June 25, 2018 | Prototype Casting

All About Investment Casting – What, Why, And FAQ

If you are like most people, and you get almost any and all needed information from Google, you’d find that investment casting has a fairly simple definition: “a technique for making small, accurate castings in refractory alloys using a mold formed around a pattern of wax or similar material which is then removed by melting.

If you dare to go a step further, you’d find that you are just a few clicks away from a more thorough Wikipedia page devoted to the technical understanding of investment casting, which, as the page instructs you, is an industrial process based on one of the oldest known metal-forming techniques, lost-wax casting. Wikipedia has this to say about a pattern being invested with, or surrounded by, a refractory material, such as brass, carbon steel, aluminum, glass, or stainless steel alloys.: “The material is poured into a cavity in a refractory material that is an exact duplicate of the desired part. Due to the hardness of refractory materials used, investment casting can produce products with exceptional surface qualities, which can reduce the need for secondary machine processes.” While we are defining our terms, refractory materials refers to any non-metallic materials which have properties that making them conducive to applications for structures or as parts of greater systems. Typically, refractory materials are used in reactors, furnaces, kilns, or in other such applications.

Why Investment Casting?

Now that we’ve gotten the fundamentals of the what out of the way, let’s talk a little bit about the why. Investment casting is typically used because of its cost-effectiveness in addition to a host of other blatant benefits. Among them are its greater design freedom, close tolerance, superior finishes, and improved alloy selection. But perhaps most significantly, using investment casting saves utilizing the method both time and money. More specifically, the process affords a better reproducibility while diminishing assembly time by using a one-piece casting method. Given the expensive nature of weldments and machine components, this is a very attractive prospect for folks who are fans of, you know, saving time and money.

Other benefits of investment casting include:

  • Less Excess Waste of Materials – One of the advantages of investment casting is that it is almost always cast to size, meaning that very little machining required in order to produce the cast. This cuts down on material cost and speeds the entire process up.
  • Tooling Costs – When compared to other metal forming methods, the initial tooling expenses are usually dramatically lower when using investment casting. Using an aluminum alloy that is easily machined means the costs stay low.
  • Tolerance – Close tolerance is another benefit of using investment casting, in the sense that your average investment casting process results in the closest tolerances you’ll find, even when comparing a range of alloys. Linear tolerances of +/- .005 inch per inch are able to be cast utilizing the investment casting technique.
  • Improved Design – You don’t need a draft requirement when using investment casting, as opposed to other approaches to casting. You can include aspects like holes, slots, contours, and even cored areas to manage weight.
  • Surface Finish – The investment casting process produces the finest finish of all casting processes. For aluminum and steel castings, a surface finish in the region of 125 RMS is typical.

Investment Casting FAQ

Now that we’ve (hopefully) gotten your gears turning a bit, you might have some lingering questions before feeling inclined to reach out to us and ask us about our particular investment casting services here at Protocast Inc., Denver’s top machine shop and foundry. Below we do our best to answer frequently asked questions regarding investment casting as well as its processes and applications.

What Are The Most Common Applications Of Investment Casting?

While we hope we made this abundantly clear above, the industrial metal forming process known as investment casting is used to create wax models, where the models are replaced with melted metals for a variety of purposes. The process is utilized for medical parts, O&G applications, and firearm components, among other applications.

What Is A Lost-Wax Process?

Lost-Wax is the original term used for describing investment casting, which is also known as precision casting. The essence of this method is, again, taking a cast from an original sculpture and making a duplicate metal sculpture on top.

How Many Parts Are Recommended To Make Investment Casting A Good Business Decision?

Well, it depends. We don’t want to speak out of turn, and it’s difficult to extrapolate without knowing the specifics of a given situation, but the number of parts recommended is connected with how many casting runs are set to take place. Generally speaking, a toolmaker’s rule of thumb is around 25 castings, but again, it’s difficult to speak concretely without knowing details, so give us a call and we’ll tailor our recommendations to your particular project.

What Kind Of Tooling And Equipment Is Required For Investment Casting?

You’ll need a split-cavity aluminum die in the shape of the final casting for each wax mold pattern. Then you’ll need a custom combination of aluminum and soluble cores as materials to be used. Most tooling costs somewhere between $1,000 and $10,000. Keep in mind that Rapid Prototypes are also able to be used, but using RP isn’t typically worthwhile for high production orders.

How Does Investment Casting Compare To The Cost Of Plastic Injection Molding Tooling?

Investment casting is significantly less expensive than the above alternative because the once expensive option of investment casting has been diminished by the long-term advancements of CAM, CDM, and machining technologies. Relatedly, the computer-driven technologies and their integration has further fueled the cost-effectiveness of processes like investment casting, if for no other reason than the labor demands have been dramatically reduced during the design and fabrication of the tooling process.

Reach Out To Protocast Inc.

If you are in need of investment casting services in Denver, reach out to us today. We offer engineering support among our many services here at our local machine shop and foundry. We have a passion for helping our clients achieve their exact goals. It’s our pleasure to be a part of any project in which our services could be of assistance. Contact us today.