The storage capacity of mass data storage devices, the hard disk drive, has increased 1000-fold in a mere 16 years − from 10 Mbytes in 1982 to 10 Gbytes (10,000 Mbytes) today, a trend which is expected to continue into the next millennium. In view of the sheer volume of drives produced annually, it is timely that the mechanical design of the drive be improved for ease of assembly and rework. This paper discusses how the Design for Assembly methodology may be applied to the analysis of a 3-disk hard disk drive. The Design Efficiency of the drive is 10.2% if ancillary operations such as re-orientation and cable alignment are included in the DFA analysis. Of the 41 discrete parts in the drive, only 17 were ascertained to be the ideal minimum number of parts, thus giving rise to the low Design Efficiency.
In the Design for Service Analysis, the DFS index reflects the cost of the serviced part as well as those parts that cannot be re-used after the servicing action. The main re-worked components are the actuator, disk, motor and PCBA which recorded DFS indices of 98.5%, 84.1%, 53.2% and 99.5% respectively. An overall weighted DFS index is computed at 90.6% which is comparable in the industry. In the process of disassembly, good components are sometimes inadvertently damaged. The DFS index was therefore modified to reflect this reality in hard disk assembly and re-assembly.