Automatic wheel balancers enable CNC valve seat grinders to maintain dimensional tolerances of under 5 microns, while producing up to 15 components a minute, 24 hours a day.

Designing and manufacturing special purpose CNC machines capableof maintaining dimensional tolerances of better than 5 microns,while producing up to 15 components a minute, 24 hours a day, isundeniably a tough task. But when these same machines are likelyto be installed in plants located anywhere from Argentina orIndia to China or South Africa, then the need for precision mustalso go hand-in-hand with reliability, durability and excellentproduct support. The same is just as true for any 3rd partyequipment incorporated in the design.

That's certainly theview taken by Earlsdon Technology; which is why the specialistmachine tool builder has specified automatic wheel balancingtechnology from Schmitt Europe for its latest generation ofpurpose-designed valve seat grinding machines.

Custom-engineeredequipment and automation solutions for high speed or massproduction applications are at the heart of EarlsdonTechnology's business.

The Coventry-based company isparticularly strong in the fields of high volume engine componentmanufacture, high performance fastener production and automatedcentreless grinding machinery.

Not surprisingly, its customersinclude many familiar names in the aerospace sector, as well asautomotive component suppliers such as TRW, Federal Mogul andEaton.

'As a relatively small, but experienced player, wehave focused our activities on niche market requirements,'says Managing Director Simon West.

'Our latest VSG-X1grinders are a typical example, being designed specifically forengine valve production.

The machines incorporate fully automaticcomponent loading and unloading and will achieve cycle times ofless than 5 seconds on components up to 160mm long and 50mm headdiameter.' 'Maximum manufacturing tolerances willnormally be less than 20 microns on seat-to-face length, 15microns TIR (total indicated run out) on seat run out, 3 micronson seat roundness and less than 0.25 microns on surfacefinish,' he adds.

Precise control - meeting these sorts ofrequirements calls for precise control of the grinding process.

Akey element in this is ensuring the dynamic balance of thegrinding wheel itself.

It is not only central to maintainingdimensional accuracy and surface finish, but also contributes toother benefits, such as extended component runs between dressingcycles, increased wheel and dresser life, minimised vibration andreduced spindle bearing wear.

These in turn, result in greaterproductivity and lower machine maintenance costs.

'Ineffect, the wheel balancing equipment plays a crucial role in theperformance of the whole machine,' continues West.'That's why we went to significant lengths to assessthe capabilities of a number of suppliers' products beforespecifying any equipment for our new valve grinder models.'During our evaluation, we were impressed by the range ofgrinding wheel balancing solutions offered by Schmitt.

Detaileddiscussions with the company led to a series of trials, and thesubsequent adoption of their SBS dynamic balancers.'Comprising a sensor, spindle mounting adapter, balance head andelectronic control unit, the SBS system provides continuousmonitoring of the grinding process; eliminating the need forpre-balanced wheels and greatly reducing set-up times.

Theequipment uses the principle of mass compensation to correctimbalance.

SBS balance heads incorporate two eccentric weights,each of which is driven independently by electric motors througha precision gear train.

In operation, vibration or imbalancedetected by the sensor is relayed to the controller at the heartof the system.

The unit processes the signal and sends commandsto the balance head to advance each weight in the correctdirection to reduce the amplitude of the input.

When the minimumvibration level is achieved, the balance cycle is complete.

Thesystem continuously monitors the machine to provide a fullyautomatic system that maintains balance even if the wheel isstopped and re-started.

Balance accuracy - SBS equipmenttypically achieves balance accuracy of 0.1 micron peak-to-peakvibration displacement, which compares to 5 microns for normalunbalanced grinding operations and a figure of around 3 micronsusing statically balanced wheels.

'Not only did the Schmittsolution provide the high balance accuracy we were looking for,but the system's components are small and neat, enablingthem to be mounted more easily in restricted accessapplications,' says West.

'The SBS control unit isequally compact and proved easier than many of its competitors tointerface with the machine control system we had designed for thenew machines.

'A further important factor in our decisionwas that, as part of a large international organisation, SchmittEurope could provide us with first class, world-widesupport.' 'Indeed, we have already taken advantage ofthis facility,' he adds.

'Through the response ofSchmitt's US-based engineers, we have quickly resolved arecent problem at one of our customers' manufacturing plantsin Mexico, where 20 of our machines are installed.' So whatare the prospects for the future?

'Part of our reputationrides on the balancing equipment's performance,' notesWest.

'Since partnering with Schmitt, we have developed aclose relationship, where both companies work together to addressany issues that arise.

'Not surprisingly, we intend tocontinue incorporating Schmitt balancing and process controltechnology on our machines; and not just on valve seat grinders,but on other equipment - such as special purpose grinderswe've developed to produce critical components for aninnovative new medical device.' About Schmitt Europe - basedat the University of Warwick Science Park, Schmitt Europe offersbalancing and vibration control solutions that harness precisionas the key to manufacturing productivity.

The company'swheel-mounted, in-spindle, ring or hydro type automatic grindingwheel balancing systems dramatically improve surface finish andwheel life, while its acoustic emission monitoring equipmentprovides precise monitoring and control of grinding and wheeldressing operations.

Schmitt also offers high accuracy, verticalor horizontal axis component balancing machines, as well asnumerous laser measuring, alignment and surface textureinspection systems..