Small horizontal is as rugged as the big models
Small horizontal is as rugged as the big models
Keywords: Daewoo, Machining, Mills Manufacturing Technology
An outstanding characteristic of the new Daewoo ACE HM500 horizontal machining centre (Plate 5) is that, although it is nominally a half-metre-cube machine, it is constructed using box section guideways normally found on larger machines, according to UK sales and service agent, Mills Manufacturing Technology.
Plate 5 The new Daewoo ACE HM800 horizontal machining centre from Mills Manufacturing Technology offers high levels of robustness and precision
The ACE HM500 is believed to be ideal for machining heavy con rod forgings and high tensile aerospace materials, for example, and for other rigorous applications where the high power available at low speeds may be used to good effect. The latter is made possible by the three-range rather than two-range gearbox, allowing deep cuts to be taken at around 100 rpm even with large diameter millingcutters.
The machine joins the Daewoo ACE HM horizontal range at the lower end, other models being the 630, 800 and 1,000 which themselves are new to the UK. Sizes 500 and 630 are available at Mills' Leamington Spa showroom for customer demonstrations and applications engineering.
More representative of the range are models 630/800, which have generous working envelopes of 1,000 x 800 x 850mm and 1,200 x 1,000 x 1,000mm respectively. Both feature a 22kW (optionally 26kW) spindle drive delivering up to 6,000rpm; rapid traverse in X, Y and Z of 24m/min with rapid acc/dec owing to powerful axis drives; and a high speed, rotary,shuttle-type pallet change system with Curvic couplings for precision location.
Again, high rigidity for accurate machining results from induction hardened,widely spaced box guideways, a massive Meehanite cast iron bed and column, both ribbed to withstand extreme cutting forces, and large diameter, double pretensioned ballscrews. Repeatability is said to be guaranteed at ±2 microns, assisted by the temperature-controlled spindle and gearbox, which are fitted as standard.
Other assets of the machines, says Mills, are competitive prices for machines of this class and high levels of reliability, a contributory factor to both being the reduced number of individual components used in their construction. Furthermore, footprints are said to be small relative to the working envelope for each model.
The bidirectional tool magazine takes the shortest path to the next 50 taper tool, capacity options being 60, 90, 120, 180 or 240 tools. According to Mills a rotary arm ATC exchanges the tool into the spindle and returns the previous tool into its original pocket in the magazine within 2.5 seconds, keeping non-cutting times to a minimum. The company considers that this fixed pocket design virtually eliminates the risk of collision when oversize tooling is used.
To give an idea of cutting performance, a 125mm diameter face mill driven at 308rpm and 1,000mm/min feed rate will, it is claimed, remove 1,200cm3of SM45C carbon steel per minute. Coolant management within the machines is commensurate with these levels of swarf generation.
Mills also informs us that a 75mm diameter drill rotating at 137rpm will achieve 72mm/min feed rate in GC30 cast iron. As far as rigid tapping is concerned, this may be performed in any gear range as an encoder is attached to the spindle. A square pattern of 100 M3 x PO.5 holes at 5mm pitch in GC30 may be tapped in a 327 second cycle using 3,500rpm spindle speed and 1,750mm/min feed rate.
The CNC system is the Fanuc 18-Mi, which has capability to control an optional 0.001 degree rotary NC table. Further options include 6, 8, 10 or 12 pallet magazines.
Further details are available from Mills Manufacturing Technology Ltd. Tel:+44 (0) 1603 827700; Fax: +44 (0) 1603 827899;e-mail: gcurran@millsgroup.co.uk; Web site: www.millsgroup.co.uk
