ase Studies

Advances In Automated Zero Defect Controls

Millions of fasteners are installed into numerous applications, many of which are automatically inserted into the component. The need to achieve consistent performance becomes paramount if automated process control is to be effective, thus avoiding machine stoppages due to rouge defect items entering the component supply chain.

Driven by 100% defect free requirements the need for accurate component compliance is very much to the fore when reaching the necessary criteria of Zero Defect and the conformity of Parts Per Million (PPM), as well as total traceability.

In recent time the advances in high speed quality inspection systems has dramatically reduced the error rates of non-conforming fasteners entering the process chain, thus ensuring that damage limitation becomes a thing of the past.

The Process Fundamentals.

Firstly we need to be acquainted with the terminology of the primary elements of the quality inspection concept with regard to verification systems.

  • Zero Defect - A quality concept and procedure for total Zero Defects. The acceptable achievement of agreed levels of defective Parts Per Million.
  • Parts per Million – Conforming Parts Per Million required for acceptance and compliance.
  • Traceability - Lot control and traceability in order to achieve quality assurance

These fundamentals are process related and at the behest of the specifier, additional criterion may be requested, depending upon the stated product accomplishment. Therefore, effective procedure’s and systems are vital to ensure that the entire chain of events, in terms of capability, is secure and conforms to the requested standards.

Sorting and Verification – Commingling.

Inevitably, mixed product can be problem for both the installer as well as fastener supplier!

Accidents will happen! Depending upon the quality specifications and criteria, product traceability will be the first issue to consider if recovery of the batch, or batches, is being considered. If a recovery is to be actioned, then high speed sorting equipment is available to assist installer and fastener supplier, making hand sorting thing of the past!

The system provides much more than just commingling problems, it can seek to confirm non-conforming defect product as well.

Advanced Sorting and Verification – Defect Measurement and Inspection.

Using high-speed inspection equipment that can perform 100% inspection procedures on multiple features and more interestingly, metallurgical properties can also be accessed, within the requirements of Zero Defect conformity.

Mectron's QuAlifier provides clientele with both laser and Magnetic Imagery™ inspection methods. The patented laser portion utilises six lasers to provide twelve inspection points through 360º. Each laser inspects two points, which are 180º from each other on the surface of the component.

As the component travels down the V-track through the laser display each inspection point scans the entire length of the fastener. The six lasers combined are capable of inspecting 84 different features with a diameter repeatability of 0.01mm (0.0004").

A component profile is displayed on the instrument's touch screen for each of the six lasers. The system software utilises a multitude of inspection techniques that enables the user to inspect for physical defects and to eliminate any non-functional fastener in the batch.

By simply passing a known conforming component into the Mectron inspection machine, automatically a profile display appears on the instruments touch screen. Utilising the component drawing, it is then possible to set up as many gauge zones for each of the 6 lasers. Each gauge zone can be customised and identified in accordance with the component part, its number can then be saved for recording purposes and retrieval.

These techniques provide the flexibility to measure from intricate data numbers to straight model profile comparisons. The QuAlifier can detect different problems associated with washer sems units, thread locking patched fastener products and flanged hexagon products, all of which pose special challenges due to orientation changes varying by component part. 

Since the inception of the QuAlifier extensive research and development has been on going. Software enhancements have help resolve special problems arising from the increasing complexity of part configurations and manufacturing defects.

The Magnetic Imagery element of the system is an advanced eddy current technique, which provides the most complete metallurgical inspection option available. This system, using the signature Shadow Gate™, provides the user with the entire part signature compared to just a peak value offered by other systems. The instrument develops a magnetic image of each part as it passes through the QuAlifier to develop the part's signature.

This full signature provides the opportunity to detect the most critical metallurgical defects such as cracks, material mixes and hardness by a visual deviation in the magnetic display. The percentage of deviation is also displayed and acceptable limits can be quickly defined using the touch screen programming capabilities. The inspection system equally caters for components that are plated.

With today's increased sensitivity to heat treated products as a result of the USA Fastener Quality Act and other product liability legislation, the use of Magnetic Imagery is essential to the fastener manufacturer as well as to the end user of the product if conformity is to be ensured. This is just one reason that GM's Delphi Group has mandated metallurgical testing be performed on all fastener products supplied to them with this system.

Most recently, different fastener manufacturers in the USA, United Kingdom, France, Germany, Italy, Brazil, Australia and China have installed Mectron systems. ISO certification and the importance of supplying Zero Defect products have been drivers in this improvement towards enhanced quality assurance. Results for rejects at the stage of installation have virtually disappeared and defect free component systems are providing tangible cost benefits for both fastener user and supplier.

Churchill Products Ltd is the major zero defect inspection specialists company in Europe, verifying 4 million fasteners and allied components weekly.

Submitted by Simon Cox – Churchill Products Ltd.

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