The speed of production
To complete the calculation of the production cost, it is necessary to multiply the hourly cost by the hours required for the machine to carry out the work. Knowing the time-cycle of one piece (in hours/piece), this figure is multiplied by the total number of workpieces N.
The production time of sheet-fed punching machine
In a sheet-fed punching machine the cycle time depends heavily on the type of machine, the route of the tool over the surface of the sheet metal and the number of tool changes required. To this punching time should then be added the time for loading the sheet and unloading the product (from 30 to 50 hundredths of a minute).
The production time of coil punching machine
In the coil punching machine, the production time is obtained with empirical formulas as follows:
[Production time] = [Number of operations per piece] x [Average time per operation] + [Length of piece in metres] x [Time per metre].
In this case the coil punching machine time is equal to the total production time, since the loading and unloading times do not exist.
The production time of stamping press
Lastly, the production time in the stamping press is minimum: every press stroke produces one piece. Productivity therefore depends on the press speed (60, 80, 120 and more strokes a minute).
In conclusion, the die press is the fastest production system, followed by the coil punching machine and lastly the sheet-fed punching machine.
It has been pointed out in the paragraph describing the technologies, that
the sheet-fed punching machine is the most flexible system, followed by the
coil punching machine and the stamping press line.At this point it is interesting
to construct a productivity-flexibility diagram, which is given in fig. 7.
Fig. 7 Diagramma
produttivitą -
flessibilitą e
collocazione delle
tecnologie in
esame.
"Punching and stamping: how to compare production cost."
Article taken from "Lamiera" Magazine: October 2005