Expertise on sheet metal design at a glance.
Expertise on sheet metal design at a glance.
Introduction laser cutting
Laser cutting enables complex geometries to be processed as quickly and precisely as possible. In addition to classic punching, laser cutting has established itself as the standard in the industry, as even small quantities can be produced economically. But even for large quantities, laser cutting remains a cost-effective alternative because of their clean, narrow, often post-processing-free cut edges.
Laser-cut parts can be obtained from almost any material and in all sheet thicknesses. With it, sheets can be cut in thicknesses from 0.1mm to 25mm. For stainless steel sheets, the maximum possible thickness for laser cutting is currently even 30mm.
Minimum dimensions
Due to the selected material thickness, minimum dimensions must be observed in the sheet metal design, since too much energy input on one surface leads to a faulty production result and the desired workpiece quality cannot be achieved:
- Minimum dimension for web width = 0.7 x Material thickness
- Minimum dimension for slot width = 0.7 x Material thickness
- Minimum dimension for hole diameter = 0.7 x Material thickness
If the hole diameter falls below the minimum dimension, subsequent drilling and thus an additional manufacturing step becomes indispensable.
Corner fillets
Sharp corners on sheets pose a risk of injury and are automatically rounded off by most programming systems. If sharp corners are required, they should therefore be marked accordingly.
Corner radii also have a positive effect on the production time of the workpiece since a simplified cutting pattern can be run. Depending on the sheet thickness, the following radii should be observed:
| Material Thickness | Corner Radius |
|---|---|
| 1mm to 5mm | 0.5mm |
| 6mm to 12mm | 1mm |
| 15mm to 25mm | 3mm |
Connectionless inner contours
Inner contours that do not have connections to the main part fall out of the sheet and can lead to errors in production. Accordingly, such contours must be removed or connected to the main part by webs.
Introduction bending
Bending is a forming process used to create three-dimensional products from flat sheet metal. Various bending processes allow classically welded or bolted assemblies to be combined into a more cost-effective single part. In industry, bending has become established for both small and large parts.
Minimum leg length
The smallest possible leg length is a tool-related minimum dimension that must be observed in the part design. If a leg length is too short, the workpiece cannot be bent according to the design.
For a 90° bend, the width W can be used to determine the smallest leg length Smin:
Smin = √2/2 * W
The minimum leg length can easily be calculated at the bottom of this page with our leg length calculator.
The following table lists the respective guide values for a 90° bend. As the material thickness increases, the minimum leg length Smin changes as a result of the tools used.
Steel sheets (1.0038)
| MATERIAL THICKNESS, 90°-BEND | MINIMUM LEG LENGTH SMIN |
|---|---|
| 1mm | 6,7mm |
| 1,25mm | 8mm |
| 1,5mm | 8,2mm |
| 2mm | 10mm |
| 2,5mm | 12,6mm |
| 3mm | 12,8mm |
| 4mm | 19mm |
| 5mm | 30,8mm |
| 6mm | 31,3mm |
| 8mm | 39,4mm |
| 10mm | 61,6mm |
| 12mm | 76,7mm |
Stainless steel sheets (1.4301)
| MATERIAL THICKNESS, 90°-BEND | MINIMUM LEG LENGTH SMIN |
|---|---|
| 1mm | 6,7mm |
| 1,25mm | 8mm |
| 1,5mm | 8,2mm |
| 2mm | 10mm |
| 2,5mm | 12,6mm |
| 3mm | 18,5mm |
| 4mm | 19mm |
| 5mm | 30,8mm |
| 6mm | 31,3mm |
| 8mm | 53,5mm |
| 10mm | 61,6mm |
| 12mm | 76,7mm |
Aluminium sheets (AlMg3)
| MATERIAL THICKNESS, 90°-BEND | MINIMUM LEG LENGTH SMIN |
|---|---|
| 1mm | 8,1mm |
| 1,25mm | 8mm |
| 1,5mm | 8,2mm |
| 2mm | 10mm |
| 2,5mm | 12,6mm |
| 3mm | 18,5mm |
| 4mm | 19mm |
| 5mm | 30,8mm |
| 6mm | 31,3mm |
| 8mm | 53,5mm |
| 10mm | 61,6mm |
| 12mm | 76,7mm |
Minimum distances to the bending edge
Workpieces that have a hole or a cut-out near the bending line in the uncoiled state must maintain a minimum distance Lmin. If the distance falls below Lmin, the cut-outs will be deformed during the bending process.
The minimum distance Lmin is calculated with the die width W as follows:
Lmin = 0.75 * W
A quick, workshop-friendly method for determining the minimum distance is to use the smallest leg length. Cut-outs and holes that have a distance to the bending line that is greater than the smallest leg length can be produced without deformations.
Z-bends
In the case of two successive bends, so-called Z-bends, a minimum step dimension Xmin must be maintained due to the bending tool used.
Steel sheets
| MATERIAL THICKNESS, Z-BEND | MINIMUM STEP SIZE XMIN |
|---|---|
| 1mm | 12,5mm |
| 1,25mm | 13mm |
| 1,5mm | 13,5mm |
| 2mm | 16mm |
| 2,5mm | 20mm |
| 3mm | 20,5mm |
| 4mm | 27,5mm |
| 5mm | 37,5mm |
| 6mm | 39mm |
| 8mm | 48mm |
| 10mm | 70mm |
| 12mm | 85mm |
Stainless steel sheets
| MATERIAL THICKNESS, Z-BEND | MINIMUM STEP SIZE XMIN |
|---|---|
| 1mm | 13mm |
| 1,25mm | 13mm |
| 1,5mm | 13,5mm |
| 2mm | 17mm |
| 2,5mm | 21mm |
| 3mm | 28,5mm |
| 4mm | 30mm |
| 5mm | 40,5mm |
| 6mm | 41,5mm |
| 8mm | 62,5mm |
| 10mm | 74mm |
| 12mm | 90mm |
Aluminium sheets
| MATERIAL THICKNESS, Z-BEND | MINIMUM STEP SIZE XMIN |
|---|---|
| 1mm | 13mm |
| 1,25mm | 13mm |
| 1,5mm | 12,5mm |
| 2mm | 17,5mm |
| 2,5mm | 19,5mm |
| 3mm | 26mm |
| 4mm | 27mm |
| 5mm | 38mm |
| 6mm | 40mm |
| 8mm | 61mm |
| 10mm | 72,3mm |
| 12mm | 86,6mm |
Bend reliefs
The run-out of the bending lines should not pass directly into the material, otherwise the compression and expansion at the bending zone will be impeded and cause cracks. Attached relief slots minimize the notch effect and thus ensure the desired bending result.
Sloping edges
Sloping edges towards the bending line must be avoided, otherwise homogeneous bending along the intended edge is not possible due to the tooling.
This can be remedied by a perpendicular distance to the bending line with the dimension of the minimum leg length or by cutting the slanted edge free.
Free bore for bending bead
For process reliability and to avoid unsightly corners when bending edges meet, a corner notch D should be provided at the intersection of the crossing bending lines. Corresponding minimum dimensions are listed in the following table depending on the material thickness.
| MATERIAL THICKNESS | D ± 0,5 |
|---|---|
| ≤ 2mm | 3mm |
| > 2mm ≤ 4mm | 5mm |
| > 4mm – 6mm | 7mm |
Closed corners
The bending manufacturing process can only be used if the entire sheet metal part can be unwound.
Consequently, if three bending lines intersect, one must be split open. If this edge also has to be closed afterwards, a weld seam or another manufacturing process must be used.
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