How to Choose the Right Tonnage (kN)? Common Misconceptions and Selection Hints

When purchasing a servo press, a common question is, "How should I select the tonnage (kN)?"
When you already know the required pressing force for your application, you can select a model based on the rated tonnage listed in the servo press specifications.
However, it is important to note that the "pressing capacity" indicated in catalogs refers to the maximum momentary force the press can exert.
The machine's structure is designed to withstand this force, and the servo motor can deliver it.
Nevertheless, this represents the "momentary maximum" capability.

Two Key Factors in Tonnage Selection

A. How long the pressing force needs to be maintained during the operation
B. The duration of idle time between operations

These two factors significantly influence model selection. If the pressing duration is short and sufficient idle time is available, a model with a slightly higher capacity than the required force may suffice.

Conversely, if the pressing duration is long or the idle time is limited, continuous force maintenance is necessary, requiring a model with a higher capacity. As a guideline, selecting a press with a listed pressing capacity approximately three times larger than the pressing force needed for your application can reduce the burden on the motor

When the Required Pressing Force is Unknown

In cases where the necessary pressing force is unknown, such as when replacing existing operations performed by hydraulic or crank presses with a servo press, it is not uncommon to know the rated capacity of the press, but not know the actual force used during machining.

In such scenarios, making a "Pressing Test" is the most effective approach.
With a Pressing Test, you can determine the appropriate force required for processing by testing at various load values.

Test Pressing with Demo Machines