Mastering Ball Cutters with LaserControl NT

Measurement of ball cutters at up to 50 radius points

Blum-Novotest, the leading supplier of innovative and high-quality measuring and testing technology, will be presenting a new software option for its LaserControl NT series in Düsseldorf (hall 13, booth A70). With this software, ball cutter errors in shape can be compensated before and during the process steps in a very precise manner. Operators will profit from a considerable improvement in workpiece quality and a remark-able reduction in tool costs.

Bruno Riedter, the head of software development at Blum-Novotest, explains: "For a long time people thought the earth was round until it occurred to someone to actually check the measurements. It’s very similar when it comes to ball cutters. If standard spherical cutters are actually tested for their roundness, not all of them will meet the requirements that are today demanded especially in tool and mould making and the aerospace industry. As machine control, however, operate on the assumption of an optimal circularity, and the contact point of the cutting edges usually lie orthogonally to the workpiece surface, such an error in shape will have a direct effect on the machining result. Therefore many operators employ expensive tools with test certificates in order to eliminate this source of error.”

Today machine controls like the Heidenhain iTNC provide the possibility of lodging a compensation value table which defines angle-dependent delta values in order to determine divergences of the tool from its ideal circular shape. In this case the system uses the actual value of the radius which is defined by the current contact point between tool and workpiece. To be able to exactly determine the contact point, the NC programme is being generated with surface-normal blocks from the CAM system. In the surface-normal blocks the theoretical centre of the ball cutter, as well as the tool orientation, is configured in relation to the surface.

The missing link for the utilisation of the described control method is an applicable measurement of the ball cutter at different angles. Neither gauging the workpiece on the measuring machine, nor the classical external tool presetting, is a viable solution. After all, any setting errors, effects of speed and temperature or tool wear that occurs during the machining process, cannot be compensated with these methods.

Blum-Novotest has now developed measuring software for the LaserControl NT measuring system, which can identify up to 50 radii of an operating ball cutter under working speed. Via cue parameters the tool data for length and radius – e.g. the length up to the cone point or the circle centre – can be inscribed into the tool table.

In standard ball cutters, typical inaccuracies in shape lie within the range between 0,005 mm and 0,010 mm. The Blum system reduces these errors to a residual inaccuracy of less than 0,001 mm. The precise residual error can be identified by conducting a control measurement of a calibration tool with an ideal sphere.

The possibility of measuring these tools at up to 50 radius points provides numerous advantages. If the operator can master the measurement of the tool, this will save them expensive and time-consuming rework. This will make manufacturing more efficient and increase its quality. Moreover, it reduces tool costs, as tools can be used up to their wear limit without compromising workpiece precision. Thus, a preventive replacement with ‚fear allowance’ becomes redundant.

„Furthermore, thanks to the new software reworked tools can now also be applied in the high precision field. Any contingently suboptimal cutting geometry can be detected and compensated with the laser system. At the recent EUROMOLD exhibition, we presented the measuring software to the professional audience for the first time. There it was enthusiastically met with the interest of the visitors from the tool and mold making sectors,“ adds Bruno Riedter.


Editors´s notes:

Established in 1968 and based in Ravensburg, Blum-Novotest GmbH is one of the global leading manufacturers of high-quality measuring and test devices for the international machine tool, aerospace and automotive industry. Today, the family business employs more than 290 staff at twelve subsidiaries in Europe, the USA, China, Japan, Taiwan, Singapore, Korea and India. In co-operation with specially trained system integrators and regional sales representatives, the company’s distribution and service network offers comprehensive support for thousands of Blum systems used world-wide.



For further information:

Blum-Novotest GmbH
Kaufstrasse 14
88287 Grünkraut
Germany

Tel: + 49 (0) 751 6008-0
Fax: + 49 (0) 751 6008-156
E-Mail: vk@blum-novotest.com
Web: www.blum-novotest.com