Iscar makes ‘titanic’ developments

HELIQUAD
HELIQUAD

Iscar UK sales manager, David Jones explains the company’s recent innovations within the area of titanium milling within the global aerospace manufacturing sector.

The strength-to-weight ratio and high corrosion resistant properties of titanium has resulted in the growing use of this engineering material in many demanding sectors, not least the aerospace industry.

The production of critical structural parts from titanium ensures they deliver the required levels of performance and reliability whilst significantly reducing their mass. Although relevant to all users of titanium, the enhanced strength and reductions in weight that the material brings are of particular importance to the aerospace industry, as these advantages improve aircraft's' performance and increase fuel economy.

The negative trade-offs produced by the use of titanium are the many problems encountered when machining this difficult-to-cut material. When used in metalworking industries, the word ‘titanium’ normally relates not only to pure titanium, but also to titanium alloys.

Machinability rating depends on the type of titanium and its treatment. The machinability of the widely used annealed titanium TiAl6V4 is approximately 35-40% less than annealed stainless steel AISI 304. However, if we take the machinability of the aforementioned titanium grade as 100%, the so-called “triple 5”, titanium 5-5-5-3, a major manufacturing headache for many machine shops, features machinability characteristics that are twice as difficult.

Machine tool manufacturers continue to introduce innovations and developments that make the cutting of titanium more effective. Modern machine tools allow operators to apply advanced machining strategies and to employ one-hit production methods. However, the typically low cutting speeds used in the machining of titanium severely limit machine tools’ efficiency potential and results in the cutting tool becoming the weakest element in the whole production system. In short, the cutting tool determines the productivity boundaries when machining titanium, and as such, has become a major factor in the quest for a radical improvement of this situation.

Beating the heat

Due to the low thermal conductivity of titanium, the main problem when cutting this material is the generation of heat. Poor heat transfer leads to considerable thermal loads being directly transferred to the tools cutting edge. Also, less of a problem when machining steel, titanium’s modulus of elasticity contributes to vibration during cutting, as a result, surface finish and accuracy problems can be encountered.

Cutting tool producers continue to apply significant R&D resources to developing progressive tools for the efficient machining of titanium. Manufacturing titanium parts is a process with significant buy-to-fly ratio, when a large amount of metal needs to be removed. The eventual weight of a finished titanium part may be only 10% or less of the original weight of a workpiece. Frequently, these parts will feature cavities, pockets and ribs that dictate milling as the main method for manufacturing. As a consequence, every new tool intended for the milling of titanium creates intense interest amongst the aerospace manufacturing community. Therefore, the latest products from Iscar, an innovator in the field, always attract the attention of the world’s manufacturers involved in the machining of titanium.

Tool material is of fundamental importance in the success of cutting tools, especially for use when indexable milling difficult-to-cut aerospace materials, in particular titanium. Within this challenging field, Iscar has developed a new carbide grade IC840, which is characterised by a newly cemented carbide substrate and an innovative hard PVD coating. The grade substrate is resistant to thermal cracks; the bronze colour, ‘chocolate’, coating boasts high oxidation and chipping resistance; whilst an advanced post-coating treatment improves overall toughness. The advantageous combination of the above IC840 features gives users the opportunity to significantly increase efficiencies when milling titanium. Iscar believes that the new ‘chocolate’ will definitely suit the taste of the manufacturers of titanium components and increase the performance of indexable cutters.

As previously mentioned, the milling of titanium usually involves removing considerable amounts of stock. Considered true ‘workhorses’ in this field, extended flute indexable tools (porcupines) are intended for the rough cutting of deep pockets, cavities and wide edges. For these common operations, Iscar has developed the HELITANG H490, a family of advanced milling tools with tangentially clamped inserts, and also the MILLSHRED P290, a range of milling tools carrying serrated inserts that provide an efficient chip splitting (even chip chopping) effect. In addition, the company offers HELITANG FIN, a family of tangential porcupines that were designed especially for semi-finish milling.

Deceptively simple tooling

Iscar has recently introduced a new group of extended flute shell mills related to the proven and popular HELIQUAD family. These mills carry one-sided square inserts, which are clamped radially. Some users have asked - why has a company, well known for its commitment to innovative cutting geometries, equipped these new mills with “traditional” simple square inserts? The answer – The deceptively simple, new extended flute tools feature a well-designed structure resulting in significantly improved dynamic rigidity and anti-vibration strength. In addition, radial insert clamping enables the inclusion of a chip gullet with a generous volume that answers the requirements of free chip flow when milling at high metal removal rates. Also, the tools of more popular diameters have internal channels, which are designed for machining with a high-pressure coolant supply. Even these “simple” square inserts are characterised by a progressive cutting geometry that provides extremely effective titanium milling.

Hence, if HELITANG H490 and MILLSHRED P290 are intended for productive roughing, and HELITANG FIN for the semi-finishing of titanium workpieces, from an application point of view, the new HELIQUAD extended flute shell mills provides high-efficiency milling resulting in semi-finish conditions.

Also, Iscar recently introduced the Ti-TURBO family of solid carbide endmills in a diameter range of 6-20mm. The new family was designed for finishing operations and also for high-speed machining of mainly slots, through the use of the trochoidal technique. Trochoidal milling features a small width and significant depth of cut, combined with a tool path dictated by a trochoid curve. Under such conditions the tool “slices” metal up at a high rate. Here, the engagement angle is small and the produced chips are very thin, this dramatically reduces the thermal load on the tool. Ti-TURBO endmills, featuring a patented design, they have 7 or 9 flutes with variable angular pitch that ensures powerful resistance to vibration. This is why the new family is regarded as a true ‘turbo-booster’ in the area of titanium milling.

Iscar’s MULTI-MASTER range of assembled tools with replaceable solid carbide cutting heads has been recently enhanced by the introduction of new, six-flute, fast feed milling heads with central coolant holes. The ultra-fine grain carbide substrate of the heads, protected by the advanced AL-TEC coating technology is said to provide outstanding wear resistance. The heads are used in productive high feed milling, resulting in significant reductions in the cycle times of roughing operations.

Manufacturers of titanium parts are constantly placing new demands on cutting tool producers. In order to meet these challenges, on a regular basis, cutting tool producers are forced to think out of the box. Iscar’s prolific R&D team continues to cooperate with many of the world’s leading aerospace manufacturers of titanium parts to ensure that the company retains its lead within this challenging sector.

www.iscar.co.uk

Company

Iscar

Tags
Related Articles
Most recent Articles

Carter enjoys success at HAI HELI-EXPO event

Acknowledged as the World’s largest vertical aviation conference and trade show, HAI HELI-EXPO 2024 provided precision bearing specialists Carter Manufacturing a perfect opportunity to exhibit its extensive range of aerospace bearing installation, removal and testing tools, along with PMA bearing options.
1 day ago News

Login / Sign up