At the Barnoldswick factory of bicycle aftermarket component manufacturer Hope Technology, nearly all parts are machined from aluminium. Due to the relatively light metal cutting involved, it is not surprising that nimble, 30-taper machining centres are found on the shop floor alongside more powerful but relatively ponderous machines having a 40-taper tool interface.
Indeed, works and production manager Lindley Pate has started to replace some 40-taper machines with 30-taper technology, although there is no conscious policy to do so. Each machine is purchased on its merits for the intended applications.
A case in point occurred earlier this year when a Japanese-built Brother R650X1 30-taper, three-axis vertical machining centre (VMC) with 650 x 400 x 305 mm travels and twin-pallet changer was delivered by Whitehouse Machine Tools. The machine replaced an ageing, 40-taper twin-pallet VMC with a similar working envelope, and the benefits have been far-reaching.
First, the Brother machine is much more productive. For example, Op 2 on three twin-piston brake calipers fixtured side-by-side now takes 19 minutes, whereas it previously took 32 minutes, representing a 40% reduction. Time savings of this order are typical across the expanding range of parts being transferred to the more agile machine.
Secondly, the footprint occupied by the R650X1 is 20% smaller, which is helpful in a busy factory requiring more and more machine tools to service a business where recent annual percentage turnover growth is well into double digits.
A third advantage is that, as any 30-taper machining centre draws less power than a 40-taper machine with equivalent working envelope, there is an ongoing reduction in energy consumption that not only saves money but is also appropriate in a company that makes equipment for carbon-free transportation. The R650X1 additionally provides power regeneration from spindle deceleration, while the Brother CNC-C00 control minimises the power consumed by motors, pumps and lights by putting them into standby when not in use.
Works and production manager Lindley Pate says: “We use ten 30-taper machining centres on our production floor and 15 prismatic metal-cutting machines with 40-taper spindles, a mix of VMCs and horizontal-spindle machines. Half of the 40-taper machines are in multi-pallet cells and that will not change; in fact at MACH 2018 I ordered another five-axis model equipped with a 32-pallet pool.
“Where there is scope for swapping to 30-taper is in respect of our single-table and twin-pallet 40-taper machines,” he adds. “The benefits are compelling due to the higher output that is possible using the smaller tool interface, while accuracy and repeatability are just as good. In fact they are fantastic on the Brother machine. We hold down to 5 µm total tolerance on some components such as cassettes, which have to mate with another sprocket set produced on a different machine to provide the higher gear ratios.”
He points to the use of a Big Plus spindle on the latest R650X1, which provides face-and-taper contact with the tool’s back end, leading to extra rigidity. The spindle allows, for instance, a 32 mm diameter face mill to skim components and achieve a fine finish on some surfaces; cosmetic features which are much appreciated by customers in more than 40 countries that use Hope’s high-end bicycle parts.
The manufacturer’s first encounter with Brother agent Whitehouse Machine Tools was five years ago when two 30-taper TC-2RB three-axis machining centres were purchased to cope with increased workload. At the time Hope used, and still does, six 30-taper machining centres of a different make; some equipped with manual pallet change.
Brother TC-2RB machines were selected owing to their superior speed and productivity, and due to the compact design of the automatic pallet changer. Brother calls this a QT (quick turn) table, which is essentially one large pallet rotating around its centre, so no time is lost by having to temporarily disengage pallets for 180° indexing into and out of the machine’s working area.
Two years ago, the first R650X1 arrived on the shop floor at Barnoldswick, again to cope with steeply increasing demand for Hope’s bicycle accessories. The machine was considerably faster in-cut than the TC-R2Bs, as well as offering similarly short idle times. Brother’s R650X1 also provided a larger table, 800 x 600 mm, instead of 600 x 300 mm, and at a competitive price. The extra table area enables more parts to be fixtured for longer run times, which is especially useful for lights-out machining during 24-hour operation, currently from Monday through to Thursday. A single shift is operated on Friday, while weekend working is according to demand.
Further benefits of the R650X1 are the option of 22-tool storage capacity rather than 14 positions on the TC-R2B, 15-bar coolant delivery through the 16,000 rpm spindle and, notably, 30 m/min cutting feed rate in all axes instead of 10 m/min in X and Y, and 20 m/min in Z on the TC-R2B. The inherent speed
of all Brother machining centres derives from fast tool changes and APC time, as well as 50 m/min rapids, all of which happen at the same time so that the tool is in position to cut the next part instantaneously after pallet changeover.
Larger memory capacity in the Brother control is useful, as two dissimilar Hope parts can be fixtured and machined on the R650X1’s pallets. In contrast, on the old 40-taper machine, a relatively complex part had to be machined two at a time due to lack of control memory. The ability to produce different parts on one machine is appreciated by Pate, who sees part numbers for machining new component derivatives arriving all the time from the design office, but very few being deleted.
In conclusion, Pate says: “There is a greater variety of 30-taper milling centres around now, and more tooling is available to use on them. They are extremely compact, helped by the carousel style of tool magazine. We use two major makes of 30-taper machine here. Brother machines have the edge in terms of speed, compactness, value for money and reliability, and they provide good access for loading and unloading parts, so are popular with our operators. Whitehouse also provides excellent after-sales backup and service.”
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