Small horizontal as rugged as the big models

Although the new Daewoo ACE HM500 horizontal machining centre is nominally a half-metre-cube machine, it is constructed using box section guideways normally found on larger machines

An outstanding characteristic of the new Daewoo ACE HM500 horizontal machining centre 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.

The ACE HM500 is 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 milling cutters.

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 850 mm and 1,200 x 1,000 x 1,000 mm respectively.

Both feature a 22 kW (optionally 26 kW) spindle drive delivering up to 6,000 rpm; rapid traverse in X, Y and Z of 24 m/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 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 bi-directional tool magazine takes the shortest path to the next 50 taper tool, capacity options being 60, 90, 120, 180 or 240 tools.

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.

This fixed pocket design virtually eliminates the risk of collision when oversize tooling is used.

To give an idea of cutting performance, a 125 mm diameter face mill driven at 308 rpm and 1,000 mm/min feed rate will remove 1,200 cm3 of SM45C carbon steel per minute.

Coolant management within the machines is commensurate with these levels of swarf generation.

A 75 mm diameter drill rotating at 137 rpm will achieve 72 mm/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 P0.5 holes at 5 mm pitch in GC30 may be tapped in a 327 second cycle using 3,500 rpm spindle speed and 1,750 mm/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.

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