Fast, process-secure ways to complete very deep drilling

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Enough emulsion for lubrication in deep channels

There is no question that users require, above all, a secure, fast boring process that enables a product result within the specified tolerances. To meet this demand, Reinhard Durst, director of research and development in the business area of hard metal and reaming tools at Germany’s Komet Group, Besigheim, noted: “For this, it is important that the cuttings are short at break-off and come securely out of the bore; in addition, the deep drilling should, wherever possible, take place on processing centres without deep-boring lubricant, using only emulsion in the usual concentration.” Komet is said to be permanently involved in optimising the geometry, surface and coating of the deep-hole drill KUB Drillmax XL. Here, it is always a question of meeting the user specification as well as of very good chip control.

Of course, the responsibility for process-secure, stable and cost-effective deep drilling lies not only with the deep-drilling tool. Herbert Volk, drilling product manager at Iscar Germany, Ettlingen, explained the situation. “Influence is also exerted by the right combination of tool, machine and cooling lubricant. It is therefore extraordinarily important to employ the cooling lubricant correctly.” In deep boring, the cooling lubricant is said to play a decisive role in the lubrication of the tool, the cooling of the cutting tip and cutting removal. “In addition, it contributes to prolonging service lifetimes and also to improving the surface quality and drilling precision,” Volk added.

Overcoming heat and lubrication problems

Deep drilling has several facets. On the market, there is competition between different procedures, such as gun drilling, BTA and ejector deep-hole processes. The application area of gun borers generally covers bore diameters between 0.5 and 40mm – with inserts going beyond this. This enables, with special deep-hole boring machines, bore depths well in excess of 100 × D to be achieved. The disadvantage of these borers lies in the small feed rates attainable and in the very high cooling lubricant pressures that these borers require for chip removal. On processing centres, therefore, the preference is for using these solid carbide borers for bores of up to 30 × D, since they enable substantially shorter process times and simpler handling.

BTA and ejector deep borers are used mainly for bore diameters larger than 20mm on special deep-hole boring machines. These processes are indeed very cost-effective, but, because of the special cooling lubricant feed and chip removal, not universally applicable. Their use is therefore mostly limited to series components such as hydraulic cylinders.

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Technology

Fast, process-secure ways to complete very deep drilling

Enough emulsion for lubrication in deep channels

Overcoming heat and lubrication problems