Product category:
Pressure sensors
News Release from: Kistler Instruments | Subject: Piezoelectric sensors
Edited by the Engineeringtalk Editorial
Team on 18 January 2005
Piezoelectric sensors watch latch
production
ArvinMeritor produces six hundred latches an hour, twenty hours a day, five days a week all of which must be tested before being released for delivery to the customer.
Few of us give much thought to the mechanism that keeps the door of our car secure, yet easy to open when we want to get in or out That mechanism, usually known as a latch, is a vital link in the chain of safety that is an essential part of modern cars
Not only must the latch operate smoothly and easily under normal conditions, it must hold the doors closed during an accident.
As a major supplier of latches to car manufacturers in the UK and Europe, ArvinMeritor produces six hundred latches an hour, twenty hours a day, five days a week all of which must be tested before being released for delivery to the customer.
Just one out of spec latch in a delivery can result in the whole batch of several thousand being rejected, not to mention the damaging effect on the company's reputation.
One hundred per cent testing at this rate of production must be an automated part of the total production process and ArvinMeritor turned to Kistler Instruments for a reliable, workable and affordable solution to the problem.
The solution ArvinMeritor Senior Engineer, Terry Heynes, and Kistler Application Engineer, Eddie Jackson, developed was to use a piezoelectric sensor to measure the force needed to actuate the latch and a miniature linear displacement sensor to measure the distance travelled during latch operation.
The output from the force and displacement sensors being fed into a Kistler CoMo IIS system that monitors the data to ensure that the force at critical points of operation is within specification.
The CoMo IIS displays the curve of force against displacement and the preset values to provide an instant, visual confirmation that the system is operating correctly.
Once a latch has been confirmed within specification, a laser coder burns a unique identifier onto the latch body.
Any latch failing, passes through the laser coder without being marked.
At the end of the line, each latch is presented to a packer as accepted or rejected and is placed by hand into the appropriate bin.
To ensure that the latches are placed in the correct bin, all rejected latches must pass through a light beam sensor mounted above the reject bin.
If this does not happen, the line is stopped until the error is rectified.
All rejected latches are passed to a manual test station for confirmation.
All the data collected by the CoMo IIS, linked to the unique identifier for each latch, is uploaded to the company's mainframe computer via an Ethernet LAN.
The data on every latch are retained in archive so that any failures can be traced back to the point of manufacture easily and reliably at any time in the future.
This is especially important in the event of a product liability claim as it allows confirmation that any individual latch was within specification when it left the ArvinMeritor plant.
Senior Engineer, Terry Heynes, says that automatic, quality control monitoring is essential to keeping tight control of production costs, essential in a highly competitive market.
The Kistler sensors and CoMo IIS system provide a very cost effective solution to the problem of reliable product testing at high production rates and generates the data needed for protection against the possibility of future product liability claims.
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