Traub turns up flexibility and productivity for Luneside

Citation

(2001), "Traub turns up flexibility and productivity for Luneside", Aircraft Engineering and Aerospace Technology, Vol. 73 No. 6. https://doi.org/10.1108/aeat.2001.12773fab.002

Traub turns up flexibility and productivity for Luneside

Traub turns up flexibility and productivity for Luneside

Keywords: Traub Heckert, Turning, Tooling, Components

Following the installation of a Traub TNA 300 65 single turret lathe which is able to accommodate bar diameters of 65mm through the spindle and carries a 250mm chuck, Luneside Engineering of Halton, UK, informs us that it has found it is able to hard turn to a tolerance that was only previously achievable by grinding (see Plates 2 and 3). In addition, the Traub Heckert of Brackley supplied lathe has reportedly enabled at least 20 per cent to be sliced from previous turning cycle times and slashed setting up times by almost 40 per cent. The end result for Luneside is said to be a major improvement in delivery lead times to customers.

Luneside is a well-established supplier of complex components and sub-assemblies to the aerospace, nuclear, defence and specialised machine tool sectors. Founded over 50 years ago, and nestling on the banks of the picturesque River Lune in Lancashire, the company offers a wide range of inhouse manufacturing facilities including turning, milling, grinding and jig boring. This is complemented by in-house tool and cutter grinding facilities and CAD/CAM.

Plate 2 Cycle time reduction from 8 mins to 90 secs and one hit machining are the orders of the day using Citizen L20 sliding heads at Dawson Precision

Plate 3 Luneside Engineering has cut setting by 40 per cent and cycle times by 20 per cent using a Traub TNA 300 65mm bar diameter lathe

The company has developed of late against a background of extensive project management experience and is able to source specialised services such as hard chrome plating. Aircraft engine fuel system airframe components and sub assemblies in addition to major aircraft landing gear components are included in the regular production schedules, and an unusual aspect of the company's activities is that it can still supply components for aircraft built over 40 years ago. All parts are manufactured under a rigorous quality control regime – Luneside was one of the first companies to gain BS 5750 Pt2 which has now become ISO 9002.

David Taylor, chief manufacturing engineer, outlines its experience saying: "We have the facilities and skills to take on a wide range of work, and we are regularly involved in prototype component development. Parts are produced from bar, forgings, castings and extrusions from a wide range of materials".

Historically, Luneside has become known for machining high tensile materials such as pins for aircraft undercarriage assemblies. These are quite sizeable, highly complicated components with tight tolerances and can be up to 75mm in diameter by 250mm long. "We have to hold around 0.015mm process size on the turned diameter ready for hard chrome plating", says David Taylor, and follows on to describe how the traditional process route had been to turn and then harden and temper followed by finish cylindrical grinding.

He then explains that one of the problems has been that batch quantities are relatively small with 100 parts constituting a very large batch with the norm being closer to 20. "That means that our processes and operations have to be highly repeatable, and need to be quick and easy to set without fear of rejects. Before we acquired the Traub TNA 300, our CNC turning facilities just could not provide the level of process flexibility. We struggled utilising all our skills, developed over the years to meet the demand. Also on certain components, there was a basic capacity shortfall in terms of the component being at the limit of what would fit onto the machine tool".

Luneside conducted an extensive analysis of its CNC turning requirements to determine the best upgrade path. Refurbishment or upgrading of the existing machinery was quickly rejected and the exercise also threw out the option of installing a bar machine. It was also determined that live turret tooling was not a priority at that time. Instead, it was decided to go for a high quality chucking-type, two-axis lathe which could be equipped with a collet chuck and coolant pressure activated bar puller to accommodate occasional large diameter through-the-spindle bar work.

Major considerations when choosing the machine were build quality and rigidity, to guarantee a good and consistent machining performance. Other requirements were flexibility and ease of set-up as the company was well aware that its diverse product mix would dictate regular and extensive tool exchange. This prompted automated or semi-automatic tool setting as a desirable item and in a more general sense, the ergonomics of the machine had to be considered important, as was long term back-up and support.

David Taylor recalls: "The decision to buy the Traub was essentially made by a committee of likely operators and supervisory staff who would be using the machine day-to-day. The exercise also involved a combination of visits to suppliers and end users. The team found the Traub TNA 300 65 stood out for its basic design integrity. The ease of programming Traub's own TX8H system and the use of VDI tooling on the 12 station disc-type turret was seen as important, which provides a very quick positive tool resetting combining rigidity and excellent repeatability".

The machine was purchased untooled though Luneside also ordered off-line versions of the Traub-FlexIPS interactive and Traub-GPS graphic dynamic process simulation programming software. Traub's automatic tool position calculator setting scope is standard with the machine and ensures a simple, but highly effective and quick setting method of determining tool offsets. In addition, a certain amount of predelivery training was taken in so that everyone was prepared to put the machine into production as soon as commissioning was completed.

According to David Taylor, an improvement in productivity and flexibility was immediately noticeable. This was achieved largely through the ease of set-up. Previously, machine set-up, which included program prove-out and first-off acceptance, would take at least four hours while the same exercise on the TNA 300 takes just 2.75 hours. Here, the VDI system enables a very slick changeover to be performed with certain tools kept permanently set up. Less regular jobs can still be quickly set using data recorded from tooling sheets.

Similarly, cycle times are said to have significantly shortened due to the machine rigidity, allowing higher spindle speeds up to 4,000 revs/min, rapid traverse and turret index which only takes 0.35 secs. Feed per rev has are also said to have typically increased from 0.25mm to 0.35mm while depth of cut achieved can now be 50 per cent greater at 3mm and at speeds between 150 and 160m/min.

It is reported that on certain jobs such as when hard turning, the machine is able to optimise on the 11kW drive and when combined with high performance cutting media such as polycrystalline diamond (PCD), grinding operations are either significantly reduced or totally eliminated. This provides a consequent roll-on improvement in component production cost and reduces operational lead times.

Maintains David Taylor: "Even on more delicate jobs we find that we can achieve a substantial cycle time reduction. We have also been able to utilise a lot of our own-developed specialist workholding on the machine. In addition, the performance of the VDI tooling system has impressed us sufficiently for us set it as our standard, resulting in four other machines now being so equipped. Three of those machines have now been equipped or modified to accept a common collet chuck system which further improves their flexibility".

In short he says: "The Traub is definitely the machine of our choice for accuracy and finish and we have certainly been very satisfied with its performance".

Further details are available from Traub Heckert UK Limited. Tel: +44 (0) 1280 705482; Web site: www.traub-uk.com