Smaller, affordable horizontal machining centre

Edited by the Engineeringtalk editorial team Nov 6, 2001

Following a recently signed agency agreement, Yamazen (UK) has added the compact Japanese-built Kiwa KNH-426 high speed horizontal machining centre to its product range.

Following a recently signed agency agreement, Yamazen (UK) has added the compact Japanese-built Kiwa KNH-426 high speed horizontal machining centre to its product range.

This brand new 400 mm2 pallet machine is being supplied as standard in this country with a 20,000 rev/min spindle, six-station pallet pool, 120-station ATC, advanced spindle core cooling system and a special mechanical tool locking arrangement.

Combined with rapid traverse rates of 60 m/min and an affordable price tag, the Kiwa stands out from other HMCs in its class.

Basic element design is centred around a fully cast machine bed which provides maximum support for the column, table and spindle head movements.

The 720 mm wide box-type bifurcated cast column incorporates internal ribbing reinforcement for added strength while all ballscrews and linear guideways are automatically lubricated by a pressurised oil/air system.

Powered by a 22 kW motor, the Kiwa KNH-426 has a working envelope of 600 (X) by 610(Y) by 665 mm (Z axis) and each of the six pallets can handle a maximum load of 400 kg.

Control is from a Fanuc 18i-M system.

The 20,000 rev/min spindle has a positive oil and air lubrication system which prevents coolant and swarf from entering the precision bearings of the spindle.

In addition to having a standard a chiller spindle jacket, the machine also features a special core cooling system to further control the thermal expansion of the spindle.

This can be used with or without through-the-tool coolant (by simply switching the flow) to circulate chilled cooling fluid inside the spindle.

Tests have shown that this innovative system reduces the thermal expansion of the spindle by more than five times compared with a machine with standard spindle cooling only.

Equipped with a No 40 spindle taper, the KNH-426 also features a special positive locking tool spindle.

The tools are held in the spindle by a mechanical locking system which improves accuracy, rigidity and power transmission which in turn leads to better finishes, higher rates of metal removal and longer tool life.

This method of tool location has many advantages over systems using Belleville springs which after time can lose their effectiveness and are prone to movement when cutting with the side of the tool.

The Kiwa system uses three rows of steel balls (contacting the sleeve at right angles) which multiply the drawbar force by a factor of five compared to the usual two as with conventional toolholding systems.

This provides for much more rigid clamping of the tool holder.

The ATC on the Kiwa is of the double arm type and tool-to-tool change time for the 120-station system is 1.3 sec.

Tools up to 95 mm diameter (when adjacent pots are full) by 360 mm long and weighing up to 8 kg can be accommodated.

Overall floor space requirements for this high speed, six pallet pool machining centre are just 3175 by 5480 mm and the APC has an exchange time of 7 sec.