Investment Casting FAQ

Why an Investment Casting?

The investment casting process offers unique advantages and cost saving opportunities over other metal forming process. Investment Castings provide many advantages such as design freedom, greater alloy selection, close tolerances and better finishes. Most importantly, the investment casting process offers cost savings in machining time, improves reproducibility and reduces assembly time by combining assembled components into a one piece casting. Investment Castings excel at reducing the high cost of machine components and weldments.   

Lower initial tooling costs: Initial tooling costs are lower than for most other metal forming techniques. Tooling is produced from an aluminum alloy that is easily machined tp keep the tooling cost low. Prototypes are produced from SLA models so no tollling is requried.

Elimination of material waste: Investment castings are cast to size or near net shape. As a result there is little machining necessary providing savings in time and material costs. Investment castings can be cored to provide additional material savings and weight reduction.

Design flexibility and capability: The Investment Casting Process offers greater design flexibility. Design engineers are now able to develop parts with more complex geometries to satisfy product performance and application requirements.

Design enhancements: Unlike other casting methods, there is no draft requirement in the investment casting process. You are able to easily design components with contours, slots, holes, cored areas for weight reduction and radii.

Consistency: The investment casting process provides a reliable and consistent product. By maintaining highly effective process control programs, dimensional consistency is maintained within batches and from batch to batch

Close tolerances : The Investment Casting Process produces the closest tolerances of any casting process over a wide variety of alloys. Linear tolerances of  +- .005 inch per inch can be cast.

Surface Finish Improvement:  A surface finish of 125 RMS is typical for steel castings and a slighly rougher finish for aluminum castings. Overall no other casting process produces a finer finish that the investment casting process.

What is an investment casting?

Investment casting is an industrial manufacturing process also know as the lost-wax process and is one of the oldest known metal-forming techniques.[1] The process was originally developed over 5,000 years ago when beeswax was formed to produce a pattern to create metal artifacts.  Today Investment Casting incorporates high-technology waxes, refractory(ceramic) materials to produce metal components in a wide variety of metals and high-performance alloys with accuracy, repeatability, and integrity .

Ceramic materials are used to build a hollow shell or mold into which molten metal is poured to make the castings. The ceramic materials are first applied as a series of coats around a wax impression of the part or wax pattern to form the ceramic shell or mold. The wax is then removed or melted out from the ceramic shell, the ceramic shell is then fired and the metal of choice poured in the shell or mold to produce the desired part. .  

The origin of the term investment comes from the solid mold process where a plaster type ceramic material is poured or "invested" into a container where a clustered tree of small wax or plastic patterns are held. These wax or plastic patterns are impressions of the part to be produced. After the plaster or ceramic has set, the wax or plastic patterns are melted or burned out leaving a hollow cavity into which the metal is poured and the metal part is produced.

Other Frequently Asked Questions

What kinds of parts are suited for investment castings?  Almost any configuration or design can be produced as an investment casting. Investment castings offer more design flexibility over any other manufacturing process. Investment castings excel at reducing the high cost of machine components and weldments.

What are the benefits of an investment casting? The investment casting process offers lower costs, greater design freedom and the largest selection of alloys to work with.

What size parts can Wisconsin Precision produce? Wisconsin Precision can pour parts in a size envelope of 20x20x24.

What alloys does Wisconsin Precision pour? Wisconsin Precision pours over 150 different non ferrous and ferrous alloys. We offer one of the broadest alloy selections in the industry ranging aluminum to stainless steel to tool steels to high temperature alloys such as Inconel and Cobalt based alloys.

What are the typical dimensions tolerances for an investment casting? Our process will hold a linear tolerance of +-.005 inch per inch.

What type of surface finish can one expect from and investment casting? A surface finish of about 125 RMS is typical for steel castings and for aluminum 160 to 190RMS.

Aren’t investment castings expensive? If so, how can they save money? While investment castings are usually more expensive than other casting processes and forgings, investment castings greatly reduce the overall cost of a metal component by reducing the amount of machining or welding and material waste that may occur.

Aren’t castings prone to porosity? No. If the parts are gated properly, designed right, and the manufacturing processes are controlled, porosity will not be an issue. Wisconsin Precision utilizes a highly sophisticated computer program know as Nova Flow to simulate how the parts are to be poured to develop a manufacturing process that eliminates the causes of porosity.

What type of tooling is required? Aluminum split die or tool is manufactured to produce a wax impression of the part that a ceramic mold is built around.

Could prototypes be produced with this process? Definitely. The investment casting process is great way to produce prototypes in metal very quickly without any tooling. Investment castings are the best way to produce your prototypes regardless of the process you ultimately choose for production. Prototypes can be produced in 7 to 10 working days. All that is needed is a solid model.

How long does it take for a quote? 24 to 48 hours for a prototype and 10 working days or less for a production component.

What is the typical lead time for parts? 7 to 10 working days for prototypes and for production parts requiring tooling and first article, the lead time is typically 8 to 10 weeks.