Innovations within traditional ISO turning technology just as important as high tech alternatives. Cost reduction is among other things possible by adapting the tools and reducing the cutting data with the result of longer tool lives. In view of the small proportion of the total cost that tooling costs account for, the increase in the tool life would however have to be very great to have an appreciable effect on the total cost. The situation is different for the cutting data: a nominal increase of 20% already results reeds in a substantial reduction in the production costs (for example 10 to 15%) and also in a clear increase in productivity. If however we considerably increase the cutting speed, the tool life falls and so we need more tools for the same number of products to be finished. In order to reconcile the conflicting interests of buyer (buying budget) and production manager (productivity) with each other, the thing is then to develop higher grade tools and cutting materials. As many lectures, seminars and specialist journals pay quite a lot of attention to advanced techniques, such as turning materials of high hardness, ultraprecision turning, dry and high-speed turning, it looks as though developments within traditional ISO turning techniques are at a standstill. Nothing could be further from the truth. Due to a technique like multidirectional turning for example often more spectacular productivity improvements and cost reductions can be achieved with the non-conventional alternatives, often with much lower starting costs. At the same time it seems that in the development of new carbide grades the boundary between ISO turning and for example precision turning of hard materials among others is becoming blurred. With new carbide grades, such as TP1000 and TP2000, with ISO turning we are back a step closer to solving the traditional dilemma: Machining tools are vital but they cost so much money. In the engineering industry it is more than ever all about increasing productivity and reducing costs. Productivity is the number of correctly finished products that are manufactured in a given time with the production facilities available. The total cost to achieve this is the sum of among other things the material costs, tooling costs, costs for the machine, wages cost plus overheads for cooling, safety, infrastructure etc. If we limit ourselves to the tools, then quality improvement and higher cutting data offer opportunities for increasing productivity. Figure 1 : TP1000 and TP2000 form the basis of the second optimisation wave (cost reduction and productivity increase) in ISO turning. Optimisation rests on three pillars: a good tool, correct cutting data and a good understanding of the machining process. The new generation of carbide grades, such as for example Seco Tools TP1000 and TP2000, in that respect play a leading role. It is now possible both to increase the cutting data and to extend the tool life. Comparative practical tests with respect to existing situations have shown that due to the use of TP1000 and TP2000 productivity is increased by at least 30% and at the same time costs reduced by at least 20%.
Traditional turning In spite of the arrival of new techniques such as hard turning (sometimes also called PCBN turning because the most optimum cutting material is usually PCBN), dry turning (or turning with minimum lubrication) and highspeed turning, the turning technology in most engineering companies can still be termed traditional. Where for example in milling, experiments are increasingly carried out with high(er) speed methods, this is only being done in dribs and drabs in turning. That is partly because in socalled ISO turning developments have certainly not stood still. The advantage of these new developments is that a real productivity increase and cost reduction can quickly be achieved without high starting costs (no new machines and/or installations are necessary). We shall briefly explain two examples of this Secolor insert selection system Figure 2 : The Secolor system helps maintain a clear view of which insert is the best choice in a particular situation. All the relevant (ISO and Secolor) information for correct use is given on the Seco insert boxes For one of these we go back to the start of the nineties, when Seco developed the Secolor concept to bring order into the enormous supply of carbide inserts, as a result of which the user could hardly see the wood for the trees any longer. Since then this concept has been further deepened and also imitated by other tool producers. The Secolor classification model formed the answer to the ambiguity of the existing ISO standard when this involved establishing the possible applications of carbide and chipgroove geometry. The choice of an insert is determined by the use situation. In the case of large series the technically most suitable insert is chosen. Test series determine which insert and cutting data are most satisfactory. An important criterion is also the tool life of the insert. The result of this approach may be that one keeps a large number of inserts in stock the most suitable for every situation. If on the other hand many small series are involved, one will try to cover the whole range of use with a limited selection of inserts. There is often no time for trial series. Furthermore one has to accept that the technologically best insert cannot be used for every application. Here are the criteria then: stock and chip control. Using the Secolor system for a given turning operation one can easily, systematically and quickly select a suitable insert (optimum balance between technically good and yet with a wide application). This is done using a matrix where the three basic types of material (steel, stainless steel and cast iron) are set off against three machining conditions (finishing, medium turning work and rough turning work). For each of the nine basic applications thus defined a basic insert is then proposed. Then, in a second phase, this choice is further optimised, where both the carbide grade and the chipgroove geometry are taken into account. The possible inserts are according to the Secolor system actually indicated on the insert packaging. The insert boxes show the range of application (within the matrix consisting of nine fields) and the basic cutting data (the recommended cutting speed, feed and cutting depth). Multi Directional Turning A second example of the way in which within traditional turning major productivity improvements can be achieved is formed by so-called multi directional turning (MDT). The idea is simple: use one tool for all the turning operations involved: facing and longitudinal turning, internal and external turning, parting off, profile turning, copying, grooving and since recently even thread-turning as well. Inserts with such a universal function are subject to alternating stress, in all directions. This therefore involves a perfect connection of the insert with the holder. Seco has chosen the solution for this of a V-top clamp combined with a serrated insert contact surface. Figure 3: The Seco MDT clamp system is, due to the combination of V- shaped clamp face and a serrated contact surface, the most solid and accurate on the market. Seco MDT also stands for reliability. These guarantee a very precise positioning (accuracy) when changing the insert and maximum stability of the insert in the holder. Stability is a crucial factor among other things for safety, machining capacity, surface quality of the workpiece, avoiding vibration and repeat accuracy.
shallow grooving, for normal copy turning, for making grooves for lockrings, dynamic and static O-rings, etc. For special applications the Seco MDT range includes a number of inserts of specific shape and geometry. Finally of course one can choose different carbide grades. New carbide grades Figure 4 : Multi directional turning is an advantageous technique for small series of complex workpieces with many different diameters, narrowings and profiles. Multi directional turning particularly comes into its own for small to medium series of complex workpieces with many different diameters, grooves and profiles. Typical examples are shafts of gearboxes, crankshafts, camshafts, fittings etc. For this type of complex workpiece one MDT tool can replace a complete set of other tools, which results in a saving in machining costs. There is also a clear logistical benefit: the number of tools to be kept falls drastically. The Seco MDT system includes different basic types of toolholders and a wide choice of inserts: single- or doubleended; with and without chipgroove geometry; with different nose radii; with different geometries; made from different types of carbide; with different insert widths. Within the ISO turning field, MDT turning, certainly since the arrival of reliable systems such as Seco MDT, has won a place alongside the already long known ISO tools. Yet these ISO tools still continue to play a very important part, even though this is only because they still represent the largest cost item within the tooling budget. This is why in the present trend towards further cost control - developments in that field are so important. It is particularly important for these tools to achieve both productivity increase and cost control. Figure 5: The Seco MDT range now also includes inserts for thread-turning. Seco MDT can therefore really carry out every turning operation now. The most economic is of course a double-ended insert (cutting edges on both sides of the insert). If because of the application one chooses a clearance over the full insert length, then the single-ended insert is preferable. It is also important to choose a narrow insert when machining with small cutting depths and low feed rates. With large cutting depths and high feed rates a wide insert is recommended. The required geometry follows directly from the application. There are for example separate geometries for finish turning and deep grooving, for normal turning and Figure 6: A chipgroove diagram gives a schematic view of the different chipgroove geometries depending on the possible applications and feed rates. The choice of a good geometry and the right feed rate forms the basis of any optimisation procedure. The chipgroove geometries are of course the first element. If during turning the chip formation and control are not the optimum, we can forget everything else. One element for increasing productivity without a proportionate cost increase is turning with high feed rates. Basic rule one to achieve optimum (productive and cheap) turning is still to machine at the highest possible feed rate. And of course to ensure that the chipgroove geometry is adapted to this. A process that has long had a restrictive effect on this basic rule was finishing. But since there have been inserts with wiper geometries the above basic rule can also be applied there.
Figure 7: With a wiper point geometry, high feed rates and good surface roughnesses can be combined. Hence during finishing one can also optimise for better productivity and lower costs. machining tests were carried out to ensure the performance of these new grades. To achieve a good surface roughness relatively low feed rates must be used. Since turning inserts have become available with wiper geometries, this no longer has to be. It is now possible to choose high to very high feed rates for finishing turning and still achieve a good surface roughness. Another possibility with these wiper geometries is still to keep the feed rates low, but then to achieve a surface roughness that is comparable with grinding. The other element is the carbide grade. If we ensure that the chip formation is carried out in a good and reliable way we can use the carbide grade (and the cutting speed) as a foundation for optimisation. Figure 9: An example of the new generation of CVD coatings. This is the basic structure of the new coatings that are used for TP1000 and TP2000. Characteristic of the new carbide grades is that the substrate is composed of a hard inner layer and a very tough strong outer layer; as a result both an excellent resistance to plastic deformation and a good cutting edge toughness is achieved. In addition Seco has developed new revolutionary coatings to fully utilise the possibilities of this substrate. Figure 8: The Seco carbide grades for turning applications (including the new TP1000 and TP2000) according to the new ISO proposal for areas of application. The table also shows the PCBN qualities. It is clear that the area of application of PCBN lies in turning hard materials. Within the Seco range the recent development of the new generation of carbide grades TP1000 and TP2000 represents an extremely important step. The insert range based on this covers the majority of the applications in the ISO P-field. The area of application is considerably greater than that of other carbide grades, due to the much higher wear resistance (= higher cutting speed) and the increased toughness (= higher feed rate) of the cutting edge. The new types are suitable for a wide range of steel and cast iron types. TP1000 and TP2000 were developed as a unique combination of wear resistance and toughness. Extensive material testing, computer simulations, lab tests and Figure 10: The basis areas of application for TP1000 and TP2000 in accordance with ISO. The optimised coating structure is composed of three functional parts and a number of intermediate layers. The inner base layer (titanium carbonitride) is responsible for a perfect adhesion and the basic cutting edge strength. The middle basic layer of aluminium oxide acts as an effective thermal barrier to permit higher cutting speeds and the outer titanium carbonitride layer together with the titanium nitride top layer guarantee excellent resistance among other things to crater and flank wear.
Figure 11: The total Secolor concept (ISO basis, carbide grade, chipgroove geometry and cutting data) is set out in a single figure. The universal applicability of TP2000 is clearly shown, as is the possibility of increasing the cutting rates at the same time. Hence TP2000 is the first carbide grade that offers the possibility of technically optimum turning with a limited number of inserts. TP1000, the carbide grade with the harder substrate, has a better resistance to higher temperatures and shows less plastic deformation compared with TP2000 when machining at high cutting speed. TP1000 also has a better resistance to wear; with stable cutting data the productivity of the TP1000 is simply excellent. TP1000 is highly suitable for applications where optimisation is advantageous, necessary or important. As a result TP1000 is the better choice if the series to be finished is rather larger. TP1000 is also an advantageous carbide grade in a number of other applications such as for example highspeed turning, dry turning and hard turning. Figure 12: The advantages of TP1000 and TP2000 can easily be shown. Replace existing carbide grades by TP1000 and TP2000, increase the cutting speed and possibly the feed rate, and profit directly from cost reduction and productivity increase, all without high starting costs. TP2000 on the other hand has a better cutting edge toughness and performs better in applications where the cutting data may lead to chipping of the cutting edge. The better toughness can also be used to increase the safety in case of unpredictable cutting data. With TP2000 the productivity and reliability can be brought to a new level. The toughness of TP2000 is comparable with that of many carbide grades for the ISO P30 field of application. At the same time the hardness and the temperature resistance is comparable with a grade for the ISO P20 field of application. This makes TP2000 the reliable choice for turning applications (if required with a higher cutting speed) in a wide range of grades of steel and steel alloys. Figure 13: The figures on the left show wear in TP1000 while the figures on the right show the wear for TP2000, used under the same conditions. The top row of figures show that TP1000 has a better heat resistance and resistance to plastic deformation when used at higher cutting rates. The middle figures show the wear rates when the inserts are used in unfavourable conditions. The better cutting edge toughness of TP2000 is clearly visible. For this reason TP2000 is also the better choice if the machining conditions are unfavourable and unpredictable. At the bottom the wear under favourable conditions is shown. The better wear resistance of TP1000 can be clearly seen here. TP1000 is therefore the basic choice in unfavourable conditions and if productivity is important. To sum up: if finishing time at the user s is a prime concern and the turning conditions are favourable, TP1000 is the first choice. High cutting rates are no problem. TP1000 is the basic choice for optimisation. TP2000 is specially intended as a basic choice for most applications where reliability is a prime concern. Due to wear resistance in combination with the high toughness TP2000 is a carbide grade that is reliable in a wide range of turning applications, even if required with high cutting rates. Know-how, information and experience This article briefly explains the possibilities of new techniques, such as for example MDT turning, and the recent developments in ISO turning, for example the new carbide grades TP1000 and TP2000. The responsibility for the practical achievement of the advantages offered lies on the shoulders of the production people. They must however have the necessary knowhow, information and interest to convert the potential possibilities of tools into real advantages. The relation with and the role of the supplier in this cannot be sufficiently stressed. Seco is one of the only tool producers that approaches
the aspect of know-how and information supply in a structural way. Each year thousands of people take part in the different activities in Seco Tools Technical Centres around the world. The information and know-how provided helps the tool users to achieve the objective of Productive and cheap machining. To determine the cutting data for TP1000 and TP2000 a software package is also available. This package is available as a download on the Seco Tools website, www.secotools.com. Seco Tools Machining Navigator is a full overview of the most recent information regarding the possibilities of modern tools and cutting materials. Decision Turning is a process that in recent years has been less in the spotlight than for example milling. However developments have not stood still and the productivity increases and cost savings that can be made are impressive. Figure 14: The possibilities of a modern turning insert are determined by the carbide grade (substrate and coating), the macrogeometry, the chipgroove geometry, the point geometry and the microgeometry (cutting edge geometry). On the one hand there are a number of changes in technology, of which hard turning will probably prove to be the most important, on the other hand there are a number of important changes in tool technology, of which the MDT tool technology is the most spectacular. But the great majority of turning operations, certainly in small series production, are still carried out with the traditional ISO tools. To make these tools and the corresponding cutting data profitable, to achieve an optimum turning process certainly deserves attention. After an initial big wave of optimisation in the mid eighties of the last century, the recently developed chipgroove and point geometries (e.g. the Seco Crossbill TM wiper point geometry) but certainly the new generation of carbide grades, such as the Seco TP1000 and TP2000, form the impetus for a second big wave of optimisation. More information regarding the techniques, tools, inserts and cutting materials discussed in this article is available from Seco Tools.
The new techniques: hard and fast The new techniques: dry Figure 15: It is really advantageous when different techniques can be combined. This example shows the combination of hard turning and multi-directional turning. Apart from the developments in ISO turning, as described in the article alongside, in the last ten years all sorts of innovative alternatives have also presented themselves. From a rather cynical point of view, in addition to great interest from the market, they also have in common cold feet about the actual application. Hard turning turning in workpiece material with hardness levels above 45 HRC is an advantageous alternative to grinding. Turning is a much more flexible machining method, cooling can be omitted, chip recycling is easier and productivity lies on a higher plane. In addition the machine, energy and tooling costs are lower than for grinding. For hard and precision turning cutting materials such as ceramics and increasingly often and better PCBN are being used. The new carbide grade TP1000 (see article) does however offer attractive prospects for hard and precision turning particularly for smaller series. Figure 16: Of all the new techniques dry turning is the easiest to use. It is enough to shut down with the cooling pump on the machine. To what extent dry turning can however be used not only depends on the tool used. Also other elements, such as machine, workpiece and operator must be looked at as a whole. When dry turning the cooling is completely omitted or turned down to a minimum (microdosage); this saves 15 to 20% of the total finishing costs per workpiece. The question whether dry machining can be used does not only depend on the tool available, but also on the material and the geometry of the workpiece, the actual process, the machine and the environmental factors, particularly the staff. For rough turning in hard materials with PCBN dry turning is in fact the only acceptable alternative. Also for dry turning TP1000 and TP2000 offer advantageous possibilities.