Stamping of metal coil

The stamping process requires that the alloys are ductile, and that they have adequate strength, good formability, toughness and corrosion resistance. In addition, the alloy should also be a widely used alloy that can be found on the market in sufficient quantities without forcing the foundry to smelt a new batch that may involve a very large amount of material.

Here are some of the main materials used:

• AISI 304 stainless steel: Austenitic stainless steel. It is one of the most common and widely used grades of stainless steel. It is chosen for numerous applications in different sectors due to several desirable characteristics and properties: corrosion resistance, widely available, good formability and weldability, high resistance to high temperatures.
• AISI 430 stainless steel: Ferritic stainless steel. It is also a very common grade of stainless steels but it is cheaper than AISI 304 because it does not have nickel in its composition. It has good corrosion resistance in normal atmospheric environments and in mildly corrosive environments. Its corrosion resistance is lower than AISI 304.
• AISI 301 stainless steel: Austenitic stainless steel. Its high corrosion resistance combined with its good deformability, elastic recovery and aesthetic appearance make it very versatile. It is suitable for applications in various sectors: automotive, electronics, medical and pharmaceutical. It is also suitable for food packaging and for the chemical and petrochemical industry, among others.
• Aluminium Alloy 5005: It is a commonly used aluminium alloy that belongs to the group of magnesium alloys. It is used, for example, in the construction of buildings and structures due to its light weight, corrosion resistance and ease of forming. It can be used in cladding, facade panels, ceilings, gutter systems and other architectural components. It is also used in the automotive industry, in the signage, container and packaging industries and is suitable for marine applications due to its corrosion resistance in saline environments. It can be used on ships, boats and other nautical equipment where good corrosion resistance and high strength-to-weight ratio are required.
• Aluminium Alloy 1050: It is a very pure aluminium alloy (99.5%) and is usually applied where mechanical resistance is not a critical factor such as electrical conductors, light reflectors, aesthetic covers and chemical components. It has very good deformability and allows varied finishes such as aesthetic anodizing.
• To select the correct alloy, it is necessary to know the final use of the part, its surface finish, the requirements of corrosion resistance, the mechanical requirements that the part should have, … and many more things.

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The metal enters the die at room temperature and therefore in a solid state, the press is lowered and all the tons of force are applied to the tooling. This is why stamping dies have to be made of special steels. These are steels alloys specifically for these applications which come with high manufacturing costs. Before going into production and while they are being processed, they have to be subjected to various, highly-controlled heat treatments, so that their characteristics are optimal. These steels reach very high hardnesses while maintaining very high toughness; this is necessary to keep the cutting edges sharp and also so they can absorb impacts without breaking.

At STAC we have a tooling manufacturing department that is responsible for the design and manufacture of the punch and die set and maintenance throughout their service life. In the stamping process the tooling require a lot of maintenance work since it is necessary that all the punches and dies are kept in perfect condition to perform the operation of cutting or forming correctly, this is something that we take care of after each manufacturing run.

Some of the most important characteristics to consider are:

• Materials for the different parts of the die: these materials must be strong and durable enough to withstand the high forces of the stamping process, depending on the part of the die we use specific steels depending on the thickness and the material of the part to be stamped.
• Materials and wear resistance: The materials used must also withstand abrasive and adhesive wear. To increase resistance we apply PVD coatings on steel when necessary, always looking for the balance between initial cost and savings on maintenance.
• Punches and dies: The die press consists of punches and dies to perform the different forming operations. These elements must be very precise and have a surface finish with high quality to ensure the repeatability of the parts and the durability of each component. It is very important to correctly define the gaps between punch and die depending on the material to be stamped and the thickness, as this will affect the quality of the piece and give a better finished product.
• Guiding and centring system: The die cutter must ensure that the part is in the correct position after each step and before the press comes down completely. Thus, it is necessary that we define the correct coil guiding system and the correct centring system so that the coil is located in the exact position to facilitate high repeatability.
• Coil width, steps and die size: The die cutter must be designed according to the part to be manufactured, the coil width should allow us to produce the part correctly with the least consumption of raw material. The metals used must be correctly dimensioned to withstand all the forces involved in the process and also the steps to be carried out must be rigorously analysed to achieve the desired final piece, sometimes making prototypes before defining the operations and / or their order.
• Wear and inserts: Stamping dies are very technical tools. When we work with stainless steels the wear on the various components is high, for this reason each die is full of small inserts to simplify and reduce maintenance costs after each manufacture.

STAC guarantees the die during the life of the tooling.

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To manufacture stamped parts, in addition to the importance of the tooling, the press and the whole production line are also important. For these reasons our stamping production lines have:

• Motorized winder to unwind the coil in a controlled and automatic way.
• Roller train at the winder outlet to ensure both horizontal and vertical flatness of the coil.
• CNC feeders to the presses that allow us to correctly advance the material step by step.
• Our presses have a loop system that allows us to efficiently and continuously control the coordination between the function of the winder and the function of the CNC feeder.
• Process speed, the revolutions per minute that the press can provide is also an important parameter that we take into account to be able to offer our customers a competitive process.
• Process monitoring and data logging capabilities that allow us to identify how manufacturing runs are done and ensure that they are performed under the same production parameters to ensure in the most reliable way that we always work under the same conditions.
• Safety: Our machines are fully robotised so that no worker comes into contact with the moving areas of the press when they are in production.

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