Metal composite material (MCM) is a sheet material consisting of two metal skins sandwiching a composite core, for a total thickness of 4 mm or 6 mm. Sometimes referred to as aluminum composite material (ACM) when the metal component is pre-finished coil-coated aluminum skins, the skins can be made with other metals such as stainless steel (SSCM), copper (CCM), zinc (ZCM), etc. These are all grouped together under the category of MCM. MCM is lightweight and rigid, having been originally developed to overcome the challenges of single-skin panels, such as 0.080-inch and thinner post-painted aluminum, which is prone to oil canning and rippling.
The two core types that are suited for use on building facades are the fire-rated core (FR) and non-combustible core. There are many types of MCM that are designed for other markets, which due to their marginally lower cost sometimes get used on building facades, but although they can be made to pass certain fire tests, the 100% polyethylene core (PE) or other corrugated plastic core panels pose a fire risk and therefore should not be used on building facades, except in rare circumstances.
There are many industry-standard specifications that cover features of MCM including the coating, bond integrity, metal alloys and more. There are some other critical factors that often get overlooked such as:
1. Like any building product, proper installation is key to the success of the product. MCM is simply a sheet product and must be installed with an engineered and tested installation system. For the MCM to perform, this system must have allowance for thermal expansion to prevent buckling and pillowing of the panels, which could result in product failure. Be wary of systems that claim to allow for thermal movement when it requires the installer to gap the panels during installation. This works on paper but requires a level of precision that is difficult to achieve with typical site conditions, leading to panel deformation in the future.
2. MCM comes in large sheets for material optimization—the most common size being 62 inches by 196 inches. This does not mean that panels on the wall should be this size. Larger panels will have more thermal expansion, will be heavy and difficult to handle, and are more likely to result in unforeseen issues.
3. MCM comes with the highest quality finish, typically a coil-coated Kynar 500 PVDF with flexible resin. The advantages of this finish are many, however often the finish is not one that can be replicated exactly in the field should a panel ever need to be replaced. When specifying MCM, be sure to specify that it be installed with a non-sequential panel installation system, to allow panels to be installed and removed independently of each other.
Quality Issue versus Product Feature
MCM is manufactured in a high-tech and controlled environment for every stage of the process. First it is coil coated, meaning the coating thickness is exact and consistent, and the MCM fusion process of bonding the skins and core is done in a consistent continuous process, the science of which is proprietary to the manufacturer. This manufacturing process yields continuous and controlled results, meaning that quality issues relating to the MCM, such as paint quality issues or delamination, are extremely rare compared to post-painted panels.
More common, however, are issues that are a result of wall assembly design or panel installation. For example, stiffener read-through can be the result of a conflict between wind-load calculations designed to stop the panel from moving, and thermal movement allowance requirements, which are designed into the panels to allow for thermal movement. Pillowing of panels can also happen if using an installation system that depends on the installer providing a gap for thermal expansion, instead of having it designed into the system.
MCM has received a lot of press over recent years, because of improper use. Like all products, there a best-practices, testing requirements, and design specifications that must be considered when using these materials.
Jerry Fossey is the general manager of Fairview Architectural North America, Bloomfield, Conn. To learn more, visit fairview-na.com.