The “FAST 2025” study by the German Association of the Automotive Industry (VDA) describes a trend towards suppliers within the automotive value-added chain. At the same time, shorter product cycles and an increasing range of models will change the car market, according to the authors. But what these changes mean for the production processes of suppliers and subcontractors can be seen through the example of shaft machining. The production of various component versions must take place on a single system with ever greater flexibility and falling batch sizes. EMAG has unveiled the VTC 100 GT, a customized production solution to meet these requirements on a single machine capable of grinding with aluminum oxide or CBN and the complete final machining of the shaft.
The all-rounder for highly flexible shaft machining
23/02/2016 - Markus Isgro
The term “shaft machining” covers a wide range of different work. The machining process for gearbox shafts, rotor shafts, pump shafts, engine shafts, propeller shafts and balancing shafts can differ massively in certain circumstances. The strength of the component plays an important role, for example, whereas strong workpieces with a defined blade can be finish-machined by hard turning or using scroll-free turning technology, a final grinding process is the method of choice for thinner and more fragile parts. The required component quality, machining time (and therefore machining costs), tool costs and energy consumption differ depending on the process used. All these factors must be weighed against each other.
And it is at precisely this point that the challenge starts for project engineers: grinding or hard turning? Depending on the component, it may be necessary to invest in a single-technology machine for a specific process, however at the cost of the general flexibility of the production process suffering. “In practice, this is often unsatisfactory,” explains Dr. Guido Hegener, CEO of EMAG Maschinenfabrik. “In our experience, lots of users manufacture very different workpieces on a single machine. For this, it is of course important that the best technology is always used for the specific component and design detail.” With this in mind, the turning and grinding specialists at EMAG are pursuing a clear aim with their new VTC 100 GT shaft hard machining center: achieving maximum flexibility of final machining by integrating all hard processes in a single machine where the methods can be changed flexibly to suit the component. The important point for this is that the outstanding accessibility of the system ensures short tooling and retooling times. This means that there is (literally) nothing more in the way of achieving a highly economical process.
EMAG design for high speed, stable processes
The typical EMAG design including integrated automation is the main reason behind this highly variable concept – the VTC 100 GT has a disk-type turret which can hold up to eleven tools, with the twelfth tool place in the turret taken up by a loading gripper. Optionally, the machine can also be equipped with a live-tool turret with powered tools and a Y-axis. It also has a grinding wheel. First, the gripper takes the component from the raw parts storage facility and transports it into the clamping position where the turret tools can then complete turning operations, for example. Any grinding process takes place immediately afterwards in a second step. The downtimes between the operations are minimal and after machining, the workpiece is unloaded out of the machining areas by the loading gripper.
Efficient processes are also ensured by the VTC 100 GT’s motor with a workpiece spindle torque of 75 Nm and a 19,5 kW drive rating providing the machine plenty of power in reserve to carry out even difficult machining processes at high speed. The substantial benefit of the components’ vertical positioning is most clear when large volumes of chips are generated while turning the shaft. The vertical design ensures that the chips can fall freely out of the way, a major bonus for production reliability.
Quality comes standard
Quality is the main criterion for shaft machining as these components determine the efficiency, or lack thereof, of the engine and gearbox. High performance components in particular have cylindrical bearing seats, shoulders and grooves which require high precision machining. The strength of the EMAG approach is its component quality, particularly considering that workpieces are fully machined in a single clamping operation. “If different machines or separate clamping operations are used for a shaft, geometry errors can have a cumulative effect. Our approach drastically reduces this risk. All the processes take place in a single clamping operation,” explains Hegener.
At the same time, the flexibility of EMAG technology also pays dividends because the tool costs can be weighed up against each other when selecting the right production process. The choice of process has a massive effect on part costs. “If necessary, we can advise our customers and help to develop a low cost, efficient machining strategy,” adds Hegener.
A cost killer all the way down the line
Finally, the machine stands out due to its much lower investment and production costs compared to other solutions. For example, users save on automation and peripheral costs because the raw and finished parts storage facility and the tool gripper are integrated components. In addition, the compact vertical design requires an extremely small footprint in the factory hall, the system is only around 1.8 meters wide and 3.6 meters deep. “At last, we have combined all the benefits in this machine,” says Hegener finally. “This compact system is highly flexible and economical to use while also guaranteeing top component quality at all times. This technology ensures that the user is perfectly prepared for the flexible final machining of shafts.”
If you want to see the VTC 100 GT live, visit EMAG at GRINDTEC 2016 in Augsburg, Germany, in Hall 4 at Booth 4040.
Benefits of the VTC 100 GT:
- Complete: Grinding (aluminum oxide or CBN), hard turning and machining with driven tools with the Y-axis – all hard processes can be run in a single machine.
- Integrated: Loading and unloading with the turret on the integrated raw and finished parts storage facility.
- Precise: Complete machining ensures high component quality.
- Safe: Vertical design prevents chip clusters.
- Compact: Machine has a small footprint.
- Fast: The tailstock and steady rests can be moved under the control of the CNC unit, thus reducing tooling and retooling times.