Stainless Steel World Magazine September 2023 | Page 63

Investment casting is a commonly used method to fabricate metal components in the aerospace industry . It is valued for its ability to produce precision components , as well as versatility and integrity in a variety of metals and high-performance alloys .

Engineering Stress ( ksi )

250 250 H925

Figure 1 . Room temperature stress-strain curves for 17-4 PH castings in the H925 and H1100 tempers . Strain to failure varies significantly due to internal casting porosity .

Engineering Stress ( ksi )

200 200 150 150 100 100 50 50

H1100

0 0 0.00 0.03 0.06 0.09 0.12 0.15 0.00 0.03 0.06 0.09 0.12 0.15

Engineering Strain ( in / in ) Engineering Strain ( in / in )

Text and images by 3DEO

While casting is one of the oldest techniques to make metal parts , having been invented over 5,000 years ago , this more traditional manufacturing method is commonly used to make components with standard alloys like stainless steels ( including 17-4 & 15-5 PH ), carbon steel , aluminum and brass , as well as nickelbased super alloys ( including Inconel 718 & 625 ). Typical aircraft , space and aviation applications include parts for the following components : air and fuel systems , cabin control systems , engines , environmental control systems ,

Stress ( MPa )

1400

1200

1000

800

600

400

200

0 0

Figure 2 . Stress-strain curve for 3DEO 17-4PH in H900 condition .

hydraulic systems , landing control systems , interface controls for operators , and the internal mechanism . Aerospace components must be able to withstand operational wear and failure , so they rely on superior durability and increased tensile strength , as well as flexible design capabilities allowing for thin walls , slots and undercut holes , and high-quality surface finish . While being well-suited for the high demands and quality requirements of the aerospace industry , investment casting allows engineers to present elaborate designs and parts of different weights and sizes . Additionally , investment casting typically produces a superior

Stress-Strain Curve

surface finish and can reduce the need for secondary operations or machining . That said , however , investment casting also comes with its set of drawbacks :

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Lead times are especially long across the entire manufacturing process ; from developing the tooling and molds suitable for the process to the actual production timeline and cycle run times .

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Holes cannot be smaller than 1 / 16 in . ( 1.6 mm ) and should be no deeper than about 1.5 times the diameter .

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Many process factors affect the integrity of the mold and resulting part , so the quality management system is challenging , especially in a highly regulated industry like aerospace .

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Part functionality problems may arise due to variability , resulting in failure or unpredictable product performance .

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Overall costs stretch beyond just unit economics , especially for short-run productions , due to significant mold , setup , run times , minimum order requirements , and the expense of iterations .

Many engineers and supply chain managers are accustomed to working with the above drawbacks , and oftentimes don ’ t realize there exists an available solution that upholds the high-volume delivery of investment casting . And while advanced technologies like metal 3D printing have long been considered as a prototyping-only method , 3DEO , a high-volume metal 3D-printing company , is competing with investment casting ’ s production and economies of scale .

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