The world of stamping for mass production is a great unknown, however it is more used than it may seem, and also, it is the cheapest manufacturing process that exists.
What is a press?
It is a machine used for stamping and drawing sheet metal, similar to a press brake but with certain differences. It normally runs from top to bottom to deform the sheet. The press itself cannot do anything, it needs a die that is interchangeable, with a series of punches or blades, depending on what we need to do.
What can a press do?
The presses can manufacture infinity of different pieces, their limitation is set by the imagination of the person who designs the die.
Types of presses
Mainly we find 2 types of presses for mass production.
They are characterized in that they have one or two flywheels driven by an electric motor, which move an eccentric axis each time we press the actuation pedal and this moves a ram downwards, causing stamping or drawing in the metal.
There is a great variety in terms of size, capacity and speed. We can find small presses of 10-15 tons of force that although it may seem like a lot, depending on the work we do, may not be enough, and we can easily find presses of 150 to 200 tons of force.
Regarding cutting speeds, the more force the press has, the fewer strokes per minute it will make. Thus we can find that the smallest can reach 100 or 120 strokes per minute and the largest around 40 strokes per minute. It is a big difference, but even in the worst case, they are capable of manufacturing 40 pieces every minute, as long as it has an automatic feeding system and can work non-stop. Forty strokes per minute is 2400 pieces per hour, which for most small factories is enough speed.
Hydraulic presses have a much simpler mechanical system in which it is more difficult to make mistakes and block the machine because we have made a mistake in the route when assembling the die.
These presses are basically a hydraulic pump, a bottle and valves that activate the movement up and down. They can also have a few limit valves to reduce the travel of the bottle and thus get more strokes per minute. They are slower but in return provide a longer life to the press itself and to the die.
The manufacturing cost is minimal compared to other systems. Take for example the press of 40 strokes per minute, or what is the same, 2,400 pieces per hour, or 19,200 pieces in an 8-hour work day. These data are not exact since it is difficult for a machine to have an uninterrupted supply of material for 8 hours, it is normal for the material to run out and we must replace the steel coil with another. Thus, we can be talking about an approximate cost of € 0.10 per hit, always depending on the cost of the die that we have to amortize, which can range from € 2,000 to € 30,000 or more, depending on its complexity.