The construction of stamping tools is a special field of toolmaking in which tools such as cutting and forming tools are manufactured for mass production. The process: A semi-finished product is formed into a new, desired shape by a cold forming process (punching, bending, upsetting or drawing). The semi-finished product is also called a stock or blank and is a workpiece or semi-finished product in its simplest form, such as a bar, tube or plate. Machining subsequently turns one thin sheet into a fender, another into a cabinet hinge, or a third into a guardrail. The items produced are then reused, for example, in the automotive industry or for household goods. From a certain number of pieces, parts can be produced quickly and cost-effectively with the help of tools.
Technical basics of the punching process
Punching can be performed either manually or by means of modern CNC technology. In manual punching, the first step is to place the sheet to be processed between the punch and the die. The punch is then guided onto the sheet metal at high pressure with the aid of hydraulic or lever force and cuts through it at the interface between punch and die. CNC punching machines also work according to this principle, but carry out the individual process steps largely independently and automatically.
The manufacturing process is usually divided into shear cutting and wedge cutting in accordance with the cutting principle. In shear cutting, the pressure surface of the punching tool has a cutting edge that first causes cracking and finally leads to tearing through the material. In wedge cutting, two wedge-shaped cutting edges cut through the sheet at a very specific cutting wedge angle.
Structure of punching tools
Punching tools essentially consist of three parts: Punch, die and stripper. High-quality punching tools are an important prerequisite for economical production. They are easy to set up, require little maintenance and make the work of punching machines even more productive. The punching tool represents the technical basis for the separating process of punching and has to meet high demands in terms of load-bearing capacity, resistance and dimensional and shape accuracy. Therefore, these special tools are manufactured from first-class steels using the most modern production processes.
Different types of punching tool
Stamping tools are divided into single technical die, composite die and continuous die. Stamping and forming tooling is used for the production of tools used for the serial production of products made of various materials such as:
- Metal,
- Non-ferrous metal,
- Plastic,
- Wood veneer or even paper can be used.
Mainly three-dimensional drawn and formed parts are produced. The active elements are made of hardened and tempered tool steel, carbide or ceramic – depending on the application.
When punching a single technical shape on a punching machine, only one operation is performed, e.g. bending, embossing, punching, drawing, stretching or bending. In most cases, this is done manually. In this process, the structure and manufacture are simple, the price is cheap, but the production efficiency is low. The main difference between continuous punching and single technical punching is that in the former, the punch is automatically fed to the press. This is more efficient on the one hand, and safer on the other. In the third type, the composite die, several die cutting operations are carried out at the same time on a single press (single station or multi-station). This process involves fully automated production – from flat sheet to punching, to forming, to finishing.
Fine blanking tools
They are characterized by the highest requirements for dimensional and shape accuracy. With the aid of fine blanking tools, the cut surfaces of the workpiece to be machined can be kept smooth and free of cracks. The corresponding manufacturing process is usually referred to as fineblanking or precision blanking. Fine blanking tools are required for the production of components with the highest demands on dimensional accuracy. These include, for example, gears with modules of 0.2 to 10 mm and small sheet thicknesses of 1 to 10 mm. Gear racks or similar machine elements are also manufactured using this process. Often, the accuracy achieved is already so high that further finishing is not necessary.
Structure of cutting tools
Cutting tools are mostly made of three raw materials: wood, steel and rubber. The steel lines – also called strip steel – are inserted into the wood plates. Depending on the material to be die cut, different knife heights and different knife hardnesses are used. Each cutting die also needs a rubber coating so that the cutting material springs back and can be ejected.
Kompetenter Ansprechpartner
The experts at RETERO GmbH specialize in prototype construction and small series production of punching tools and bending tools and see themselves as problem solvers even for very complex punching tools. Precision is the measure of all things. Most of the tools that leave our ISO-certified company meet very specific industry requirements and regulations. We would be happy to advise you on your very special project. We accept your inquiry at info@retero.swiss.
