DFMA as Applied to the Swingline 747 Desktop ... - University of Utah

whichever is larger and where
f(chamfers) = -100 (no chamfer)
-220 (chamfer on hole)
-250 (chamfer on peg)
-370 (chamfer on both)
DFMA as Applied to the Swingline ® 747 Desktop Stapler
ti = 1.4L + 15 ms
or
ti = -70 ln c + f(chamfers) + 3.7L + 0.75d ms
2.5e Miscellaneous Effects on Assembly Time
When designing parts to be assembled, obstructed views and access should be
considered. The effects of an obstructed view or obstructed access are that time for
assembly is increased and there is also a risk of harm to the worker. The inability to see
the parts can lead to fumbling, dropping or other time penalties, and obstruction may
force the worker to slow down, cause repeated small motions in awkward positions (i.e.
ulnar-deviated wrists while turning a wrench). The cost of time and ergonomics then
becomes an issue. Manual clamping also has a deleterious effect on time and has
ergonomic considerations. There are many parameters, born both empirically and by
experience, which bear consideration while designing for manual assembly. However,
the data presented are averages and therefore should not be taken to be cumulative. In
some cases, the times are overestimated, in others it is underestimated. Also, in the
situation where the assembly requires various different parts, care should be taken not to
accumulate times caused by different features. Only when large quantities of similar
parts are used should these results be consulted.
2.5f Further Guidelines
The minimum parts criteria also give the following guidelines:
• Avoid connections by placing parts to be connected at the same location.
• Design so that assembly access is not restricted.
• Avoid adjustments.
• Use kinematic design principles to avoid over-constrained designs.
Also, for large assemblies with large numbers of parts, the differences in assembly time
generated by different parts will generally cancel each other out.
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