244 APPLYING EFFICIENCY PEINCIPLBS
Not only is every hide different froin every other hide,
but the problem of fitting the odd shapes of the shoe
parts into the hide, is never twice the same.
Nevertheless the value of the material has caused
shoe manufacturers to set standards.
The process is to establish grades of shoes and of
leather, commonly known as A, B, C and D. An order
for a lot of shoes goes first to the leather store room.
There a skilled workman sorts out the necessary material
for the order in the proper proportions of A, B,
C and D. Notwithstanding the difference in hides, an
expert sorter will pick out any number of lots of hides
for several hundred pairs of any grade, so that any
one of the lots will cut to the order with practically the
same waste as any other lot.
The work of the sorter adapts the conditions to a
close enough approximation, so that it is practicable
to set standards, which are commonly expressed as so
many square feet of uncut hide per pair of shoes of
any size, width, pattern and grade. The sorter calculates
from the standards the number of square feet of
hide needed for the order, and issues this amount to
the shoe cutter.
Standards of waste of material in use are commonly
set either by averaging ail previous records, by averaging
previous records of exceptionally good performance
only, or by giving a sample job to an especially
expert and economical workman and deriving the
standard from his result. Any of these methods is
preferable to having no standard; but one can not be
sure of a correct standard, unless the determination
includes the analytical study of waste in at least one
sample case. In order to be sure that the error of
sampling is not great, it is a good plan to compare
