Working With Core Drills; Special Information On Handling Switchable Permanent Magnets - ALFRA ROTABEST RB 50 SP Mode D'emploi

Working with Core Drills

• Push the ejector pin (centring pin) through the core drill head.
• Core drills with Weldon shank are tightened with clamping screws (DIN 913) on both clamping surfaces.
Risk of injury! Always wear gloves since the edges are sharp.
• Set the core drill on the workpiece and start drilling until the whole cutting area is marked as a circular ring.
• The core drill should be cooled constantly during the drilling process. Optimum cooling is possible through our
coolant equipment using inner cooling.
• Do not switch the drive motor off during drilling, and after the drilling process pull the core drill back with the
motor still running.
• Remove swarf and core after every drilling process.
Use a swarf key to remove the swarf. Do not touch with your bare hands. Risk of injury!

Special Information on Handling Switchable Permanent Magnets

The magnetic surface is located on the underside of the magnetic core drilling machine and generates the
magnetic holding force through magnetic flux when activated. The magnet can be activated independently of the
mains voltage by pressing the lever down. For the magnet to be released, the black safety tab must be pushed by
using the ball of your hand and the lever pulled upwards. The machine remains attached to the workpiece even in
the event of a power failure.
Material thickness
The magnetic flux of the TML permanent magnet requires a minimum material thickness of 8 mm to flow
completely through the workpiece. If this material thickness is not given, the maximum holding force is reduced in
accordance with the material thickness. Conventional electric or permanent magnets have a deeply penetrating
magnetic field similar to tree tap roots, and require a large material thickness of more than 25 mm to achieve the
maximum holding force. The compact magnetic field of the TML magnets is similar to a shallow root and achieves
maximum holding force even with small material thicknesses, so that drilling can be done with sufficient holding
force even on thin sheets from only 3–4 mm thick.
Material
The load-bearing capacity of the permanent magnets is determined using an S235 material. Steels with a high
carbon content or whose structure has been changed by heat treatment have a low holding force. Foamed or pore-
flawed cast parts also have a lower holding force.
Material
Non-alloyed steel (0.1-0.3% C content)
Non-alloyed steel (0.3-0.5% C content)
Cast steel
Grey cast iron
Nickel
Stainless steel, aluminium, brass
18
Magnetic force in %
100
90-95
90
45
11
0