When selecting raw materials for CNC machining, operators need to be aware of the different preparations used when forming metals and how this affects their properties. These properties affect the final results of milling or other machining. This is why operators should be aware of the exact grade of the aluminum they are working with and how the machining process they are using can affect the material. Aluminum, like common rolled 6061, tends to distort when portions of one side are removed but not the other. Accounting for those potential distortions will help determine whether to use cast aluminum plates vs. rolled aluminum plates while it is being machined.

Cast Aluminum Plates vs. Rolled Aluminum Plates

Different internal stressors are in play when it comes to cast aluminum and rolled aluminum plates. This can change how the aluminum behaves when material is removed during CNC machining and the dimensions of the final product due to how the different internal forces may warp or distort the plate.

Cast products like MIC-6 are designed specifically to resist this distortion due to internal stresses. They are also highly resistant to warping due to temperature changes. Understanding the properties of cast and rolled plates is especially useful for smaller components or those that require high tolerances.

Cast Aluminum

Cast aluminum plates are created through a process that feeds molten metal into a mold. Special formulations like MIC-6, Alimex, and Alca 5 utilize proprietary continuous casting processes to avoid imperfections like voids and seams. They also take care to avoid thermal gradients during the casting process by carefully controlling heat in the surrounding equipment to avoid creating internal stresses. These cast aluminums are also given an additional heat treatment that fully removes internal stresses from the plate.

The result of this extra effort is an aluminum cast plate that achieves incredible flatness tolerances–typically finished to 20 microinches on both sides. More importantly, the additional effort to remove any internal stresses in the finished product makes it much less likely to deform when the machining process removes portions of the material. This makes it especially useful for components with exacting tolerances or meeting production deadlines for machined aluminum components when there is no room for errors.

While rolled aluminum plates like 6061 are good aluminums for general purpose use when components have to be machined to exact tolerances, cast aluminum is a nearly irreplaceable material.

Rolled Aluminum

Rolled aluminum is created by taking a heated ingot of aluminum and processing it through parallel rollers to draw it out into a longer, flatter piece. This is a common method for creating aluminum plates and bar stock. It is a simple process that efficiently creates large quantities of flat aluminum stock. It is a forging process, rather than a casting process, so it requires less heat.

This means that forged aluminum plates are comparatively cheap compared to cast aluminum. In the case of aluminum grades like 6061, the result is a light and strong, weldable, and versatile metal. It’s widely used for structural and mechanical components on everything from buildings to aircraft. However, the action of rollers on the hot metal introduces tensile stresses on either side of the plate and compressive stresses on its interior volume. These forces effectively pull the plate into its shape and balance it once the plate is intact.

A graphic about tensile stress showing the direction of caving inMachining tends to remove material from only one side of the plate, though. When the workpiece is rolled aluminum, this can cause the tensile stress on the opposite side to bow the workpiece, potentially ruining the part. While this isn’t something that always happens, the potential is enough that many machinists try to avoid both ruined parts and missed deadlines by opting for cast aluminum plates which have better distribution of forces than rolled plates.

Choosing a Trusted Supplier That Understands the Differences

Industrial Metal Service carries Alca-5, Alimex, and 6061 rolled aluminum plates along with verified remnant alloys available for a fair price compared to new stock. Remnant stock may be an ideal option for prototypes or limited production runs. Manufacturers wondering about cast aluminum plates vs. rolled aluminum plates can get in touch with one of our expert staff to ensure their needs are met with cut-to-size at a price that works for them.

Contact us today,  to get in touch with one of our expert staff to ensure the job gets done — quickly.
Contact Us
IMS Team

IMS Team

Industrial Metal Service has decades of experience and over 1.1 billion pounds of metal sold and recycled. Our founder, Jeff, has spent his life in the industry and prides himself on offering fair, efficient, trustworthy, knowledgeable, outstanding customer service. We offer metal salesmetal recycling pickup service, and other associated services, such as precise metal sawing, machinery teardown, and warehouse cleanupGive us a call and we’ll get it done.