machining
EMO 2007 saw
the introduction
of a new way of
turning tapered
bores and outside
diameters using
horizontal
machining centres More read more about
machining at
www.mwponline.com
New Products
and Services
■ Takisawa turning centre
available from Ward CNC
Ward CNC
http://tinyurl.com/22l3je
Case Studies
■ Rotary Power’s
investment in Mazak
machines
Mazak
http://tinyurl.com/2yhkwl
to the point
CONVENTION suggests that the way to machine ODs
and bores on a 4- or 5-axis machining centre is to revolve
the component on the rotary table, and feed in a static
turning tool mounted in the spindle to machine the OD.
However the need to use a long right-angle head
compromises bore accuracy; turn-cutting is a patented
technique which offers a more accurate alternative.
The turn-cut function in the control of the Okuma
OSP-P200M allows a single-point turning tool in the
spindle of a horizontal machining centre to turn a static
component, even on a 3-axis machine. This is achieved by
taking advantage of linear feed rates up to 60m/min to
circular-interpolate the X and Y axes rapidly while
feeding forward in Z. The clever part, which forms the
core of the patent, is the ability of the control to
continuously orientate the tool in the spindle by rotating
it at precisely the same speed as, and in synchrony with,
the circular X/Y path. The tool therefore cuts at the
correct rake angle at every point throughout the 360 o to
ensure efficient and precise metal removal. Cylindrical
bores and ODs are easily achieved by keeping the X/Y
travels constant, while tapers and other profiles can be
turned by varying the amplitude of circular
interpolation.
The benefit of turning on a machining centre is that
components can be finished in a single clamping,
New generation VMC range embraces all requirements
FROM a stable of 10 variants, Colchester-Harrison has created a single source for European designed vertical machining centre
(VMC) solutions for almost any production requirement from a simple, low-cost but high rigidity general purpose
machine, to a high specification machine with 15,000 revs/min and 48 m/min rapid traverse.
This ‘new generation’ Colchester-Harrison Storm VMC range also maintains the well-proven tradition of value for
money with high operational flexibility and performance but with the added advantage of a specification
that can be easily customised to suit the intended applications.
Set into four main product groups, all having two large slide-aside doors giving good
operational access, the SP or standard machine is available in three sizes, the SD comprises
two heavy duty types, the SH four versions, that are all high specification mid-range
production machines and the SV, comprises two top of the range model classifications,
directed at higher performance, higher accuracy machining cycles.
The Storm range provides options to tailor the machine for any designated drilling or
milling task. High rigidity and power are critical, and this is qualified by the use of high
classification Meehanite castings to which the most desirable specification is added. Heavy
duty solid box ways are used on the SD 55 and SD 75, a combination of box ways on the Z
axis and linear ways on X- and Y-axes on the SP 600 and SP 1000. Meanwhile, the larger SP 1500
is a heavier duty design through the use of box ways with the number of bearing surfaces
doubled to four on the Y-axis. Both the SH and SV machines are totally dedicated to linear ways.
www.colchester-harrison.co.uk
44 MWP january 2008
avoiding a subsequent set-up on a lathe and the
consequent handling costs, increased floor-to-floor time
and tolerance build-up. If parts are heavy and/or have
eccentric bores or ODs, rotating them for conventional
turning becomes difficult, requires expensive lathes and
can lead to further inaccuracies. At EMO, the machining
centre demonstrating the turn-cutting technique was an
Okuma MA-600HB, which can machine workpieces
weighing up to 1.2 tonnes within a nominal 1m cube.
Turn-cutting accuracy is to within microns and it is this
degree of precision that is crucial, and, claims the
company, distinguishes it from competing offerings
The MA-600HB features the manufacturer’s Thermo
Friendly Concept. Symmetrical design and electronic
compensation from sensors around the machine
structure and spindle hold dimensional drift to below
10μm, even if the ambient temperature changes by up to
8 oC. Repeatability is ±1.5μm.
While turn-cutting is applicable to any component,
the company singles out large, multi-port valves as
particularly suitable for being machined in this way. Not
only can the bores and flange ODs be conveniently
turned, but it is also possible to single-point cut an
accurate scroll pattern on the flange faces for improved
sealability.
www.ncmt.co.uk
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