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Reasons Why Indexable Tools Will Challenge Solid Carbide For Small Diameters

Reasons Why Indexable Tools Will Challenge Solid Carbide For Small Diameters

Rotating one-piece solid carbide tools traditionally dominate the market for diameter ranges of up to 20 mm (.75”) and indexable tool manufacturers have not yet succeeded in penetrating this solid stronghold. Several important factors contribute to the historical perception of solid carbide as a better bet for tooling reliability. 

SOLID carbide tool accuracy compares favorably with that of indexable tools, particularly for small-diameter endmills and for tools with diameters beyond the range. However, the role of reduced accuracy for tools of small diameter (for example, a milling cutter’s radial run-out) increases in significance as a factor affecting tool life.

An indexable tool is made up of a tool body, replaceable inserts, and mechanical parts such as clamping screws or wedges, which secure the inserts in the body. Decreasing the tool diameter necessitates reducing dimensions of the assembly components. Reducing the size of the securing elements leads to weakening their strength and the tool becomes unable to withstand cutting loads under normal machining data. This seriously limits the tool application and further decrements may cause degradation of the entire assembly structure.

The prices of small rotating tools are also often high compared to the assembled concept, which adds to the perceived limitations of indexable tools in the small diameter range.

The Indexable Option

Indexable tools possess several distinct advantages that makes applying these tools within the above range very attractive in the eyes of the customer. In many cases, especially in rough machining, changing a worn cutting edge by simple indexing provides more economic benefits as compared with having to replace a whole life-expired solid tool with a new tool. In addition, there is no need to use up time and resources on regrinding and recoating worn-out one-piece cutters.

Tool manufacturers have made significant progress in developing reliable designs that could be commercially viable against the solid carbide concept. Work in this direction has already shown results, and assembled mills and drills with interchangeable cutting heads are proving to be a realistic alternative to solid carbide tools.

Competitive Performance

 The introduction of tools with replaceable solid carbide cutting heads signifies a change in focus. ISCAR provides two examples of this concept with the ISCAR MULTI-MASTER milling line and the CHAMDRILL line in drilling.

Performance and accuracy characteristics have positioned the new tools to be functionally competitive with solid carbide designs. Versatility of these lines, where a head can be mounted in different bodies and vice versa, where a single body can carry different heads, facilitates various assembly combinations and contributes to reducing the number of items in a tool stock.

Another important design approach which is the “no set-up time”, characterises these lines, as a worn-out head does not require spending time on set up and can be replaced while the tool is still clamped in the machine tool spindle. This cuts cycle time and, consequently, reduces production costs. In contrast, replacing a worn-out solid carbide mill or drill inevitably leads to a new set-up procedure.

In addition, the concept ensures sustainable use of cemented carbide with all the associated advantages. The principle of “indexable” carbide tools has distinct merits and features strongly in tool design within the diameter range that is under discussion. The minimal diameter of MULTI-MASTER milling heads is 5 mm and that of SUMOCHAM drilling heads is 6 mm, while the MULTI-MASTER combined countersink heads for center drilling feature a minimal 1 mm diameter.

The LOGIQ Factor

 ISCAR has recently introduced a new range of small-size indexable rotating tools under its new LOGIQ line campaign. The company proposes several families of cutters with a nominal diameter of up to 20 mm. A brief look at some of these families can provide a clearer understanding as to whether the new tools will be able to breach the solid stronghold wall.

The new families of indexable milling cutters within the diameter range of 8-16 mm attract the most interest. They have several common features: the cutters carry triangular-shape inserts with three cutting edges and the mechanical part that secures the inserts is represented by a screw. These families are intended for milling square shoulder or fast feed (high feed) milling. But it is here that the similarity ends, and the difference begins. While the design of the HELI3MILL and MICRO3FEED families for tool diameter 10-16 mm is committed to the classical principle of insert securing, by clamping screw through the central hole of an insert, the NANMILL and NAN3FEED families for tool diameter 8-10 mm have adopted another concept.

Within such a small diameter range, the central clamping screw, as noted previously, does not provide an acceptable solution. According to the new concept, the screw is located above the insert, and the screw head plays the role of a wedge. This approach provides reliable and rigid clamping, and ensures a durable homogeneous insert structure with no hole. Allowing for the insert indexing to be quick and simple.

It is predicted that these new families will be particularly effective in manufacturing compact parts and in machining small-in-size cavities, pockets and small parts utilised in industrial sectors such as die and mold making, as well as in producing miniature components.

Small Change, Large Impact

 A 1 mm change in size: is this a lot or a little? For indexable tools in the small diameter range, it does make a noticeable difference. ISCAR’s new SUMOCHAM 5 mm diameter drilling head represents an important step ahead in expanding the application fields of indexable drills.

Within the small diameter range, indexable tools can offer precision and performance advantages that position them competitively against the more traditional solid carbide tools.  Indexable tools are beginning to shear their way into metalworking practices and the industry is taking note.

Article contributed by ISCAR.

The Right Grade Creates The Right Tool: Selecting Tool Materials

The Right Grade Creates The Right Tool: Selecting Tool Materials

Cutting tools have different design configurations. Some of them are assembled comprising a body with replaceable cutting elements (indexable inserts, for example), another is wholly produced from solid material. Functionally, a cutting tool may be divided into a cutting part that is involved in cutting, and a mounting part, which is necessary for mounting the tool in a holder or a machine spindle.

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Jet Engine Part Production—An Aerospace Industry Challenge

The requirements for materials used in jet engine parts are necessarily very exacting. They must survive extremes of temperature and force, while being as light as possible and ultra-reliable. Contributed by Iscar

Image Source: Iscar

A turbojet engine can be divided simply into three sections – the compressor, the combustor and the turbine. The compressor pressurises the air flowing through the engine before it enters the combustion chamber, where the air is mixed with fuel, ignited and burnt. The compressor components are predominantly made from titanium alloys, while the combustor and turbine components are typically made of a nickel-based superalloy such as Inconel 718.

Nickel-Based Alloys

The excellent physical properties that characterise nickel-based high temperature alloys make them ideal for use in the manufacture of aerospace components.

Properties such as high yield strength and ultimate tensile strength, high fatigue strength, corrosion and oxidation resistance even at elevated temperatures enable the usage of nickel-based high temperature alloys in many applications and over a very wide temperature spectrum.

The aerospace industry accounts for about 80 percent of the nickel-based high temperature alloys used in manufacturing rotating parts of gas turbines, including  disks and blades, housing components such as turbine casing, engine mounts, and components for rocket motors and pumps.

Nickel-based high temperature alloys contain 35-75 percent Ni and 15-22 percent Cr; they constitute about 30 percent of the total material requirement in the manufacture of an aircraft engine and are also used as structural material for various components in the main engine of space shuttles.

The very same properties that make nickel-based alloys such a great choice for jet engine parts also cause substantial machining difficulties.

The cutting forces and temperature at the cutting zone are extremely high due to the high shear stresses developed and the low thermal conductivity. This, coupled with the reactivity of nickel-based high temperature alloys with the tool material, leads to galling and welding of the chips on the work piece surface and cause excessive tool wear, which can limit cutting speeds and reduce useful tool life.

All these characteristics contribute to low material removal rates and short tool life, resulting in massive machining costs.

Titanium-Based Alloys

Due to their high strength to weight ratio and excellent corrosion resistance, titanium alloy parts are ideally suited for advanced aerospace systems. Titanium-based alloys which contain 86-99.5 percent Ti and 5-8 percent Al, are immune to almost every medium to which they would be exposed in an aerospace environment.

Image Source: Iscar

Very large quantities of titanium can be found in jet engines, where titanium alloy parts make up to 25-30 percent of the weight, primarily in the compressor. The high efficiency of these engines is obtained by using titanium alloys in components such as fan blades, compressor blades, rotors, discs, hubs, and other non-rotor parts—for instance inlet guide vanes.

Titanium’s superior properties and light weight allow aeronautical engineers to design planes that can fly higher and faster, with high resistance to extreme environmental conditions. However, titanium has historically been perceived as a material which is difficult to machine due to its physical, chemical and mechanical properties.

The material’s relatively high temperature resistance and low thermal conductivity do not allow generated heat to dissipate from the cutting tool, which causes excessive tool deformation and wear. Titanium alloys retain their strength at high temperatures, resulting in relatively high plastic deformation of the cutting tool resulting in depth of cut notches. During machining, the high chemical reactivity of titanium alloys causes the chips to weld to the cutting tool, leading to built-up cutting edges and chip breakage problems.

Over the past few years, Iscar has invested many resources in research and development to resolve these obstacles and optimise the machining of nickel-based and titanium high temperature alloys, with solutions that include the creation of customised grades and implementation of high pressure coolant technologies to develop cutting tools that will handle the heat issues.

Grades

For high material removal rates, Iscar developed ceramic grades to facilitate machining nickel-based alloys at cutting speeds of 200–400m/min:

IW7—Whisker-reinforced ceramic grade, provides high hardness with excellent toughness used for roughing and semi-finishing continues operations at 8-10 times faster cutting speeds when compared with carbide grades.

IS25—Reinforced SiAlON composite grade, Excellent for machining Ni based high temperature alloys at continuous and light interrupted applications.

IS35—Reinforced SiAlON composite grade, Excellent for machining Ni based high temperature alloys at light & heavy interrupted applications.

A series of carbide grades was developed specifically to create tools for machining nickel-based and titanium alloys:

IC806—A hard submicron substrate combined with a thin TiAlN PVD coating. The unique coating procedure which involves a special post coating treatment creates a thinner and smoother coating layer providing the insert with the best characteristics suitable for machining nickel-based and titanium alloys.

IC804— Same TiAlN PVD coating on a harder submicron substrate designed especially for machining Ni based alloys used in newly designed jet engine parts that feature very high hardness (40-47 HRC).

IC20—An uncoated carbide grade which is highly recommended for machining aluminum and titanium. IC20 provides very high performance and is mostly used for continuous cut applications.

High Pressure Coolant Tools

Image Source: Iscar

Although high pressure coolant features have been in existence for a long time in the metal removal world. Today high pressure coolant tools play an increasingly significant role in the machining process, facilitating enhanced productivity and chip control especially for hard to machine materials such as titanium and nickel-based alloys. Incorporating high pressure is the key to directing coolant to exactly where it is needed in order to flush the chips away from the cut.

Iscar was one of the first cutting tool producers to respond to market needs by developing and manufacturing tools for the optimal use of high pressure coolant in lowering high temperatures and regulating chip flow, including Jetcut custom high-pressure coolant tools.

While the aerospace parts OEM/PMA sector is under constant pressure to keep costs down, the quality and life expectancy of the parts produced cannot be compromised—and this represents an enormous challenge for all involved.  Iscar’s enhanced cutting tools allow jet engine manufacturers to utilise the ideal materials for the production of high quality parts, with minimum wastage and maximum efficiency.

Iscar: High Speed Spindle

Iscar: High Speed Spindle

Iscar has developed the SpinJet, a coolant driven high-speed spindle. The range has been specifically
designed for use with small diameter tools on low rpm machine tools and is suitable for semi-finish and finish machining applications such as milling, drilling and grinding.

The system utilises the machine tool’s existing coolant supply, driven by a high pressure pump (minimum 20 bars) as an effective energy source to rotate an integral turbine at speeds up to 40,000 rpm.

The device is not intended to replace a machine’s spindle, but rather to upgrade existing machines. The system is said to increase productivity by up to 65 percent when compared to machining with a machine’s existing low rpm spindle.

Achieving Sustainability In Manufacturing

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The hype of the manufacturing world in recent years is centred on sustainability—of practices, of technology or of waste disposal—for a better future. But what exactly does ‘sustainable manufacturing’ mean, and how can a manufacturer achieve or engage in it? By Michelle Cheong

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Where The Cut Starts And Ends

Where The Cut Starts And Ends

APMEN was invited to the Iscar customer seminar in Tefen, Israel to check out the latest products and innovations and have a chat with Jacob Harpaz, CEO of Iscar and President of the IMC Group. Syed Shah reports from Israel.

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Getting Automotive-ated

Constantly changing factors such as unstable oil prices, ever more demanding environmental protection legislations and the evolution of more efficient technologies ensures a continually changing global automotive market place. These factors also increase the ongoing competition between carmakers and OEMs and dictate today’s automotive industry manufacturing trends. By Oleg Eliezer, Iscar’s automotive industry manager.

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Big Solutions For Miniature Parts

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The global medical manufacturing industry is one of the world’s fastest growing industrial sectors. It has accounted for more than 10 percent of the gross volume of metalworking activities recorded in 2015. Yair Selek, product manager of face grooving systems and miniature industry, Iscar, tells us more about machining medical parts.

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