VISION FOR CODING

As consumer demands continue to spiral upwards, and with a blanket of stringent legislation and regulations covering all areas of manufacturing, the need for a product to be traced from “cradle to grave” has been of paramount importance for some time. This not only appeases the regulators, but delights the end users who receive products, supplied as per the agreed requirements.

With the buzzwords of “coding” and “traceability” increasingly everyone’s lips, the rise in machine vision usage became inevitable in order to ensure full traceability could be realized. With system capabilities and costeffectiveness increasing dramatically, vision evolved at a considerable pace across all manufacturing sectors, and the use of 1D (one dimensional) and 2D (two dimensional) codes soon became commonplace. And as good news travels fast, the benefits of code reading and traceability quickly became realized within the logistics sector.

STARTS WITH THE CODE

To ensure traceability, the first essential ingredient is a code. Typically, 1D bar codes encode only numeric, whereas 2D can encrypt alphanumeric (up to 150 alphanumeric are standard in a 48 cell x 48 cell, 10 mm x 10 mm) for a printed label. Usually, 1D bar codes operate against a look-up table whereby a unique serial number is encrypted within the code and referenced against a database. However, without access to the database, which is a common scenario in the logistics sector, the code on its own has no relevance.

In comparison, all 2D code data can be encrypted within it (unique serial number/ date/destination and so on) without any need to access an internal database, allowing for full traceability in the field. This flexibility is proving vital for logistics companies where a significant amount of code reading and product/shipment checks are conducted “on the road” where access to a database would be impossible.

With essential information required on a product to ensure full traceability is achieved and with space often being a key factor, the 2D Data Matrix code ECC200 emerged as the industry standard. Significantly smaller than a standard bar code, the versatile nature of the Data Matrix code propelled it to the forefront of product traceability. It is now in use across a wide variety of products, from car parts and circuit boards, to gas bills and medicine bottles.

Data Matrix code uniquely identifies each product or part manufactured, and a digital imprint marked directly on a part surface can ensure internal traceability on the production line and external traceability during the entire lifecycle of the product.

The primary tasks of the Data Matrix code are to ensure:

• Error-proofing

• Part traceability

• Part authenticity

• Supply chain management

On the standard ECC200, there are 24 square formats and six rectangular formats available. This provides the user with the flexibility to encode between six and 3,116 numeric characters or 2,000 alphanumeric in a single code. However, a more typical figure for everyday use would be around 30-40 alphanumeric characters in a single code.

Information stored on a Data Matrix code can include: date and lot numbers; batch numbers; manufacturer details; serial numbers; and specific product data, such as destination

MARKING OPTIONS

Primary methods used to produce Data Matrix codes for direct part mark identifi cation include dot peening, laser marking, electro-chemical etching and inkjet printing. Important factors infl uencing the marking process decision include part life expectancy, material composition, environmental wear and tear, and production volume. Other considerations include surface texture, the amount of data to be encoded on each part, as well as the available space and location of the mark on the part.

Dot Peening

This is achieved by pneumatically or electromechanically striking a carbide or diamond tipped stylus against the surface of the material being marked and is widely used in the automotive and aerospace industries due to the demanding life cycle requirements.

Laser Marking

This applies heat to the surface of a part that causes the surface of the part to melt, vaporize or change in some way in order to produce a mark. The resulting quality depends upon the interaction of the laser with the material it is marking. A laser can produce both round and square modules and off ers high speed, consistency and a high level of precision. Laser marking is widely used in the semiconductor, electronics and medical device industries.

Electro-Chemical Etching (ECE)

ECE is a process whereby the mark is produced as a result of the oxidation of metal from the surface being marked through a stencil impression. ECE is recommended for round surfaces and for stress-sensitive parts, and is often used to mark medical devices.

Inkjet Printers

These can propel ink drops to the part surface precisely, after which the fluid that makes up the ink dot evaporates, leaving a colored dye on the surface of the part creating the pattern of modules that make up the mark. Inkjet marking provides fast marking of moving parts and offers very good contrast.

READING RIGHT

A code marked on the particular part or product is of little use unless it can be read accurately. This is where machine vision takes up the reins and ensures that full product traceability is achieved.

Traditionally, machine vision systems were used in manufacturing to measure, gauge, verify, inspect and guide, and were often installed at a single point in the production process to carry out one particular task. With both increased customer demand for product traceability and heightened regulations in place, the range of vision systems designed specifically for the ID (identification) market has increased dramatically.

Machine vision systems are used to verify Data Matrix codes and do so with accuracy and reliability. Such is the advanced technology now available, vision systems are more than capable of handling the most challenging high-speed production lines.

For a typical manufacturing application, as the marked part passes in front of a vision sensor, an image of the Data Matrix code is captured and then processed using specialized image preprocessing and identification algorithms. Using this technology, code reading performance remains unaff ected by low contrast or poorly formed codes, which can result from marking issues or general wear and tear of the product.

In addition to reading the data stored on the code, the sensors can also provide production process feedback on the quality of the specific marking, in order to ensure products are marked with the highest quality of 2D codes. Perfecting the quality of the codes to eliminate any waste will lead to improved overall production efficiency and reduced operating costs.

EQUIPMENT OPTIONS

Most machine vision systems are integrated into the production line in the form of fixed-mount sensors, which are used in identifying parts that are handled and moved automatically by conveyor, indexer or robot. In operation, this type of reader is mounted in a fixed position where the mark can repeatedly be placed in front of the reader in either continuous or indexed motion. They can often be configured with either an integrated light source or an external light source, as required by the application.

However, to allow maximum flexibility, advanced ID code readers are also available as handheld devices. These are preferred in environments where part handling is not automated or parts vary greatly in size. This method is ideal for use in the logistics sector where a product often needs to be checked in several locations before it reaches its final destination. Although both 1D and 2D readers are used in the logistics sector, the emerging majority of readers used are 2D areabased imagers. The main reason is that the 2D readers are future proofed, in so far as they have the capability to read both 1D and 2D codes, whereas 1D laser scanners can only read 1D barcodes.

In addition, 1D laser scanners (the preferred method for bar code scanning) suffer from the need to have 80 per cent contrast between the foreground and the background. In comparison, 2D code readers can read down to levels of 20 percent contrast (and sometimes below), as well as being unaffected by code rotation. All these are important factors to consider when investing in code reading technology.

CAPTURING THE ESSENCE

The two key benefits realized by traceability in the logistics sector are more data being able to be stored in smaller areas, and a greater tolerance level to damage within the codes. Traceability using a 2D code allows logistics companies to transport goods safe in the knowledge that each item can be tracked quickly and efficiently at every stage of its journey.

Application uses within the logistics arena include:

• 1D/2D/Optical Character Verification (OCV) to determine where a product is at any time

• Correct label on product

• Correct packaging on product

• Packaging not defective (such as all f laps being closed)

• Correct data/lot code on product, plus quality of date and lot code

• Date/lot code or expiry date corresponds to 1D/2D codes

With the impressive volume of data that can be carried within the 2D code, data formatting functions can be extensively utilized, along with encryption of record separators and industry standard formatting characters, to allow plug and play of the data within the 2D codes, into SAP and various ERP back end systems. Data can be stripped out and sub strings easily formatted directly into back end databases without the need to connect to a database to look up the required information to input.

Didier Lacroix is Senior Vice President, International Sales & Services, Cognex Corporation (www.cognex.com).

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FUTURE-PROOFING BAR CODE INVESTMENTS

Asian supply chain businesses do not need to know their exact bar code technology requirements for tomorrow to make good device decisions today, says PENNY CHAI.

As the region recovers from the economic slowdown which characterized much of 2009, organizations (large and small) across Asia are beginning to plan for the future and reconsider their supply chain technology needs. However, given that technology has a tendency to move quickly and can become outdated before any tangible return on investment, an equipment or systems upgrade program can often be a daunting task for supply chain managers.

The key to a successful technology upgrade in the supply chain sector focuses on how to best achieve a ROI through choosing the right equipment. Supply chain technology – such as bar code scanners and printers – that provides flexibility to a growing business and avoids expensive rip-andreplace upgrades, can help to ensure a degree of future-proofing vital to achieving that return on investment.

HIGHER SCANNING

In recent years, there have been important innovations and improvements in bar code scanning capabilities. For companies that are already using mobile computers with integrated bar code readers in their warehouses, some of the productivityenhancing scanning options offered now were not available during the last deployment. As an example, there are area-imaging scan engines that can be integrated into mobile computers today that can read both 1D and 2D bar codes at distances from an arm’s length to 15 meters.

Such long-range scanning, which was unheard of just a few years ago, is an important advancement because it allows warehouse workers to meet all their scanning needs – such as scanning a shipping label from arm’s length away during receiving, to scanning a small part label from inches away during picking, to scanning a high-rack location label 15 meters in the air – with a single device without having to limit business processes around the range of the scanner, or to purchase and maintain separate devices. If current or future business processes call for reading bar codes at a variety of ranges, area imagers with range flexibility are an excellent choice.

Importantly, imaging technology – like that provided within today’s increasingly sophisticated mobile computers – provides more investment protection and future proofing than laser scanners because imagers can read and decode all 1D and 2D bar code symbols, as well as being equipped with features such as megapixel cameras and enhanced mobile document imaging (eMDI).

Mobile computers with imaging technology are extremely useful in supply chain settings as they can be used to take time-stamped digital pictures of goods at receiving bays to document damage that occurred before the facility took possession, or to photograph outbound goods to prove they were shipped in good condition. Imagers are also at cost parity with laser scanners for integration with mobile computers, so by specifying them, companies can protect themselves from having to upgrade in the future without spending more now.

PRODUCTIVE PRINTING

In addition to evaluating bar code scanning technology, Asian supply chain businesses also need to think about bar code printers and the diff erent ways they plan to use them in their facility. Combined with advanced scanning technology, mobile bar code printers can enhance operations like receiving, put-away and picking. And wireless mobile bar code printers allow workers to generate and apply labels literally anywhere in a warehouse or factory.

By printing labels on demand, at the point of activity, workers print only the labels that are needed and are much less likely to apply the wrong label to an item or package. Additionally, positioning the printers closer to areas where the work actually gets done also eliminates trips back and forth from the workstation to the centralized printer.

These walks to the printer may take only a few minutes, but multiplied across dozens of workers on multiple shifts, they represent an opportunity for tremendous time savings and productivity improvements. Eliminating unnecessary walking also helps eliminate distractions that lead to labeling errors and lost productivity.

FEATURES FOR FLEXIBILITY

Mobile bar code scanners and printers alone won’t future-proof warehouses against future needs; wireless networks must provide a migration path as well. Scanning technology add-ons like voice, video, locationbased services, remote management and other beneficial transmissions are increasingly finding their way into operations. Even if organizations don’t envision using advanced communications and supporting different transmission types, they can prepare for them at no incremental cost.

To adequately protect their technology investments, organizations throughout Asia should also look closely at their bar code device service maintenance agreements to ensure that these carry both depot repair and on-site service options, which bridge productivity gaps to ensure business continuity and worker productivity.

Asian supply chain businesses do not need to know their exact bar code technology requirements for tomorrow to make good device decisions today. Rather, they need to be able to identify those features that provide flexibility. It makes good business sense to invest in the technologies of tomorrow, as it helps to minimise the cost of upgrades, bridging the gap between the old and new environments of a growing business.

Penny Chai is Channel & Marketing Director for Intermec Asia-Pacific (www.intermec.com)