Overprinting, coding and marking on label applicators

The inclusion of a thermal, hot-foil, inkjet or laser printer with a label applicator head creates a labeling system that can electronically or mechanically add overprinting, coding or marking information on-demand to a pre-printed or blank label, or generate an entire unique printed label run at the point of application.

Such facilities are most often used to print barcodes, batch codes, lot numbers, time or date stamps, price and weight details, and tracking and trace information. The print and apply principle is also used widely to add unique labels to shrink wrapped traded units, chemical drums and complete loaded pallets of products, together with a whole range of turnkey applicators designed and built for specific industries or end-use applications.

HAND HELD PRINTER LABELERS

Hand held labelers with the capability of mechanically coding/printing one, two or three lines of information before applying the label are used by high street retailers, factory outlets, department stores and cash and carrys around the world for their daily price and seasonal price marking requirements, 'sell-by' or 'use-by' data, egg box labeling, simple coding, dating and batch labeling needs.

They are also found in many different industrial and manufacturing applications for SKU control, department identification, product identification, inspection, test and ISO 9001 : 2000 accreditation, coding and batch numbering operations found on production lines, in laboratory research applications or for basic job processing and sequential numbering requirements.

Another key area of application for hand-held printer labelers (See Figure 6.1) can be found in the field of distribution and shipping, warehousing, storage, packing and logistics management and control.

Durable machines and labels are also available for use in outdoor applications, such as garden centers and DIY. Virtually any retail, manufacturing or packing operation can benefit from the versatility of these simple to operate machines. 

Depending on the manufacturer or supplier, and on the particular end-use application, hand labelers of this kind with print capabilities may also be known as pricing guns, label guns, labeling guns, coding guns or sequential number labeling guns (sometimes also called numbelers).

There are many different hand labelers on the market capable of adding some level of ink coding and printing. The most widely available are:

One-line label guns. These are usually capable of printing between 6 and 10 alphanumeric characters/digits in a single line on plain or pre-printed labels. One line labeling guns are ideal for the retail trade or simple coding, dating and batch labeling needs. Also used for batch numbering.

Two-line label guns. These can print two rows of up to 10 alphanumeric characters each (20 characters/digits in total) onto labels, again either using plain or pre-printed labels.

Three-line label guns. These print up to three lines of data on a plain or pre-printed label. The amount of data that can be communicated (up to 14 characters per line) allows for extremely cost-effective and complex bulk labeling solutions. Three-line labeling guns are ideal for production control and quality control purposes.

By combining, for example, three ten digit bands with up to 40 characters, the quantity of information that can be conveyed is enormous.

Alternatively, customers can have 'data bands' installed with pre-defined specific names, such as location, date or production line codes.

Sequential number labeling guns. These are much like normal labeling guns but each time the handle is squeezed the next number in the sequence is printed. A dial enables the desired print to be achieved, from a simple date to an alphanumeric part number. They typically print from 0 to 9999, and may also have a number of fixed characters.

The information that can be printed on hand labelers is dependent upon the print head bands, which can have a range of pre-set characters. Inking of the alphanumeric or numeric characters is achieved with either inking rollers or pads. A range of ink colors are available. The ink rollers and pads are easily replaced when the print quality starts to deteriorate.

Hand-held labelers with print capabilities are easy to operate and users become proficient within minutes. A simple dial enables the desired print to be achieved from a date to an alpha numeric number. Each time the handle is squeezed the next label in the sequence is printed, dispensed and applied. They are normally very robust and require minimal maintenance.

PRINT APPLY LABEL APPLICATORS

Print and apply label applicators incorporate a printer and software to print or overprint labels on demand with details that may include a batch number, production date, contents, weight, price and transit data as well as simple graphics for product branding.

Print and dispense or print and apply labels are widely used by retailers to print weight and price information at or near the point of sale onto products as diverse as meat, fresh fruit and vegetables and other products not pre-packed prior to arriving in the supermarket. Often the labels will include a bar code which will be scanned at the supermarket check-out.

Print and apply labeling equipment is also commonly found in warehousing and distribution to provide delivery, batch and other transit information which can be used to track, trace and confirm that the product has arrived where it should, on the correct date and in the right quantity.

These labels may be printed directly on to the outer transit container or onto a label which is then applied to the transit container. Information can be printed in both standard type and as a bar code.

On-demand print and apply labelers, also called 1-to-1 labelers, apply the label that has just been printed. The print engine and print head are right at the dispensing edge. These machines – whether semi-automatic or fully automatic – are used for applications where label data changes regularly, such as in distribution/logistics operations, sandwich pack labels, pharmaceutical/clinical trials applications, pallet labeling, or anywhere where products arrive in a random or non-linear order or need time and date marking for tracking purposes.

Print heads used with print and apply label applicators are typically thermal transfer with thermal ribbons suited to the label substrate, print surface or end-use application.

There are also batch print and apply labelers that feature a thermal transfer print engine located away from the dispense edge, so that the two tasks can work independently. In this case, labels are printed into a tension controlled loop, giving opportunities for high-speed direct wipe-on application which is not limited by the speed of the printing. Typical batch applications include bakeries and other fresh food labeling, outer case labeling, and price and promotional labeling.

Tracking labels may also be applied at the beginning of a manufacturing cycle, for example when tracking a complex engineered component through a fully automated machining and inspection system.

PRINTER SOFTWARE

To fully utilize print and apply label applicators, it is necessary to either transmit data to them or to create at the printer a label format and content file so that the labels can be printed with the required information and quantity.

A number of label design software packages are available, such as BarTender, LabelView or NiceLabel, which can send label information directly to the printer. This usually involves using the software’s printer driver to convert the data into a format that the printer understands.

Another common approach is to design a label file that is formatted in the programing language of the printer and send it straight to the label printer, with no label software involved. This is often used in large enterprises, where the company’s ERP software is set up to send a formatted file to the label printer when a label is required.

Each printer manufacturer has its own proprietary programing language. By virtue of having the largest market share in barcode printers, Zebra’s ZPL programing language has become very much a standard for developing label files. The other printer manufacturers have their own programing languages: DLP for Datamax and IPL (Fingerprint) for Intermec are just two examples.

For end users, getting locked into the language of one printer company makes it hard to switch brands: the aggravation of reformatting a whole lot of label files can be too much.

To try and overcome this, label print engine companies have developed emulation firmware allowing their product to work with label files designed for other brands of printer. This enables a user to send, for example, a Datamax DPL file to a Zebra printer. The printer software will then convert this to compatible Zebra language and produce the correct label.

PRINT ENGINES

A number of print technologies can be added to applicator lines to provide last-minute text, codes, date information, pricing, weight, volume, graphics or personalization. The print technology used depends on:

• Label size and dimensions

• Print quality

• Amount of type or data to be printed

• Size of print characters – very small/large

• Bar codes required

• Printing speed to match line speed

• Type of applicator

• The size, dimensions and label positioning on the product being labeled

• Ease of set-up and changeover

• End-usage conditions - hot, cold, outdoor, product resistance, etc.

All these factors will need to be taken into account when deciding on the most appropriate print technology. It should also be remembered that print heads and items like thermal papers, hot foils, thermal ribbons, inkjet cartridges and inks are consumable items that need to be changed or regularly purchased.

Simply neglecting to clean a print head can potentially halve its life and therefore add to print OEM print engines used on label application lines engine running costs.

The range of available OEM print engine technologies are shown in Figure 6.2.

Thermal direct uses a heat-sensitive, chemically coated label substrate into which the print images are ‘burned’ at standard printer temperature and pressure settings. Heating of the thermal material is with a print head consisting of many miniature heating elements distributed along its printing width, which turns the image areas dark to create the required printed label (See Figure 6.3). 

The elements are selectively heated by pulses of energy which create points or dots of black (other colors are possible with appropriate paper) in the thermal coating, and these dots create the image held in the computer memory.

Direct thermally printed images can be variable text, bar codes, or diagrams used for frozen or fresh food labels in supermarkets, industrial bar-coded labels and tags. It may also be called chemi-thermal material.

Thermally coated substrates are of course heat sensitive, so cannot be used for applications where the label may be exposed to sun, heat or abrasion. However, there are thermally coated substrates with different reaction temperatures that can be used to minimize or overcome some types of heat sensitivity issues.

Thermal transfer printing is a very similar indirect printing process to direct thermal printing, where a heat sensitive ribbon replaces the heat sensitive thermal paper. Very smooth and receptive conventional paper, or a suitable film, is printed by means of an electronically-controlled printing head which transfers variable data – including bar codes – to the label, ticket or tag face material via a heat-sensitive printer ribbon placed between the printing head and the face material.

The thermal transfer printing head (Figure 6.4) makes use of very small resistors or elements which are arranged across the printing width, which are selectively heated and cooled. The heated elements come into contact with a thin film one-pass ribbon, which carries a heat-activated ink or coating on the underside.

By rapidly heating and cooling the resistor dots on the print-head, the required character or image is created and so transfers the selected heat-activated ink coating from the film carrier to the substrate according to the pattern or shape of the heated elements.

Thermal transfer printing is used for printing variable batch codes, date codes, sequential numbers, text, diagrams and bar codes onto pallet, carton or box end labels. Typical end uses are for warehousing and distribution, bakery labels, DIY, industrial labeling, and for a variety of tickets and tags.

Thermal inkjet printers make use of electrically heated cartridges. Each cartridge contains a series of tiny chambers, each containing a heater.

When the ink is heated by a pulse of current passing through the heating element, a bubble is formed, causing a large pressure increase and propelling a tiny drop of ink onto the label substrate. Once the droplet has been ejected the bubble in the chamber collapses, the chamber refills and the whole process repeats.

The technology offers high resolution coding for the food, beverage, tobacco and cosmetics industries and may be found in intermittent or low volume production as well as higher speed coding.

Hot foil printing is a dry printing process which uses very thin aluminum foil in a variety of metallic colors – such as gold, silver, red or blue – rather than inks from which to print. Hot foil printing is achieved by transferring the colored metallic pigment coating from a ribbon of plastic material known as the ‘carrier’ onto the surface of the label material using a hard printing plate which bears the image to be hot-foiled.

The transfer is achieved through the application of heat, pressure, and the length of time the heated coating area is in contact with the substrate – known as the dwell time.

The balance and control of these elements is critical and must be individually calculated for the surface to be printed, and the type of ribbon or foil used. In particular, accurate pressure setting is vital. Too high a pressure may lead to line downtime with glassine liners.

The hot foil process uses relatively simple equipment and can print on a wide range of surfaces. On-line hot foil coders are used to code expiry dates, product identification information, lot and batch numbers, or may be used to provide a luxury (metallic) look on many cosmetics, toiletries, health and beauty labels, on wines and spirits labels and in other higher added-value label applications.

Hot-melt drop-on-demand inkjet uses solid, wax resin-based hot-melt ink blocks that are instantly touch dry after printing. The ink blocks are solid at room temperature (and can be picked-up and handled) and are melted internally by the system as required for printing. The ink, now in liquid form, is expelled from the nozzle by piezoelectric technology. The ink solidifies and hardens immediately on contact with the label substrate.

Drop-on-demand inkjet printing ejects ink droplets from a nozzle to the substrate on an ‘as needed’ basis, instead of a ‘continuous’ basis, eliminating the need for an ink recirculation system. DOD print heads are made up of many nozzles, each capable of emitting up to 30,000 finely controlled droplets per second.

The technology provides high quality and high speed digital printing of variable data, serialization, traceability and offers fast job changeover. It is found in applications including confectionery, frozen foods, dairy, personal care and pharmaceuticals.

Laser technology is used for high-speed printing of large coding areas and can be found in the food, beverage, cosmetics, toiletries and pharmaceutical sectors. Laser printers (see Figure 6.7 for an example) print image characters using a laser and a photosensitive metal drum.

The laser imprints the image on to the drum, changing the electrical charge. Toner then adheres to the charged areas on the drum and is then transferred to the label material.

Laser printers require larger cartridges as well as the printing drum and are therefore typically larger that inkjet printers – and require more space.

INVESTMENT DECISION

Before investing in a label applicator print technology, a total cost of ownership study should be undertaken, including consumable inks, ribbons and spare parts along with an assessment of the label substrate/media. Using cheap label materials can reduce the life of print heads, for example.

The quality of the overprint information should also match the quality of the pre-printed label, while the accuracy, quality and readability of bar codes is essential and needs to be carefully evaluated before investment takes place.

If budgets are determined in separate locations, the total applied print cost and code readability evaluation may often be missed. Failure of bar code readability at the point of sale can certainly be very expensive.

Developments in print technologies are continually taking place and it is essential that application machine producers and end-users keep abreast of new technology developments.                                                                      

WEIGH PRICE LABELING

Weigh Price Labeling systems are used in grocery store backrooms for the labeling of fresh meat, poultry, fruits, and vegetables, prepared meals, convenience foods, fish and cheese. Flexibility, speed and reliability are all critical factors in selecting a labeling system.

Packers and importers of foodstuffs must ensure that packaged goods are labeled with the quantity. Key requirements are that information printed must be visible, accurate, easy to read and understand; be labeled in the same field of vision as the name of the food; not be misleading; and not be able to be damaged.

The rules on quantity labeling of pre-packaged foods changed in Europe in December 2014. Businesses now have to comply with the requirements of the EU Regulation on the Provision of Food Information to Consumers (1169/2011).

This states that all packaged foods of 5gm or 5ml or more are required to comply with FIC and that the packages must display;

• The net quantity (in g, kg, ml or l) directly on the package or attached label

• Drained net weight and net weight for foods packed in a liquid medium.

As with the print and apply systems already discussed, weigh price labeling equipment comes in a range of manual, semi-automatic, fully automatic systems. Standard thermal label printing solutions are used.

Typically, weigh price labeling applications require input and data from an in-motion checkweigher to populate the labels with the correct information, weight and lot number. Usually, weigh price labeling is located toward the end of production line operations.

Apart from incorporating a printhead and a weighscale interface, weigh price labeling systems are commonly supplied with a touchscreen controller to control the weighing and labeling operations. The latest generation of open architecture equipment can also collect real time data on packaging line productivity and status of customer orders.

The more sophisticated weigh price application machines have systems able to recognize different cuts of meat, for example. Differential prices per kilo are calculated and five or six applicators place printed labels onto different height packs.