The leading metal-working company Walter AG (www.walter-tools.com), which has a UK subsidiary in Bromsgrove, has introduced a number of developments in milling-cutter technology.

Designed to provide cost savings and improved ‘process integrity’ benefits for users in a variety of industry sectors, they comprise: a new PCD cutter (pictured) that can machine both aluminium and bi-metal (grey iron-aluminium) workpieces by using a number of indexable inserts that are each optimised for different applications; two new long-life solid-carbide cutters (MC319 and MC320 Advance) specifically for roughing; an expanded range of M4000 cutters up to 315mm in diameter for larger workpieces; and the next-generation Xtra.tec XT (Xtended Technology) shoulder and face mills, which are configured to give increased productivity and process reliability.

Aimed at automotive OEMs and ‘top tier’ suppliers, Walter’s new PCD cutter uses a variety of standard inserts in a single tool that can rough-mill (up to 8mm deep) and finish-mill (0.5 to 0.8 mm) aluminium, as well as finish-mill bi-metal workpieces.

This means the cutter can reduce tooling costs by obviating the need for multiple tools for varying operations on different workpiece types.

While around 70% of modern engine blocks are of aluminium, bi-metal blocks usually have components like cylinder liners of grey cast iron inserted into the aluminium body.

The machining process, especially the rough and finish milling of such workpieces, was previously only possible using a range of different tools, raising tooling costs as well as increasing the time (and cost) spent on tool logistics and tool changes.

Aluminium alloys can be rough- and finish-machined very easily at high feed rates, but process reliability and surface quality are influenced by chip removal and the presence of cavities — and there are numerous cavities found on engine blocks, including drilled holes and recesses.

Furthermore, subsequent cleaning routines add to overall production costs but do not guarantee that all chips are removed.

Walter has designed this new cutter with a coolant channel running through the centre of the tool, thereby ensuring that the flow of coolant removes any chips; and with regard to cavities that form during the casting process, these are ‘ripped open’ during milling and, if untreated, can result in leaks.

An additional milling operation is usually required to create a homogeneous finish where the porous surface has been ‘filled in’. The new cutter can perform both finish-milling and lubricated-milling operations.

Roughing operations

Designed specifically for the universal roughing of a variety of materials, the MC319 and MC320 Advance solid-carbide milling cutters feature a castellated profile (designed to maximise tool life), three to eight cutting edges (depending on tool diameter) and an ‘edge cutting to centre’ design.

Moreover, the power requirement during machining is around 30% less than comparable tools with smooth (rather than castellated) cutting edges; and the new cutters allow full slotting at depths up to twice the tool diameter, while producing very short chips and achieving high metal removal rates with a particularly smooth milling process.

Meanwhile, the M4000 universal milling system is now available in diameters up to 315mm (compared to the usual 160mm); and with four cutting edges, the universal inserts help to reduce inventory costs.

The design consists of a basic body plus four adjustable and interchangeable cartridges carrying Tiger.tec Silver and Tiger.tec Gold inserts.

The most striking design feature of the next-generation Xtra.tec XT (Xtended Technology) shoulder- and face-milling cutters is the position of the indexable inserts; they have a greater radial seating angle and a larger contact surface than traditional cutter types, to reduce surface pressure in the seat and increase stability.

The large screw-hole cross-section is designed to stabilise the inserts, while the long screws hold them in place securely; and with an optimum amount of material behind the insert seat, the cutter body is also very stable.

Furthermore, the position of the indexable inserts allows for the addition of an extra tooth, thereby increasing productivity, while the precise 90deg angle of the shoulder milling cutters helps to reduce the need for additional finishing operations.

Also new is the fact that smaller inserts can be fitted; and with the M5009 face mill in particular, this combines the use of small depths of cut with the advantages offered by double-sided Walter Tiger.tec indexable inserts with eight cutting edges instead of the usual four.