By Matt Perkins, Vertical Marketing Manager, Videojet Technologies
Baked goods companies are increasingly offering individual and smaller portionedpackages,necessitating faster packaging line speeds, as well as a greater variety of products, requiring greater line flexibility. One preferred packaging formatto best meet these challenges is flow wrapping.
Flow wrapping can wrap and protect a wide variety of baked goods productsand the size and shape ofeach product can impact packaging line speeds. For example, coffee cakes may be packaged at 65 products per minute, while individual crackers can be packaged at over 300 per minute.
The challenge: Coding on fast-moving flow wrapped baked goods with TTO
Regulation requires bakeries around the globe to include expiration and manufacturing information on their products, and flow wrapped products are no exception. It’s a challenge: the speed of flow wrappers are increasing to improve throughput and yet codingon faster lines becomesmore difficult. Baked goods companies have a variety of coding technologies, such as roller printers or hot stamp printers, and digital printers, such as Thermal Transfer Overprinters (TTO), to solve this challenge.
Digital coding printers offer reliability, flexibility andfast changeovers, facilitatingmaximum productivity and attractive cost of ownership. There are three specific types of digital printers specifically suited to be integrated with flow wrapping machinery: TTO, Continuous Ink Jet (CIJ), and Laser Marking Systems.
TTO,the most prevalent technology, prints high resolution codes directly onto flexible films by using a precision thermal printhead and a thermal ribbon.These systems print crisp and near letter quality text, graphics, batch numbers, real-time dates and bar codes.Most advanced TTO printers can print a resolution of 300 dots per inch (DPI) or 12 dots per millimeter.
TTO printers must be integrated directly with thepackaging equipment. Thus, when purchasing aTTO printer, one should carefully consider theintegration of their new TTO printer with theirnew or existing flow wrapper.While the function may be the same, flowwrappers from different manufacturers are builtdifferently and can require specialized bracketsand other accessories. Therefore, it is importantto find a company with the right experience andaccessories to complete the integrationseamlessly.
Regardless of the margin profile of the product, hitting production targets every day is critical and any unscheduled downtime that stops product from getting out the door should be reduced or virtually eliminated. Thus, baked goods companies should look for TTO printers that have been designed for maximum uptime and a low cost of ownership. TTO printers can be extremely reliable and require minimal maintenance as compared to other coding technologies, but some TTO printers maximize the use of ribbon in the printer which leads to ribbon savings and reduces downtime required to replace the ribbon on the line. Additionally, the time between changes can be increased with the use of longer ribbons, and since ribbon replenishment will be required for any TTO printer, one should choose a printer that makes ribbon replacement easy.
Alternatives to TTO: CIJ and Laser
Although not a common occurrence, line speeds of more than 300 packages per minute may exceed traditional TTO print cycles. Speeds greater than 1,000 millimeters per second and pack rates greater than 400 packs per minute are at the extremes of most TTO capabilities. In this case, alternative coding technologies such as CIJand Laser Marking Systems are better suited.
Unlike TTO, CIJ and Laser Marking Systems can code on packaging either before or after products are wrapped. Coding ideally occurs before the film has been formed around the package where control of the film is greatest. Installation of the CIJ printhead or Laser Marking System within the wrapper can be challenging but the reward is better print quality and precise code positioning. Many CIJ printers have custom head mounting and configurations such as 90° bends on the printhead to accommodate machines with tight clearances. Similarly, many Laser printers offer accessories such as beam turning units and specialized brackets to integrate with flow wrappers.
Once products are packaged, they tend to be conveyed without strict guides. Variation in product positioning such as distance from the printhead and the laser and variable speed can affect print quality and positioning. Yet CIJ and Laser Marking Systems are tolerant of some variation in distance and substrate variation.
CIJ isthe most versatile of all coding systems. With CIJ, printed characters are made up of individual ink drops, which formdot-matrix characters. This method of marking is used most often to print alphanumeric codes such as expiration dates or manufacturing data.Matched with application specific inks and solvents, this type of printer can be used on nearly all types of package types and speeds.
One should choose a CIJ printer with easyand predictable maintenance and thatallows for long run times without even handling the printer. Yet selecting the right CIJ printer is only part of the solution. Choosing the right ink is just as important. Different package types and production environments require different ink technologies. Some inks are environmentally friendly and can be found in different colors. Some are water resistant and others have special characteristics such as ‘Ultraviolet (UV) readability’ inks.
Laser systems mark products in one of three ways: by ablation or removal of surface coatings revealing what is underneath, by changing color of the marked substrate or by exciting an ink with a pigment to change color. A major benefit of laser marking is that codes are permanent. The code is resistant to most abrasions and solvents and marks can only be destroyed through physical removal of packaging material.
Unfortunately, while laser marking systems can keep up with high speed lines, the systems cannot mark on all type of films. Typically, on metallized foil, it is possible to ablate the laminate or the ink on the laminate but it is usually not possible to apply laser codes on polyethylene film. To help ensure laser marking success, it’s important to provide film samples to a coder equipment supplier for testing and evaluation.
In fact, every flow wrapping application is different and may have special requirements that better suit one coding technology over another. To best gain the competitive edge, baked goods companies should work closely with an innovativeleader in video coding that will help specify and install the best solution.
