Old world ingenuity. Cutting-edge science. Two worlds that appear to be mutually exclusive.
But they blend together perfectly at The C.A. Lawton Co., where engineers and craftspeople create high-quality, high-performance castings for some of the world’s most demanding OEMs. At a recent Iron 101 workshop, OEM design engineers and procurement people got a first-hand education on the art and science of modern ductile and gray iron castings. They came away 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 recent 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: Where the magic happens
From a design perspective, a successful casting is the result of 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.
Iron 101 students learned about the material 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 that shapes molten metal into a finished part.
“The course helped me visualize how copes, drags and cores fit together to make a casting,” said one recent Iron 101 attendee.
They also learned about part geometry, castability and solidification modeling. The latter is a 3D technology that is used to simulate 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 are removable patterns that help to 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.
To ensure that a casting cools uniformly, without hot spots and voids, casting engineers will utilize risers and chills. 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 down into the mold to fill these gaps.
Solidification modeling is used to optimize 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 sections of the casting.
What Iron 101 reveals is the amount of planning and collaboration between the foundry and the customer goes into the design, casting and machining of each part. This ensures the highest levels of quality and performance.
“Iron 101 helped me understand how to make a better, low-cost design,” another attendee remarked.
A visit to the foundry floor
No class on modern casting would be complete without a 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 you won’t soon forget. Students also got to see 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 MDI boards in each department that outlined team goals for continuous improvement. In the foundry office, they viewed the company’s transformation calendar – which contains a timeline of all of the larger improvement projects it is working on.
At the end of the day-long class, the attendees were impressed by what they learned and saw. They left Lawton’s De Pere, WI facility with a new appreciation for the engineering and ingenuity that go into creating a successful casting. Plus, they came away armed with new insights into the company’s far-reaching efforts to accelerate its processes and deliver high-quality castings.
Click here to learn more about Iron 101 and to learn when the next class will be scheduled at The C.A. Lawton Co.