Why You Should Consider Investment Castings (Lost Wax Castings) for Your Steel Casting Project
The investment casting process has much to offer for a company looking for a cost-effective and highly versatile way to produce custom parts
Written by: Brad Done
Since 1927, Reliance Foundry has been involved in the metal casting industry. Over the years, we’ve gained broad experience in the different processes and techniques for creating metal parts. Intricate parts with detailed, complex angles and faces can be produced using a variety of methods. However, investment casting provides the ultimate technique for low-weight, precision, steel casting production.
Investment Casting Defined
Investment casting is commonly referred to as lost wax casting because wax is used to create the mold and then it is “lost” (or melted away) from the mold prior to metal being added to fill the cavity left behind by the “lost” wax. If you need a custom, precision metal part created, investment casting is one way of getting that part made. This process is used in many industries to make parts from a variety of metallic material types. Nickel and cobalt-based superalloys account for 50% of total output by value, steels (of all types) account for 35%, aluminum accounts for about 10%, and copper and titanium alloys make up a large part of the remaining 5%.
An investment casting mold is made in foundries by first making a wax impression produced from high pressure dies or special investment cast tooling; the wax can be replaced by other materials such as foam (lost foam), or some other material that can be melted away during the investment casting process. This wax impression is then dipped and coated in a refractory ceramic slurry, forming an investment casting mold with a hard skin. After this, the entire mold is then placed in an oven and the wax is melted away. Because the mold is formed around a one-piece wax impression (which does not have to be pulled out from the mold as in a traditional sand casting process), very intricate parts, and undercuts can be made.
Cost-Efficiency
Investment casting is an extremely cost-efficient process. It reduces costly machining operations — sometimes even eliminating them. Several parts can be made as one casting. This eliminates the need for fabrication, which reduces assembly, welding, handling & inspection costs. Any company that deals with high assembly costs benefits instantly when investment casting techniques are employed for manufacturing.
Investment casting also enables relatively small quantities of an item, typically for research and development trials, to be produced prior to commitment to larger production quantities. Rapid prototyping is also possible using wax impressions produced from digital models.
Overall, reduced material, reduced labor costs, and the elimination of some assembly steps makes investment casting an extremely attractive option.
Versatility and Accuracy
Investment casting also provides tremendous design flexibility for engineers and designers; it is regarded as a precise casting process to fabricate near-net-shaped metal parts from almost any alloy - thus the versatility. The name “near-net-shaped” points to the quality and volume of the “net” or final shape. Near-net quality in the final investment casting reduces the costly and time consuming finishing that is usually done by machining or grinding. The investment casting process is capable of producing precise detail and dimensional accuracy in parts weighing from many pounds to just a few ounces.
Although its 5,000 year history lies to a great extent in the production of jewelry, the most common use of investment casting in more recent history has been the production of components requiring complex, often thin-wall castings. The one-piece mold gives rise to a component shape that is aesthetic and uniform. It can be used to make parts that cannot be produced by normal manufacturing techniques, such as turbine blades that have complex shapes and would require unusual coring in standard sand casting processes.
Nearly every industry relies on investment casting to produce lightweight precise dimension parts with fine details including helicopter, marine, automobile, and even jet engine companies. Parts that require sharp finishes can be cast without extra effort. Lettering, precision holes, splines, serrations, bosses, and even some threads can be investment cast. Reproducing the fine detail necessary in these by using investment casting ensures consistency across production.
Reliance Foundry provides production of intricate parts and cost effective replacements for many types of sand castings, die castings and metal fabrications through the steel investment casting process. Few, if any, alternative metal forming methods can offer such a unique and broad spectrum of advantages.
About Reliance Foundry Co. Ltd.
Reliance Foundry has been a family-owned business since 1927. Investment castings are one of its main product lines, along with industrial wheels, bike parking products and bollards. Reliance sources products globally and offers quick and convenient delivery in the United States and Canada from its Vancouver location.
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