Casting Molds
2008-08-20

Brass molds for the casting of soft metal ornaments out of Britannia, pewter, spelter, etc., should be made out of brass that contains enough zinc to produce a light-colored brass. While this hard brass is more difficult for the mold maker to cut, the superiority over the dark red copper-colored brass is that it will stand more heat and rougher usage and thereby offset the extra labor of cutting the hard brass. The mold should be heavy enough to retain sufficient heat while the worker is removing a finished casting from the mold so that the next pouring will come full. If the mold is too light it cools more quickly, and consequently the castings are chilled and will not run full. Where the molds are heavy enough they will admit the use of a swab and water after each pouring. This chills the casting so that it can be removed easily with the plyers. Molds for the use of soft metal castings may be made out of soft metal. This is done with articles that are not numerous, or not often used; and may be looked upon as temporary. The molds are made in part the same as when of brass, and out of tin that contains as much hardening as possible. The hardening consists of antimony and copper. This metal mold must be painted over several times with Spanish red, which tends to prevent the metal from melting. The metal must not be used too hot, otherwise it will melt the mold. By a little careful manipulation many pieces can be cast with these molds. New iron or brass molds must be blued before they can be used for Casting purposes. This is done by placing the mold face downward on a charcoal fire, or by swabbing with sulphuric acid, then placing over a gas flame or charcoal fire until the mold is perfectly oxidized. A good substantial mold for small castings of soft metal is made of brass. The expense of making the cast mold is considerable, however, and, on that account, some manufacturers are making their molds by electro-deposition. This produces a much cheaper mold, which can be made very quickly. The electro-deposited mold, however, is very frail in comparison with a brass casting, and consequently must be handled very carefully to keep its shape. The electro-deposited ones are made out of copper, and the backs filled in with a softer metal. The handles are secured with screws. Process by which molten metal is forced by a plunger or compressed air into a metallic die and the pressure maintained until the metal has solidified. Die castings are accurate, are sharply outlined, have a good surface finish, and can be made in complicated designs. Zinc, aluminum, and magnesium alloys are the principal metals used. The high cost of the die usually limits the process to large-scale, high-speed production. Typical products are carburetor bodies and zippers. Type-casting machines are specialized die-casting machines. manufacturing process

Casting is a manufacturing process by which a liquid material such as a suspension of minerals as used in ceramics or molten metal or plastic is introduced into a mould, allowed to solidify within the mould, and then ejected or broken out to make a fabricated part. Casting is used for making parts of complex shape that would be difficult or uneconomical to make by other methods, such as cutting from solid material. Casting may be used to form hot, liquid metals or meltable plastics (called thermoplastics), or various materials that cold set after mixing of components such as certain plastic resins such as epoxy, water setting materials such as concrete or plaster, and materials that become liquid or paste when moist such as clay, which when dry enough to be rigid is removed from the mold, further dried, and fired in a kiln or furnace. Substitution is always a factor in deciding whether other techniques should be used instead of casting. Alternatives include parts that can be stamped out on a punch press or deep-drawn, forged, items that can be manufactured by extrusion or by cold-bending, and parts that can be made from highly active metals. The casting process is subdivided into two distinct subgroups: expendable and nonexpendable mold casting: Expendable mould casting

Expendable mould casting is a generic classification that includes sand, plastic, shell, plaster, and investment (lost-wax technique) moldings. This method of mould casting involves the use of temporary, nonreusable moulds. Waste molding of plaster

A durable plaster intermediate is often used as a stage toward the production of a bronze sculpture or as a pointing guide for the creation of a carved stone. With the completion of a plaster the work is more durable (if stored indoors) than a clay original which must be kept moist to avoid cracking. With the low cost plaster at hand the expensive work of bronze casting or stone carving may be deferred until a prosperous patron is found, and as such work is considered to be a technical, rather than artistic processes it may even be deferred beyond the lifetime of the artist. In waste molding a simple and thin plaster mold, reinforced by sisal or burlap, is cast over the original clay. When cured it is then remove from the damp clay, incidentally destroying the fine details in undercuts present in the clay, but which are now captured in the mold. The mold may then at any later time (but only once) be used to cast a plaster positive image, identical to the original clay. The surface of this "plaster" may be further refined and may be painted and waxed to resemble a finished bronze casting. Sand casting Sand casting requires a lead time of days for production at high output rates (1-20 pieces/hr-mold), and is unsurpassed for large-part production. Green (moist) sand has almost no part weight limit, whereas dry sand has a practical part mass limit of 2300-2700 kg. Minimum part weight ranges from 0.075-0.1 kg. The sand is bonded together using clays (as in green sand) or chemical binders, or polymerized oils (such as motor oil.) Sand in most operations can be recycled many times and requires little additional input. Preparation of the sand mold is fast and requires a pattern which can "stamp" out the casting template. Typically, sand casting is used for processing low-temperature metals, such as iron, copper, aluminum, magnesium, and nickel alloys. Sand casting can also be used for high temperature metals where other means would be unpractical. It is said to be the oldest and best understood of all techniques. Consequently, automation may easily be adapted to the production process, somewhat less easily to the design and preparation of forms. These forms must satisfy exacting standards as they are the heart of the sand casting process - creating the most obvious necessity for human control. Plaster casting (of metals)

Plaster casting is similar to sand molding except that plaster is substituted for sand. Plaster compound is actually composed of 70-80% gypsum and 20-30% strengthener and water. Generally, the form takes less than a week to prepare, after which a production rate of 1-10 units/hr-mold is achieved with items as massive as 45 kg and as small as 30 g with very high surface resolution and fine tolerances. Once used and cracked away, normal plaster cannot easily be recast. Plaster casting is normally used for nonferrous metals such as aluminium-, zinc-, or copper-based alloys. It cannot be used to cast ferrous material because sulfur in gypsum slowly reacts with iron. Prior to mold preparation the pattern is sprayed with a thin film of parting compound to prevent the mold from sticking to the pattern. The unit is shaken so plaster fills the small cavities around the pattern. The form is removed after the plaster sets. Plaster casting represents a step up in sophistication and requires skill. The automatic functions easily are handed over to robots, yet the higher-precision pattern designs required demand even higher levels of direct human assistance. Casting of plaster, concrete, or plastic resin Plaster itself may be cast, as can other chemical setting materials such as concrete or plastic resin - either using single use waste molds as noted above or multiple use piece molds, or molds made of small ridged pieces or of flexible material such as latex rubber (which is in turn supported by an exterior mold). When casting plaster or concrete the finished product is, unlike marble, relatively unattractive, lacking in transparency, and so is usually painted, often in ways that give the appearance of metal or stone. Alternatively, the first layers cast may contain colored sand so as to give an appearance of stone. By casting concrete, rather than plaster, it is possible to create sculptures, fountains, or seating for outdoor use. A simulation of high quality marble may be made using certain chemically set plastic resins (for example epoxy or polyester) with powdered stone added for coloration, often with multiple colors worked in. The later is a common means of making attractive washstands, washstand tops and shower stalls, with the skilled working of multiple colors resulting in simulated staining patterns as is often found in natural marble or travertine. Shell moulding

Shell molding is also similar to sand molding except that a mixture of sand and 3-6% resin holds the grains together. Set-up and production of shell mold patterns takes weeks, after which an output of 5-50 pieces/hr-mold is attainable. Aluminium and magnesium products average about 13.5 kg as a normal limit, but it is possible to cast items in the 45-90 kg range. Shell mold walling varies from 3-10 mm thick, depending on the forming time of the resin. There are a dozen different stages in shell mold processing that include: Initially preparing a metal-matched plate Mixing resin and sand Heating pattern, usually to between 505-550 K Inverting the pattern (the sand is at one end of a box and the pattern at the other, and the box is inverted for a time determined by the desired thickness of the mill) Curing shell and baking it Removing investment Inserting cores Repeating for other half Assembling mold Pouring mold Removing casting Cleaning and trimming. The sand-resin mix can be recycled by burning off the resin at high temperatures. Investment Casting

Investment casting (lost-wax casting) is a process that has been practised for thousands of years, with lost wax process being one of the oldest known metal forming techniques. From 5000 years ago, when bees wax formed the pattern, to today’s high technology waxes, refractory materials and specialist alloys, the castings ensure high quality components are produced with the key benefits of accuracy, repeatability, versatility and integrity. The process is suitable for repeatable production of net shape components, from a variety of different metals and high performance alloys. Although generally used for small castings, this process has been used to produce complete aircraft door frames, with steel castings of up to 300 kg and aluminium castings of up to 30 kg. Compared to other casting processes such as die casting or sand casting it can be an expensive process, however the components that can be produced using investment casting can incorporate intricate contours, and in most cases the components are cast near net shape, so requiring little or no rework once cast. Nonexpendable mold casting

Nonexpendable mold casting differs from expendable processes in that the mold need not be reformed after each production cycle. This technique includes at least four different methods: permanent, die, centrifugal, and continuous casting. Permanent mold casting

Permanent mold casting (typically for non-ferrous metals) requires a set-up time on the order of weeks to prepare a steel tool, after which production rates of 5-50 pieces/hr-mold are achieved with an upper mass limit of 9 kg per iron alloy item (cf., up to 135 kg for many nonferrous metal parts) and a lower limit of about 0.1 kg. Steel cavities are coated with refractory wash of acetylene soot before processing to allow easy removal of the workpiece and promote longer tool life. Permanent molds have a life which varies depending on maintenance of after which they require refinishing or replacement. Cast parts from a permanent mold generally show 20% increase in tensile strength and 30% increase in elongation as compared to the products of sand casting. The only necessary input is the coating applied regularly. Typically, permanent mold casting is used in forming iron-, aluminium-, magnesium-, and copper-based alloys. The process is highly automated. Die casting

Die casting is the process of forcing molten metal under high pressure into the cavities of steel moulds. The moulds are called dies. Dies range in complexity to produce any non-ferrous metal parts (that need not be as strong, hard or heat-resistant as steel) from sink faucets to engine blocks (including hardware, component parts of machinery, toy cars, etc). In fact, the process lends itself to making any metal part that: must be precise (dimensions plus or minus as little as 50 µm--over short distances), must have a very smooth surface that can be bright plated without prior polishing and buffing, has very thin sections (like sheet metal--as little as 1.2 mm), must be produced much more economically than parts primarily machined (multicavity die casting moulds operating at high speed are much more productive than machine tools or even stamping presses), must be very flexible in design; a single die casting may have all the features of a complex assembly. If several machining operations would be required or assembly of several parts would be required (to make a finished part), die casting is probably far more economical. This level of versatility has placed die castings among the highest volume products made in the metalworking industry. Common metals used in die casting include zinc and aluminum. These are usually not pure metals; rather are alloys which have better physical characteristics. In recent years, injection-molded plastic parts have replaced some die castings because they are usually cheaper (and lighter--important especially for automotive parts since the fuel-economy standards). Plastic parts are practical (particularly now that plating of plastics has become possible) if hardness is not required and if parts can be redesigned to have the necessary strength. Centrifugal casting

Centrifugal casting is both gravity- and pressure-independent since it creates its own force feed using a temporary sand mold held in a spinning chamber at up to 90 g (882.9 kg m/s²). Lead time varies with the application. Semi- and true-centrifugal processing permit 30-50 pieces/hr-mold to be produced, with a practical limit for batch processing of approximately 9000 kg total mass with a typical per-item limit of 2.3-4.5 kg. Industrially, the centrifugal casting of railway wheels was an early application of the method developed by German industrial company Krupp and this capability enabled the rapid growth of the enterprise. Small art pieces such as jewelry are often cast by this method using the lost wax process, as the forces enable the rather viscous liquid metals to flow through very small passages and into fine details such as leaves and petals. This effect is similar to the benefits from vacuum casting, also applied to jewelry casting. Continuous casting

Continuous casting is a refinement of the casting process for the continuous, high-volume production of metal sections with a constant cross-section. Molten metal is poured into an open-ended, water-cooled copper mould, which allows a 'skin' of solid metal to form over the still-liquid centre. The strand, as it is now called, is withdrawn from the mould and passed into a chamber of rollers and water sprays; the rollers support the thin skin of the strand while the sprays remove heat from the strand, gradually solidifying the strand from the outside in. After solidification, predetermined lengths of the strand are cut off by either mechanical shears or travelling oxyacetylene torches and transferred to further forming processes, or to a stockpile. Cast sizes can range from strip (a few millimetres thick by about five metres wide) to billets (90 to 160 mm square) to slabs (1.25 m wide by 230 mm thick). Sometimes, the strand may undergo an initial hot rolling process before being cut. Continuous casting provides better quality product as it allows finer control over the casting process, along with the obvious advantages inherent in a continuous forming process. Metals such as steel, copper and aluminium are continuously cast, with the largest tonnage poured being steel. Cooling rate

The rate at which a casting cools affects its microstructure, quality, and properties. The cooling rate is largely controlled by the molding media used for making the mold. When the molten metal is poured into the mold, the cooling down begins. This happens because the heat within the molten metal flows into the relatively cooler parts of the mold. Molding materials transfer heat from the casting into the mold at different rates. For example, some molds made of plaster may transfer heat very slowly, while a mold made entirely of steel would transfer the heat very fast. This cooling down ends with (solidification) where the liquid metal turns to solid metal. At its basic level a foundry may pour a casting without regard to controlling how the casting cools down and the metal freezes within the mold. However, if proper planning is not done the result can be gas porosities and shrink porosities within the casting. To improve the quality of a casting and engineer how it is made, the foundry engineer studies the geometry of the part and plans how the heat removal should be controlled. Where heat should be removed quickly, the engineer will plan the mold to include special heat sinks to the mold, called chills. Fins may also be designed on a casting to extract heat, which are later removed in the cleaning (also called fettling) procees. Both methods may be used at local spots in a mold where the heat will be extracted quickly. Where heat should be removed slowly, a riser or some padding may be added to a casting. A riser is an additional larger cast piece which will cool more slowly than the place where is it attached to the casting. Generally speaking, an area of the casting which is cooled quickly will have a fine grain structure and an area which cools slowly will have a coarse grain structure. Shrinkage

Castings shrink when they cool. Like nearly all materials, metals are less dense as a liquid than a solid. During solidification (freezing), the metal density dramatically increases. This results in a volume decrease for the metal in a mold. Solidification shrinkage is the term used for this contraction. Cooling from the freezing temperature to room temperature also involves a contraction. The easiest way to explain this contraction is that is the reverse of thermal expansion. Compensation for this natural phenomenon must be considered in two ways. Solidification Shrinkage

The shrinkage caused by solidification can leave cavities in a casting, weakening it. Risers provide additional material to the casting as it solidifies. The riser (sometimes called a "feeder") is designed to solidify later than the part of the casting to which it is attached. Thus the liquid metal in the riser will flow into the solidifying casting and feed it until the casting is completely solid. In the riser itself there will be a cavity showing where the metal was fed. Risers add cost because some of their material must be removed, by cutting away from the casting which will be shipped to the customer. They are often necessary to produce parts which are free of internal shrinkage voids. Sometimes, to promote directional solidification, chills must be used in the mold. A chill is any material which will conduct heat away from the casting more rapidly that the material used for molding. Thus if silica sand is used for molding, a chill may be made of copper, iron, aluminum, graphite, zircon sand, chromite or any other material with the ability to remove heat faster locally from the casting. All castings solidify with progressive solidification but in some designs a chill is used to control the rate and sequence of solidification of the casting. Patternmaker's Shrink (Thermal Contraction)

Shrinkage after solidification can be dealt with by using an oversized pattern designed for the relevant alloy. Pattern makers use special "contraction rulers" (also called "shrink rules") to make the patterns used by the foundry to make castings to the design size required. These rulers are 1 - 6% oversize, depending on the material to be cast. These rulers are mainly referred to by their actual changes to the size. For example a 1/100 ruler would add 1 mm to 100 mm if measured by a "standard ruler" (hence being called a 1/100 contraction ruler). Using such a ruler during pattern making will ensure an oversize pattern. Thus, the mold is larger also, and when the molten metal solidifies it will shrink and the casting will be the size required by the design, if measured by a standard ruler. A pattern made to match an existing part would be made as follows: First, the existing part would be measured using a standard ruler, then when constructing the pattern, the pattern maker would use a contraction ruler, ensuring that the casting would contract to the correct size. FAQ about Die Casting

Die casting is a versatile process for producing engineered metal parts by forcing molten metal under high pressure into reusable steel molds. These molds, called dies, can be designed to produce complex shapes with a high degree of accuracy and repeatability. Parts can be sharply defined, with smooth or textured surfaces, and are suitable for a wide variety of attractive and serviceable finishes. Die castings are among the highest volume, mass-produced items manufactured by the metalworking industry, and they can be found in thousands of consumer, commercial and industrial products. Die cast parts are important components of products ranging from automobiles to toys. Parts can be as simple as a sink faucet or as complex as a connector housing. History

Die casting was invented by Elisha K. Root, an inventor in the employ of Samuel W. Collins at the Collins ax-making factory in Canton, Connecticut in the 1830s. The earliest examples of die casting by pressure injection - as opposed to casting by gravity pressure - occurred in the mid-1800s. A patent was awarded to Sturges in 1849 for the first manually operated machine for casting printing type. The process was limited to printer’s type for the next 20 years, but development of other shapes began to increase toward the end of the century. By 1892, commercial applications included parts for phonographs and cash registers, and mass production of many types of parts began in the early 1900s. The first die casting alloys were various compositions of tin and lead, but their use declined with the introduction of zinc and aluminum alloys in 1914. Magnesium and copper alloys quickly followed, and by the 1930s, many of the modern alloys still in use today became available. The die casting process has evolved from the original low-pressure injection method to techniques including high-pressure casting — at forces exceeding 4500 pounds per square inch — squeeze casting and semi-solid die casting. These modern processes are capable of producing high integrity, near net-shape castings with excellent surface finishes. The Future Refinements continue in both the alloys used in die casting and the process itself, expanding die casting applications into almost every known market. Once limited to simple lead type, today’s die casters can produce castings in a variety of sizes, shapes and wall thicknesses that are strong, durable and dimensionally precise. The Advantages of Die Casting Die casting is an efficient, economical process offering a broader range of shapes and components than any other manufacturing technique. Parts have long service life and may be designed to complement the visual appeal of the surrounding part. Designers can gain a number of advantages and benefits by specifying die cast parts. High-speed production - Die casting provides complex shapes within closer tolerances than many other mass production processes. Little or no machining is required and thousands of identical castings can be produced before additional tooling is required. Dimensional accuracy and stability - Die casting produces parts that are durable and dimensionally stable, while maintaining close tolerances. They are also heat resistant. Strength and weight - Die cast parts are stronger than plastic injection moldings having the same dimensions. Thin wall castings are stronger and lighter than those possible with other casting methods. Plus, because die castings do not consist of separate parts welded or fastened together, the strength is that of the alloy rather than the joining process. Multiple finishing techniques - Die cast parts can be produced with smooth or textured surfaces, and they are easily plated or finished with a minimum of surface preparation. Simplified Assembly - Die castings provide integral fastening elements, such as bosses and studs. Holes can be cored and made to tap drill sizes, or external threads can be cast. Die Casting Process The basic die casting process consists of injecting molten metal under high pressure into a steel mold called a die. Die casting machines are typically rated in clamping tons equal to the amount of pressure they can exert on the die. Machine sizes range from 400 tons to 4000 tons. Regardless of their size, the only fundamental difference in die casting machines is the method used to inject molten metal into a die. The two methods are hot chamber or cold chamber. A complete die casting cycle can vary from less than one second for small components weighing less than an ounce, to two-to-three minutes for a casting of several pounds, making die casting the fastest technique available for producing precise non-ferrous metal parts. Die Casting vs. Other Processes Die casting vs. plastic molding - Die casting produces stronger parts with closer tolerances that have greater stability and durability. Die cast parts have greater resistance to temperature extremes and superior electrical properties. Die casting vs. sand casting - Die casting produces parts with thinner walls, closer dimensional limits and smoother surfaces. Production is faster and labor costs per casting are lower. Finishing costs are also less. Die casting vs. permanent mold - Die casting offers the same advantages versus permanent molding as it does compared with sand casting. Die casting vs. forging - Die casting produces more complex shapes with closer tolerances, thinner walls and lower finishing costs. Cast coring holes are not available with forging. Die casting vs. stamping - Die casting produces complex shapes with variations possible in section thickness. One casting may replace several stampings, resulting in reduced assembly time. Die casting vs. screw machine products - Die casting produces shapes that are difficult or impossible from bar or tubular stock, while maintaining tolerances without tooling adjustments. Die casting requires fewer operations and reduces waste and scrap. Choosing the Proper Alloy Each of the metal alloys available for die casting offer particular advantages for the completed part. Zinc - The easiest alloy to cast, it offers high ductility, high impact strength and is easily plated. Zinc is economical for small parts, has a low melting point and promotes long die life. Aluminum - This alloy is lightweight, while possessing high dimensional stability for complex shapes and thin walls. Aluminum has good corrosion resistance and mechanical properties, high thermal and electrical conductivity, as well as strength at high temperatures. Magnesium - The easiest alloy to machine, magnesium has an excellent strength-to-weight ratio and is the lightest alloy commonly die cast. Copper - This alloy possesses high hardness, high corrosion resistance and the highest mechanical properties of alloys cast. It offers excellent wear resistance and dimensional stability, with strength approaching that of steel parts. Lead and Tin - These alloys offer high density and are capable of producing parts with extremely close dimensions. They are also used for special forms of corrosion resistance. Die Construction Dies, or die casting tooling, are made of alloy tool steels in at least two sections, the fixed die half, or cover half, and the ejector die half, to permit removal of castings. Modern dies also may have moveable slides, cores or other sections to produce holes, threads and other desired shapes in the casting. Sprue holes in the fixed die half allow molten metal to enter the die and fill the cavity. The ejector half usually contains the runners (passageways) and gates (inlets) that route molten metal to the cavity. Dies also include locking pins to secure the two halves, ejector pins to help remove the cast part, and openings for coolant and lubricant. When the die casting machine closes, the two die halves are locked and held together by the machine’s hydraulic pressure. The surface where the ejector and fixed halves of the die meet and lock is referred to as the "die parting line." The total projected surface area of the part being cast, measured at the die parting line, and the pressure required of the machine to inject metal into the die cavity governs the clamping force of the machine. There are four types of dies: 1. Single cavity to produce one component 2. Multiple cavity to produce a number of identical parts 3. Unit die to produce different parts at one time 4. Combination die to produce several different parts for an assembly. Hot Chamber Machines Hot chamber machines are used primarily for zinc, copper, magnesium, lead and other low melting point alloys that do not readily attack and erode metal pots, cylinders and plungers. The injection mechanism of a hot chamber machine is immersed in the molten metal bath of a metal holding furnace. The furnace is attached to the machine by a metal feed system called a gooseneck. As the injection cylinder plunger rises, a port in the injection cylinder opens, allowing molten metal to fill the cylinder. As the plunger moves downward it seals the port and forces molten metal through the gooseneck and nozzle into the die cavity. After the metal has solidified in the die cavity, the plunger is withdrawn, the die opens and the casting is ejected. Cold Chamber Machines Cold chamber machines are used for alloys such as aluminum and other alloys with high melting points. The molten metal is poured into a "cold chamber," or cylindrical sleeve, manually by a hand ladle or by an automatic ladle. A hydraulically operated plunger seals the cold chamber port and forces metal into the locked die at high pressures. High Integrity Die Casting Methods There are several variations on the basic process that can be used to produce castings for specific applications. These include: Squeeze casting - A method by which molten alloy is cast without turbulence and gas entrapment at high pressure to yield high quality, dense, heat treatable components. Semi-solid molding - A procedure where semi-solid metal billets are cast to provide dense, heat treatable castings with low porosity. Automation and Quality Control Modern die casters use a number of sophisticated methods to automate the die casting process and provide continuous quality control. Automated systems can be used to lubricate dies, ladle metal into cold chamber machines and integrate other functions, such as quenching and trimming castings. Microprocessors obtain metal velocity, shot rod position, hydraulic pressure and other data that is used to adjust the die casting machine process, assuring consistent castings shot after shot. These process control systems also collect machine performance data for statistical analysis in quality control. Die Casting Design Die casting is one of the fastest and most cost-effective methods for producing a wide range of components. However, to achieve maximum benefits from this process, it is critical that designers collaborate with the die caster at an early stage of the product design and development. Consulting with the die caster during the design phase will help resolve issues affecting tooling and production, while identifying the various trade-offs that could affect overall costs. For instance, parts having external undercuts or projections on sidewalls often require dies with slides. Slides increase the cost of the tooling, but may result in reduced metal use, uniform casting wall thickness or other advantages. These savings may offset the cost of tooling, depending upon the production quantities, providing overall economies. Many sources are available for information on die casting design, including textbooks, technical papers, trade journals and professional associations. While this section is not intended to provide a comprehensive review of all the factors involving die casting design, it will highlight some of the primary considerations. Additional sources of information are listed in the "Resources" section of this brochure. Alloy Properties One of the first steps in designing a die cast component is choosing the proper alloy. Typical properties for the most commonly used alloys are shown on the linked charts. Comparing Materials The cost of materials is another important design consideration. Accurate comparisons require looking beyond the cost per pound or cost per cubic inch to fully analyze the advantages and disadvantages of each competing process. For instance, the relatively greater strength of metals generally allows thinner walls and sections and consequently requires fewer cubic inches of material than plastics for a given application. Effective Design Load example illustrations to help show how design and engineering can affect final production.