The method of rough machining with significantly increased feed per tooth – known as fast-feed milling or high-feed milling – found its industrial application in the 1990s. Die and mould making was one of the first industries to adopt high-feed milling in its production practices, following a massive increase in customer demand for reduced the manufacturing time for dies and moulds. High-feed milling answered this need while also providing an effective tool for boosting productivity.
The high-feed milling method is based primarily on two principles: the geometry of a milling cutter; and the high-speed feed drive of a machine tool. A typical fast-feed milling tool features a small cutting edge angle, normally 9-17 degrees. This design characteristic results in three important outcomes.
The first is the possibility of considerably increasing feed per tooth due to a chip thinning effect. For example, in the face milling of low-alloy steel, 0.2mm per tooth is a near-maximum value feed, but high-feed milling the same material with a 2mm per tooth feed is normal. The second is a shallow depth of cut that ensures this geometry for the tool. Milling with reduced depth of cut diminishes cutting force and power consumption. Finally, the third point relates to minimising the radial component of the cutting force combined with maximising its axial component, which acts toward the axis of the machine tool spindle – i.e. the direction of the maximum machine tool rigidity. This improves machining stability.
Increasing feed per tooth means greater feed speed that requires the appropriate feed drive of the machine tool. In the above example of high-feed milling low-alloy steel, the feed peed may be 7,000-9,000mm per min – the next-higher order versus conventional values.
Recognising the market’s needs, machine tool manufacturers developed a variety of machines intended specifically for high-feed milling. These relatively low-power machines have “triple high” characteristics: high torque: a high-thrust spindle; and a high-speed feed drive. The machines feature advanced computer numerical control (CNC) hardware and software.
Introducing high-feed milling substantially changed the concept of rough milling. Instead of intensive material removal at large depths and width of cut by using high-power machines, the method proposed extremely productive milling at shallow depths by low-power machines fitted with a cutting tool that runs very fast.
The fast-feed milling method has since undergone some interesting changes. Originally considered as an effective way for rough machining cavities and pockets that was typical for die and mould making, high-feed milling soon proved advantageous in face milling (“fast-feed facing” or “triple F”). The diameter range of the fast-feed milling cutters was increased, and the group of engineering materials suitable for cutting by the high-feed milling method expanded.
Fast-feed milling quickly penetrated to many industrial branches. It began to be more than an effective technique for the applicative niche of die and mould making, embracing all metal cutting areas as a generally recognised productive method.
Steel and cast iron may be known as the main “consumers” of fast-feed milling, but stainless steel, titanium, and even high-temperature superalloys can be successfully machined by the method as well. This in turn led tool manufacturers to introduce a variety of fast-feed milling cutters in different forms. Indexable or solid in concept, they can have shank- or arbor-type design configurations, integral or modular body structures, and cutting geometry that varies according to the machined material group.
Iscar leads the way
Iscar’s line of high-feed milling cutters illustrates this diversity, with almost dozens of fast-feed mill families; today the company is unique in this field, with an extensive range of options. By the late 1990s, Icscar had already introduced a family of indexable tools with one-sided inserts for fast-feed milling, and continued to expand its line by adding more indexable milling families, with designs that provided added value to customers.
In one case, the tools carried cost-beneficial double-sided inserts; in another, an advanced cutting geometry considerably improved ramp-down abilities for better performance in milling by helical interpolation. For applications requiring small-size cutters, the company developed fast-feed solid carbide endmills and replaceable milling heads for the company’s “Multi-Master” products.
Efficient use of high-feed milling tools in face-milling operations generated new demands, and Iscar not only introduced appropriate cutter families but also suggested an original additional solution: the specially designed insert. These inserts, intended for mounting in general-purpose cutters in the standard milling line, transform the latter to fast-feed milling tools. The solution won the recognition in particular of small and medium-sized manufacturers, as it allowed more effective usage of already-purchased tools.
In its latest LogIQ campaign, Iscar has introduced four new fast-feed milling tool families as well as upgrading several existing lines. What was the motivation behind these developments? Iscar is renowned for its commitment to innovations, driven by research & development (R&D) advances and manufacturers’ needs.
The first noticeable feature of the new families is a substantial decrease in the size of indexable fast-feed milling cutters. For example, the diameter range of Iscar’s FFT3-02 Nan3Feed endmills is 8-10mm – “classical” dimensions for solid carbide tools. The company is confident that the indexable concept represents a competitive solution.
These endmills are characterised by the original clamping method of miniature carbide inserts. The inserts do not have a traditional central through-hole that weakens the insert structure. A screw head, which acts as a wedge, secures the insert, allowing insert indexing to be quick and simple. As the insert is very small in size, it is placed in the pocket via a key with a magnetic boss on the key handle. The proposed design ensures a multi-tooth tool configuration – two and three teeth for diameters of 8mm and 10mm respectively – and three indexable cutting edges of the insert provide cost-effective using cemented carbide.
Another example is Tang4Feed, a family of fast-feed shell mills carrying tangentially clamped rhombic inserts. The mills are designed mostly for rough machining medium- and large-size cavities and pockets. The tangential clamping principle, combined with a dovetail profile of matching surfaces for secure insert mounting, ensures a durable mill structure. The insert’s rhombic shape significantly improves mill performance in ramping-down and side-plunging operations. The Tang4Feed inserts are double-sided, resulting in four cutting edges.
The inserts of both the Nan3Feed and Tang4Feed families are provided in several cutting geometries for optimal milling of different engineering materials.
The variety of high-feed milling tool family options inevitably raises the question: how should one choose the most suitable tool? In addition to Iscar’s ITA (Iscar Tool Advisor) software, the company has developed a quick tool selector guide, providing a compass for manufacturers to find the most effective solution for fast-feed milling.
The case of Iscar’s high-feed milling line is good evidence that developing fast-feed milling cutters is still far from its high point. The newly introduced tool families offer logical answers to real manufacturer demands. High-feed milling, as a productive method of rough machining, has optimistic prospects, and the metalworking industry will continue to require faster and faster milling cutters for high metal removal rates.