As a cutting tool supplier to the global aerospace manufacturing industry, Iscar prides itself in ensuring the continuous development and delivery of what they describe as the most efficient, cost-effective cutting tools that are applicable to each of the sector’s diverse machining needs. In addition to other areas, the company has an excellent reputation for its innovative answers to the efficient production of blisks.
A blisk (“bladed disk”) is an aero-engine component consisting of a rotor disk and multiple blades in a single part. As blisks replace the traditional assembly of an individual disk and multiple removable blades, since their introduction in the mid-eighties, the use of blisks continues to grow in popularity. Also known as integrally bladed rotors (IBRs), blisks are usually machined from a solid piece of material.
The use of blisks in the compressors and fans of modern turbojet engines not only leads to gains in performance; it negates the need to assemble the rotor disk and blades and also allows the vital component to be produced in a single setup on the same machine tool.
Due to their complicated shapes, the machining of blisks requires the use of multi-axis machine tools and advanced CNC software. Naturally, such machining demands effective and reliable cutting tools. As the majority of blisk machining consists of milling, the quality of the milling cutters used is of paramount importance. Usually, blisks are produced from titanium (Ti) or nickel-based alloys (Ni-alloys), therefore the milling cutters used need to meet the stringent productive and fail-safe machining requirements of these hard-to-cut materials.
As a major supplier in the global aerospace manufacturing industry, Iscar has developed a wide range of long lasting, technically superior milling cutters that not only help guarantee the premium quality of blisks, they also boost users’ productivity. Iscar’s answer to the efficient production of blisks is provided by the company’s high-quality coated, solid carbide endmills and innovative Multi- Master tools.
Products of the company’s prolific R&D department, Iscar uses premium submicron and ultra-fine carbide substrates, which in combination with nano-layer PVD coating technology and advanced post-coating Sumo Tec treatment, significantly improves tools’ impact strength and wear resistance, resulting in longer tool life and enhanced working characteristics.
As the milling of blisks begins with rough slot milling, Iscar has developed solid carbide endmills ECK-M specifically for this demanding operation. These highly efficient tools feature a unique reinforced geometry of their cutting edges, and are ideal for the efficient milling of titanium.
If the slot to be milled is deep and narrow, Iscar’s Multi-Master tools provide high performance characteristics; in addition they are ideal for milling fillet areas. Multi-Master end milling tools consist of a shank carrying interchangeable solid carbide cutting heads that are treaded to allow a quick-change connection with the shank.
The benefits of the flexible Multi-Master system include minimum setup time and the ability to configure the system in more than 15,000 ways from standard shanks and heads. If necessary, the assembly can be extended by the use of extensions. A range of shanks are available and made from steel for general-duty applications, tungsten carbide with greater rigidity and heavy-metal for increased vibration resistance considerably increasing assembly options.
In some blisk rough slot milling situations, such as the machining of Ni-alloys, the trochoidal technique is the most productive machining method, therefore, a trochoidal tool path is highly recommended. Iscar’s solid carbide Chatterfree endmills EC-H7 have been developed specifically for this method. Chatterfree’s seven flutes have different helix angles, enabling high stock removal rates.
When finish milling of blisks, a high-quality surface finish and predictable long tool life are vital requirements. The cutting tool often works with a high overhang that raises the requirement of the tool’s stability. For these situations, Iscar recommends the use of solid carbide Chatterfree tapered ball nose endmills, which are characterised by different helix angles of the end-mill flutes. Also, in many cases the tapered ball nose Multi-Master heads provide acceptable and economical means.
Productive milling of blisks is based on three pillars: a high-velocity multi-axis machine tool, advanced CNC and CAD/CAM software, and not least efficient milling cutters. The development of a wide range of highly effective Iscar cutting tools with new carbide grades and innovative geometries has enabled many global manufacturers of jet engine blades and blisks/IBR to achieve considerably reduced Cost Per Unit (CPU).
