Punching metal

Applications of punching

Punching is suitable for producing parts from sheet metal. These can be components for equipment building and the automotive, electronics, and construction industries, for example.

With Contour’s punching machines, materials such as stainless steel, aluminum, steel, Zincor, and Sendzimir up to 8 millimeters can be given contours, holes, forms, and threads easily and accurately.

This Contour punch laser machine can punch, nibble, and laser cut. This way the ideal combination of cutting techniques can be chosen for each product.

More about sheet metal

Nibbling

In nibbling, contours or larger shapes are punched by punching overlapping holes with a punching tool that is smaller than the contour to be cut. This way all kinds of shapes can be punched, even though the shape of the hole does not exactly match the shape of the punching tool.

Advantages of punching

Punching has several advantages, an overview:

• Speed

  Punching is often faster than other sheet metal operations, especially for high-volume production and large numbers of holes. Unlike laser cutting, no hole has to be pierced with a laser beam. Piercing with a laser can be time-consuming. Piercing quickly at high power risks spatter of liquid metal. For this reason, at Contour we often replace the piercing with a punching tool and then complete the contour by laser cutting from the punched hole.

• No heat input

  Unlike laser cutting, punching puts no heat into the sheet. This prevents discoloration, deformation, and contamination.

• Efficiency and capacity

  The machines at Contour can produce unattended thanks to the link with the fully automatic warehouse. This increases capacity and reduces costs.

• Accuracy

  Thanks to advanced punching machines, complex shapes can be produced accurately.

• Little to no processing marks

  Thanks to a brush bed and an active bottom die, it is possible to punch with virtually no tool marks. The active bottom die moves down as soon as the sheet is moved.

Disadvantages of punching

Punching also has some disadvantages:

• Limited freedom of shape

  Punching is less suitable for extremely complex shapes and thin materials. If the punching tool does not have the exact shape of the contour to be cut, the shape has to be made in several strokes. This is time-consuming, especially when the tool has to be changed between strokes. Nibbling complex curves also leaves minimal punching transitions. Laser cutting, on the other hand, can cut any line you want.

• Punching transitions

  Nibbling leaves a slightly noticeable punching transition. A punching transition is a small ridge on the cut edge of the material where the punching tool overlaps the previous punch.

• Tool changes

  Changing punching tools can take time and limits flexibility.

• Material loss due to the tool

  When the outer contour of a sheet metal product is cut by nibbling, the individual products to be punched must be at least the width of the punching tool apart. The punching tool is wider than the kerf of a laser. Depending on the dimensions of the product, this can mean that one extra product just does not fit on a standard sheet.

• Material loss due to the clamp strip

  Because large forces act between the top and bottom die during punching, the sheet moves instead of the punching head during punching and nibbling. To make this possible, the sheet is clamped along its long side with a clamp strip. Where the sheet is clamped, it cannot be punched or cut. For this reason no product can be nested where the clamps grip the material.

Punching or laser cutting?

Several criteria must be considered when choosing between punching and laser cutting.

• Cost factors

  Production speed, complexity, and series work play a role in the choice between punching and laser cutting. Which technique is preferred depends on the contour to be cut and the number of holes.

• Materials

  Punching and nibbling can be used up to a maximum of 8 mm. Thicker sheets must be laser cut.

• Shape

  Punching is ideal for rectangular materials and for radii and shapes for which a specific punching tool has been bought, while laser cutting is better for irregular shapes. For high-volume production we invest in customized tools for the contours to be punched.

• Material efficiency

  Especially for larger series, using both punching and laser cutting on the punch-laser combination can achieve higher material efficiency (less scrap).

Video of bending on a punch laser

With the Multibend tool we can bend small flanges on our fully automatic Trumpf TruMatic 7000 punch laser machine.

Sources

• Internal process documentation and experience
• Machine documentation from the manufacturer Trumpf