FEATURE CODING, MARKING & LABELLING MACHINE READING MAKES ITS MARK
Machine-readable markings have become an essential part of manufacturing and asset tracking, but failing to verify their quality could cause huge problems. Alastair Morris, sales director at Pryor Marking Technology, reveals all...
T
he use of machine-readable codes to enhance part identification is on the
rise. While the aerospace sector has blazed a trail in this area, other industries are now following its lead. For suppliers, part marking is fundamental to OEM component specifications, and many incorporate it into their internal quality and traceability processes. Most modern component marking standards use 2D data matrix codes. These can be applied in a variety of ways, including dot peen, laser, mechanical or chemical etching and ink jet printing, while redundancy and check features ensure that the code remains usable even when it is dirty or damaged. In order to be fit for purpose, a mark
must be readable. For this reason, all common marking standards include stringent quality criteria covering dot size, shape, position and contrast under suitable lighting. Most organisations use some kind of verification process in their operations – though some have drawbacks, which could result in a ‘verification pass’ that does not meet the standard.
VERIFICATION METHODS The simplest verification process involves reading the mark, either directly after application or later in production. Machine reading is fast, fully automatic and easy to integrate, even into high- speed production operations. However, companies can fall victim to the power of automated reading equipment. Modern code readers use sophisticated image processing to read damaged, poorly lit or poor quality marks. Operations and maintenance teams can read more marks than ever before, but it can create problems later on – if a mark needs to be read with an inferior quality reader, or if it is damaged.
22 DECEMBER/JANUARY 2018 | AUTOMATION
At the other end of the scale, marks can be inspected in the quality laboratory, with specialist equipment. This ensures that a mark meets the full specification requirements, but is time consuming and expensive. Companies can usually only inspect a small sample of parts, so may miss individual deviations. If a mark fails the laboratory check, other marked components from the same batch may need inspecting or rechecking.
DUAL PROBLEM If product markings do not comply with required standards, two problems can arise for manufacturers. First, a non-compliant mark might be
rejected by the customer, if their equipment cannot properly read the parts or if their own quality checks identify deviations from the standard. This can be costly and disruptive, especially if parts have already been shipped when the deviation is identified. Second, a ‘non-compliant’ mark needs
only minimal degradation before it becomes unreadable. This stores up problems for in-service use, especially in ‘smart’ manufacturing environments where marks are used to track components during production.
VERIFIED SOLUTIONS Technology offers an answer, in the shape of dedicated verification systems, which can be installed on the production line, and directly on the marking equipment if necessary. These work like conventional code reading systems, but use a high resolution imaging camera, and tight control of lighting and reading conditions. They check that the correct data has been marked on the part, and ensure that the size, shape and position of the dots comply with standards. A single camera
can do this within the cycle time of the machine – as rapidly as two parts per second in high-volume applications. The most advanced verification systems do not simply check and prove the quality of product markings, but can improve and maintain that quality. Some have built-in intelligence that identifies common marking issues and provides advice to line operators: if peened dots are becoming too large or small, relative to the cell size of the mark, the system will advise that punch force is adjusted, for instance. They can also perform ‘condition monitoring’ to identify subtle changes in mark geometry that might indicate the need for adjustment or recalibration.
CHECKING SERIAL NUMBERS The latest automated verification systems not only work with machine-readable 2D data matrix codes. They can also verify the quality of human-readable codes, such as serial numbers or automotive VIN codes, and integrate with ERP or MES systems – checking each marked character against manufacturing records and providing an accurate quality score. This level of integration brings automated verification into environments that have been difficult for machine vision systems, such as automotive body markings where the colour or contrast of the mark may vary depending on the colour of the vehicle. The most advanced systems for these applications can adjust their lighting and calibration settings automatically, providing a robust read for every model and colour combination on the line. Many industries recognise the value of
part identification using machine- readable codes, because it boosts quality and traceability, ensures that the correct parts are used in the right places, and quickly identifies affected parts. However, it is vital to ensure that these component markings are properly verified – otherwise they will fall short of the quality and traceability demands of OEMs.
Pryor Marking Technology T: 0114 276 6044 E:
info@pryormarking.com www.pryormarking.com
/AUTOMATION
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