The method of rough machining with significantly increased feed per tooth – known as fast feed (FF) milling or high feed milling (HFM) – found its industrial application in the 1990’s.
Die and mold making was one of the first industries to adopt HFM into its production practices, following a massive increase in customer demands for reduced die and mold manufacturing time. HFM answered this need while providing an effective tool for boosting productivity. The HFM 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 tool features a small cutting edge angle, normally 9-17°. 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 face milling low-alloy steel, 0.2 mm/tooth (.008 ipt) is a near maximum value feed, but high feed milling the same material with a 2 mm/tooth (.08 ipt) feed is normal. The second is a shallow depth of cut (DOC) that ensures this geometry for the tool. Milling with reduced DOC diminishes cutting force and power consumption. And the third point relates to minimizing the radial component of the cutting force combined with maximizing 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 7000-9000 mm/min (275-355 ipm) – the next-higher order versus conventional values.
Recognizing market 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, high-thrust spindle, and high-speed feed drive. The machines feature advanced computer numerical control (CNC) hard- and software. Introducing HFM 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 mold making, HFM soon proved advantageous in face milling (“fast feed facing” or “triple F”). The diameter range of the FF milling cutters was increased and the group of engineering materials suitable for cutting by the HFM 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 mold making, embracing all metal cutting areas as a generally recognized 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’s line of high feed milling cutters illustrates this diversity with almost dozens of fast feed mill families; today it is unique in the field with an extensive range of options. Already in the late 90’s, the company introduced a family of indexable tools with one-sided inserts for fast feed milling, and continued to expand their 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 FF solid carbide endmills and replaceable milling heads for the company’s “Multi-Master” products. Efficient use of HFM tools in face milling operations generated new demands, and the company not only introduced appropriate cutter families but suggested an original additional solution: the specially designed inserts. These inserts, intended for mounting in general-purpose cutters in the standard milling line, transform the latter to FF tools. The solution particularly won the recognition of small and medium manufacturers, as it allowed more effective usage of already purchased tools.
In its latest “LOGIQ” campaign, ISCAR introduced four new FF tool families and upgraded several existing lines. What was the motivation behind these developments? ISCAR is renowned for its commitment to innovations, driven by R&D advances and manufacturer needs.
The first noticeable feature of the new families is a substantial decrease in the size of indexable FF cutters. For example, the diameter range of FFT3-02 “NAN3FEED” endmills is 8-10 mm (.315-.394”) – “classical” dimensions for solid carbide tools. The company is confident that the indexable concept represents a competitive solution. These endmills are characterized 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: 2 and 3 teeth for diameters 8 and 10 mm (.315-.394”) correspondingly; and 3 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 4 cutting edges.
The inserts of both mentioned families are provided in several cutting geometries for optimal milling of different engineering materials.
The variety of HFM tool family options inevitably raises the question: “How to choose the most suitable tool?” In addition to ISCAR’s ITA (Iscar Tool Advisor) software, the company developed a quick tool selector guide, a compass for manufacturers to find the most effective solution for fast feed milling.
The case of ISCAR’s HFM line is good evidence that developing FF milling cutters is still far from its high point. The newly introduced tool families offer logical answers to real manufacturer demands. HFM, 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.
