Shuttle concept lets the main spindle work continuously

For Lacom Machinefabriek in Budel, increased spindle efficiency was the decisive reason for purchasing their first HEDELIUS RS 100 in mid-2006 as a replacement for a conventional flatbed milling machine. As soon as a product is ready, the spindle shuttles to the other position to continue its work there on the next workpiece, while product changeover takes place at the adjacent position. With a cycle time of around 60 to 120 minutes, this productive use of the changeover time – which can easily be around 20 minutes at Lacom – makes an immediate and substantial difference in spindle efficiency. Incidentally, introduction of a zero-point clamping system and robots for product and pallet handling is also planned for the future in order to reduce the reclamping time (and thus the spindle idle time) on the other machines. In addition, three-axis machining on the flatbed machine was increasingly showing its limitations, as can be seen from the words of director Driek Lammers. ‘It involved a whole lot of handling and reclamping in order to fully machine the product, with all the associated risks of mistakes and loss of accuracy.’ The combination of flatbed and five-axis machining also provides major flexibility. At Lacom, the rough machining is often performed on the long-bed portion, where several products can sometimes be clamped at the same time (depending on their length), while the finish machining is performed at the five-axis station. All sorts of products can be machined in any desired order with this arrangement. According to Richard Hermans of Promas in Maasbree, which markets the HEDELIUS machines in the Netherlands, the shuttle concept makes the machines scarcely more expensive than comparable machines with only one station, ‘What it means is that you simply have an extra clamping station at a comparable price level.’

Complete line

For Lammers, their positive experience with their first RS 100 provided the incentive for new investments in the past months – first in a somewhat smaller RS 80, and most recently in a hefty RS 125. ‘Now we have a complete line of machines that we can use to make all of our products.’ The RS 25 is the first machine of this type that has been placed in the Netherlands by HEDELIUS. To give an idea of the size and capacity of the machines, the RS 80 at Lacom has a working envelope of 2300 x 800 x 600 mm, while the RS 125 has a working envelope of 4500 x 1250 x 770 mm. The diameter of the rotary tilt table is 800 or 1000 mm, respectively, and it is suitable for workpieces up to 600 or 1500 kg (the corresponding figures for the long-bed portion are 1500 and 2500 kg). The figures for the RS 100 lie roughly in the middle. These are thus machines for fairly large jobs, which makes them an excellent fit with Lacom’s line of business, since this market segment is where Lammers sees the greatest growth potential. In addition to the three machines installed at Lacom, HEDELIUS also markets an even smaller model, the RS 60. In addition, all models can be supplied in various versions. Hermans calls this ‘a single concept with all sorts of options in terms of length, power, spindle and rpm’. For example, the long-bed section can optionally be fitted with a pivot mechanism that allows the workpiece to be rotated. For a complete overview of all the options, see www.promascnc.nl and www.hedelius.de.

25 percent

As it happens, avoiding idle time during product changeover is only one of the gains realised with the HEDELIUS machines. Tool changeover time is also significantly better. For instance, the clamp-to-clamp time is only 7 to 9 seconds, which means that a time savings of around 1 minute for each tool change can be booked. With around twenty tool changes per machining cycle, this adds up quickly.

Lammers also praises the stability of the machine, which makes higher feed rates possible – as well as larger metal removal volumes. To give you an indication, a metal removal volume of up to 650 cm3/min is possible with the RS 80, and the RS 125 can manage as much as 900 cm3/min. As an example, Lammers showed us a large slewing ring for a crane, for which the pure machining time (on the RS 125) was reduced from 108 minutes to 82 minutes. He also estimates that the machining cycle times for other products have been reduced by about 25 percent on average.

Dual guides

The stability of the HEDELIUS machines arises in part from the construction of the linear motion axes, according to Hermans. For instance, the column has dual linear guides in the Y direction, with the Y-axis guides located at the top of the column. ‘This allows an optimum play of forces to be achieved with a minimum of friction and deviations. As a result, the Y travel range of the HEDELIUS machines can be larger than with machines that use cross-sleds.’ According to the HEDELIUS specifications, even the RS 125 can achieve a positional accuracy lying within a tolerance range of ±3 μm.
HEDELIUS uses an extremely robust separable-bearing suspension for the rotary tilt table to achieve a high degree of stability and accuracy in this area as well. The table can rotate over a full 360° and tilt over a range of +10° to –90°.

No fear

Hermans also mentioned the good accessibility of the machines as a plus point for HEDELIUS, and Lammers fully agrees with this. ‘You stand very close to the table, and that works much better.’ All three machines at Lacom are fitted with a laser measuring system to monitor the length of the tools and check them for breakage. The tables are also fitted with suitable hydraulic actuators in preparation for the future zero-point clamping system.
Lacom uses its HEDELIUS machines in particular for machining large products for the offshore sector, the recycling industry, and the road transport industry. ‘Thanks to the dramatically improved spindle efficiency, we don’t have to be afraid of foreign competition’, remarked Lammers. ‘We have no problem handling the price competition, and we can offer our customers better delivery reliability and better quality as added benefits.’ He went even further: ‘Thanks to the capabilities of the HEDELIUS machines, Lacom is attractive to a new group of customers, and we are in a position to acquire higher-quality work.’

Some tips from Lammers for purchasing a new machine:

• Carefully consider whether the capabilities of the machine match your productivity and speed requirements

• Go for stability – with regard to metal removal volumes as well as quality

• Pay attention to the factory (or the service) behind the machine

Focus on large jobs

‘Our main strength is that we can offer a complete package’, according to Driek Lammers, director of Lacom Machinefabriek. What he means with this is the dimensions of the components (with diameters of 10 to 100 mm and lengths up to 3 metres), as well as the fact that they can be assembled to form tested and ready-to-install subassemblies. Over the years, the focus has also shifted more and more toward relatively large jobs, because this is where Lammers sees the biggest promise for the future. The machinery – with numerous CNC lathes for diameters of 10 to 900 mm, machining centres and turning/milling centres, complemented by welding equipment and welding robots – is aligned to this trend.

The major sales areas include offshore, the recycling industry, crane construction, and road transport. Lacom, which has 35 employees, also delivers directly to OEMs – primarily Dutch companies with international operations. They are now working on an expansion of their premises, with 400 m2 of off ice space and 1500 m2 of production area. For more information, see www.lacom.nl.

The experiences of other users

Blokland Metaalbewerking in Hardinxveld-Giessendam has a BC 100 and a C 60 – both with the combination of a long bed and f ixed table – and an RS 100. A fourth machine – a C 60 with a 2-metre bed – is presently on order. Director J.W. Blokland is especially satisf ied with the machines. His conclusion: ‘In particular, the shuttle function works very well, and it enables us to boost the spindle eff iciency by 50 to 60 percent.’ The C and BC machines are used primarily for machining large and long products, while the RS 100 is used mainly for relatively complex products that must be machined on f ive surfaces. Now this can be done with a single clamping operation.

Horstra Technology books spindle hours on a C 80 that has been in place since 2004, and which was joined by a C 60 and a RS 80K in early 2007 (see Metaal Magazine no. 2/2007, pp 30–31), although the latter machine also serves as a stepping-stone to f ive-axis machining. ‘If you only buy a f ive-axis machining centre, you are right away at its mercy’, commented director Harman Horstra. ‘You have to master the process right from the start, and you need to have enough work for it. With the HEDELIUS, we can build things up gradually.’ Horstra is ‘more than satisf ied’ with the HEDELIUS machines, and the C 60 now runs more than 20 hours a day for most of the year. By clamping several products at the same time, machining cycles of around 10 hours in a single stretch can be achieved.

A HEDELIUS RS 100K was installed at Tuinte Machinenfabriek in Hengevelde in the fall of 2004. It was purchased then on account of its operational f lexibility and high spindle eff iciency. According to director Martijn Tuinte, the machine has completely full f illed their expectations in these areas, and he mentioned its accessibility as an extra plus point. ‘There are no restrictions for the operator in this regard; it’s just like working at a desk.’ He is also satisf ied with the service, in part because spare parts are available from HEDELIUS in Meppen (Germany), only an hour away by car. His conclusion after three years of experience with the RS 100K: ‘It’s simply a solid, stable machine, with nothing to complain about.’ In early 2007, Tuinte also bought an MC 40 (with two three-axis stations) from HEDELIUS for relatively simple jobs.

Opinions on special machines

The experiences of the users of 26 special machines, as previously published in Metaal Magazine, are available in the ‘machine masterclass’ archive on the website at www.metaalmagazine.nl.

Jan Oonk

metaalmagazine 1 2008

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