3 Fundamentals of press design

Organization of stamping plants
Table 4.9.1: Criteria for press selection
part spectrum
complete part
production
low
investment
low space
requirement
die change
time [min.]
large-panel transfer presses
crossbar
transfer
large, unstable parts
and double parts
tri-axis
transfer
press lines
with differing
bed sizes
medium-sized parts all parts
++ + 0
0 + ++
+ ++ 0
10 10 30
The selection and loading of presses depend primarily on the number
of vehicles to be produced. The number of vehicles determines the
production requirement of all parts per day. If the A-parts of a vehicle
type are manufactured on large-panel transfer presses, the stamping
plant must have a capacity of between 3 and 4 million parts per year
(basis of planning: 1 vehicle type = 100,000 vehicles per year).
The production scope per year, i.e. the number of parts which can be
produced on the press system per year, must be co-ordinated with the
production requirement. This calls for an output analysis of the individual
press system. The basis for calculation is the production stroking
rate. In transfer presses, this is equivalent to the stroking rate set at the
press. In the case of press lines, the production stroking rate is reduced
to some 50 % to 60 % of the set press stroking rate due to standstill periods
caused by the single stroke operation. The number of parts which
can be produced during press operation also depends on the forming
requirements of the individual parts. A complex part requires a longer
processing time. In addition, the time necessary for transportation of
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
393