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Cliff Holste

Supply Chain Digest
Material Handling Editor

Logistics News - Sorting It Out

Cliff Holste is Supply Chain Digest's Material Handling Editor. With more than 30 years experience in designing and implementing material handling and order picking systems in distribution, Holste has worked with dozens of large and smaller companies to improve distribution performance.

January 25, 2017

Sorting It Out : Laser & Camera Based Scanning Solutions


Eliminating No-Reads Improves System Performance

 

Today’s highly mechanized order fulfillment systems would be all but impossible without dependable and accurate data collection devices. Laser scanners have long been considered the cornerstone of barcode scanning. They continue to be an effective tool for scanning bar codes on cartons and other items moving on conveyor systems at speeds up to several hundred feet per minute. There is a huge array of laser scanners available that are suitable for a broad range of applications. They can accommodate:

  • A range of bar code label placement on cartons and other items
  • Less than perfect labels
  • Conventional and two-dimensional bar codes.

Holste Says...

While laser scanners will continue to play an important role going forward, in recent years camera based scanners have become more cost competitive – especially for DC applications where reducing the frequency of no-reads is an on-going cost avoidance objective.

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Also worth noting are the compact fixed-position scanners that fit in cramped spaces making data collection possible at previously inaccessible locations.

While laser scanners will continue to play an important role going forward, in recent years camera based scanners have become more cost competitive – especially for DC applications where reducing the frequency of no-reads is an on-going cost avoidance objective. For example – suppose a DC with a throughput of 50,000 packages per day has a relatively conservative no-read rate of 1.5%. Still that’s 750 packages per day that must be processes off-line. If each no-read takes a worker two minutes to handle at a cost of $20 an hour, that’s an annual cost of about $130,000. For that reason, business managers who are looking to improve the performance their current laser scanning solution are considering adding cameras.

While laser scanners have software that can decode less than perfect bar codes (smudged, torn, and otherwise damaged) and correctly fill in the gaps in the data, no-reads are bar codes that for whatever reason cannot be decoded by the software. This is where cameras have a huge advantage over lasers – the ability to capture an image of the whole label or scanning area. By viewing a snapshot, a worker can immediately see the reason for the no-read and address the issue on-line. The expense of manually processing no-reads off-line decreases while system throughput increases. In addition, the camera image data can be used for optical character recognition (OCR), further optimizing the process of resolving no-reads and increasing throughput.

Manufacturers are replacing cardboard cases with the lighter and cheaper plastic shrink wrap package. Cameras can read barcodes under these types of reflective surfaces better than lasers. This is because a camera provides the full 2D image of the barcode (so it has full spatial information to work with). Therefore, if only part of the bar code is distorted or blocked by reflection, the camera may still be able to decode the data.

Finally, all other things being equal, a camera can read barcodes faster than any other type of bar code reader. This is important because conveyor speeds are increasing to speeds unheard of just a few years ago. At the same time new induction and sorting software is decreasing the gap (distance between cases), which in-turn can significantly increase the cases/minute rate of an existing systems.

Comparative Benefits

This does not necessarily mean a camera is the best choice for every application. Laser scanners have the advantage of being able to provide greater depth of focus for a given bar code density. This may be critical in applications that handle a wide range of pitch and skew with varying sizes of packages.

Most laser systems are simpler and easier to install than camera systems. Generally, cameras take longer to set up. And, if the application calls for image capture, then it must be integrated with an image server. On the other hand, new-generation camera systems equipped with an auto-configuration wizard, integrated decoding and illumination, can actually be installed faster and at a lower cost than lasers – the choice really depends on the application.

Final Thoughts

As one would expect the choice between laser and camera based scanners depends on the best fit between the needs of the operation and the scanner’s capability. In some applications integration of both technologies may be required to produce the desired result. Automated scanning is a highly specialized area that offers real potential for improvement. The best opportunity to learn more about this important technology can be found at: ProMat 2017 April 3-6, 2017, Chicago, IL. www.promatshow.com

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