Modern milling, as a metal cutting method, originated in the late 18th century and quickly became one of the
primary machining technologies. Today, it is hard to imagine any machine shop without milling machines on
the shop floor. Milling is an essential process in manufacturing.
Milling, is an integral part of machining technology, driven by the increasing demands of manufacturing.
However, there are specific aspects that uniquely impact the advancement of milling.
Today, we are witnessing significant changes in manufacturing that will have profound consequences on the
development of directions of milling. These changes are driven by various factors, such as the increasing
accuracy of metal shaping through precision investment cutting and precision forging, the widespread
adoption of 3D printing, the growing usage of new composite and sintered materials, the need to enhance
productivity in machining hard-to-cut superalloys and titanium grades, and the strong focus on electric and
hybrid cars in the automotive industry, contributing to these changes. In addition, advancements in
multi-axis machine tools have opened up new possibilities for precise machining of complex parts and have
enabled the implementation of new cutting strategies to improve productivity. In modern technological
processes, there is a tendency to significantly reduce the amount of machining stock intended for milling
operations, while simultaneously increasing the requirements for surface finish and accuracy.
Therefore, the advancement in milling is driven by the need for higher productivity, more precision, and
sustainability in milling operations. Consequently, the main developments in milling can be characterized as
follows:
- 1. Fast metal removal focuses on boosting the metal removal rate (MRR) to achieve higher productivity by
significantly increasing cutting speed or feed per tooth. This is achieved through techniques such as
high speed milling (HSM) and, in rough operations, high feed milling (HFM).
- 2. Precision milling provides higher accuracy in milling operations.
- 3. Multi-axis milling is characterized by the utilization of multi-axis machining centers to enable
complex milling operations.
- 4. Adaptive milling aims to develop intelligent milling systems that can adapt to changing conditions
during the machining process.
- 5. Sustainable milling strives to reduce the environmental impact of milling operations. It involves the
development of eco-friendly cutting fluids, recycling and reusing of materials, and the use of
energy-efficient machine tools and milling cutters.
The success in these areas relies on the synergy of several key components, namely machine tools, cutting
tools, and computer-aided engineering (CAE) systems. High-speed milling, for instance, necessitates machine
tool technologies capable of handling exceptionally high rotational velocities, as well as advanced cutting
materials and coatings for milling tools. Simultaneously, enhancing the precision of milling operations
requires not only milling cutters with tighter tolerances but also improved control systems and linear motor
drives. In the case of multi-axis milling, the breakthrough lies in the addition of more effectively
controlled axes of movement, along with the application of appropriate cutting geometries for milling tools.
Adaptive milling, on the other hand, incorporates innovations such as the use of state-of-the-art monitoring
systems, high-sensitive sensors, and efficient algorithms to optimize cutting data and tool paths in
real-time. Moreover, sustainability advancements require energy-efficient milling strategies that employ
suitable machine tools, cutting tools, and eco-friendly coolant techniques.
Indexable milling reflects the ways of advancement that feature exchangeable cutting inserts in machining
operations.
- a) Advanced insert materials is an ongoing process to improve the cutting materials for indexable
milling inserts including the development of advanced carbide grades, ceramics, and ultra hard cutting
materials.
- b) Coating technologies with continuous R&D focuses on new coatings to improve wear and heat
resistance while enhancing lubricity.
- c) Progressive cutting geometry optimizes cutting geometry and chip forming topology of inserts to
improve cutting action, diminish cutting forces, and chip flow in milling operations.
- d) The effective utilization of cutting material incorporates intelligent insert design to provide
maximum indexable cutting edges without reducing cutting capabilities.
In addition, the distinct course on smart manufacturing requires the integration of digitization into
milling operations and milling tools. Referring to milling tools, digital twins and appropriate software
applications have already become the "must" features of a comprehensive tool range.
How can cutting tool producers rise to the challenge? Which milling tool solutions will provide the right
answer to the emerging trends? Is the field of cutting tool manufacturing, often considered conservative in
metalworking, capable of delivering a timely response to current demands? The recent advancements from ISCAR
provides greater insights to these subjects.
High speed trochoidal milling involves following a curvilinear tool path to maintain a constant load on the
cutting edge, thereby eliminating sudden spikes in load during material entry. This strategy is highly
efficient for milling deep slots, pockets, and cavities, especially in cases of low machining stability.
Additionally, trochoidal milling has shown excellent results when working with challenging materials such as
hard steels or high-temperature superalloys (HTSA).
The CHATTERFREE EC-E7/H7-CF is a new family of multi-flute solid carbide endmills, which are intended
specially for trochoidal milling techniques. The geometrical design of the family includes different helix
angles and variable angular pitches to improve dynamic behavior. These endmills are available in a range of
cutting length-to-diameter ratios (Fig. 1).
With the help of modern machine tools, highly productive milling of aluminum alloys can be achieved at
extremely high spindle speeds, reaching up to 33000 rpm. To meet this machining challenge, ISCAR has
developed 90° indexable milling cutters that accommodate large-size inserts for a depth of cut of up to 22
mm (.870") (Fig. 2). The cutters have been specifically designed to eliminate insert radial displacement,
which may occur due to the high centrifugal forces generated during very high rotational speeds.
High feed milling (HFM) has become a widely adopted method for efficient rough machining of both complex and
flat surfaces. ISCAR offers a comprehensive range of HFM products to meet the demands of various industrial
applications. Recently, the range has been expanded with new additions. The LOGIQ-4-FEED family of HFM
tools, featuring specific bone-shaped inserts (Fig. 3), now includes tools with larger inserts. These new
products significantly broaden the application range, particularly in high feed milling of large-sized
cavities in the Die and Mold industry. Another addition is NEOFEED, a family of HFM tools with double-sided
square inserts, providing 8 cutting edges for improved cost-effectiveness.
Advancements in multi-axis machine tools and CAD/CAM systems have given rise to precise milling of complex
shapes with minimal machining stock, using segment or barrel-shaped endmills. ISCAR's program for these
endmills encompasses three design concepts: a solid carbide design, an exchangeable MULTI-MASTER head, and a
one-insert approach (Fig. 4).
When milling high-temperature superalloys (HTSA), cutting ceramics offer the ability to substantially
increase cutting speeds. In fact, cutting speeds can reach up to 1000 m/min (3300 sfm). ISCAR's latest
ceramic tools include ceramic solid endmills and indexable milling cutters with double-sided round ceramic
inserts. The double-sided design is aimed at maximizing the utilization of ceramic material grades, such as
"black" ceramic, whisker-reinforced ceramic, and SiAlON (a type of silicon-nitride-based ceramic).
These selected examples serve as good illustrations of the main directions of advancement in milling tools.
As new demands arise, new solutions are required, and these new challenges will fuel the search for
innovative tool designs.
