Helmut Diebold GmbH & Co.

Size: px

Start display at page:

Download "Helmut Diebold GmbH & Co."

Rodger Pearson
5 years ago
Views:

1 Can tool holders be made with runout below 1 micron? If so, why and how? By: Hermann Diebold, CEO, Helmut Diebold Goldring-Tool Company. Since 1980, since I work in the tooling industry, I keep hearing the saying we try to cut below one micron". Of course, everyone would like to manufacture products with accuracy under one micron, but in the past this saying was rather a phrase than reality in the tool or machine tool industry. pockets became possible. Even today we are missing modern software to program CNC machines. The way we create CNC programs, I do still consider it that we are in the stone ages. But I m sure that industry 4.0 will bring out new technology to manipulate CNC controls. After the first implementation of CNC controls there were only small steps of improvements. With the advent of faster controls industry took the next step into faster machine movements or multi-axis work. But then the industry really took off. From one fair to the next, new and improved concepts came out. Now we have arrived in the state of high-speed machining and micromachining. New machine concepts with higher spindle speeds, better accuracy and stiffness are being presented. These technological changes require also better tool clamping systems and cutting tools. Cutters made from improved materials, new cutter geometries and coatings made highperformance cutting possible. How small 1 micron really is Now, at Diebold we arrived exactly where we wanted to be for decades, namely to manufacture tool holders and spindles with concentricity of less than 1 micron. Some significant changes were necessary, both in mechanical engineering, machining equipment and we needed a climate controlled facility. And last but not least a change in measuring technology. From science fiction movies, we all know what the human imagination can think of. But only engineering and technology help to realize such ideas. One example from the world of milling is the change in spindle speed. In the 80's, max. milling speed was at 4500 r.p.m. For many years there was no significant progress. When the first CNC controls came out, simple milling of The tool holding systems changed from steep taper to HSK tapers. The HSK taper is well accepted worldwide. It maybe not be the most perfect technical solution, but at least it was implemented as a standard and made it usable for everyone worldwide. HSK tapers must be manufactured very precisely. HSK tapers are oversized and must be deformed by the tool retention force so that the tool will be pulled to face contact with the spindle nose. If the spindle taper and tool taper tolerance are at the high end of the ISO tolerance, the clamping force of the holder face against the spindle will be reduced by 35% causing vibration, wear of the taper and instable cutting processes. At least in high-speed machining poor surface quality and lower tool life is the result. In the long range the spindle taper and the tool taper will be damaged caused by this vibration, and the bearings of the spindle will wear out.

But if all tolerances of spindle and holder taper are accurate, the repeatability of the HSK interface may be less than 1 micron, a great advance from which one

Especially shrink fit chucks made their way into high tech manufacturing. ThermoGrip shrink units allow to fit and remove shrink fit tools easily.

We know since decades that collet chucks of different versions have quite good concentricity, but not good enough for high precision cutting.

concentricity <1micron. The special made ER collets have runout less than 2 micron.

2 But if all tolerances of spindle and holder taper are accurate, the repeatability of the HSK interface may be less than 1 micron, a great advance from which one could previously only dream of. One-piece tool holders can now be manufactured with a concentricity of 3 micron and they are inexpensive. Especially shrink fit chucks made their way into high tech manufacturing. ThermoGrip shrink units allow to fit and remove shrink fit tools easily. But for very small tools with diameter below 3 mm, shrink fit is difficult. We know since decades that collet chucks of different versions have quite good concentricity, but not good enough for high precision cutting. HSK taper unclamped-clamped position Diebold now manufactures a specially crafted ER collet chuck system named CentroGrip where the collet chuck body has concentricity <1micron. The special made ER collets have runout less than 2 micron. The clamping nut is made so that the concentricity of the whole system does not exceed 3 micron measured at extension of 3xd HSK Tool Holders CentroGrip Collet Chucks High frequency spindle What influence do holding forces, concentricity and vibration damping mean to the lifetime of the tools? High-precision clamping devices can duplicate the life of your expensive cutting tools. These

collet chucks are only marginally more expensive than conventional collet chucks and often return on invest is there after 4-5 tool changes.

If this damping behavior is combined with excellent concentricity, they fit perfect for high-speed machining or micro production. DIEBOLD CentroGrip -Collet chucks and collets are the right product.

Selection of the right materials and the elaborate hardening process make it possible to reach new quality levels with runout of 1 micron.

3 collet chucks are only marginally more expensive than conventional collet chucks and often return on invest is there after 4-5 tool changes. CentroGrip Collet Chuck Collet Chucks have superb damping characteristics. If this damping behavior is combined with excellent concentricity, they fit perfect for high-speed machining or micro production. DIEBOLD CentroGrip -Collet chucks and collets are the right product. To reach the high runout demands in our production, high-quality production and measuring equipment is required. Selection of the right materials and the elaborate hardening process make it possible to reach new quality levels with runout of 1 micron. CentroGrip is the perfect clamping device for users who wish to improve their cutting results. There are already several systems on the market that promise this concentricity, but end users may experience the difference at their work piece where they compare systems of different manufacturers. What is necessary in manufacturing when such accuracy is required? First of all manufacturing in a perfect climatecontrolled environment is necessary. Diebold has a fully climate controlled facility since But constant temperatures in the building are not enough when chasing low tolerances. Our energy-saving air-condition system additionally provides temperature control of the coolant of all machines. If only the air temperature of the production halls is constant at 21 degrees C it is insufficient to reach work piece tolerances under 1micron. At Diebold we can compare what accuracy level can be reached in the old buildings compared to the perfectly temperature controlled new facility. ER-collet

Diebold manufactures taper gauges and especially the masters for measuring of spindle tapers and tool holder tapers. Basically all tool holder manufacturers worldwide are using Diebold`s taper gauges.

But after that we had to invest in new machine technology capable to guarantee runout of less than 1micron.

At Diebold that did not work at the first attempt, but based on decades of experience in producing high-precision clamping tools and high-precision spindles, the base was there to go for the future.

4 Diebold manufactures taper gauges and especially the masters for measuring of spindle tapers and tool holder tapers. Basically all tool holder manufacturers worldwide are using Diebold`s taper gauges. Diebold factory with climate controlled extension Excellent temperature conditions are the base for high precision manufacturing. But after that we had to invest in new machine technology capable to guarantee runout of less than 1micron. Today excellent grinders are available, but the trick is to develop the grinding process and the clamping devices so that in serial production this high concentricity level may be achieved. At Diebold that did not work at the first attempt, but based on decades of experience in producing high-precision clamping tools and high-precision spindles, the base was there to go for the future. We had to develop new test equipment and measuring devices to make sure that runout under 1 micron can be documented. HSK Master Taper We have installed professional techniques that enable us to calibrate our measuring instruments for production or inspection so that we are sure that a measured micron really is a micron. Traceability to the standards of the DKD (German Calibration Service) have been installed. For the certification of master tapers we invested in the latest measuring technology, including a CMM room of class 2 with temperature accuracy +/- 0.5 Kelvin and monitored humidity control. HSK Master Gauge

Hermann Diebold, CEO CMM Our electronic runout test equipment works with a resolution range of 0.

Runout test <1micron To measure high-precision collet chucks more than one inspection method is required.

This measurement technique in conjunction with top-modern manufacturing methods makes it possible to reach new

5 Hermann Diebold, CEO CMM Our electronic runout test equipment works with a resolution range of mm, before we were working in the range of 1-5 micron. Runout test <1micron To measure high-precision collet chucks more than one inspection method is required. Three different verification methods are used at Diebold to ensure the desired concentricity. This measurement technique in conjunction with top-modern manufacturing methods makes it possible to reach new quality levels. But it is only possible when it s done by highly skilled people. More than 70% of our employees have gone through the famous German apprenticeship system at Diebold. And exactly this skill of my staff I am most proud of.

What to do when the HSK interface between spindle and tool does not work?

What to do when the HSK interface between spindle and tool does not work? HSK tapers are over-determined and must be deformed by the clamping force so the tool will be pulled up to face contact. If the