Milling

End mills are fundamentally either shank or arbor-mounted tools that feature one or more cutting edges. In addition to insert-equipped cutter bodies, shank mills are also available as high-speed steel and solid carbide end mills. The number of high-speed steel end mills has been decreasing over the years and they are now mainly used in manual milling machines. The quality and price of solid carbide end mills, relative to the productivity of the tool and the machining methods enabled by modern machining centers, have established this tool type as the most common end mill model. There is a wide range of shank mills for various applications, such as traditional straight end mills for chamfering and slot milling, long-cut end mills equipped with multiple cutting edges for end mills for dynamic milling, end mills with a large face radius for end mills for high-feed milling, radius or barrel mills for 3D surface milling, as well as various rounding, bevel, T-slot, and dovetail slot mills. Insert-equipped mills refer to steel cutter bodies to which replaceable inserts (blade plates) are attached with screws. Insert mills are cost-effective, and due to the replaceable blade plates, tool maintenance is easy. It is also possible to place different blade geometries, with varying grades and coatings, onto tool bodies for machining various materials. Insert-equipped mills come in both shank and arbor models, and they are generally larger in size than solid carbide end mills. Insert mills include, for example, face mills, form mills, corner mills, high-feed mills, shell mills, slot and disc mills, etc.

Dynamic milling is a machining method developed collaboratively by tool manufacturers and CAM software developers. Dynamic machining methods were originally developed for the roughing of difficult-to-machine materials such as hard steels and heat-resistant superalloys but are also very suitable for milling other materials. The method utilizes the full cutting depth of the tool, which results in even wear across the entire cutting length and extends the tool life.

The basic principle of dynamic milling is a large axial (ap) and small radial (ae) depth of cut compared to traditional machining methods. In dynamic milling, the aim is to avoid milling at full tool width and linear movements, favoring smoother machining motions instead.

Dynamic machining generally involves climb milling, in which the tool returns to the start of a new cut at high feed (non-cutting feed) once a chip is completed. The approach and exit motions from the machining path are always carried out on a curved trajectory (approx. 10% Dc). In dynamic milling, the tool diameter (Dc) should be at most 70% of the width of the area being machined. The side step ae in dynamic high-speed milling is usually around 5-20% Dc, depending on the tool and the material being machined.

Common cutting tools can be used in dynamic milling, but the best advantage is gained by using solid carbide end mills specifically designed for dynamic milling, which are equipped with multiple cutting edges and chip-breaking grooves. Such examples are the end mills from the Walter Tools MD133 series, which feature cutting lengths of 3xD, 4xD, and 5xD. Variables affecting the side step in dynamic machining paths include the tool used, the machining depth, the material being worked, the machining center used in the process, the machine's tool holder, the toolholder, and the workpiece clamping. To ensure the functionality of the machining process, always use the machining parameter calculators provided by the tool manufacturer, which take the aforementioned factors into account. An example of such a calculator is Walter GPS.