The limitations of three-axis machining when producing complex moulds, tools and components have been well documented over the years, in particular the difficulties associated with readily achieving the required levels of accuracy and surface finish without a considerable amount of additional work.
Furthermore, parts will often need to be turned on their side — or turned over — to gain access to all machined features, which takes time and can introduce inaccuracies; and when moulds weigh between 10 and 15 tonnes, the difficulties of relocating and maintaining exacting tolerances are compounded — as Lofting Services North West Ltd knows only too well.
Formed in 1996 by two brothers — Richard and David Fielding (both former Aerospace engineers) — the company now employs 32 people and is a major sub-contractor, undertaking work for both UK and European aerospace companies, as well as the automotive industry; LSNW also undertakes work for North American companies that require high-technology high-tolerance cost-effective tooling — and it is cleared for classified military work.
In addition to its CNC machining, highspeed machining, mould making and tool making, LSNW also has its own design company — CAD-CAM Ltd — which uses the latest design/machining software packages, allowing it to supply full 3-D models in most formats, including Catia V5, Powershape and Solidworks. Moreover, the design facility is linked via Exostar secure encrypted FTP, ISDN and e-mail, allowing enquiries and designs to be sent efficiently and in a variety of forms.
LSNW’s design arm has also invested in a pair of seven-axis Faro arms with laser probe, plus the latest conversion software — Delcam’s PS Exchange — to ensure that it has the ability to read any format that a customer supplies information in.
Managing director Richard Fielding says that while there are a number of UK companies that can accommodate large workpieces of the type required by the aerospace sector, few of them can achieve the levels of accuracy and surface finish required. He knew that, with the right type of machine, LSNW could not only gain new work but also undertake existing projects far more effectively. “UK engineering can make money if it is willing to invest in the right technology. We can’t compete with China and Asia on ‘standard widget’ production; they are great on duplication, but not so good at innovation.”
To accommodate the large-scale moulds that LSNW specialises in machining, as well as components in difficult-to-machine materials such as titanium, Inconel and Nimonics, Mr Fielding knew that he needed a gantry-type travelling-table machine with a work envelope of at least 4,000mm in X, 2,500mm in Y and no less than 1,500mm in Z — the latter being greater than the norm for machines with this footprint.
Of the companies that Mr Fielding considered, only three were able to satisfy the basic machine requirements, but it was Milton Keynes-based Axe & Status (Tel: 01908 647707 — www.axestatus.com) that was prepared to get involved with the manufacturer and design the machine from the ground up to the specification required, rather than supply a standard specification machine.
“The Taiwan-manufactured Eumach machine — a DVM-4025 five-axis — was tailored to incorporate a Heidenhain TNC 530i control, a modified Z-axis height and an increased structural rigidity that took the machine’s all-up weight to some 60 tonnes. Probably the most important change was the integration of a tailor-made fiveaxis head from the Italian company ISA. This substantial head was designed specifically for this machine and our applications, weighs some 750kg, is accurate to ±0.01mm in all axes and is the first head of its type in the UK. Unusually for a head of this type, it also incorporates through-spindle coolant at up to 50 bar. At the recent MACH 2010 exhibition, Axe & Status showed another smaller VMC with a similar KW2-HT five-axis head.” The new machine — the tenth CNC machine supplied to LSNW by Axe & Status (the first was bought in 2000 as a result of an advert in Machinery Market) — was installed in November 2009 on pre-prepared foundations. When LSNW was building its new ‘state of the art’ temperature-controlled factory in 2006, it incorporated four suitably reinforced areas, specifically to accommodate large machines such as the DVM-4025 five-axis (which also features thermal compensation).
In conclusion, Mr Fielding says: “This Taiwanese machine — with British engineering input to tailor it for our type of demanding work, the addition of a German control and an Italian milling head, plus British software — gives us the ideal five-axis solution that allows us to reduce the number of operations, achieve tighter tolerances and better finishes; it also opens up opportunities for new work and new customers. Indeed, the addition of this new machine has already boosted enquiries by nearly 30% and new contracts by 25%; and with further opportunities currently being developed, we are now planning additional expansion for later this year.”
Specification for the Lofting Services machine
The Eumach DVM-4025 ram-type double-column vertical machining centre as supplied to Lofting Services has travels of 4,200, 2,600 and 1,500mm in X, Y and Z respectively. It also has extra height on the Z-axis columns. This gives 2,100mm of clearance under the bridge to accommodate the 850mm depth of the five-axis head and accommodate components up to 1,000mm high. The X axis features four slideways (two roller and two linear), the Y axis features three roller slideways, and the Z axis has a 380 × 380mm ram and Rulon-coated slide ways (all eight faces).
Other features include a chip conveyor, 40-tool ATC, full guarding, Heidenhain iTNC-530 control, and Heidenhain linear scales on the X, Y and Z axes. The ISA head features an ISO 50 4,000rev/min 30kW spindle with a maximum torque of 900Nm. The A-axis angular displacement is ±105deg, and the C axis offers 360deg of continuous rotation.
Article reproduced with kind permission from Machinery Market- July 2010