QMT Features: May 2007
Inspection savings
Pressings, inspected and correlated to the CAD model of a car, saves West Bromwich Tool £69,000 in labour each year.

Many suppliers in the UK automotive sector do not realise that they will soon have to provide inspection reports on manufactured components in a  particular  format.  Instead of supplying a list of dimensions supported by statistical process control charts, the results will need to be referenced to the  intended vehicle's car-line co-ordinate system, a datum axis running longitudinally from the middle of the front  axle.

This is already the case in Sweden, where Volvo Cars Corporation and Saab AB stipulate that all subcontractors, from Tier 1 right to the bottom of the supply chain, must submit metrology data in a form that can be correlated with  the CAD  model of the entire car. In this way, the OEM is able to assess tolerance build-up, ensure that components will assemble correctly, and carry  out virtual 'gap and flush' checks. UK carmakers have announced that they intend to follow suit within the next few years.

One Midlands pressworker that is ahead of the game is West Bromwich Tool and Engineering, which has installed a Metris LK Ascent co-ordinate measuring machine (CMM) and CAMIO software capable of providing car-line inspection data.

There are few automotive OEMs in the UK whose vehicles do not include a component from this West Bromwich supplier, predominantly on or behind the dash or inside the doors, but also in cosmetic positions, such as tread plates for covering the rear load space sill. Recently, the company was awarded the contract to supply two assemblies  for  the new BMW Mini - the lid and chute for the airbag module, and a bracket   assembly for the CD changer.

The extra business prompted a £400,000 investment in further robotic welding cells  and the new computer-controlled CMM, which  replaced an older manual model.

Commented Simon Bullows, quality manager at West Bromwich Tool and Engineering, "Our  customers are demanding ever tighter tolerance parts and assemblies, pressed and  welded to typically ±  0.25 mm. They also want reliable  and  repeatable inspection data, especially for safety-significant components, to prove we are achieving a minimum of Cpk 1.67 process capability, although we aim at 2.0, ie six sigma."

The new CMM provides the required SPC reports automatically, supported by graphics, as the inspection cycle progresses.  "The LK Ascent is simple to use, even by new operators after a minimum of training, as we can  import photographs of components and fixtures into a graphical front  end to show how they should be set up,” says Simon Bullows. “It is then a simple matter to click  on a photograph to select the appropriate inspection routine. Most importantly, the CAMIO software allows us to orientate each  component  on the CMM in car-line, so all the measured results are referenced  back to  that datum. It  will not be long before it will be impossible to win business for major car  programmes without this facility.  An alternative would be to subcontract  the inspection, but outsourcing such a key function could have negative implications for us in terms of cost, delays and quality of service."

A further benefit of the CAMIO software is its ability to import an OEM's CAD model of the component to be manufactured.  The IGES data can then be used to create a program to inspect the part or assembly on the CMM, before it has been pressed and/or welded; even before the  press tool has been made.

Unusually, West Bromwich Tool and Engineering has evaluated the overall financial benefit resulting from the number of operator hours saved using the LK CMM and software, compared with the old manual machine.  The result is £69,000 per year, which  will translate into a very fast return on  investment.

The  firm was assisted in its selection of the LK CMM and software by Amrit Singh of  the Premium  Automotive Research and Development (PARD) programme within Warwick  Manufacturing Group’s International Automotive Research Centre,  located at the  University of Warwick. Mr Singh works on the Craftsmanship Project, which focuses on raising the quality of  luxury vehicles as perceived by customers.  Ford’s Premier Automotive Group, which manufactures Jaguars and Land Rovers, is a key partner in the venture and so too is Metris. Said Mr Singh, "We are currently working with 16 tier-one automotive  suppliers in the West Midlands, some of which are West Bromwich Tool and  Engineering's customers.  So we are ideally placed to know what they are looking for in their suppliers.  In general, it is better consistency of parts and of measurement data being passed up the supply chain.

 "We help subcontractors to understand how to use inspection data to highlight process capability problems, if there are any, and to present data using various industrial methods to suit the needs of their  customers." l

Metris UK E-mail: sales@metris.com

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