QMT Features: January 2009
Maximising productivity
Machine tool probes improve production efficiency and increase lights-out machining in a low volume, large variety, high  complexity production environment.

An m&h 20.10 radiowave touch probe is fitted to two Mori Seiki B-axis mill-turn centres recently purchased by Camera Dynamics.

Equipment that supports broadcast cameras has become much more complex and precise over the last decade, according to leading British manufacturer, Camera Dynamics.  To assist in machining the component parts to the required accuracy, many of its machine tools at the Bury St Edmunds factory have been fitted with spindle probes and units for detecting broken tools.  Supplied by m&h UK, the probes have not only improved production efficiency, but also increased the level of lights-out machining.

Commented Andy Griggs, manufacturing manager at Camera Dynamics, “There are several probing systems on the market, but from the outset we decided to standardise on m&h products from Germany for two reasons. “First, the products cost around 25 per cent less than those of equivalent quality from other suppliers.  Second, and more important, they are much easier to set up and use on our machines, as the software is simpler.”

In the 1990s, Camera Dynamics (then called Vinten) introduced its Vision range of camera supports, which necessitated increased use of aluminium die castings.  Clocking each casting into position manually on machining centres at Bury St Edmunds was too time consuming and prone to human error.  So the decision was taken to adopt spindle probing to automate datuming of components and update work offsets in the control.

The first machine to be fitted with a spindle-mounted m&h touch probe was a Niigata PN 40 horizontal machining centre with 12-pallet pool, purchased to cope with increased demand for the Vision product range.  Up to a dozen components were fixtured at a time on each pallet and set with an m&h 25.10 infrared probe.

Mr Griggs was impressed by the speed with which the probe was fitted onto the Niigata by Chris Woodhouse, General Manager of m&h’s UK subsidiary.

Mr Woodhouse said, “Our software was revolutionary, as it worked for all Fanuc, Yasnac and Mitsubishi controls.  All that is needed to calibrate a probe is to specify the make of CNC system controlling the machine and write one line of code, which is why the process is so quick.

“Customers were writing their own measuring programs within hours, whereas sometimes it took days for users to become confident enough to use some of our competitors’ software.”

Mr Griggs added, “It seems to me that m&h has maintained its software advantage.  It is so easy to reconfigure one of their probes that it can be done on our shop floor. In the case of other vendors’ probes, off-site specialists are normally involved, as its software includes cumbersome sub-routines that need to be extensively rewritten.  It makes the whole process more time consuming and takes the machine out of production for longer.

Moreover, the m&h software is built in such a way that its probes can communicate with other suppliers’ installed infrared receivers, saving even further cost.”  In this connection, Chris Woodhouse commented that there are factories around the UK with m&h probes providing cover for many probes from different suppliers.

Since it was installed at Bury St Edmunds, the Niigata horizontal machining cell has operated 16 hours a day in what is best described as a low volume, large variety, high complexity production environment.  There have been no problems with the m&h probe, or with any others subsequently installed and this is the reason that Camera Dynamics has continued to select them.

Following the success of the first spindle probe, other vertical and horizontal machining centres at Bury St Edmunds to be fitted with similar probes include three Kitamuras, one with an 80-pallet pool, as well as Takisawa, Mori Seiki and Matsuura machines.  The latest to be installed by the latter supplier, a MAM 72-63V, is Camera Dynamic’s first 5-axis machine, the others on site all being 4-axis.

Invariably, the machining centres have also been fitted with an m&h 35.10 table-mounted touch probe for tool breakage detection, again with unattended and lights-out production in mind.  Mr Griggs finds that physical contact between the tool tip and probe, following rapid approach, is faster than other systems on the market that rely on a laser beam being broken by the tool to verify its presence.
The 35.10 probes are not normally used for tool setting at Bury St Edmunds, as preset cutters are resident in the large tool magazines of between 120 and 250 pockets.  Only if a cutter breaks and there is no sister tool in the magazine will an m&h probe be used for on-machine setting.

Within the last couple of years, Camera Dynamics has invested in two new Mori Seiki NT4250DCG B-axis mill-turn lathes, each fitted with an m&h 20.10 touch probe.

Loaded into the milling spindle from the 100-position tool magazine, the probe communicates with the lathe control via radiowave transmission.  It was considered the better solution, as infrared signals require line of sight for data transfer, which could have been obstructed in the crowded machining area on the B-axis lathe.  Radiowave communication does not have this problem.
The purpose of the probes is to check the location of preformed features in the main spindle or to verify the orientation of a part in the counter spindle after synchronous transfer.  Positional data is fed back to the control, which reorientates the component in the chuck using the C-axis before the next prismatic machining element of the cycle begins.

By the end of 2008, there was a total of 24 m&h probes in use across two Camera Dynamics factories in Bury St Edmunds and Costa Rica, the latter production plant having recently come on stream to serve the American market.  Technology transfer from the UK to the new plant has included two weeks’ training given by Chris Woodhouse to the Costa Rican production staff. 

 E-mail: uk@mh-inprocess.com


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