The challenge of barcode grading in a serialized world
Barcode grading assists in maintaining a standardized level of quality and operability.
The barcode is so pervasive in worldwide commerce that it’s hard to believe its use is still increasing. Now add prescription drug anti-counterfeiting measures to the list.
In November 2018, the FDA will start enforcing the Drug Supply Chain & Security Act (DSCSA) regulation that requires all manufacturers and packagers to apply a unique 2-dimensional (2D) barcode (the GS1 DataMatrix) on every prescription drug container (e.g., bottle/carton and case) to be sold in the U.S. Similar regulations are taking effect around the world that will eventually impact re-packagers, distributors and other supply chain organizations as well.
Although most of us take barcodes for granted, a poorly printed barcode can wreak havoc in the supply chain, potentially interrupting supply and hampering business performance. With this concern in mind, suppliers, wholesalers and brand owners have urged manufacturing and packaging organizations to grade their DataMatrix barcodes to maintain a standardized level of quality and operability.
Scanning vs. grading
Barcode reading (also called scanning) isn’t the same as grading (a.k.a. verifying). Poor-quality barcodes can be read under ideal conditions (e.g., excellent lighting) and vice versa. Simply being able to read a barcode in one location provides no assurance that the code will be readable elsewhere in different surroundings. Barcode grading establishes a baseline for quality that greatly improves the chances for successful barcode scans throughout the supply chain by providing a number or letter score that quantifies multiple barcode attributes against known standards.
GS1 DataMatrix is the ISO/IEC-recognized and standardized implementation of the use of the 2D data matrix barcode, with the GS1 standards body working in close cooperation with regulators and the healthcare industry to develop standards for encoding required serialization information. Barcode grading standards have been developed by various standards organizations (ISO/IEC, ANSI).
GS1 DataMatrix barcode attributes are graded on a number (4-0 - ISO) or letter (A, B, C, D, F - ANSI) scale. The final overall grade reflects the lowest score of any one attribute. Most pharmaceutical distributors are requiring grades of B (3) or higher. The attributes are:
- Decode: The ability of the barcode to be read. If decode fails, the overall barcode grade is a failure.
- Contrast: The difference between light and dark squares or dots in the barcode. Pure black and bright white provide the best contrast/highest grade.
- Modulation: Variation, or differences, in contrast throughout the barcode. Less is better.
- Fixed pattern damage: The quality of the squares/dots that form the perimeter of the barcode, plus the presence of the “quiet zone” surrounding the barcode.
- Grid non-uniformity: The barcode’s fit within specified horizontal and vertical boundaries.
- Axial non-uniformity: Alignment of the barcode with horizontal and vertical axes.
- Unused error correction: Amount of available error correction in a symbol, with 100% unused being the ideal case. Error correction reconstructs data that is lost via damage, erasure of the symbol, or poor printing.
Grading conditions and methods
Conditions for barcode grading (e.g., lighting, angle of illumination, number of scans) are also specified in the standards. Whenever possible, the barcode should be graded in its final configuration (i.e., label on bottle or case).
Two general types of barcode verifiers are available: off-line and on-line. Off-line verifiers are typically tabletop units. On-line graders mount directly to a packaging line.
Off-line graders provide tight control and repeatability of the test conditions per the ISO standard and are easily calibrated. However, operators must pull samples from the line and bring them to the grader. This process takes extra effort and prohibits 100% verification of all codes.
On-line grading offers 100% inspection of every barcode that is printed. Any degradation in barcode quality is immediately detectable and can be addressed. However, it is virtually impossible to replicate ISO-specified conditions with a system mounted on an active line. Suboptimal lighting or vibration, for example, can yield erroneously lower or failing grades due to poor image capture.
Off and on-line systems can complement each other. A good approach would employ off-line grading to establish a baseline, traceable barcode verification process supplemented by on-line verification to provide continuous comparative checks of each barcode.
Printing and substrates
Creating high-quality barcodes is a function of printing and substrates. There are three primary types of systems used to print/mark barcodes and human-readable data – thermal transfer, inkjet and laser ablation/marking.
Thermal transfer applies heat to an ink-laden ribbon, which causes the transfer of the heated wax-based ink onto a substrate and is common for printing on labels on a web. Thermal transfer systems have wear parts and consumables. Poorly maintained systems could result in lighter print (lower contrast and/or modulation) or missing elements (failed decode, lower fixed pattern and unused error-correction grades).
Inkjet printers are often used for printing directly onto cartons and labels. The nozzles must be kept clean and ink level must be monitored/maintained. The carton material should also be unvarnished to allow the ink to effectively dry and adhere to the substrate.
When printing directly onto a carton, it is important for the carton conveying/handling system to maintain firm control of the carton. This will minimize potential for skewed positioning and vibration that could cause an imprecisely shaped barcode (affecting grid/axial non-uniformity), wrongly positioned barcode (causing an inadequate quiet zone), or poorly defined elements.
Laser ablation is the process of removing a coated material from a surface by irradiating it with a laser beam. Laser marking is the process of irradiating a reactive layer of material, which changes color to create the required markings. Laser printing processes are precise and do not consume any materials. A strong contrast in color between the coating material and underlying substrate is needed to get good grades for contrast and modulation using laser ablation. For laser marking, the darkness of the coated substrate when irradiated must be sufficient to contrast the lighter unaltered substrate. Proper handling/positioning of the package/label is again important.
In summary, the use of the 2D DataMatrix will increase dramatically with the advent of prescription drug anti-counterfeiting regulations throughout the world mandating a unique serial number on each saleable unit and shipper label. Manufacturers and packagers will need to ensure that the barcodes used to carry critical product authentication data are precisely and accurately marked and verified. Good packaging and artwork design, properly selected and maintained printing systems, and an effective barcode verification process will all be needed to keep product moving safely and efficiently throughout the global supply chain.
Vantage Consulting Group (vantageconsultinggroup.com) is a focused manufacturing solutions provider helping pharmaceutical and food companies deliver safer, higher quality products. It solves complex manufacturing automation problems – including vision inspection, serialization and packaging – by providing end-to-end expertise that spans strategic guidance, design, implementation and validation.