasks are strenuous and require standing, stooping, lifting, and carrying.
Foundry work is hazardous, and the injury rate is higher than the average for all manufacturing industries. Sand molders risk burns from the hot metal, as well as cuts and bruises from handling metal parts, molds, and power tools. Many foundries, however, have introduced safety programs and equipment, which has helped reduce injuries.
The foundry is a noisy place to work, and molders are exposed to dust, dirt, fumes, heat, and sudden temperature changes when the molten metal is being poured into the molds. These conditions could cause rheumatism, colds, pleurisy, and other lung ailments. Many plants have installed improved ventilating and air-conditioning equipment to reduce these health hazards, but such problems still exist in some older foundries.
Sand molders may suffer the loss of some of the intrinsic value of their art as machines replace hand molding. They may compare modern practices unfavorably with the time when molding was largely a manual operation requiring individual talent. However, as sand molders expand their work to all-around molding, they often find increasing satisfaction in that their jobs involve exacting work requiring specific skills and that they contribute to an essential occupation.
Molder Career Outlook
There are relatively few new workers becoming molder apprentices today, as positions for molders have declined significantly during the last decade. Molders are skilled artisans who are gradually being replaced by technicians who can set up and maintain automated mold making machinery. Those who are entering this field are mainly replacing workers who retire, transfer, or leave the occupation. Competition for available openings can be intense as positions are more likely to be filled by experienced workers who are already in the industry. Employment of molders is expected to decline through 2014, despite increases in foundry production. In general, this is because of the continued trend toward labor-saving automated machine molding. Also causing the decline in employment opportunities is improved productivity, advances in technology, and increased foreign competition. There is likely to be more employment growth in plastics-molding, core-making, and casting machine operation.
The amount of work available for those who enter this occupation may fluctuate greatly from year to year because the market for certain foundry products is affected by changes in the economy. In addition, many manufacturers are using more sophisticated computer systems to track production (the number of parts made) and inventories (the amount of unsold parts). When inventories start to grow to certain levels, manufacturers may slow production down. During such times, foundry workers may be laid off or scheduled to work shorter weeks.