Upgrade a Centuries-Old Manufacturing Technique with FDM

Investment casting has stood the test of time. One of the world’s oldest manufacturing methods, it is used for the low-volume production of highly-accurate metal parts with excellent surface finishes.

But after thousands of years, additive manufacturing is helping to improve the process and increase its efficiency.

Traditionally, investment casting starts when a wax pattern is coated in ceramic slurry, which hardens to create a shell around the pattern. After it is heated, the wax melts and leaves behind a hollow ceramic shell. The shell is filled with molten metal and after it cools, the ceramic material is blasted off to reveal a completed metal part.

Many investment casting applications use injection-molded wax patterns. But they can also be made faster and with less expense with additive manufacturing technologies like Fused Deposition Modeling (FDM).

3D printing

The process works the same way, but because FDM parts are built with thermoplastics, they will not melt like their wax counterparts. Instead, the plastic burns and turns to ash, which is easily washed out of the ceramic shell.

In addition to easy burnout, choosing FDM patterns provides a number of advantages over injection-molded wax, including:

Eliminate time and cost of tooling:

Producing injection-molded parts requires the creation of tooling, which is expensive and time consuming. None of these concerns apply to FDM parts, built one layer at a time without any tooling needed, and within a matter of days, not weeks or months.

Experience total design freedom:

One of the biggest strengths of FDM, and additive manufacturing as a whole, is the ability to create parts with geometries that would not be possible with injection molding. FDM patterns can have non-uniform wall thicknesses, undercuts and overhangs, expanding the complexity of your metal parts. Size is also not an issue; patterns can be built separately and bonded together, giving them the strength as if they were built in one piece.

Update patterns as needed:

When a product is in the prototype phase, functional testing often reveals design defects. Design changes with injection molding means tooling modifications—an additional expense that also delays production. FDM patterns can be tweaked on the fly, the only thing required is an adjustment to the design file and a new part can be created immediately.

Create durable patterns:

Injection-molded wax can easily be damaged or deformed when transported. The durability of FDM thermoplastics ensures your patterns maintain their shape and structure during transportation and in a variety of environments.

Achieve smooth finishes:

Secondary operations like sanding or vapor smoothing give FDM parts an excellent surface finish, providing you injection-molded quality without the time and expense.

While investment casting is a tried-and-true manufacturing method, a minor upgrade to the process can improve how you make your metal parts.

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