Alstom Aerospace has implemented Blum laser tool measurement and setting technology as part of its focus on implementing high-tech manufacturing excellence in machining highly complex jet engine components.
In the competitive world of the global aerospace industry, Lincoln-based Alstom Aerospace maintains a healthy presence in the aerojet engine field by a combination of design flair and high-tech manufacturing excellence. An example of this approach is the adoption of Blum high-tech technology for laser tool setting on the Hermle 5-axis CNC machine tools machining highly-complex jet engine components.
One area of special expertise at the Lincoln plant is the production of extremely complex rotating components for what are known in the aerospace jet engine business as 'cold-end' assemblies.
These include not only impellers, blisks and turbine disks, but now also multi-stage rotating compressor elements of gas turbines, sometimes combined in single monolithic units as used in small to medium-sized aircraft and helicopters.
Such component parts are machined from exotic materials, including inconel and titanium alloys, which often require a mix of heavy roughing cuts and extremely-fine precision work all at a single setting.
The full five-axis capabilities of the Hermle machines installed are exploited to the limit for some of the metal cutting operations devised by the Alstom team.
Each machining centre uses a large number of different tools. One machine has had to be configured with no less than three 29-position tool carousels to meet the demands placed on it during long complicated machining routines. Yet calls for quick changeovers at other times when machining families of parts still have to be met.
Tool-setting times reduced to one sixth
When the first machine was introduced, tool pre-setting was carried out off the machine in the time-honoured fashion. However, when tasked with acquiring a second machine and after cutting trials on a Hermle VMC using an 87-position tool magazine, the need to save time and labour led to negotiations with Blum for the inclusion of its pioneering laser tool setting controls.
Not only did the adoption of the Blum laser system lead to tool-setting times being reduced to as little as one sixth of that needed previously, but perhaps more importantly, far higher levels of reliability and machine flexibility have been achieved.
Given that the facility is often run flat out on a 24/7 basis, the ability of the laser tool setting system to cope under such arduous conditions was paramount in its selection.
Another advantage of the Blum system was its ability to accurately check gauge length or tool standout in a machining environment where massive volumes of coolant were ever present creating misty conditions.
Important to note is that the nature of this work and the skills developed by Alstom to carry it out effectively, entails the use of large numbers of extremely small tools of very complex geometry. While the biggest end mill might be a full 0.5 inches in diameter, some tools can be as small as 0.036 inches diameter. The delicate operations involved call for constant reassurance with regard to tool breakage or damage, which the system handles as a matter of course.
Drills, end mills, reamers, taps and chamfers are just a few of the many and varied tools required at each set-up, often needing up to three trigger points per tool.
The Blum LaserControl system has the laser transmitter and receiver modules sited about 1m apart, externally to the machine, and the beam is pre-focused to whatever part of the machining envelope the user desires. This focused beam feature, unique to Blum, offers particularly high levels of precision.
On the first machine so fitted, this focal point was at the centre of the X-axis, thereby reducing spindle movement to a minimum to save time. With the transmitter/receiver units well out of the way, the unit proved to be totally effective.
A second laser system was ordered for the first Hermle machining centre installed at Lincoln. As this was a retrofit however, it was necessary for the laser transmitter/receiver units to be bolted on within the actual working environment of the machine and therefore would be a far more severe test of the system's capabilities.
Repeatability tolerance 0.00005”
In practice, reports Alstom Senior Manufacturing Engineer, Jon Count: “It has proven to be equally effective and we have never had cause to make any calls on Blum for service”. He says that, important as absolute accuracy may be, repeatability when carrying out tool checks is a prime requirement and is happy to find that levels lower than 0.00005" can be demonstrated.
Given the tough conditions applying within this machine's environment, an important operational aspect of the Blum optic system is that it is internally sealed against coolant and chips by a smart mechanical protection system with low-maintenance operation and minimum energy cost.
Given the success of the two systems, the latest Blum laser tool setting system was again specified when a third, even more advanced, Hermle C40U machining centre was ordered and this is now in full production.
Beating low labour-cost competition
Speaking about the company's success in having an installed base of more than 30,000 laser units in operation worldwide, Blum Novotest UK's general manager, Dave Mold, says he believes that, in combination with highly-automated machine tools, it has helped many European manufacturers to compete effectively with suppliers from low labour-cost countries.
In Alstom's application, says Mold, the software used to auto-correct for offsets was installed by Blum and has been found to work perfectly with the Heidenhain CNC machine controls concerned.
This was confirmed by Jon Count, who has found setting programs to be both straightforward, and quick to integrate into CNC programs.
He also likes to emphasise how the computerized process brings peace of mind, when set against the manual method, by ensuring the correct tool offset data are input eliminating the possibility of incorrect tool lengths being inadvertently entered by machine operators.
Based in Ravensburg, Germany, Blum is recognized worldwide as a developer of leading-edge measurement and testing technology with more than 35 years of experience as a supplier to the international machine-tools, aerospace and automotive industries.
Illuminated by the beam from the Blum LaserControl is a chamfering tool of Alstom’s own design. It serves to highlight the way Alstom has developed its own expertise for aero-jet engine component manufacture. Called a forward/back chamfering tool, it has four flutes (eight cutting edges in total, four on top and four underneath) and is used for creating 45 degree chamfers on both the top and back faces of holes by circular interpolation. The Blum LaserControl unit measures the gauge length of the tool at set radius values on both top and bottom edges. To set the length on the bottom edges the tool is driven into the beam in the Z- direction and, as shown in the illustration, the length to the top cutting edges are set in the Z+ direction.
The Blum LaserControl NT system ensures reliable tool monitoring even when a large volume of coolant is present.