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When is RFID better than barcode?

15 December 2008

Tim Stokes, RFID and Barcode Product Manager of SICK (UK) suggests that a look at advantages and limitations of both technologies can help the food industry to make informed choices



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RFID promises much for the food processor in terms of enhanced data capture and security, but investment is high and the extra information provided may be unnecessary. Recent developments in direct part marking, particularly in the humble barcode, are the product of a long evolution and series of step changes and offer cost effective alternatives to RFID.

RFID works by marking an individual part, product or container with a transponder tag. The signal to and from the tag is both transmitted and picked up by antennae usually positioned on the conveyor line. The data is read by an interrogator system and communicated to a PC or other control systems.

The benefits of RFID

RFID can store large amounts of complex data, including complex security codes. Tags are reprogrammable and can be added to, and can be read when obscured (e.g. splashed food stuffs) or even when out of line of sight (within limits) and over a comparatively long range.

However, data quality is variable when codes are read at the extremes of range (around 6m for an unpowered tag), products must be spaced to avoid signal overlap and RFID cannot be used to pinpoint an object anywhere in the factory.

Read rates and accuracy are high when the application is successful but are not actually better than for barcodes if the barcode reading environment is favourable. UHF systems are close to those used in microwave cooking and may be distorted or masked by water contained in food or personnel.

To achieve high end RFID performance with ranges over 700mm (HF) or 3m (UHF), and conveyor line speeds over 1.5m/s, food processors need to consult systems providers with extensive high end applications experience.

The case for barcoding
Simple 1D barcoding, and 2D datamatrix coding can carry extensive amounts of data, and can be sized and shaped to suit the application and read distance; reading is line of sight. In addition, the codes can be applied by printed label or by Direct Product Marking, i.e. direct printing (inkjet, transfer, etc), laser etching, tattooing, etc to the product.

The 2D datamatrix coding carries more data in far less space than barcoding; direction of reading does not matter. Tolerance of poor contrast and error is high but the range is shorter and needs accurate placement.

1D barcoding is available in different formats, can be printed from a PC and read at speed with flexibility in orientation. It is cheaper than 2D, with a high informational density but requires high contrast printing.

Three questions to ask

To gauge Return On Investment (ROI), we suggest this three step acid test as a preliminary to a detailed cost analysis.

1. Do you need to write to the label? A = Yes B = No
2. Can the reader see the label every time? A= No B = Yes
3. Is the environment too dirty for clear barcode reading? A = Yes B = No

Straight As, of course, suggest an RFID system could be best, 3 Bs probably not, whilst a mixture will mean you will have to weigh up the costs and benefits very carefully.

The hidden costs and some ROI examples

A good quality, reliable 100% tested passive tag currently costs around 50p. If a cheaper, batch tested tag is used on a high value product, but suffers a 5% or worse failure rate, a lot of money could be lost. Recently, for example, cheap tags added to animal carcasses unfortunately resulted in inadequate stock control and expensive waste.

RFID success

Where RFID has made a real contribution to efficiency and costs is in permanent captive tagging of distribution containers for retail distribution and re-used. A typical pilot project with a chilled food operation in the West Country used SICK high frequency interrogators for a high speed (2.5m/sec) conveyor. To date, this has produced more than 5 million asset readings over two years and the assets and investment are retained within the food company, so that the initial cost has been spread over a long time and many individual units.

In conclusion, despite the claims and enthusiasm that accompanies the promotion of any new technology, the manufacturer needs to take a rational look at the costs versus investment and the possible benefits accruing. High quality data is essential in complex operations, but a balanced decision on the best route to obtaining the data required is more likely to deliver a favourable return on your investment.

SICK has produced an easy-to-use guide to Direct Part Marking. For a copy or for more information on the SICK Barcoding, Direct Part Marking and RFID systems please contact: Ann Attridge or Andrea Hornby on 01727 831121 or email ann.attridge@sick.co.uk or Andrea.hornby@sick.co.uk


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