Machining sheet metal: This is how it is done

Processing sheet metal - the most important questions

Sheet metal can be found everywhere. Sheet metal, whether steel or aluminium, is used to make the bodywork of most motor vehicles. The housings of household appliances and some consumer electronics devices are made from sheet metal. Sheet metal can be moulded in a variety of ways and adapted to the respective requirements. Sheet metal is always made of metal. However, not every metal is suitable for the production of sheet metal. Steel, aluminium, copper and zinc are the most common metals for sheet metal.

Sheet metal working is a separate area of metal processing. Our own tools and machines for sheet metal working have been developed and continuously improved over the past decades. Today, sheet metal working machines and tools are also affordable for DIY enthusiasts. In terms of robustness and precision, these machines are hardly inferior to professional machines. In this guide, we have collected and answered the most important questions about sheet metal working for you.

Table of contents Sheet metal processing:

Why is it important to pay attention to the rolling direction when processing sheet metal?

Paying attention to the rolling direction is important when bending sheet metal. During rolling, the fibrous structure of a sheet is aligned in the rolling direction. This alignment occurs in sheet metal regardless of the material and thickness of the sheet. The more rolling passes are required to achieve the desired thickness, the more pronounced the alignment. However, it often plays no role. For example, with aluminium foil, which is basically a sheet with a thickness of only around 0.05 mm.

However, if the sheet, for example a steel sheet, is bent along this rolling direction, it can tear on the outside if it is stretched too much. This means that the bending radii must not be too small when bending along the rolling direction. If, on the other hand, the sheet is bent at right angles to the rolling direction, significantly tighter bending radii can be realised.

How do you weld thin sheet steel?

Thin sheet steel with a thickness of 1 millimetre or less can be welded using two different welding methods. Autogenous welding (gas fusion welding) and inert gas welding with a MAG (metal active gas), MIG (metal inert gas) or TIG (tungsten inert gas) welding machine are suitable for welding so-called thin sheet metal.

In autogenous welding, the edges of the two workpieces are heated with a torch until they melt. The molten metal flows into each other and forms a solid joint as it cools. With a little practice, oxyfuel welding does not require any additional material in the form of a welding rod. In gas-shielded welding, a high current is used to generate an arc from the so-called handpiece to the sheet metal. The shielding gas protects the heated area from oxidation by the oxygen in the air. A wire fed through the handpiece of the welding machine fills the seam and creates a solid connection between the two workpieces.
 

Why shouldn't a twist drill be used for drilling sheet metal?

Conventional twist drills, as used for drilling solid steel, aluminium or brass workpieces, are not suitable for drilling thin sheet metal with a thickness of up to 1 millimetre due to their cutting edge geometry and short tip. At the very least, special sheet metal drills should be used when working on sheet metal with a hand drill. Conventional twist drills tend to get stuck in thin sheet metal. This can lead to injuries.

Special sheet metal drill bits are designed so that they cannot get caught. If certain hole diameters need to be drilled , so-called step drills are recommended. Sheet metal with a thickness of around 3 mm or more can also be drilled with normal twist drills. The thickness is sufficient to prevent the drill bit from hooking when the tip emerges.

What is a beading machine used for when processing sheet metal?

A beading machine is used to form a straight or curved bulge, known as a bead, in a sheet of metal. The bead stiffens the sheet metal. Beading is used in particular for larger sheets in the automotive industry to prevent the sheets from fluttering. A beading machine always consists of two rollers that are shaped differently. In order to produce beads in different shapes, the rollers can usually be exchanged. The rollers are either driven by hand or by machine. Depending on the design of the beading machine, the upper roller can be adjusted so that the depth of the bead can be adapted to the requirements.

What is a nibbler?

A nibbler is a special cutting device for processing sheet steel. Nibblers are available as attachments for drills and cordless screwdrivers. Thanks to the electric drive, a nibbler makes it easier to cut large sheets of metal. These devices can be used to process sheet metal up to a thickness of around 1.8 mm. A nibbler can always be used when smaller sheets need to be cut out of a large sheet of metal and the cutting lines are not long or straight enough to carry out this work with guillotine shears. Nibblers the size of a large milling machine are used in industry. These machines can process entire sheets of metal in one piece

Deburring sheet metal - here's how

Regardless of whether a piece of sheet metal has been notched or a hole has been drilled in the sheet metal, the machined areas should be carefully deburred after every sheet metal machining operation. The sharp edges of drilled holes or edges can cause serious and severe bleeding injuries. The burr should therefore be removed with a special deburrer, a fine file or suitable sandpaper immediately after processing. An elegant and reliable method for deburring sheet metal is electrochemical deburring. This process can now also be used in workshops and even in private hobby rooms.

Tips for craftsmen when working with sheet metal:

1. bending sheet metal

Depending on the thickness and material, sheet metal can be bent by hand or with simple tools such as a vice and hammer. The thicker the sheet metal, the more force is required to bend it. It is therefore advisable to use a suitable bending machine for thick sheets.

2. cutting sheet metal

Sheet metal can be cut using various tools. The simplest method is cutting by hand with tin snips. Longer cuts are made with lever shears. There are also special tools for curved cuts. Sheet metal can also be cut with a plasma cutter or a cutting torch.

3. sheet metal pressing

Sheet metal pressing is a process in which sheet metal workpieces are formed in three dimensions. With the appropriate machines and tools, very complex geometries can be realised using sheet metal pressing. The disadvantage, however, is that the tools for pressing sheet metal are sometimes very expensive. Pressing is therefore often only worthwhile for larger quantities.

4. sheet metal stretching & upsetting

Stretching and upsetting sheet metal is a process that is used particularly in car body construction and somewhat less frequently in the construction of housings. When stretching, the sheet metal becomes thinner as the material is distributed over a larger area. During upsetting, the sheet metal is pulled together. The structure becomes denser and denser and the workpiece harder and harder.

5. punching sheet metal

Punching sheet metal is a very common task. For example, the holes for rivet or screw connections are usually punched. However, punching can also be carried out at the edge of the sheet metal. If smaller segments are cut out at the edge of a sheet using a punch, this punching is known as notching.
 

6. bending sheet metal

Bending sheet metal is an important and frequently used process in metalworking. When bending, metal sheets are processed by bending the edges, for example to produce housings. Bending sheet metal permanently changes the shape of the material. This allows sheet metal parts to be manufactured precisely and cost-effectively for a wide range of applications.

CONCLUSION:

Although sheet metal processing is not a high art, it does require some experience and practice for various processing methods if the result is to be accurate. It is no coincidence that there are various professions that centre on sheet metal processing. However, with the help of modern machines and tools, even non-professionals can now process sheet metal and prepare it as required. You also simply need a good sheet metal working machine.
 


Questions for the expert:
 
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