Page 9 - Centerdrill Produktkatalog 2020 English

Short introduction

Machines and tools
The precondition for a professional flow drilling process is working with a suitable machine that provides
the required RPM and kW-power. This can be either a column drilling machine, a CNC machining center, or a milling
machine. The required spindle RPM and kW powers can be found online and as well as in the catalogue. If the RPM is too
low, the tool may overheat and decrease the quality of the flow-forming hole. However, if the kW power is too low, your
machine may stop working and there is a possibility that the Centerdrill tool may crack.

Basic equipment
The Centerdrill should be first fixed in a collet, and then, in a collet chuck with an aluminum cooling ring, as this is the
only way to ensure the concentricity, a proper hold of the Centerdrill flow punch former, and to prevent it from
overheating of the machine spindle. It should be noted that the Centerdrill tool is always fully clamped with the entire
shaft in the collet and the union nut is tightened with a hook wrench. However, it is recommended to retighten it regularly.
To reduce the build-up of the metal on the outside of the Centerdrill, our white Centerdrill parting paste should be applied
thinly on the Centerdrill flow punch former. During the thread forming process, it is essential to apply a good
lubricant to the thread former. We also offer all the required products, combined in our Centerdrill Beginner Set.
You can find them in the catalogue on pages 56-59.

Machine settings
It must be ensured that at the very beginning of the flow drilling process, the Centerdrill tool is smoothly placed on the
workpiece surface and penetrates the metal at a feed rate of approx. 50-150 mm/min, provided that the RPM is set correctly.
With this feed rate, the Centerdrill tool will move down with approx. 2.5 mm per second. The depth-stop of the machine
regarding the workpiece surface depends on the fact whether the collar should be preserved or removed. If you require
the collar on the surface, the flow drilling process ends at about 0.5 - 3.0 mm above the workpiece surface. It depends on
the thickness of the material and the size of the core hole diameter. When the collar on the surface is to be removed,
the cutting edges of the Centerdrill tool must be flush with the workpiece surface. In this case, the feed rate should be also
min. 900 mm/min. In this way, the cutters of the Centerdrill are spared. The workpiece to be machined must be firmly clamped
so that it does not move horizontally or vertically. Otherwise, the Centerdrill tool may crack. The workpiece should never
be held by hand.

Flow drilling process
Once the Centerdrill tool and your workpiece are firmly clamped, the machine starts working at the appropriate
rotational speed and thus, the machine achieves the required kW power. Then, the tip of the Centerdrill tool can be
placed smoothly on the workpiece surface and the corresponding axial pressure must be applied, whereby the material is
heated and melted until it becomes red-hot. The Centerdrill tool can now quickly penetrate the material and form
the bush downwards and the collar upwards. The Centerdrill tool should be moved out quickly once reaching the
corresponding depth-stop. If the Centerdrill tool turns too long on the spot, the material overheats. On average,
the flow-forming process takes only a few seconds. If the collar is to be removed to obtain a flat surface, the feed rate
must be increased significantly at the end of the process. The removed chips may fly off randomly.
Therefore, suitable protective clothing should be worn or a protective shield must be installed at the machine.
The hot workpiece should be allowed to cool down at the end of the flow drilling process, or it may only be handled with
appropriate tools or gloves. Afterwards, we recommend to form the thread and not to cut it. Our Centerdrill
standard core hole diameters are also intended for thread forming only. As a result, you can obtain a stable,
turning-free and wobble-free connection from your own material in just two operations.

Parting paste
It is recommended to apply our white parting paste to the Centerdrill flow punch former in order to avoid the
build-up of metals on the Centerdrill tool (depending on a material and material thickness, every 1-5 holes).
The application of the parting paste can be done manually, for example with a brush. It is important that the
parting paste is applied from the beginning and from the top to the bottom of the band of the Centerdrill. A thin film
is sufficient. However, too much white paste reduces the required heat of the process and has a negative effect
on the quality of the formed bush and collar. The release agent is water-soluble and oil-free, so it is also optimally
suitable for components to be coated subsequently where no residues may remain on the surface. Read more on page 60.

Lubricants
During thread forming, our lubricants should always be applied, i.e. in every threading process, otherwise the
lifetime of the thread former may be significantly reduced because of the high friction and the high torque.
Likewise, we also offer easily washable oils, and oils for spraying in the catalogue, page 61.

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