The quality requirements for, in particular, components used by the automotive industry and provided by its sub-contractors are getting ever more stringent. The demand for tighter tolerances is coupled with that for greater efficiency. To fulfil these demands EMAG increasingly rely on complete-machining of components in a single setup. The application of different technologies – such as turning + grinding, for example – leads to a consolidation of the process stream, with all its attendant advantages for the user: less capital outlay and lower unit production costs, shorter throughput times, higher workpiece quality, greater process integrity and a reduction in floor space requirements.
Complete-machining of chucked components with the help of process combinations
17.07.2008 - Oliver Hagenlocher
Process integration offers rationalisation potential.
The process combination of hard turning + grinding brings gains in component quality and flexibility. But process combinations can also be used to great effect in reducing cycle times. When the complete hard fine-machining process is carried out on a single machine, throughput, transport and interim storage times are all significantly shorter. Further advantages accrue as time and effort spent on setting the machine are also reduced.
An excellent example of a combination machine for the manufacture of chucked components is the VSC platform from EMAG REINECKER. The VSC DS is a highly flexible machine. It can be used as a fully-fledged grinder as well as a fully-fledged turning machine; and the pick-up principle fulfils all the demands for a good chip clearance. With the machine axes doing the work, the VSC is quick and easy to load. Equipped with turret, Y-axis, B-axis and stationary grinding spindles the machine covers a wide range of applications that require turning, drilling, milling and grinding work. The VSC DS series is specially designed for the process-capable, cost-effective precision machining of medium and large batches of components. Typical workpieces machined on the VSC DS are gearwheels, sprockets, sliding sleeves, CVT components, link pins, con-rods, rocker arms, bearing races and piston rings. In each case, the machining process chosen is the optimal and most economical one for the workpiece and its inherent quality requirements. The advantage for the customer is that he has the flexibility to select the best possible technology for each job.
The advantages of the VSC DS series
- Vertical hard turning and finish-grinding in a single setup, on a single machine.
- All workpiece sections that can be turned with the required process reliability are hard finish-turned and only ground (after hard pre-turning) where component quality and process reliability demand.
- A better quality of component and higher productivity levels, as the workpiece is machined in a single setup, whereby the hard turning process leaves an allowance of just a few micrometres to be ground away in the subsequent operation.
- The grinding operation has to remove little stock. This subjects the grinding wheel to considerably less wear, reduces the frequency of dressing operations and offers considerable advantages in cycle times.
- As the grinding operation has to remove only a small amount of material, the grinding wheel specification can be chosen to reflect the desired finish-machining quality. This allows for surface finishes in the range of Rz < 1.2 µm to be achieved with great process reliability.
- Back faces are difficult to grind as they are not easy to reach with grinding wheels. This problem can be solved by employing hard turning operations.
The VSC DS series – developed for combination machining
An important requirement for combination machines is the unhindered flow of hard turning chips and grinding residue. The vertical work spindle and arrangement of the tools below the workpiece offer the best possible chip flow conditions.
All machine modules are mechanically exceptionally sturdy and particularly vibration resistant in their design. This is achieved with a machine base in MINERALIT® polymer granite – a material with great damping effect – and with the design of the work spindle. The latter has been integrated into a very sturdy quill unit that utilises a high-precision hydrostatic guideway to carry out its movement in Z – a design principle that also has an excellent damping effect.
The tooling systems, firmly embedded in the machine base, form a stable basis for demanding turning and grinding work. This is an important precondition for time-saving hard turning operations and for the excellent surface finishes that the hard finish-turning or grinding operations are asked to produce.
Moreover, the number and design of the fixed tooling systems can be varied to suit machining requirements. The whole machine is a thermo-stable entity, as work spindle, grinding spindles, turrets and machine base are all fluid-cooled. The operating temperature is quickly reached and kept within tight limits of the ambient temperature by a powerful cooling unit.
Like all machines of the EMAG VSC series, the VSC DS uses the pick-up principle to load itself. This disposes of the need for expensive, space-devouring gantry loaders or other loading devices that involve time-consuming resetting.
Quality control is already integrated
The VSC DS series is ideally suited for complex manufacturing processes. Whether large volumes of chips need to be removed in turning and milling operations or grinding is the order of the day – the VSC series offers the possibility to apply almost any metal cutting technology going. Depending on machining requirements, the VSC DS can be equipped with turning, milling, drilling, grinding, even honing and hardening modules, and also with combinations of them. In fact, the machines can be equipped with the technologies that best suit the individual requirement. The advantages are obvious: machining in a single setup, and with it the total elimination of re-chucking errors. Measuring cycles can also be integrated, offering the inclusion of quality control procedures for the whole process. The measuring probe is located between machining area and pick-up station, where it is optimally protected. As the workpiece remains clamped during the measuring process, interim measurements can also be taken.
REINECKER, KARSTENS, KOPP and NAXOS-UNION are the technological centres of excellence for grinding in the EMAG Group. For many decades now, REINECKER has been the specialist in combination machining and the precision grinding of chucked components.
VSC DS at a glance:
- Combined vertical pick-up turning and grinding centers
- Process-capable, low-cost, precision machining of medium and large batches of chucked components
- Hard turning, scroll-free turning and grinding on a single machine
- Complete-machining in a single setup
► better workpiece quality and increased productivity rates
- Greater life expectancy of turning, grinding and dressing tools
► minimization of tooling costs
- Little grinding sludge
► minimization of waste disposal costs
- Considerable reduction in the grinding allowance
► makes dry machining possible