The unit cost of a stamped part is not determined at the press. It is determined at the drawing board. Anyone who realises that too late pays the price in every cycle of every subsequent series. With high volumes, every second of cycle time and every tool maintenance session counts towards the final price.
Tool design determines production run costs
A punching tool is an investment with a long payback period. The initial tooling costs are visible and tangible. What is less visible are the costs that a poorly designed die generates over its lifespan: shorter wear intervals, unplanned downtime, increased scrap waste and post-processing that could have been avoided. At companies that focus on metal stamping is tool design therefore always assessed in relation to the expected volumes and the desired cost per unit.
In a progressive tool for a connector component in 0.8 mm copper alloy, the number of steps in the strip directly determines the cycle time and material usage. A design with two extra steps costs tens of extra press hours over a run of five million pieces. Those are real costs that are not visible at the start, but always turn up during post-calculation.
At Eurotechniek, tool design is therefore always assessed in relation to expected volumes and the desired cost per part. That relationship is leading, not technical feasibility in its own right.
Material saving through smart strip layout
Material costs in stamped sheet metal are the largest expense in many projects. The strip layout, also known as nesting layout or coil layout, determines how much material is consumed per part. An improvement of a few percentage points in material utilisation yields a substantial amount on large production runs.
The bridge between two products in the strip must be wide enough to transport and guide the strip, but no wider than necessary. The same consideration applies to the side margin. An experienced tool designer pushes the limits without compromising process reliability.
A concrete example: for a mounting bracket in 1.5 mm galvanised steel, a rearrangement of the strip layout improved material utilisation from 68 to 79 per cent. On an annual volume of 800,000 units with coil material at a given price per kilogram, this represented a significant direct material saving, without any modification to the final product.
Maintenance intervals and tool life
A well-designed stamp lasts longer and requires less frequent maintenance. That sounds obvious, but in practice tool designs are too often optimised for initial manufacturability rather than total lifecycle costs.
The choice of tool steel, the hardness of cutting edges, the design of the punch guidance and the accessibility of replaceable wear parts are all design decisions. Together, they determine how long a tool can last between regrinds or maintenance intervals.
In a progressive die for a beryllium copper electrical contact, the design specified modular punch holders. This made it possible to replace wearing parts without removing the entire tool. The setup time per maintenance service dropped from four hours to less than an hour. At a maintenance frequency of once every 200,000 strokes, over a total tooling lifespan of four million strokes, that represents a saving of twelve hours of press time.
Automation and integrated process steps
A punching tool that only punches misses opportunities. In progressive tools, it is possible to integrate bending operations, bead drawing, embossing of markings, and even the insertion of inlay parts alongside punching. Every operation that takes place within the press is a secondary operation that is eliminated outside the press.
The integration of operations requires precise design of the strip tension, the sequence of steps and the positioning. That is more complex than a single cutting tool, but the savings on handling, transport and separate processing stations are significant for large production runs.
Eurotechniek has developed a tool for a customer in the automotive supply chain that combines blanking, double folding and the sinking of a locking lug profile in a single progressive tool. The original production route required three separate machining steps. These have been fully integrated. The cycle time per part fell by 40 percent and the number of operations per batch by more than half.
Tolerances and dimensional accuracy over large volumes
A tool that produces dimensionally accurate parts for the first thousand strokes but then shows drift is a problem in high-volume production. Dimensional consistency over the entire tooling life is a design objective, not a given.
Tool wear affects burr formation and the dimensional accuracy of the cutting edge. Guide element wear affects the positioning of the strip and therefore the dimensional accuracy of the final product. Both effects are predictable if the design is based on known wear characteristics of the chosen material combinations.
For a batch production programme of two million pieces per year for a precision component in medical instrumentation, the maximum permissible dimensional deviation was set at plus or minus 0.05 mm over the entire tooling lifespan. This required a design featuring hardened guides, TiN-coated punch edges and a defined grinding schedule based on measured wear data. The tooling achieved the required quality level over the entire agreed lifespan of eight million strokes.
The role of simulation and validation for series production
Tool designs are nowadays validated with FEM simulation before the first steel is milled. That simulation calculates the material flow, the stress in critical zones and the springback in bending operations. That reduces the number of try-out rounds and accelerates the lead time.
However, simulation does not replace experience. The interpretation of simulation results and their translation into practical tool adjustments requires knowledge of the actual behaviour of materials in the stamping process. A simulation indicating that a certain radius is achievable must be assessed by someone who knows how that material behaves with variations in coil quality, temperature and press speed.
During the validation of a new tool for a 2 mm thick high-strength steel chassis component, the initial simulation yielded a springback value that proved to be 15 percent higher in practice. That deviation was predictable based on practical experience with this material type. The tool correction was incorporated in advance, which saved a full tryout round.
Frequently asked questions about cutting tools and cost saving
How much influence does tool design have on the cost per part?
The influence is significant and increases with volume. For small production runs, tooling costs weigh heavily and the influence of the unit price is limited. For large production runs, the ratio shifts. Then cycle time, material utilisation, maintenance frequency and the number of post-processing operations together determine the actual cost price per item. A tool design optimised on all these points can reduce the cost per item by ten to thirty percent compared to a design evaluated solely on manufacturability.
When is it worthwhile to have an existing tool redesigned?
Redesign pays off if the remaining lifespan of the existing tooling is sufficient to recoup the investment, or if the tooling is due for replacement. Signals that justify a redesign are: rising failure rates, increasing maintenance frequency, integration of post-processing operations that currently still take place outside the press, or a significant volume increase that makes optimisation economically attractive. A technical analysis of the existing tooling provides insight into what is feasible.
Which materials require special attention in tool design?
High-strength steel, stainless steel and beryllium copper alloys place higher demands on tool steel, coatings and cutting edge geometry. These materials wear tools down faster and require more precise adjustment of the cutting clearance. Thin materials under 0.3 mm and materials with a strong springback, such as spring steel, also require specific design measures to combine dimensional accuracy and tool life.
Design dictates production run costs
A stamping tool is not a commodity. It is a production asset whose quality and sophistication directly impact every batch produced with it. Those who invest in a well-conceived design during the tooling phase recoup that investment through lower unit costs, less downtime and a longer tool life.
Contact Eurotechniek for a technical assessment of the tool design for your next production programme.