Forget torches, saws and grinders, the only way to achieve a truly perfect weld end preparation is through cold machining. Today it is possible to find a machine for any diameter, any wall thickness, any material and at any price. The quality depends on a lot of parameters but without the right machine it is just impossible to even think about achieving the quality shown in the photo above.

Nach der Wahl der richtigen Maschine, ist die zweite Sache das Werkzeug. Das Werkzeug muss scharf sein, mit guter Geometrie und die Beschichtung muss zum Material passen, das bearbeitet werden soll. Beispielsweise ein Super Duplex Rohr benötigt ein TiCN beschichtetes Werkzeug, um richtig zu bearbeiten. Die Werkzeuge können teuer sein, aber es ist besser, ein teures Werkzeug für ein gutes Ergebnis zu haben, anstatt 3 oder mehr verschlissene, die ein schlechtes Ergebnis erzielen.

Set-up is the step you cannot miss. A bad setup means that you need to start over. Time spent for proper setup is not lost time. Set-up accuracy will depend on the skill of the operator, but also on the machine. On-site machines have to be easy to set-up because operators don’t have time to constantly be adjusting the machine.

The machining speed is the most important parameter necessary to achieving a good quality weld end preparation. The speed adjustment will depend on many factors; the material, the pass depth, the geometry of the bevel, etc. To adjust the speed perfectly, some experience is needed but some tips can help you, which are detailed in the following sections:

Lubrication can help you achieve the perfect weld end preparation. Lubrication maintains the tool sharpness, guarantees a better surface finish and cools the machining area. It is not always necessary or even allowed to use lubrication, but for hard materials it is often necessary to use it. The best lubricants are oil-based lubricants, but they are often forbidden and have to be replaced by water-based lubricants.

This section is only for the perfectionist. If you want a surface finish like a mirror you might need to make several machining passes. The first passes are called roughing passes. These are passes where you remove the material without being concerned about the surface finish. The second time you will do a finish pass with other tools, removing just a small amount of material. With this technique it is possible to achieve a nearly perfect surface finish.

Maybe the strangest advice I can give you, but a lot of information can be deduced from machining noise. If you hear vibrations, the speed has to be reduced. If you hear a noise like metal against metal, it means that the pass depth is too small or that a chip is blocked between the tool and the tube. With experience you will be able to recognize different noises and adjust the parameters based upon what you are hearing.

The color and form of the chips are excellent indicators. If the chips are small, the depth pass is too small. If the chips are large and look like they were torn off the tube, the depth pass is too big or the tool is dull. If the chips are blue, they are heat-affected. It could mean that the machining speed is too high, however it is something normal when machining with a High Speed Beveller.

On-site projects are always facing unexpected problems. Time and cost pressure will crush inexperienced people. Experience is the only way to avoid or to deal with such situations. That’s why hiring the right people to do your on-site machining is extremely important.

Choosing the right machine or choosing the right tool requires experience. For some resellers the goal is to sell, without taking care of the client’s real need(s). The role of an advisor is to find long-term solutions and have a real partnership with the client that is understanding of their unique requirements.