Focus on label markets: Industrial labels

In almost all cases, industrial labels must be machine-readable, and be adapted to the industrial process in question. The industrial label is also generally a key component of a track-and-trace system ensuring traceability and combatting the counterfeiter. The different types of industrial end-user are very varied. Some of the main end-user industries are shown in the chart (right), together with the main labeling requirements.

More details on each category are given here.

Some regulations are common to all industrial labels. Most apply only to certain categories. Below are some of the rules which label converters must comply with, and which designers, label and pack producers must all be aware of when selecting types faces, substrates, inks, printing processes, label types and methods of application.

REGULATORY BACKGROUND

There are many regulations governing industrial labels, just as there are different categories of risk. Fire extinguishers for example, which may be kept for many years in hot, humid or weather-exposed places, must have a label which retains its color, legibility as well as its resistance to corrosive chemicals over many years.

Automotive and tire labels, as described later in this article, are also subject to strict labeling requirements. One of the most stringent regulations concerns the labeling of hazardous and non-hazardous materials in drums or barrels. For this there exists now (at last) a single Globally Harmonized System of Classification and Labeling of Chemicals (GHS).

This is an internationally agreed-upon system, created by the UN beginning in 1992 and now fully implemented by all major trading countries. It replaces the various classification and labeling standards formerly used in different countries.

The GHS requires manufacturers and exporters of chemicals to provide a label that includes a harmonized signal word, pictogram, and hazard statement for each hazard class and category (see Figure 7.1). It must also state clearly the nature of the hazard and the precautionary measures necessary. Particular care must be taken to identify clearly chemicals which, though inert in themselves, can become volatile if mixed with, or even stored with, other chemical products (failure to respect this precaution is believed to have been the cause of the disastrous explosion at a fertilizer plant in Toulouse in 2001, which cost 31 lives and injured 2,500 people). 

However, the most hazardous products are drums containing certain chemicals, explosives, petroleum, or radioactive materials. In the US, labels for these products must comply with complex and sometimes contradictory safety standards established by organizations like the EPA (Environmental Protection Agency), OSHA (Occupational Safety and Health Administration), and the US Department of Trade. For Europe, the EU Directive 2002/95/EC applies. Drum labels in all cases must be permanently applied and must stand up to the harshest of transport and storage abuse.

If hazardous chemicals are to be transported by sea, drum labels must now also comply with guidelines such as British Standards BS5609 for weather and salt water immersion. Researchers at one of Avery Dennison’s laboratories have developed a labelstock which retains its adhesion even after three months’ immersion in seawater; for this product the company has received a special certification from the globally recognized product security consultancy Underwriters’ Laboratory (UL).

Such is the complexity of regulations for durable industrial labels that some labelstock producers offer a service to help converters get fast approval.

SUBSTRATES, ADHESIVES, PRINTING PROCESSES AND INKS FOR INDUSTRIAL LABELS

A) Substrates

Industrial labels are nearly always self-adhesive. Face materials for industrial labels come in many varieties, but heat-resistant filmics predominate.

They are most frequently white, corona treated, and with extremely high tear strength in combination with good weather and chemical resistance.

They may be overprinted with a clear varnish or overlaminate (usually a clear PET film) to give added protection. Polyester based labeling materials in particular have in recent years come a long way in terms of durability and availability. They now come in high gloss, mat, white and various colors. With the higher temperature ratings of today’s polyester labeling materials, a polyester can often be used to lower the cost of labeling in place of some polyimide materials. This substitution is happening particularly in the industrial labels sector.

Metallic foils and metalized substrates are often used for applications such as rating plates, under-the-bonnet, electrical and electronic goods labels.

Whatever the face material used, if the label is destined for outdoor use it needs to be proof against light, and also to withstand a wide ranges of temperatures, water contamination, humidity and abrasion. Inventory control for example is a necessary function in any company, and some fixed assets may have a life of several decades, during which time the identifying label must continue to be legible (and usually machine-readable). Such labels are generally one-color self-adhesives (though sometimes color-codes are used for different classes of asset), and are individually generated using a computer-linked thermal or thermal transfer printer.

Industrial labeling also makes extensive use of thermal transfer (TT) or laser printed labels. These will often be pre-printed with standard information (e.g. a logo, or company name) then just-in-time TT or laser printed with the variable data (which could be a serial or batch number).

Sometimes the label converter will do both operations, but generally the variable element is added by the end-user. By pre-printing part of the label the cost per label can be reduced.

B) Adhesives

Many adhesives are used for self-adhesive industrial labels. However rubber based p/s adhesives generally have poor long term aging properties, and for most applications UV acrylic adhesives are preferred, because they give a strong and permanent bond on difficult surfaces, and do not require solvents. Challenging surfaces for industrial adhesives include: glass, metals and polyester. UPM’s RX15 is a catalyst activated adhesive for high-temperature automotive labeling, and Wacker has launched a range of silicone polymers for industrial labeling.

C) Printing processes

The durability of pre-printed and non-variable industrial label printing is the most important factor. High performance durable printing using screen process, and hot stamping (using both pigmented and metallic foils), as well as more conventional printing using special inks. Today, industrial labels may use quite sophisticated inkjet printing technology (although this does not always give sufficient durability), as well as laser printing, laser etching and engraving.

D) Inks

Broadly, three families of inks are used for labels: solvent-based, UV curable, and water-based. Solvent inks give good and durable printing results, but are less and less used, as they are not considered to be environmentally friendly. Water-based inks use inks with colorants that are dispersed or dissolved in water. They do not react well to water or humidity and are not suitable for many industrial label applications. UV inks contain pigments, pre-polymers and UV-sensitive materials. They are ‘dried’ (or cured) by a chemical reaction to UV light. The hardened ink has excellent resistance to water and fading. UV flexo and UV inkjet are the preferred medium for many industrial labels.

THE INDUSTRIAL LABEL AS PART OF A LOGISTICS MANAGEMENT SYSTEM

Label converters need to understand at least the broad outlines of their industrial customers’ logistics and warehousing system. This is best seen in the requirements for medical, automobile and aerospace parts, where security is paramount. Labels will be used a) on the individual part, b) on the case and c) on the pallet. For each of these levels, the labeling requirement will be different but each label must conform to the logistics system used.

For industrial labels, even more than for other categories, barcodes, data matrix codes and QR codes are almost universally used. Barcodes have the advantage of being cheap to create and to print. Their main drawbacks are that they do not identify unique items and that scanners need a line of sight to be able to read them. QR and datamatrix codes (see box) are more expensive to create and manage, and can be used to identify single items, but still need line-of-sight reading. RFID-enabled labels are the most complete (and most expensive) solution, since an RFID-label-based logistics management system can not only determine the number and types of units in every pallet, it can also record date/time of entry/exit from the factory or warehouse. This highly efficient system however requires goods to pass under an RFID-enabled portal each time they are moved to a new location. The costs involved are the main reason why this type of logistics management is not widely used.

SHOCK AND DAMAGE INDICATORS

For the shipping of fragile goods it is important to check at each stage of the transport whether the consignment has been dropped or exposed to seawater. Smart labels containing two or more chemicals are used to give visual warning (for example by a change of color) that an incident has occurred. Such labels are generally single-use, but multiple (re-settable) indicators are also used. Other specialty labels can signal an alert when a product has been tilted. Battery-powered models for all these labels can in addition indicate the time at which the incident occurred. All devices are used in evidence to settle insurance claims.

WHY ARE RFID LABELS NOT USED MORE OFTEN FOR INDUSTRIAL LABELING?

When RFID (radio-frequency identification) labels became generally available in the 1990s many people foresaw their general use in keeping track of any movable asset. Everything from a fleet of hire cars to a batch of hospital trolleys can usefully be tracked and managed via an RFID label.

The reason that this has not happened (much) is firstly the cost, secondly the less than 100 percent reliability of the labels, and thirdly the fact that they can only be machine-read at short range. If a hospital trolley gets pushed into the river, no amount of RFID labels will locate it. Even ‘active’ RFIDs (with battery and transmitter) can only emit a weak signal, and none at all when the battery runs out. However, terrorist attacks have changed people’s priorities, and within the past three years airlines have reviewed all their security arrangements: one of the weak points found was the absence of security for aircraft galley equipment and trolleys. To remedy this, several RFID-based solutions have been developed.

One recent development is called ‘Air-Seal’. This ‘smart’ closing and securing device is based on encrypted banking algorithm technology. When the smart closure is fitted, only authorized staff with the correct ID-tagged security device will be able to open the trolleys. Every action performed on every trolley along the whole supply chain can then be electronically monitored and logged, regardless of location. The system, developed by several European research institutes, is said to be ‘tamper-proof, and impossible to duplicate or infiltrate’ (see Figure 7.2). At present the system is too costly to install in anything but high-risk locations like aircraft, but similar applications such as hospital equipment could well follow soon.

END-USER APPLICATIONS - AUTOMOTIVE AND AERONAUTICAL LABELING

The average automobile can contain up to 300 labels, some visible, others seen only by your garage mechanic. In most cases they must remain visible and in place over the life of the vehicle, and must resist weathering and extremes of heat and exposure to oils and greases. The same requirements apply to trucks, vans, agricultural tractors and mowers and earth moving equipment, while aircraft will have labels running into thousands covering everything from engine parts to cabin safety notices. Major aircraft manufacturers like Airbus and Boeing have their own labeling standards, often more stringent than the legal requirements. Similar stringent requirements are required for the labeling of aerospace components.

Automotive parts: the ISO TS 16949 standard stipulates that in serial and spare part production in the automotive industry all elements contained in the final product must be identifiable at all times and uniquely labeled with information such as manufacturing date, expiration date or batch number. In the United States an independent testing institute (Underwriters Laboratories Inc., or UL) inspects products for compliance with consumer protection standards. UL certification is an essential criterion for products supplied to the American automotive industry.

Similar regulations exist in Europe and in most other countries. Automotive parts generally carry a secure label, sometimes with RFID chip. The prevalence of counterfeit car parts, and the danger that can result from using substandard parts, means that security labeling (using holograms, safety seals, and so on) on such parts will soon become universal. 

This applies both to parts for new vehicles and for spares for repair garages.

Labels on new vehicles: each new vehicle, worldwide, has a unique Vehicle Identification Number (VIN), also called chassis number. The VIN label must be securely and permanently fixed (usually to the engine block). It is a favorite target for counterfeiting by unscrupulous used-car dealers. Each label on a new vehicle must conform to rigorous specifications. UV-cured acrylate hot-melt adhesives for example provide especially strong adhesion, even on highly curved, rough, dusty and oily surfaces; face materials must be easily printable, yet scratch and smudge resistant.

All this applies to the visible labels, and particularly to under-the-hood labels which need to withstand high temperatures and still remain legible throughout the life of the vehicle.

Substrates and converters: special labelstock developed by Avery Dennison, UPM Raflatac, Herma and other producers can offer the right solution for even the most critical vehicle label application. With all these exacting conditions to be met it is not surprising that just a few label converters specialize in automotive labels. The lucky (or skillful) few are rewarded with lucrative contracts signed with major automobile manufacturers.

Special applications: a section dealing with automotive labels cannot be complete without reference to some advanced electronic labels using OLEDs (Organic Light-Emitting Diodes). OLEDs are made by placing a series of organic thin films between two conductors. When electrical current is applied, a bright light is emitted. They can be made very thin, which makes them suitable for displays and lighting. An early application developed by Schreiner Protech has seen OLEDs used in the interior decoration of certain vehicles. Because they can be made flexible and transparent, they are also being embedded into vehicle windshields.

END-USER APPLICATIONS - TIRE LABELING

Tire labeling is also hemmed in by regulations and with the additional problem that the surface of a tire requires particular adhesives if the label is not to fly off with the first gust of wind. We tend to think of the tire as part of a car, but vans, trucks, aircraft, tractors, and earth moving equipment all need tires, and their specifications are even more stringent than for cars. In Europe, The Tyre Labelling Regulation (EC/1222/2009) which came into force in 2012, introduces labeling requirements with regard to the display of information on the fuel efficiency, wet grip and external rolling noise of tires (Figure 7.4).

In the United States the National Highway Traffic Safety Administration has published mandatory regulations requiring tire manufacturers to label their products with ratings on fuel efficiency, traction and durability. It can be said that today, worldwide, tires have become a branded product and the label is how the brand communicates with the consumer. The rough, low-energy surface of a tire requires a rubber-friendly, generous adhesive coating.

In some cases backside siliconization is used to stop labels sticking too firmly to the liner. Major labelstock producers have product grades recommended for this application: an example is Germany’s VPF which produces a labelstock with glossy white PET face material with permanent lamination of a polyester barrier, designed for attractive, durable, digital inkjet printing of tire labels (yet another way in which digital printing is making headway).

Some converters specialize in the tire label. An example is Serbian label converter Biografika; tire labels supplied to major car manufacturers in ex-Yugoslavia are an important part of this converter’s business.

END-USER APPLICATIONS - LABELS FOR ELECTRONIC AND ELECTRICAL TOOLS/COMPONENTS

For electronic components a label must perform under some of the most extreme processing and use environments. Labelstock producers offer a range of materials using thermostable face materials (generally polyimides). These are labels which must withstand temperatures up to 200 deg C, exposure to chemicals, humidity and abrasion.

They must be clearly machine-readable to ensure efficient track-and-trace. Electronic component labels may be printed using any current print technology, but in practice most use thermal transfer or digital.

All electrical goods must carry warning labels showing power specifications, hazard warning information, wiring instructions, plus a serial number (see Figure 7.5). These labels must remain for the life of the goods, which may be up to ten years or more.

END-USER APPLICATIONS - PRINTED ELECTRONICS

Scientists and engineers have spent many years trying to print microchips and other electronic parts using a roll-to-roll (and generally narrow-web) process. Some people foresaw the day when label converters would partner the chipmakers of the world to produce low-cost components to power the world’s computers, smartphones and every other electronic gadget.

This has not yet happened, for several reasons, but mainly because today’s silicone-based electronics (i.e. practically all of it) does not like being bent or curved. Also, the conductive inks required are expensive (often using silver). The accuracy of printing presses has increased enormously in the past decade, but what is good enough for high-quality primary labels is still not good enough for printing with accuracies in the nanometer (billionth of a meter) range.

A company in Accrington, England, reckons it will soon be able to mass-produce electronic devices such as thin-film transistors, using a narrow web process. It is printing sequential coatings onto a filmic or metallic web using electron beams to direct the conductive ink with very high accuracy.

The use of graphene-based inks (cheaper than silver) could open the way for a new generation of smart labels with or without printed batteries. The first printed transistors used screen inks that were components for, for example, display electronics.

Today’s inkjet technology offers wider end-uses. The wiring of circuit boards, for example, can now be printed. This dispenses with the etching/light exposure that is needed for conventional semiconductor manufacturing. Advocates of this process say it saves energy and reduces the need for chemicals, and is therefore an environmentally friendly manufacturing process.

The essential advantage of inkjet is its accuracy in jetting minute quantities of conductive inks. Each droplet of a single picoliter (one trillionth of a liter) can be accurately placed on the substrate at speeds of 6 m/minute. So far this technology is still at the testing stage. It has the potential to open up vast new end-user markets for narrow web inkjet printing.

END-USER APPLICATIONS - LABELS FOR CABLES

Wire and cable labels are an ideal solution for electrical, telecommunication and data communication identification. Wire and cable identification labels are available from many suppliers and in a range of materials suitable for many different environments or applications. Some firms (Brady and Brother are just two examples) specialize in offering a wide range of ID label options, from tags to wraparounds. Portable printers and readers enable the electrician or IT engineer to quickly identify lines during troubleshooting or repair.

END-USER APPLICATIONS - WELDED LABELS FOR MACHINERY OR PARTS

Welded or riveted labels may be used for identifying machinery. They are generally made of plastic, aluminum or steel, and they are permanent.

Printing processes for these include laser or conventional engraving / embossing. Potential buyers of used machinery (or cars) would be well advised to hang onto their money if there are signs that the welded labels have been tampered with.

END-USER APPLICATIONS - MUNICIPALITIES AND PUBLIC UTILITIES

These are perhaps the least glamorous end-users. However, gas, electricity and water suppliers are major users of labels to warn or inform the public. Municipalities and local councils also often have generous budgets for things like anti-litter campaigns.

According to a label converter who specializes in this sector, the labels required use high-gloss polypropylene face materials, and with adhesives that make it ‘easy, but not too easy’ to remove. Surprisingly, this converter says orders often come with very short lead times. That is why his business has been flourishing since he invested in a digital press.

END-USER APPLICATIONS – MILITARY AND DEFENSE

Governments around the world operate with standardized labeling requirements in all their military and defense procurement specifications. For example, MIL-STD-130 is a US Department of Defense (DoD) mandate that requires suppliers of goods to the DoD to identify items for tracking and efficiency purposes. An added requirement for a Unique Identification Number (UID) may be stipulated in the contract.

Each qualifying item must be marked with a permanent 2-dimensional data matrix encoded with the CAGE Code, Serial Number, Part Number and other data elements necessary to construct a Unique Item Identifier (UII). The UID identification must last the expected life of the product or until it comes back to be refurbished.

MIL-STD-130 requires labels to last the expected life of the product even under the harshest environments of water, sand, salt-spray, grease, high temperatures, abrasion, sunlight, chemical exposure, and other elements. Suppliers to the US Department of Defense must be able to prove that their labels meet the requirements of MIL-STD-130, with regard to both Data Matrix Code quality and data accuracy.

For NATO with its many different languages, labels make extensive use of a wide range of Military Symbols. These symbols are designed to enhance Nato’s joint operability by providing a common standard.

PRINT-AND-APPLY

Print-and-apply label applicators go from the very simple price-weigh label dispensers, as used by your corner store (and generally using direct thermal printing), to complex industrial applicators incorporating a printer and software to print or overprint labels on demand with such variable data as batch number, price, contents, weight, price and other item-specific information, generally including a barcode.

Print and apply labeling equipment is also used in shipping, warehousing and distribution to provide variable data, for example date of dispatching, which can be used to track and trace goods. Printer manufacturers such as Dymo, Intermec and Zebra have their own proprietary programing languages, and for end users, getting locked into the language of one printer supplier makes it hard to switch brands. End-users in industry or logistics can create their own full color labels on computer, then download them to hand-held devices.

Operators can then add any variable data before printing and applying the finished label. Software built in to the printer will frequently be pre-programed with relevant industry symbols and will ensure compliance with industry standards. The hardware most frequently seen in industrial applications today is the hands-free industrial label printer. Suited to many kinds of trade such as plumbing, electrical installation or maintenance, the hand-held device is ideal for rapidly printing and applying self-adhesive labels for electrics, pipes, cabling, data communications equipment and machinery in offices, homes or construction sites.

The print technology used for print and apply label applicators is typically thermal transfer. The In terms of quantity (but not value) unprinted rolls, most frequently paper, vinyl or polyester are a significant part of total label demand (up to 5 percent according to some experts).

DIRECT PRINTING – A RISK FOR THE INDUSTRIAL LABEL CONVERTER?

The latest inkjet printing technology opens the way for end users to use direct-to-product printing – without the need for labels. In many cases these end-users may have extensive knowledge about inkjet printing already. Will component and product manufacturers take the new direct-to-product inkjet printing technology in-house? And will this make a dent in the demand for industrial labels?

POINTS TO REMEMBER:

• National or International regulations govern the labeling of many industrial goods

• Industrial labels must often withstand extreme conditions of temperature and/or humidity, and require special substrates and adhesives

• Labels frequently carry QR codes or RFID chips and are integrated into the end-user’s logistics system

• Print-and-apply industrial labels are often produced using a hand-held device

• RFID-based smart labels can provide heightened security

• Many industrial labels are printed using thermal transfer, but screen and hot-foil are also used