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

DFMA as Applied to the Swingline ® 747 Desktop Stapler
no longer has to be threaded through the guide, saving on handling time. The time to set
the guide aside, insert the staple slide, and then later reacquire the guide is also reduced.
These have the effect of cutting the total assembly time from 108.86 to 97.86 and
increasing the efficiency from 53% to 58%. All other processes and methods were
believed to be adequate and therefore left unchanged.
3 Discussions
Due to numerical analyses performed on changes that were suggested, it was
determined that the overall design of the 747 stapler is adequate. The manufacturing cost
savings of $3650.00 for re-tooling, die costs, etc. and the assembly time savings of only
11 seconds do not justify implementation of those changes. For example, the time
savings only yields a 6-cent per unit saving. One such manufacturing change that DFM
suggested was to change the anvil manufacture method from blanking to cut off. This
would result in a savings in cost through die, reduced scrap, and cycle time. However,
DFA showed that it should not be implemented due to the sharp corners that would be a
safety issue both in the assembly and daily use of the product. Also, strength analysis
revealed residual stresses at the corners. Another change implemented was to create a
two-part foot pad. DFM recommended this change based on saving in time, cost and die
manufacture and reduced cycle time. Again, DFA showed this change to be unwarranted.
A basic principle of DFA was violated; reduce part numbers.
Thought was given into changing the materials in the manufacture of the stapler.
The DFM material selection analyses run according to Boothroyd-Dewhurst [4] revealed
that the material selected were already DFM compliant. However, consideration was
given to the use of plastics, particularly for the cover and the base. These changes were
ultimately rejected due to durability factors, cyclic loads, and severe impact safety factors.
Also, Swingline ® makes different models made with plastic. Had the recommendations
to change the 747 to plastic been implemented, there would have been a reduction in the
variety offered to the consumer.
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