Multi-component products should strive for material unification to promote disassembly and value retention (minimize material diversity)

Material diversity in a product occurs to meet the customer requirements. For example, an automobile seating system has many requirements that cause material diversity.

• The seating surface has to be comfortable to sit, pleasing in appearance, and should blend with rest of the interior.
• The area below the seating surface has to be firm but not hard for a driver to sit and travel long distance without any discomfort while the seat itself can be adjusted to provide lumbar support etc.
• To accommodate various size and shape of drivers, the seating system should have other subsystems to provide adjustment to move the seat up/down, forward/backward, tilt the seatback, etc.

As one can see, the list of these requirements and other requirements causes an automobile seat to have different materials.

Material diversification causes many sustainability issues. For example, at the interface of the two materials, there can be chemical corrosion resulting in loss of strength and also cause environmental issues during disposal. Also, if the design does not accommodate ease of separation at the end of life, the land fill will either have to spend enormous resources to separate them to either reuse or recycle them or leave them as it resulting in contamination of the landfill.