There are many reasons for making chamfers on the edges of workpieces. The most important reason is to remove sharp material edges, which can be formed during several sheet and plate machining methods. For example, if metal sheets and plates are cut to size by shearing, only a certain part of the material thickness is actually cut. The remaining part is torn off due to the high shearing forces. This produces razor-sharp burrs, which on the one hand constitute a risk of injuries and on the other hand impair the fit accuracy during further working.
If thermal cutting methods are used, for example, no burrs are formed which are the case under mechanical loads. The high heat effect, for example, during laser cutting, causes material to be melted and a concentrated gas jet blows the melted material out of the cutting gap (clearance). Especially where thicker metal plates are machined, scale and slag can deposit on the back of the plate.
Possible uses for chamfers
By making chamfers, material edges can not only be relieved of sharp burrs, scale and slag deposits. A chamfer also improves the visual properties of a workpiece and due to the high accuracy of it, it also simplifies the subsequent joining of several parts to form welded structures. If workpieces have to be welded together at a specific angle, the material edges to be joined can be more easily positioned if they are chamfered, as the chamfers act as a guide and therefore make it easier to comply with the required dimensional accuracy.
Laser cutting chamfers
In February 2012, a new laser cutting machine was put into service at Rime, with which sheets and plates with dimensions up to 16 x 4 metres can be chamfered. Thanks to the steplessly swivelling cutting head, chamfers within a range of -30° to +45° are possible.
Chamfering is fast and above all cost-effective with our welding edge former (nibbler). This machine can be set continuously in any chamfer angle between 20° – 45°. Depending on the strength of the material the sheet or plate metal thickness is up to 15 mm with a strength of 400 N/mm². At the maximum possible material strength of 600 N/mm², metal sheets and plates up to 6 mm thick can be machines.
Our Trumpf welding edge former (Trumpf name: beveller) is suitable for making chamfers for all standard K, V, X and Y shaped welds. In addition, the machine can be used for both straight and curved material edges. It is even able to chamfer pipe ends, if they have a minimum diameter of 100 mm. Although our welded edge former is a manual machine, it can also be mounted on a tripod. In manual mode the machine can be used in positions that our otherwise difficult to reach. By using the stand, chamfering small workpieces is made easier. For particularly long workpieces we mount our nibbler on a trolley. It can then be guided along the workpiece without any great effort.
How it works
The machine has a broaching tool, which is mounted on an eccentric shaft. The shaft moves the broaching tool up and down. If the machine is now positioned at the material edge, this movement cuts the material across the width of the broaching tool at the set angle. If the machine is now guided uniformly along the material edge, the chamfer is formed gradually. The movement of the broaching tool causes a fluted pattern on the surface of the chamfer. For this reason, this process is also called nibbling.
When preparing a weld, the pattern plays a secondary role, as welding melts the material. Weld preparation with the edge former (nibbler) is a cost-effective alternative to milling.