Since QESC joined The Lawton Standard family, we’ve learned more about iron casting. Because we’ve always been known for quality steel castings, we wanted to ensure that our iron castings were of high quality too. One thing that has helped us learn is Iron 101 workshops.
At Lawton Standard foundries, engineers and craftspeople create high-quality, high-performance castings for some of the world’s most demanding OEMs. At our Iron 101 workshops, OEM design engineers and procurement people receive a first-hand education on the art and science of modern ductile and gray iron castings. As a result, they leave with a much deeper appreciation of these finely-engineered products.
“The course was fantastic. I learned a lot of new information and understand the overall process better,” said one Iron 101 attendee. “It’s a great course for new hires and existing customers. It really is a great overview of the Lawton processes,” added another.
Casting design: A formula for success
From a design perspective, a successful casting results from a close collaboration between the OEM design engineer and the foundry’s casting engineer. The design engineer is concerned about factors like shape and space optimization, the component’s life cycle, fatigue strength, and other performance-related factors. Casting engineers consider issues like castability, material properties, structural soundness, and dimensional requirements.
A metallurgist also gets involved to help decide the ideal “recipe” of alloys to deliver the material characteristics the customer requires. The goal is a casting design that is optimized to perfectly meet the needs of both parties and requires a minimum of machining to reach its final specifications.
Material choice and testing
Iron 101 students learned about the properties of gray and ductile iron, how these materials are tested, and the basics of thermal testing. Using a physical model, the instructor showed how the cope (the top half of a horizontally parted mold), drag (the bottom half of a horizontally parted mold) and cores (sand inserts placed within a mold to shape the interior of the casting) fit together like an intricate jigsaw puzzle to form a complete mold.
“The course helped me visualize how copes, drags, and cores fit together to make a casting,” said one Iron 101 attendee.
They also learned about part geometry, castability, and solidification modeling. The latter is a 3D technology that simulates how molten metal flows into a mold design and where and how it cools. It enables a casting engineer to optimize the mold design to minimize defects and voids in the finished piece. It also ensures that the part quality is consistently high from one piece to the next.
Cores, chillers, and risers, oh my!
To achieve the desired part quality, cores are often required. These removable patterns help shape the interior of the final casting. The goal is to minimize the number and complexity of the cores required yet still achieve the shape, size, and material characteristics the OEM requires.
Casting engineers will utilize risers and chills to ensure that a casting cools uniformly, without hot spots and voids. Risers are structures that stick out of the top of the mold. As molten metal is poured into the mold, it flows into these hollow towers. As the material in the casting below cools, it sometimes leaves small voids. The molten metal in the risers flows back into the mold to fill these gaps.
Solidification modeling is used to optimize the locations and sizes of these risers to ensure uniform material quality. Once the part has cooled, these risers are machined off because they aren’t part of the finished casting.
Chillers are blocks of iron inserted into a mold to enable faster and more uniform cooling of certain casting sections.
A visit to the foundry floor
No class on modern casting would be complete without a foundry tour. Students got to see how mold patterns are made and had an opportunity to witness a pour – where 2,500-degree iron is poured into a mold. It’s an experience they won’t soon forget. Students also saw how castings are processed and machined after they have cooled.
Finally, during their foundry tour, students saw evidence of Lawton’s commitment to LEAN manufacturing. Tour guides pointed out goals for continuous improvement.
At the end of the day-long class, attendees were impressed by what they learned. They left the workshop with a new appreciation for the engineering and ingenuity of casting.
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