When to Use Investment Casting - Foundry FAQs #1
Thanks for joining us for our very first Foundry FAQs! In this series, we'll explore frequently asked questions we get at our Utah, Texas, or International Foundries. There's a lot to learn in the world of investment casting, from basic concepts to the nitty gritty details of fine-tuning production lines. While we won't get to every question today, we hope this series will be a solid resource for learning about metalworking, investment casting, and what goes on inside a modern foundry.
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Without further ado, let's get into it!
When Should I Use Investment Casting?
Investment Casting (aka Lost Wax Casting or Precision Casting) is one of many metal forming techniques, and whether or not it is good for your particular needs depends on a few factors.
1) How many parts do you need?
2) Your Dimensional Tolerances.
3) The surface finish you require.
4) The complexity of your design.
Investment casting also has a few bonus advantages, like the ability to cast your logo onto your part or recyclability, which we'll explore more below. First, let's tackle each of these four points.
Number of Parts
Perhaps the most straightforward way to determine if investment casting is a good fit for your project is by asking how many parts you need. Investment casting is most cost-effective when producing numerous metal parts, often with production numbers in the hundreds or thousands. The casting process requires pattern development, tooling, and mold making (i.e., creating a template that is used to make wax patterns of your part numerous times). Furthermore, pre-production includes optimizing the wax trees of your part, allowing you to produce multiple parts in one pour (see image below). These steps can be costly if you produce only a handful of parts.
Investment casting allows for pouring multiple parts at the same time. In this image, you see a tree with over two dozen parts ready to be produced in one go.
Dimensional Tolerances
Investment casting uses wax patterns to form molds for metal forming. These molds allow for complex, extremely precise, and repeatable castings that would be impossible or incredibly expensive to reproduce using other metal-forming methods. For example, the industry standard for dimensional tolerances for investment castings is +/- 10 thousandths inch per inch. If you want to check out IPC's tolerance table, download it here.
Using alternative metal forming techniques may require intensive and expensive finishing processes to reach even mildly comparable levels of quality.
Surface Finish
Investment casting allows for a super smooth surface finish when compared to methods like sand casting. Depending on your part's application, they may not require secondary finishing techniques (sanding, grinding, etc.). Furthermore, your part won't have a dividing line because investment casting only uses one mold instead of two.
Design Complexity
If your design is relatively straightforward, you may not require the precision investment casting affords. However, if you have thin walls, intricate patterns, very small parts, or a design with strict tolerances, investment casting is likely the only way to achieve such precision; without prohibitively expensive machining or secondary/tertiary finishing work.
Bottom Line
To sum up, investment casting is primarily for situations where you need to affordably and accurately replicate hundreds/thousands of parts. It is particularly adept at producing parts that have tight dimensional tolerances, have complex designs, or require a silky smooth surface finish. Your specific part(s) may be the perfect fit for an investment casting, or it may make more sense to get parts machined, sand cast, or use a different method. Always consider your budget and the requirements of your project. Also, never hesitate to ask around! A good investment casting partner will answer questions specific to you.
Bonus Perks of Investment Casting
Recyclable Materials:
If eco-mindedness is important to your customers or brand, nearly 100% of wax used in investment casting is recyclable. Furthermore, in the United States, many investment casting foundries are shifting to more green manufacturing processes due to a recent surge in government grants and mandates for cleaner production.
A Surface Finish with Your Logo
Because of the precision that investment casting allows, you can include your logo, numbers, or other symbols on the surface of your part. This is a cool way to make your end product stand out.
What is the average turnaround time for Investment Casting?
Many variables impact turnaround times, including material availability, work backlog, prototyping, tooling, and more. However, as an estimate, the average turnaround time industry-wide is 8-10 weeks.
Some foundries have super-optimized production cycles with automation at every step. Such foundries offer lightning-fast turnaround times of as little as two weeks.
If speed is of critical importance, be sure to ask about expected turnaround times during the quoting process.
Modernization in metalworking has allowed for shorter turnaround times and 24/7 production cycles
How Long Has Investment Casting Been Used?
Above, we mentioned that investment casting is also known as "lost wax casting". While the method has seen technological advancements and refinements, the basic process has been used by humans for at least 5000 years. (1.) If it isn't broken, don't fix it, right?
Today, robotics have taken the process to new heights, allowing for next-level precision and speed. Stay tuned for future articles, where we will explore automation, eco-friendly additions, and new technology introduced to the casting process.
Sources:
“Investment Casting.” Wikipedia, November 5, 2023. https://en.wikipedia.org/wiki/Investment_casting.
Disclaimer:The content provided in this blog is intended for informational purposes only. We make no guarantees regarding the completeness of the information presented. It is imperative for individuals seeking casting/manufacturing solutions to define their specific requirements clearly. This blog does not offer manufacturing or casting advice, and readers are encouraged to contact our dedicated team for more detailed quotes, personalized information, and expert assistance tailored to their unique needs. 