What are clad materials and why are they so relevant for modern material solutions?

Clad materials are metallic composite materials. In these materials, two or more metals are bonded together, primarily by roll bonding.

The use of such materials is widespread. They are used for decorative products, electrical applications and mechanically stressed parts in corrosive environments.

Miba combines roll bonding with the advantages of strip casting specific bearing materials. This results in precisely tailored and economical products for highly stressed applications.

The clad materials produced by Miba in this way are used as starting materials in bearing manufacturing. Miba supports its customers with comprehensive materials and engineering expertise, from product design to industrial series production.

What is roll bonding? What advantages does it offer compared to other processes? How can strip casting of bearing materials be effectively integrated into the process chain? We answer these questions in this article.

What is roll bonding and how does the process work?

Roll bonding is a process for joining different metals together using mechanical rolling pressure, without any welding or soldering.

The process works as follows:

• After surface activation, two or more metallic materials with activated surfaces are stacked together. This usually takes the form of strips or sheets.
• These packages are passed through a rolling mill under high pressure and, in some cases, at elevated temperatures.
• The pressure and simultaneous elongation of the material create a permanent metallurgical bond at the interfaces between the materials.
• Optionally, a heat treatment step can be carried out afterwards. This improves the bonding of the materials and precisely adjusts other material properties.

What advantages does roll bonding offer over other joining processes?

Roll bonding offers decisive advantages over conventional joining methods such as welding or soldering. This is particularly the case when it comes to the production of large-area composite materials.

The most important advantages include:

• High bonding strength through plastic deformation under high pressure
• Precise control of layer thicknesses for optimized functionality
• Effective electrical and thermal conductivity through flat metallurgical bonding
• Targeted material combinations that cannot be joined in any other way
• Scalability for industrial series processes with high cost-effectiveness

In contrast to thermal or chemical processes, the bond formed during roll bonding is purely mechanical. This means that no intermetallic phases form at the interface. The heat-affected zone, which is undesirable but unavoidable in welding, does not occur in this process either. The material bond is solid, durable and free of additional materials.

Compared to other cladding processes such as explosive cladding, roll cladding is a reliable, process-secure and cost-efficient solution. This is particularly true in combination with a coordinated casting process such as strip casting.

Miba offers in-depth manufacturing expertise for a wide range of industrial applications and products. 

What is strip casting and what role does it play in clad materials?

In continuous casting, liquid metal is cast directly into a thin, endless strip. This eliminates the need for large semi-finished products/slabs and subsequent heavy rolling.

Miba relies on the proven belt caster process for the energy-efficient and material-saving production of continuous bearing alloy strips with a defined microstructure.

The cast alloy strip offers several advantages in downstream roll cladding:

• Dimensionally stable and can be produced in very thin thicknesses – reduced material usage
• No post-processing required or greatly reduced
• Defined, uniform structure across the entire strip width

Strip casting enables the production of high-precision clad strips for clad materials. This is particularly the case with materials such as aluminum alloys, which Miba processes. The combination of strip casting and roll bonding forms a continuous process chain. It offers both technical and economic advantages.

How does Miba manufacture clad materials and what combinations are possible?

The production of clad materials is based on an efficient process chain in which casting, cladding and further processing are optimally coordinated:

• Depending on requirements, the process begins with strip casting of the specifically tailored bearing metal alloy.
• This is followed by roll bonding, in which the bearing metal strip is metallurgically bonded to the substrate material.
• The layer thickness, the combination of alloys, and the overall material structure can be customized to meet customer specifications.

Miba uses both standard and special alloys to meet different physical, tribological or thermal customer requirements.

Typical material combinations are:

• Steel + aluminum alloy, including for bearing applications in large engines where adaptability and reliability are required
• Steel + copper alloy, including for highly stressed bearing points in optimized applications

Miba supports you with its materials and engineering expertise, as well as its many years of application and simulation experience. Talk to our experts. Together, we will find the right solution for your requirements.