Customers for investment castings appreciate the precision and detail the process provides, but keep asking for more. In response, foundries are implementing new techniques and technologies that cut lead time and costs while improving quality and expanding capabilities. Here’s a look at what’s new and what’s coming.

Innovation Drivers

Investment casting uses wax patterns to create single-use molds. The patterns are injection molded, then coated with a ceramic slurry. After the ceramic has dried, the wax is melted out to leave a mold cavity for metal to fill.

In series production patterns, and the associated cores used to form hollow areas within the final metal part, are produced at the rate the foundry needs them. For samples and starting-up production though, pattern lead times are longer than buyers want to wait.

At the same time, buyers also want better quality, higher precision, finer detail, and the ability to cast larger parts. Plus, competitive pressures mean foundries are always looking for the most efficient and productive methods and processes.

The result of these forces is to push investment casting innovation along three vectors:

• Shorter lead times
• Increased quality and lower costs
• Enhanced process capabilities, and lower costs

Here’s a closer look.

Shorter Lead Times

The main issue is the time needed to make the mold tools for the wax patterns. This is being addressed through 3D printing. It’s now practical to 3D print these patterns rather than molding them. The production rate is slower than injection molding but printing eliminates tooling lead time and cuts weeks from the time taken to get initial sample parts.

A second, albeit significantly smaller, lead time issue arises at shell-making. The problem here is that each layer of ceramic slurry needs to dry thoroughly before the next one can be applied. To overcome this, the ceramic manufacturers are working on faster drying formulations that can be applied in thicker layers. In parallel, oven producers are bringing out innovations like infrared heating, vertical conveyors, and improved airflow that reduce drying time.

Increased Quality and Lower Costs

Robots provide remarkable levels of repeatability, which is one reason they’re being deployed in shell-making. Their function here is to dip the wax “tree”, (the assembly of multiple wax patterns onto a central sprue for metal feeding), into a vat of ceramic slurry.

One advantage of robotic dipping is that it provides the consistent approach angles and rotation speed that ensure repeatable coating thickness. Another is that the machines can run unattended through breaks, increasing productivity while protecting human workers from what can be an arduous and even hazardous operation.

Likewise, robots can now assemble the wax trees used for dipping. Again, this increases consistency and can also lower waste due to mistakes in manual handling.

Enhanced Process Capabilities, and Lower Costs

In addition to speeding up drying and reducing the number of ceramic layers needed, material producers are working on creating strong shells. This will allow larger masses of metal to be cast, enabling either larger investment cast parts or the addition of more patterns to the sprue. With this latter improvement more parts can be cast per shell, helping to improve the economics of the process.

Partner With a Technology Leader

Leading investment casting foundries like those run by Impro are constantly on the lookout for techniques and technologies that will benefit them and their customers. The latest innovations are reducing lead times, lowering costs, and expanding the capabilities of the process.

If you need a source for high quality, investment cast parts, Impro can help. Contact us to discuss your project.