ACM (aluminum composite material) is a flat panel consisting of two thin aluminum sheets bonded to a non-aluminum core, typically made of polyethylene. ACM is commonly used in signage because it is lightweight, durable, and easy to work with.

ACM makes good signage because it is weather-resistant and can withstand outdoor elements such as rain, wind, and sun exposure. It is also resistant to fading and corrosion, which makes it a long-lasting choice for outdoor signage. The material is also easy to cut and shape, allowing for a wide range of designs and sizes.

ACM is used in various types of signage, including building signs, directional signs, wayfinding signs, and billboards. It is also used for indoor signage, such as lobby signs and trade show displays.

ACM is commonly used in outdoor signage because it is weather-resistant and can withstand harsh outdoor conditions. It is also a popular choice for large signs and billboards because it is lightweight and easy to install. Additionally, ACM is often used for signs that require complex designs or custom shapes.

In summary, ACM is a popular material for outdoor signage due to its durability, weather resistance, and versatility. It is commonly used in a variety of sign types, and is especially suitable for large or complex signs.