Modularity and maintainability

In complex assemblies, sub-assemblies or individual parts may degrade at different rates. If such a product is subject to rapid technological diange then it may be more appropriate to design in a modular form which permits replacement and upgrading of obsolete parts in a way that is adaptable to the main structure. Computers with upgradable hardware are designed in this manner. Firm control of tolerances and dimensions of the manufactured parts is a prerequisite for this approach [32]. 

A product designed for a long life normally requires maintenance to retain optimum performance. To this life potential it is necessary to design products in a way that makes maintenance simple, fast, and cost-effective. The balance between the price of a new product and maintenance costs can be decisive for when it comes to retiring a product. The maintainability of a product can be measured by the time required to restore it to a specific condition in accordance with prescribed procedures and resources [34]. 

When designing a product for maintainability, several factors should be taken into account  

Good maintenance requires design for assembly and disassembly. Short disassembly and reassembly times are crucial since the economy of maintenance 

Labour costs often constitute the lion s share of maintenance costs. Service will be significantly simplified if the product is simple, and wear parts are made easily accessible for the maintenance personnel and adapted to the tools they have available. 

---