Electron Beam Drilling/Perforating: Precise Results at a High Drilling Frequency

The electron beam is the typical method for drilling many small holes in thick and tough materials.

"Many" means in this context 2.000 holes or more per machining cycle. By "tough" we particularly understand metal-based materials, but also other materials (figure 1). All metal-based materials means of course that CrNi or Co alloys as well as titanium, aluminium or copper can be machined without any problem. Diameters ranging from 80µm to 2mm we consider small holes and this at an aspect ratio (hole diameter to material thickness) of up to 1:20 (figure 2).

Benefit from our strengths:
Extremely fast drilling or cutting rates with relatively low heat input and distortion.

One of the main application areas of the electron beam is the drilling of centrifugal disks for the production of glass wool used in insulating materials.

There are also many application possibilities in the food and chemical industries. One example which we always like to mention is our "tofu tray", i.e. a sieve having 12 million holes per square meter for tofu production.

The electron beam method is also applied in aerospace industry, particularly for drilling holes used for adding cooling gases into engine components. These holes can be positioned up to 30° to the surface.

General mechanical engineering:
Here are many electron beam applications in the fields of sieves and filtration. The electron beam method is particularly used when other processes prove to be inadequate. Examples: pulp and paper / paper industry, perforated baskets for plastic recycling etc.

Similar to the welding process, electrons are accelerated in vacuum with 120kV to almost 2/3 of the speed of light. When colliding with the workpiece the electrons give off their kinetic energy to the workpiece in the form of heat. Thus, a local molten pool is created in the center of which a vapor capillary emerges. As soon as this melt channel with the vapor capillary in the center has penetrated the workpiece completely it will meet the backing material, which vaporizes explosively after contact driving out the molten material in opposite direction (figure 3).

The result is a very smooth hole (channel) having a resolidified molten layer of 5-10µm on the hole walls. At the point of entry (side where the beam enters) the hole edges have a slight rounding. In addition, on the upper side (side where the beam enters) a slight burr is formed on the hole edges since the cut material partially sticks to them.

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Downloads

Hole_drilling_by_means_of_an_EB.pdf
drilling.pdf