Cutting Tools
State-of-the-art laser process measuring technology for precision machining
Demands for integrated production measuring technology
Finishing processes on grinding machines often demand exacting tolerances in relation to dimension, form and position accuracies, as well as highly accurate surface qualities. Often companies have empirical values available to fulfil these requirements. However, with small lot sizes in particular process evaluation on the machine is desirable, as intermediate measurement on external measuring machines and the resulting corrections prolong the processing time for part machining. These control measures would significantly increase process reliability and productivity. Solutions that can be flexibly used for a wide variety of workpieces are ideal and preferable.
Possibilities of process measuring technology in grinding processes
Production engineers have diverse measuring functions available for process evaluation, which are based on different principles of production measuring technology. The measurement of process forces such as grinding forces (Ft, Fn) or comparative grinding spindle currents, for example, provide an index for achieving the service life of tools or, equally important, they enable the determination of fluctuating allowances, which can influence process stability and compliance with required tolerances. In addition, tool costs can be reduced, as excessive dressing is prevented. Familiar acoustic touch sensors assist so-called contact detection in the grinding process to reduce grinding time, or monitor the true-to-profile dressing process with its envelope curve functions. Tactile measuring systems such as measurement and control systems for diameters or workpiece lengths, pneumatic systems or microsensors for longitudinal expansions of spindle systems also support increased process reliability. Other measuring functions can also be described here, such as the use of camera or laser systems for process monitoring. Laser measuring technology in particular opens up interesting fields of application.
Integration of laser measuring technology into STUDER universal cylindrical grinding machines
STUDER can draw on more than 10 years of experience in the use of machine-integrated laser measuring technology, which have been evaluated for trials in the measurement of grinding wheels or workpieces. Such fundamental studies have a tradition at STUDER, to ensure the company is prepared for future trends in production technology. This knowledge and experience has been used to respond to the current requirements. The systems used in other industries for tool monitoring have been further developed STUDER-specifically on the basis of the latest laser measuring technology, only recently available, for measuring workpieces on grinding machines.
The necessary measuring device (see U-profile in figure 4) is mounted mechanically, similarly to our measuring probes on our B-axes, which carry the relevant grinding spindle. In fact, this situation is not an unfamiliar one for the operators.
The size of this measuring device can be adapted to the workpiece diameter. The existing air nozzles for blowing off the workpiece during measurement and the newly developed dirt screens efficiently protect the laser optics from the cooling lubricant in the machine. In comparison to previous models, the laser unit manufacturer also uses an enhanced, more accurate laser optics. However, the most striking element from our point of view is the possibility of generating many thousands of measuring points for evaluation with the workpiece rotating. This significantly reduces measuring time. These features have been integrated into the STUDER-specific measuring cycles. The user is thus provided with a suitable method for non-contact measurement for the machining of precision workpieces.
It should also be mentioned that not only can different diameters be recorded with a laser measuring device, but precise control measurements can also be carried out on “interrupted” diameters, such as shafts with keyways or longitudinal grooves and toothed gears in the diameter range (see Figure 2). The setup and resetting of previously used tactile in-process gauging devices is omitted, and efficiency rises dramatic.
Figure 1: Example of universal use.
Figure 2: Measuring record for a workpiece.
The measuring cycle can be selected as desired after each machining operation or at the end of the grinding process. The STUDER software logs (see Figure 3) the measured values per diameter after each measuring cycle. This process enables the operator to ascertain the quality of the ground component at a glance.
Example of application of laser measuring technology for cutting tools
A very efficient example of the use of an integrated measuring strategy is the complex machining of small batches of tools with PCD cutting edges. Often the question here is who is machining who, the diamond grinding wheel the tool, or vice-versa. The so-called “closed loop process” with tactile measuring devices is often used for this purpose (Figure 3). The cutting edges are measured, ground, measured, etc. in several iteration stages. Diameter tolerances of +/- 1.5 micrometer are achieved with this measure, which is a very good result. An increasing demand for non-contact measurement has developed for these applications, as the PCD cutting edges sometimes react sensitively to tactile measurement.
This demand for non-contact measurement of tools in this tolerance range, which have cutting edges or guide rails, can now be met with the integrated laser measuring technology described here (Figure 4). Typical measuring tasks which are required in this sector are, for example:
Measurement of a tool with cutting edges, where the smallest and largest cutting edge diameter are determined in a measuring plane.
Measurement in two different planes of the cutting tool, i.e. in different planes of the measuring cylinder generated by rotation, gives the dimension of the desired taper on cutting tools, which can now be output.
Depending on the measuring differences between the diameter of cutting edges and guide rails of a cutting tool in the same measuring plane, the laser optics can determine this diameter even with the workpiece rotating. This will be the case for most tools and will have a positive effect on measuring time reduction.
STUDER measuring cycles can help anyone who wants to know before machining and with the tool to be ground clamped, how large the runout is from the tool shaft to the cutting edge diameter at the end of the tool.
Figure 3: Tactile measurement of cutting tools.
Figure 4: Non-contact measurement of precision tools with laser measuring technology.
Cutting narrow incisions with ultra-high precision in high density materials using waterjet technology requires a specific waterjet cutting process: the Fine Abrasive Waterjet process (FAWJ). The first FAWJ cutting head was developed by Water Jet Sweden in 2008.
Fine Abrasive Waterjet bridges the gap
Waterjet cutting is a common method for processing parts in high density materials such as aluminum, stainless steel, titanium and carbon composites. The FAWJ cutting process bridges the gap between micro laser and EDM cutting and brings water jet cutting into the field of micro part processing.
To enable such levels of precision you need two things: (1) a cutting head and cutting process for FAWJ cutting, and (2) a machine built for extreme accuracy. The NCM 10 Micro from Water Jet Sweden fulfils both of those requirements.
FAWJ cutting process for 0.2 mm incisions
The first micro waterjet cutting head was developed by Water Jet Sweden in 2008. It is a high precision cutting tool producing one of the most precise abrasive water jets in the world. The unique cutting head enables an abrasive jet diameter down to 0.2 mm. The FAWJ cutting process requires very fine abrasives of 230-240 mesh and a special CNC controlled dosage abrasive feeder.
Machine table designed for ± 0.008 accuracy
To reach the levels of accuracy required in micro part manufacturing, the NCM 10 water jet has a number of unique design features to create a rigid table that withstands temperature fluctuations:
Mineral Casting Bearlit table frame – a table frame made of a composite material with exceptional stiffness that withstands vibrations and temperature fluctuations. The frame is integrated in the machine construction and motion system as a complete unit.
Rubber suspended stainless steel water catcher – the free-standing catcher solution prevents vibrations and temperature variations from influencing the cutting process. Stainless steel makes it maintenance free.
Renishaw Invar Scale in X and Y – with a Renishaw Absolute Linear Encoder fitted in both X and Y axes you have a micrometer scale with an extremely low expansion coefficient and ultra-high resolution.
Prepared for any kind of fixtures
The palettized cutting table makes it easy to install fixtures and presses for different types of machining. Maximum table size is 1×1 m which covers most cutting applications. The cutting table is fixed into the table frame to enable ultra-high precision cutting.
“There are many suppliers who state that they offer micro cutting machines, but not many can offer a true micro part cutting tool with 0.2 mm incision combined with ± 0.008 accuracy,” says Tony Rydh, co-founder and CTO at Water Jet Sweden.
With a view to promote skills development and training, Sandvik Coromant has partnered with WorldSkills for the prestigious ‘Skills Olympics’ that will take place in Kazan, Russia on 22-27 August 2019. As a silver partner, Sandvik Coromant will support the “Production and engineering technologies” competition as well as leads the skills contest “Manufacturing team challenge”.
WorldSkills is the global hub of skills that brings together influences, educators, industry, national governments and international organizations to facilitate salient research and provide the best global benchmark for vocational systems. The 45th WorldSkills competition will welcome more than 1,300 young professionals from 63 countries to compete in 56 different skills. The event will be held at the KAZAN EXPO International Exhibition Centre where up to 1,300 experts will evaluate the competitors’ work. The championship features skills within six categories: Information and Communication Technologies, Manufacturing and Engineering Technologies, Construction and Building Technologies, Social and Personal Services, Creative Arts and Fashion, Transportation and Logistics.
Metal-cutting skills are essential to the global economy and the future of the manufacturing industry. Sandvik Coromant is committed to help bridge the skills’ gap in the metal-cutting industry and reinforces its longstanding partnership with WorldSkills. The skills competition lead by Sandvik Coromant “Manufacturing team challenge” will require participants to create a concept for a production project, then develop and implement the project in a team. The key task of the competition is to assemble a team of specialists whose skills and knowledge will complement each other. In addition to personal talents, team members must make their own contribution to the overall work, clearly know their strengths and weaknesses, have the skills of interpersonal interaction, think beyond their competence.
“Along with other leading manufacturing companies, we have been supporting the WorldSkills movement on the local level for many years, because this is the only way to solve complex technological problems, train young professionals, and thus, contribute to the development of the industry as a whole. Teamwork is one of the core values that underpins Sandvik Coromant’s corporate culture around the world. Therefore, “Manufacturing team challenge” was an obvious choice for us,” says Sergey Shpak, Sales Cluster Manager Russia East.
The new Genesis® 160HCD Hobbing Machine for cylindrical gears integrates a newly developed process for chamfer cutting. Chamfer Hobbing ensures precise chamfers according to customer specification – with minimum tool cost.
The new Gear Hobbing Machine with Integrated Chamfer Hobbing is based on the extremely successful Genesis Machine Series with hundreds of installed machines globally. With the new Genesis 160HCD Gleason integrates a newly developed chamfer cutting process which is executed in parallel to gear hobbing. Chamfer Hobbing provides very short cycle times and minimum tool cost per workpiece. This new chamfering process ensures burr-free gear faces without the requirement of additional, subsequent deburring steps. Likewise, no measurable burrs are created on tooth flanks. The workpiece is ideally prepared for the subsequent hard finishing process.
Chamfer Hobbing is a very efficient process due to the ability to shift the chamfer hobs for maximum tool life. Compared to special deburring tools, chamfer hobs can be easily reconditioned, keeping tool cost under control and cost-per-piece at a minimum.
Ideally suited for the highly economical manufacture of cylindrical gears up to a module of 4 mm and an outside diameter of 160 mm, the 160HCD can be optionally extended to a workpiece diameter of 210 mm. Its updated part loading concept with a fast gantry system minimizes part handling and setup times thanks to its complete integration into the machine’s control software.
The new 160HCD is the latest addition to the Genesis Series of Hobbing Machines offering another method to chamfered gears precisly and economically: Whether as a dedicated hobbing machine, or integrated with different chamfering solutions available through Gleason – a Genesis Gear Hobbing Machine can satisfy a wide range of customer requirements.
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