FEATURE HAZARDOUS AREA EQUIPMENT A LEADING ROLE FOR AOI
BEKA associates is using automated optical inspection (AOI), a key tool for effective quality management, during the manufacture of its display instruments certified for use within potentially hazardous areas. Andy Bonner, MD at Cupio Yestech Europe, explains further
was carried out by a human operator using a camera-based comparator. Now it is performed with a Nordson Yestech benchtop AOI system. As the PCBs within the instruments have become steadily more densely populated with ever smaller and harder to read components, the threat of errors arising from incorrect inspection has grown accordingly. Therefore, BEKA regarded the move to AOI as essential to maintain its compliance capability. BEKA’s experience has shown that AOI
T
he failure of a product can lead to manufacturers incurring safety risks,
costs and damage to its reputation. Therefore, effective quality strategies are vital to any manufacturing process. One such manufacturer is BEKA
associates, an independent British company which designs and manufactures display instruments for use in potentially hazardous areas. BEKA associates instruments comply
with international IECEx standards and the European ATEX Explosive Atmospheres Directive which, for protection by Intrinsic Safety, define the maximum energy that may be transferred to, and may be stored within, the instrument under specified fault conditions, thus eliminating the risk of igniting an explosive material. All aspects of instrument design and
manufacture are controlled by a quality system. Design and quality compliance is verified by a third party Notified Body which includes design assessment against published IEC and ATEX safety standards, plus regular factory and product audits. BEKA associates manufacture a range of display instruments for use with most process control signals including 4/20mA analogue current and both Profibus and Foundation fieldbus digital communications. The third party Intrinsic Safety certification of each instrument demands that every component upon which safety depends must be 100% inspected, to ensure compliance with the certified production documentation. This includes inspection of markings, part numbers, legends and colour coding bands on components down to 0402 size. BEKA regard this inspection as integral to its manufacturing process. Previously, it
16 APRIL 2014 | ELECTRICAL ENGINEERING
Right: as the PCBs within the instruments have become steadily more densely populated with ever smaller and harder to read
components, the threat of errors arising from incorrect inspection has grown accordingly
As part of this, BEKA may populate one
batch of typically 600 PCBs. This quantity would have been a challenge for a human inspector to complete at reasonable speed without error, whereas the required 100% inspection becomes easily manageable for an AOI system that can complete 25,000 inspections in 40 seconds. Problems can be spotted and rectified early - well before the boards are actually needed for production. The AOI system generates a list of any issues spotted - the operator can then
Above: BEKA has utilised a Nordson Yestech benchtop Automated Optical Inspection (AOI) system
has achieved this, with improved throughput and other benefits as well. These can be understood by looking at the manufacturing process that BEKA follows to maintain quality and compliance, and AOI’s impact on this.
BEKA’S MANUFACTURING STRATEGY The process uses a strategy that BEKA refers to as ‘mass customisation’. Within this, they build a batch (or possibly a series of batches) of an instrument model in which the platform of components, PCB and display within an enclosure is mass produced, but then each individual instrument is finished by being tested, configured, scaled and calibrated for its particular application. BEKA benefits as much as possible from mass production economies, while each customer receives exactly the instrument they need for their particular application.
decide which need action and which can be ignored. AOI inspection is used at a couple of
stages within the manufacturing process, which starts with bare PCBs and component reels being free-issued to a local CEM. The PCBs are returned with all SMT components mounted. These are inspected, after which all fault-free boards are available to be re- issued and populated with through-hole components and connectors. Upon return, the boards go through AOI again before being booked into stock ready for later production. Meanwhile any faulty boards can be returned to the manufacturer for timely repair or analysis, while the root cause of the problem can also be investigated and corrected.
WIDER IMPACT OF AOI While the AOI system removes the human element and its capacity for errors and delay, it also makes the inspector’s job more rewarding. Their task now comprises programming the machine for each new board and inspection sequence, while checking and entering component part numbers. This effectively becomes an early part of the QA process. Once inspection starts, component identification - ensuring the right part is in the right place - is key, but manufacturing faults such as solder fillets on components are checked with the side as well as top cameras. Ben Brough, managing director at BEKA
associates, commented, “We feel that the AOI system helps to promote our credibility. Maintenance of our product certification requires that our procedures and drawings are audited every three months. The rigour imposed by the AOI system is reflected in this documentation. This helps to satisfy the auditors that our manufactured instruments truly comply with our certified documentation. “We look forward to progressively deriving further value from the AOI system, by extracting more reports and exploring more programming possibilities.”
Cupio Yestech Europe
www.cupio.co.uk T: 01962 832 654
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