Saving time and money with the right concept

How standardised punching tool concepts influence the cost of a punched part
Gerhard Krammel (PresseBox) (Wolfurt, ) Many tool makers make their tools always following the same concept. Even if the parameters depending on the quantity produced per year are changing, this concept is maintained. But what are the parameters that influence the cost of a punched part depending on the quantity produced?

In punching, speed and precision are the key issues. Especially for large quantities it is important that the cost for the individual part is as low as possible in order to be competitive. Meusburger provides standard tool concepts and thus standardised solutions and this also ensures flexibility. To begin with, the following comments highlight the performance-related parameters:

Number of strokes: The larger the quantity produced, the more important is it to select the optimal number of strokes. Attention should be paid to the fact that the highest number of strokes is not always the best; a higher speed increases the risk of tool breakage and damage. The priority objective is to maximise the parts output per shift at the required quality standard.

Automation: The larger the quantity produced per year, the more important is a quick coil change. This can be achieved by welding together the strip ends by means of strip welders. It is also important to relieve the machine operators of their workload by automating the peripheral devices. The time saved can be used to inspect the produced parts.

Positioning systems: Positioning systems are very important when the tool is changed frequently. The setting-up time can be reduced by preparing the equipment that is required for changing the tool beforehand, while the machine is still in operation. Positioning systems help avoid costly machine downtime even if not many tool changes are required.

Use of standard parts: Standard parts are very important in many ways, for producing both small and large quantities.
- They ensure easy exchangeability
- They can be quickly replaced
- Price advantage when producing large quantities

Tool costs: The influence of the tool costs per punched part is reduced with increasing annual quantity due to the fact that the tool costs can be divided by the number of parts produced.

Depending on the quantity, different tool concepts should be used in order to achieve the optimal production costs / tooling costs ratio. The following criteria help select the optimal tool concept:
- Geometry of the parts: The complexity of the parts' geometry determines the number of process sequences and, consequently, the tools' dimensions.
- Punching machine: The size of the table and the tonnage are the crucial factors for deciding if one or more punching processes are required for producing the part.
- Strength and thickness of the material: They determine which material is used for the active components such as cutting and bending punches.
- Accuracy of the components The use of ball or sliding guide bushes may influence the components' accuracy. It can also be increased by using a SP precision die set where the guide pillars are fixed in the centre.
- Punching and bending operations: Depending on the complexity of the punching and bending operations effected, slides or other additional components are required.
- Quantity per year: The quantity of the parts produced per year determines if a simple tool can be used or if an optimised tool concept is required.
- Frequency of setting-up processes: For frequent setting-up it makes sense to invest more time and money in optimising the work steps in order to reduce fitting time - like preparing the equipment that is required for changing the tool beforehand, while the machine is still in operation.

The diagram above illustrates four different standardised tool concepts. The matrix shows the different criteria and their influence on each project.

For better understanding, we will explain the criteria by taking the specific example of a progressive die (second column from the left).

In this specific case, the available machine with a table of 400 mm x 650 could be used. Due to the material's thickness (0.6 mm) and the accuracy of the components, a ball guiding system was used. An SP precision die set, where the guide pillars are fixed in the centre, was chosen. Due to the low complexity of the part's geometry and the low number of process sequences required it was possible to use a simple progressive die.

The small quantity in combination with a high number of small jobs made it necessary to use adequate positioning systems such as a tool centering device which helped reduced clamping time. Keeping the same strip inlet height increased the efficiency due to the fact that more than one tool could be used on the same machine.

In summary, it can be stated that selecting the adequate tool concept is decisive for achieving competitive advantages as early as in the tender stage. In the end, the decision for which is the best concept depends, above all, on the products and the customer's requirements.


Meusburger Georg GmbH & Co KG
Kesselstr. 42
A-6960 Wolfurt
Eveline Steurer


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