non-cutting applications of diamond
Circular sawing machines
tools eg anvils for powder testing,
Fig 10 shows a saw blade with bonded
compact diamond teeth on it used in the wood industry. Although it is very difficult to machine these saw blades, they give excellent performance and long life on wood and they can be used on the normal machinery,which is mainly new and has good bearings. The quality of the surface of the cut is good, the corners do not break and, therefore, the wood industry is using polycrystalline compact diamond tools more and more.
Fig 11 Guilloching diamond, 120° cone
Fig 11 shows a so-called "guilloching diamond" with a 120 ° cone for putting a polished line on to thin
sheet metal such as lighters, ball point pens, powder and jewel boxes etc. The material is over-stressed and adapts to the shape and the surface quality Of the diamond cone. This is non-cutting machining like many other
Probing with poor access
Electron beam welding
Other applications
Use of a recently announced kit of three extension bars and a knuckle joint should ease probing in applications with poor access. The three extension bars, measuring 50, 100 and 200 mm, allow Renishaw probes to be mounted remote from the head. The knuckle joint, which is 80 mm long, allows the probe to-be tilted to any angle required in any position. All electrical connections are automatically made when the threaded connections are clamped. Renishaw Electrical Limited, Gloucester Street, Wotton-under-Edge, Gloucestershire GL12 7DN, UK
Corrigendum Design analysis of ecm toolings The authors, V.K.Jain and P.C.Pandey, would like to draw readers' attention to the following errors in their article in the October 1979 issue: Equation (1)
Electron beam welding has been used in the space, electronics and nuclear industries for over a decade. With the introduction of the EBW 300 series of complete machines ready for installation, the technique can now be used in any workshop. In electron beam welding, electrons are generated by a heated filament in an electron gun, accelerated by a high voltage towards the workpie~e situated in a vacuum chamber, and focussed on the weld line by electromagnetic coils. Deep, narrow, full penetration welds are produced at high speed. The main advantages claimed for the system include: no distortion and low heat shrinkage with minimum heat affected zone due to comparatively low heat inputs; no contamination or oxidisation as welding is performed in a vacuum; high speed (up to 4000 welds per day with an unskilled operator); and the ability to join dissimilar material and different thicknesses.
incorrect Ye=E EvK FPm
Fig 1, The caption: Fig 2, The caption: Fig 5, Y-axis scale:
outward flow inward flow I nterelectrode gap, mm x 10 -2 Fig 6, Y-axis scale: ~,-1 mm-1 Fig 7, Y-axis scale: current density, A/m x 10 Fig 8, Legend: t = 05 Fig 11", 12 The arrow associated with 'Feed' vertically downwards
PRECfSION ENGINEERfNG
correct Ye=E EvK FPmFF inward flow outward flow I nterelectrode gap mm x 10 -1 ~-1 mm-1 x 10 -1 current density, A/m 2 x 10 .4 t = 0s should be pointing
hardness measurement diamonds (some of them being transparent to measure the indentation of a Vickers hardness indenter through the axis from the rear end of the diamond), wear parts, lapp. ing stops, measuring and gauges, contact surfaces for automatic measuring machines, V-bearings, slides, optical prisms, semi-conducting diamonds for heat sinks as well as electrically semiconducting diamonds. Diamonds are used as tracer styli for surface measurement instruments, as diamond gramophone needles with high polish and gloss for optimum performance for drawing dies, and many other applications, including spade drills for drilling holes.
These advantages are said to permit simplification of design, reducing costs and, in some cases, electron beam welding is claimed to be the only way certain designs could be produced. It is suited to production of large quantities of small precision parts and for application in industries where conventional welding cannot be used. Electron Beam Welding Inc., 5850 Centinela Avenue, Los Angeles, Ca 90045, USA or TI Rockwell Ltd, Welsh Harp, Edgware Road, London NW2 7AA, UK
Diamond tooling According to De Beers, application of their Syndite synthesised polycrystalline diamond can give,considerable advantages over tungsten carbide tooling. Depending on theapplicatiort, tool life may be longer, machining time reduced, and overall costs cut. De Beers claim that comparative tests, involving the interrupted cutting of titanium alloy workpieces, reveal that Syndite outperforms tungsten carbide tools in terms of both life and workpiece finish. 145mm long, 65mm square blocks of Ti-6AI-4V, the titanium alloy most widely used by the aerospace industry, were turned on a Colchester Triumph 2000 lathe to a diameter of 63mm using first a multi-coated tungsten carbide tipped tool and then a 90 ° Syndite segment brazed to a steel shank. Using a feed rate of 0.05mm/rev and a workpiece speed of 56m/min, the carbide tool accomplished a single lmm deep cut over a length of 70mm before becom-
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