How is the DFA Index calculated?

For a product where all items and tools are within easy reach the DFA index is the assembly time for an "ideal" design divided by the total assembly time and expressed as a percentage. An "ideal" design is one containing only minimum items; in other words, one where all the "candidates for elimination" have been eliminated or combined with other items. Also, in an "ideal" design all of the items are easy to assemble, each one taking a time of 2.93s.

DFA Index = Nmin x 2.93/tma
where Nmin is the minimum item count and, tma is the total assembly time modified as follows:

1. tool acquisition times are each replaced by 2.9 seconds
2. item acquisition times are replaced by the times which would apply if the items were within easy reach

The "ideal" assembly time used to calculate the DFA Index is the time taken to pick up and insert a peg into a hole which has the following characteristics:

1. the peg is within easy reach and can easily be grasped and oriented with one hand
2. the peg can be inserted either way into the hole (alpha symmetry equals 180) in any angular orientation (beta symmetry equals zero)
3. the peg is easy to insert and is secured immediately by a snap fit which requires only a small engagement force.

In calculating this index for large products, the total assembly time is modified by assuming that all parts and tools are within easy reach and there are no penalties for the size of large items.