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In recent years, we have noticed the following 2 trends in the tooling world: 1. On simple, less powerful machines, taper shank HSS drills are applied for the production of large holes (fig. 1.22). Because only inferior hole quantities are possible under these conditions, the tools are often bought from the cheapest supplier. Here, quality is not a priority. 2. On more powerful machines, however, tools with carbide indexable insers are preferred for the production of larger holes (fig. 1.23). They may only produce one hole, but they show less fatigue and are, therefore over-all, more economical. Fig. 1.22: Standard HSS taper shank drill. Fig. 1.23: Tooling system with carbide indexable inserts. Everything is relative. Even profitability. We set out with a decisive priority list convinced that more profitability and higher accuracy were possible. T 800 is our solution, a tooling system using 2 tool holder types GT 800 and RT 800 with PM HSS-E or carbide interchangeable inserts (fig. 1.24). The innovative concept of T 800 is the standardised interchangeable insert clamping, developed and patented by us (fig. 1.25). A clamping screw adjusts and positions our insert so accurately that there is just no equal when it comes to quality and the concentricity. We guarantee less than 0.02 mm deviation from concentricity with the carbide insert and less than 0.05 mm with the HSS insert. In order to change the insert, just release or tighten the clamping screw. The required torque settings are shown in fig. 1.25. Fig. 1.24: Tooling system T 800 - the complete economical alternative to carbide and HSS drills > Ø 16 mm. Fig. 1.25: Exact and accurate positioning of insert guarantees secure clamping in tool holder. Different design of indexing and clamping pocket eliminates incorrect installation into tool holder. The new design of the T 800 system has a major advantage which makes it superior to all other known interchangeable insert drills: The interchangeable insert possesses 2 complete, symmetrically positioned cutting lips and an optimised point grind preserving the complete drill geometry. This symmetrical design allows considerably higher feed rates than the asymmetrical insert designs of conventional insert drills. The inserts of conventional interchangeable inserted drills have 2 holes, through which the clamping screw clamps the insert. These clamping screws require, to some degree, parallel plane surfaces creating a helix angle of 0º, ideal for the machining of short-chipping materials. But what is the situation when machining steel? It's machinability is practically forced using chip breakers with more or less satisfactory chip formation and only minimum chip transportation. There is a vast improvement with T 800 inserts, the clamping principle provides a clear, uninterrupted helical flute form Each tool holder of the T 800 tooling system covers an insert diameter range of max. 5.0 mm (fig. 1.26). The tool holder driameter is at least 0.3 mm smaller than the smallest insert diameter of the corresponding diameter range. Consequence: many inserts, few tool holders. Fig. 1.26: The T 800 program, our recommendation for the economical solution of multiple, "large" tasks requiring very few tools. For tool holders without internal coolant ducts (type GT 800 WP), there is an additional tool holder available for each diameter range in order to reduce the space between the larger insert diameter and the smaller tool holder to a minimum. Consequently, even when machining long-chipping materials, chips are unable to enter this space and cause any damage to tool holder and hole. Hereby, we gain the following 3 advantages: I. Versatility, flexibility The 3 tool holder types (fig. 1.26) can be applied on practically all existing machine tools: The Morse taper GT 800 WP tool holder (without internal cooling) can be applied on pillar drilling machines, lathes, and also older milling machines. It is most likely that "only" PM HSS-E inserts will be used with this tool holder. The straight shank GT 800 WP to DIN 6535 HE (without internal cooling) is surely interesting for older machining centers, where the exchange between HSS inserts and carbide inserts probably occurs most frequently. RT 800 WP tool holders have been designed for internal cooling. Their range of application is primarily on modern machining centers and when high performance and accuracy are required. Consequently, carbide inserts with Ratio drill geometry are regularly applied. However, this does not imply HSS inserts don't occasionally fly the flag in this area. As already mentioned, all the inserts can be applied on all tool holders of the tooling system T 800. II. Increase in performance We have developed type GT 800 WP and it's TiN inserts with the aim of replacing conventional, cheap, HSS taper shank drills long-term. As a basis for comparison, however, we are using the more expensive TiN-coated, HSCO taper shank drills. Fig. 1.27: Performance comparison between cheap standard HSCO drills and interchangeable insert drills GT 800 WP. Workpiece: 86CrMoV7 (900 N/mm2), tool Ø = 18 mm, drilling depth ap = 1.7 x D, feed f = 0.2 mm/rev. We are not saying that the GT 800 WP achieves increases in performance when compared to the "oven fresh," solid, conventional taper shank drill, although we have experienced this (fig. 1.27). Our comparison is rather based on the assumption of equal performance. But after the first regrind - and this is the point - GT 800 WP performs consistently better! The reasons are obvious: HSCO drills are hardly ever recoated after the first regrind. The new, replacement inser of the GT 800 WP is logically always perfectly coated and the original geometry remains unchanged. A further point is the omission of regrinding costs. Solid drills are usually flogged to death. Temperatures can rise to well over 600ºC and the consequent loss of hardness is still noticeable after regrinding. On a higher scale, RT 800 WP aims at 2 further veterans, the indexable insert drill and the carbide tipped drill. For larger holes without high quality requirements, the indexable insert drill can not be beaten due to it's lower cost. However, when demands are greater, e.g. when hole quality IT 9 is required and the drilling depth exceeds 4 x D, RT 800 WP is the ideal solution. Although it may seem a little cannibalistic - the carbide tipped drill, RT 800 WP's 2nd comrade-in-arms, has some fundamental disadvantages. TO start with, the energy consumption and the environmentally unfriendly brazing must be mentioned. This technique causes stresses as 2 different materials (carbide tip, steel shank) with varying expansion coefficients have to be heated simultaneously and stresses generally always increase the risk of breakages. Furthermore: brazed carbide tipped drills can be reground up to a maximum of 2 to 3 times and the body is ready for the scrap heap after 4 applications. If the carbide tipped drill needs recoating after regrinding, there is also danger of the body losing hardness. III. Economy The RT 800 WP is considered a high performance tool (fig. 1.28). It comes into it's own when it's cheaper, conventional competitors can no longer master the technical hurdles. The GT 800 WP, however, is the economical alternative to uncoated taper shank HSS drills (fig. 1.29). If you have doubts, we are confident that we can convince you. Let's work it out between ourselves! We are not allowed to publicise details, competition comparisons in publications are not allowed in Germany. Initially, we recommend you to request the brochures T 800, RT 800 WP and GT 800 WP. Take advantage of your option to request these brochures online. Fig. 1.28: Performance comparison between type RT 800 WP and conventional indexable insert drill. Workpiece: 42CrMo4V (1000 N/mm2), Ø = 20 mm, drilling depth ap = 2 × D. Fig. 1.29: Cost comparison between TiN-coated standard HSCO drills and interchangeable insert drills GT800WP. The costs incluse purchase, storage, handling and regrinding costs. Workpiece: 42CrMo4V (1000 N/mm2, Ø = 20 mm, drilling depth ap = 4 × D, feed f = 0.25 mm/rev.

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