- THE MAGAZINE
To meet these needs, new decoration processes must be developed that are fast and capable of being fully automated, and that also provide greater production flexibility. Computer technology will also play a key role. Remote access by computer allowing the ceramic artist and/or designer to work from home and download the information using a modem can reduce overheads. Modern computer technology can also allow producers to use just in time (JIT) or print on demand (POD) working practices, giving them more flexibility in reacting to customer demands and allowing continuous production practices.
One new decoration technique that meets these criteria is instant decals. By combining digital technology and thermal transfer printing, instant decals provide a fast, flexible way to add decorations and barcodes to just about any glass or ceramic product.
Personalizing and Identifying ProductsDecals have conventionally been produced though a time consuming and expensive process due to the many stages that are involved, from reprographics and screen making to printing. In the past, the only way to reduce the unit cost per decal has been to order in large quantities.
The instant decal process significantly reduces the steps required to produce decals by combining digital technology and thermal transfer printing. The designs are computer generated and controlled and thus are easily manipulated and changed, enabling short order runs and fast production.
Thermal transfer printing is one of the most popular methods used to produce high quality, free format, random, on-demand printed images. The advantages of low equipment and maintenance costs, good image quality and small size make this technology well suited for printing barcode symbols. Instant decal ribbon printer development began in the early 1960s and intensified in the late ’70s. In the early ’80s, large numbers of instant decal printers began to reach the market. Development of this technology continues today, with further enhancements and refinements of ribbon films, ink coatings, receiver media and printer mechanism designs.
Instant decals are a flexible, low cost technology that uses existing application and firing techniques. During printing, a ribbon, which has thermoplastic ink coated onto a thin polyester film, and the covercoated paper pass under the print head. The contact points that have been heated melt the thermoplastic ink and allow it to be transferred from the ribbon to the substrate (see Figure 1).
In 2000, after five years of research and development, a patented instant decal printing system for producing personalized ceramic decals for tableware and barcode decals for use in sanitaryware was introduced.** The printer can be fitted with a guillotine, if required, to enable the decals to be cut for production purposes. Systems have been sold commercially for both applications with successful results.
Product identification using variable information decals is becoming increasingly important for a number of different applications that require high temperature firing. For example, the sanitaryware industry is currently using barcodes to improve product tracking by being able to identify the product from its green state to delivery to the stock warehouse.
Using advanced software** and a user-friendly interface, sequential barcodes can be produced with the instant decal system. The software allows the user to determine the start number of the barcode run, thus allowing different sequential barcodes to be allocated to different product groups. The labels can also be printed in batch quantities for either daily or weekly stock usage.
The barcodes can be produced in a number of different formats, sizes and configurations, allowing the same barcode format to be used for a group of factories while also allowing individual site/factory identification. As with the decorative decals, the printer can be fitted with a guillotine to enable strips of five motifs of barcode decals to be cut for production purposes.
Printing and Applying the DecalsThe print head is the most important part of the instant decal printer, and it consists of a series of electrically heated needles that are controlled by the computer. A polyester ribbon coated with a wax/resin/pigment system is bought into close contact with the head. When the heated needles come in contact with the ribbon, they melt the color and cause it to be transferred to the covercoated paper due to the thermal gradient created with the paper. The printer has a 400-dots-per-inch (dpi) resolution with a print speed of 3 in. per second, making it ideally suited to the printing of ceramic decals.
The printer is easy and quick to set up. The covercoated paper is fed between two metal feed plates, and the ribbon passes underneath the print head onto a take-up spool. The whole operation of loading consumables into the machine takes a matter of minutes. The printer drivers are suitable for all Windows® 95, 98, ME and NT systems but are not Apple Macintosh® compatible.
Ribbons are available in black, simulated gold and sepia for the onglaze decoration of tableware. A black ribbon is also available for either underglaze or inglaze decoration or bar coding for sanitaryware, and a blue ribbon is available for glass. While the system is not suitable for grayscale or trichromatic (four-color) printing, contract ribbons for different firing ranges or customized colors can be developed.
The decal or barcode can be scanned (using a variety of conventional scanners) at any of the operation processes, and this information can be linked into a production management system. The ease and flexibility of the process allows the decorations or barcodes to be placed anywhere on the article. Additionally, the pigments used are dishwasher-safe, and they do not release any toxic metals (if fired to the recommended temperatures), enabling them to be safely fired with open stock or bespoke decals.
Covercoat LayoutsThree basic covercoat layouts can be obtained with the patented instant decal system. The standard covercoat layout of the web paper is 101 x 225 mm, which is suitable for a mug wrap. The paper is printed with a registration mark that allows the paper to be accurately indexed during printing, enabling it to be used for multi-color applications. To switch to a different color, the paper is rewound and a different color ribbon is put into the machine. The paper will then index forward using the registration mark, allowing subsequent colors to be printed in registration.
An alternative covercoat layout is 100 x 100 mm. This paper is also printed with a registration mark that provides the possibility of multi-color printing.
For barcodes, the layout is in blocks of five of 45 x 25 mm, and the paper is printed with a registration mark that allows for guillotining into strips if required. Using the registration mark, the paper stops at a precise position, and the software in the machine activates a guillotine that cuts the paper.
The covercoat layout can also be adapted to specific requirements.
Benefits of Instant DecalsThe instant decal process offers a number of advantages, including:
- Flexibility. Since the designs are computer generated and controlled, they are easily manipulated and changed.
- Low volume production. Printing one motif is as easy and economical as printing a thousand motifs.
- Enhanced decorating. Multi-color decals can be easily printed.
- Fast printing speeds. A completed decal is automatically produced within seconds.
- Low capital outlay. The print mechanism is simple, inexpensive, small, clean and quiet, providing unobtrusive operation with low maintenance requirements.
- High-density barcode capability. The high-density printing capability of the instant decals ensures that the finished barcodes can be read easily.
- Use of existing technologies. The completed decal is similar to existing decals using existing application and firing techniques, so firing temperatures and application techniques, dishwasher durability and toxic metal release remain the same as with existing decals.
For More InformationFor more information about instant decals, contact David Cartlidge at CERAM Research Ltd., Queens Rd., Penkhull, Stoke-on-Trent, Staffordshire, UK ST4 7LQ; (44) 1782-764237; fax (44) 1782-412331; e-mail email@example.com; or visit http://www.ceram.co.uk.
*Foresight 2000, compiled by the UK ceramic industry.
**The patented system and its related software were developed and are supplied by CERAM Research Ltd.