3DP Wax Patterns Enhance Investment Casting

April 20, 2020
Printing castable patterns lets an investment caster turn around projects faster, with a surface quality that supports an expanded offering of prototypes and pre-production products.

Buyers of investment-cast parts assume they will pay a premium for precision – in design and production — but that does not reduce the pressure on investment casters to deliver parts with dimensional and surface quality, and to respond to buyers' demands or needs promptly. For investment casting foundries, the metrics for competitive are multifaceted, and the standards are likely to change frequently. 

Early on, the emergence of additive manufacturing was identified as a threat to investment casters, because of the perception that any precision part may be printed more efficiently than it is cast. But for some of those foundries the emergence of additive technologies has been a boon to competitiveness.

Microfound, an investment casting foundry established in Barco, Italy, 27 years ago works with customers in various industrial sectors. Its products are steel and specialty steel castings, but its approach to the market emphasizes technological proficiency.

Recognizing the opportunity to improve its service and results via additive manufacturing, Microfound invested in 3D Systems’ wax printing technology to address the time and cost constraints that are inherent to developing investment castings.

The specific value of investment casting is precision design, including thin walls, internal shapes, and voids. Design and production time and effort add to the cost of investment casting. A part’s final shape is formed in full detail, typically in wax. This shape (or multiple versions of it) are attached to a “tree”, and the tree is dipped in ceramic slurry that coats and hardens around the wax form. This process is repeated until a hard ceramic shell forms. These shells are the molds that will receive molten metal.

But, getting the wax form right is the first and essential step, because a design error in that step will be repeated; and any design changes the customer issues will take the process back to the wax form.

Since it purchased a 3D Systems ProJet® MJP 2500 IC wax 3D printer, Microfound has enhanced its competitiveness and accelerated its ability to produce quality prototypes and pre-production series wax patterns.

3D Systems’ digital foundry portfolio includes the investment casting-wax 3D printer (part of the MultiJet Printing series) and VisiJet wax material, as well as 3D Sprint® software. 3D Sprint is an additive manufacturing software that coordinates file preparation, optimization, and printing. Developed to be user-friendly, this combination of tools helps investment casting foundries simplify the transition of a CAD file to a cast part, with no intermediate tooling.

Prior to purchasing the ProJet MJP 2500 IC, Microfound outsourced this process to a firm that used an alternative 3D-printing technology to create molds for pouring wax patterns. Since it adopted wax 3D printing, Microfound has been able to shorten its pattern turnaround time by several days, while achieving superior surface finish and details. 3D Systems’ VisiJet® M2 ICast material is 100% RealWax and integrated seamlessly into Microfound’s investment casting process.

“3D Systems’ printer and material offer maximum compatibility with our melting process, which has significantly reduced the time it takes for us to achieve a final cast part,” said Microfound CEO Marco Bigliardi.

In addition to accelerating pattern production, 3D Systems’ digital foundry platform has improved finished part quality. “We have definitely noticed aesthetic improvements to the surface quality of particular products, and we are having great success with precision parts as well,” Bigliardi added.

3D Systems’ MJP technology and VisiJet RealWax material deliver industrial casting patterns that hold tight tolerances and are reliable for manufacturing complex components, with reduced or no finishing work.

Beyond helping Microfound upgrade and accelerate its prototyping service, the print quality of the ProJet MJP 2500 IC also is helping the foundry improve its ability to supply pre-production series and products — especially in small to mid-sized batches that are equivalent to series production parts.

“The printer is very easy to use,” Bigliardi said, confirming the ease with which his operation adopted the digital foundry solution.

Combined with the intuitive interface of 3D Sprint software, the process of optimizing individual parts and builds is straightforward, so more parts can be printed in less time and with higher quality. 3D Sprint is able to analyze and optimize the placement of support structures on parts and ensure the best placement of parts within the build platform. “We like 3D Sprint because it is a very intuitive and easy-to-use software,” said Bigliardi.

Since implementing 3D Systems’ digital foundry platform, Microfound is a faster partner to its customers, and more competitive in its offering of prototyping services. It also can offer more and faster pre-production series parts. “ProJet MJP 2500 IC has enabled us to be more productive and to diversify our offerings,” said Bigliardi. “The ability to create high-quality lost-wax castings without building a mold is a great advantage, and has quickly become a fundamental part of our operations.”