By Craig Smith, President Innovative Digital Systems, LLC
Published in July/August 2011 edition of Plastic Decorating / Technology
Remember the days when a customer asking for decorated parts or components needed to order custom decorated parts by the thousands or more? Now, order sizes are getting smaller, while deadlines are shorter. With digital printing, industrial printers can meet the needs of today’s market.
Beyond the Basic Advantages of Digital Printing
Industrial markets have quickly recognized the advantages of digitally printing their products. The basic – and well-known – advantages include fast turn-around time, minimal changeover time and rapid sampling and prototyping, thanks to the ability to change artwork via computer. Small sample quantities can be run back-to-back with large quantity projects since screens and plates aren’t necessary. With UV inks, no solvents are involved and there is no time-consuming ink mixing, reducing ink waste. Tooling costs are low, since digital printers do not use clichés, pads, plates, or rollers, providing more cost and time savings. In addition, digital printers have a relatively low investment cost, considering the flexibility offered with custom printing, leading to a rapid return on investment.
Digital has been around long enough to be a proven process. The UV inks allowed the digital process to enter the industrial market from its safe haven in sign and graphics. Now the trick is to adapt the equipment to the applications and as an industry to coordinate print head production, ink manufacturers and integrators. So the challenges of industrial printing can be conquered, this has started to happen as the industry recognizes the vast potential of this market. Therefore you have support for R&D expenses and time to work on solutions. These revolutionary solutions are developed quickly, which would not have been the case 10 years ago. This is a great time to seriously look at the digital process.
There are advantages to digital printing that go beyond the basics. These include sustainability, customization, reduced inventory and an increase in quality.
Green is a very popular color these days. The digital printing process has distinct advantages in this area. If companies are serious in applying green solutions in their decorating processes, digital printing should be considered. There is very little waste and numerous recycling programs for consumable items. Give your company the ability to produce in your market area by keeping the on-demand decorating jobs in-house and still allowing the necessary outsourcing of parts. The ability to decorate in your selling target area equals savings in transportation costs and that also has a positive and green environmental impact. When choosing a digital supplier, if you are considerate of the environment, look at how the inks are packaged. Ink cartridge versus ink bag versus ink liter bottle container. It is more environmentally friendly to throw away an ink bag as opposed to a cartridge and a refillable container is in larger bulk size which allows for cutting down on the amount of plastics being used. UV LED curing lamps are more environmentally friendly than Mercury Vapor UV lamps (mercury lamps have special disposal requirements), take advantage if this works in your printer selection.
Delivery Lead Times
Digital printing allows the flow from order entry to production floor to run seamlessly. Example, if you are printing widgets, in past if you wanted to change graphics on the part to respond to a customer order a set up was involved. Can you imagine having the ability to: receive an order on-line, then filtered to the printer, and communicating with the printer what to print on your product? It can be that simple. Simply taking parts from your current inventory or manufacturing floor and sending them directly to the printer. In your production line, you have the ability to continuously print a widget (product) with the same image and easily switch to a completely different image on your same product line, using an artwork file as opposed to changing plates, clichés, rollers, etc. Again, seamless. This dramatically lessens your lead times. With a digital printing integration, the printer not only decorates the parts, it can also send information that the part has been printed, direct to the next step packaging, and shipping directly to your end customer.
No one wants to keep a stock-pile of decorated product on shelves waiting out the 80/20. Whether you are manufacturing the parts or purchasing inventory, that 80 percent may sit for months or years, eventually to be considered scrap. Many times in manufacturing the same component is sold to a variety of customers. The components then need to be identified with individual company specifications and branding. There was a time that there were no other easy decorating options for small runs or individualized / personalized products – now there is digital printing. The bottom line is that everyone wants what they want now, without commitment – on demand. Who wants to purchase high minimums of decorated parts that may never be sold?
We have seen explosion in personalization in the past year. The younger generation is very focused on personalization. This generation is computer savvy and the Internet is their comfort zone. The uber popular on-line shopping is their wheelhouse. Placing orders on-line and uploading personal graphics is second hand – you cannot ignore this strong market segment. With the ease of on-line ordering comes the expectation of quick turnaround for product deliveries.
Personalization opens up new markets to a company with existing product. With the ease of changing artwork, this can take an existing product line to a new level, adding value that increases the bottom line. Think outside the box for your personalized printing.
High Quality Graphics
Many markets are moving towards less packaging and more direct product decoration, which increases the need for high quality graphics. With digital printing, the imaging comes from the computer-generated artwork and is sent directly to the printer. Plug and print, resulting in high-quality print with excellent drop placement accuracy. Printing CMYK (Cyan, Magenta, Yellow, Keyline – Black), white and clear when needed. Direct digital printing offers high resolution of up to 1200x1200dpi, compared to 300dpi with traditional pad printing or silk screening.
Entering the Digital Print Market
First and foremost, pick a company with experience that can offer you a total decorating solution for your digital printing. Expertise in overall product decoration allows for a smooth transition from your current method of decoration to digital printing. Look at how a digital integrator addresses future developments – and whether or not they will adapt to the future needs of your company. The digital world is still an emerging market that is ever-changing, with new developments occurring on a regular basis. A company should have all of the solutions for digital printing, including access to major print head manufacturers, ink development (don’t settle for a one ink fits all solution), in-house printing, testing capabilities, software and good technical support.
Evaluate the product and the printing expectations. Can your product be decorated with the digital process? Are there any printing difficulties to overcome? Don’t over-engineer a printing solution – be practical with the limitations of the digital printing process to your application. Ask questions: how is this digital process more cost-effective and what is the value added?
Once the product evaluation is done, if your product is a good direct digital candidate then ink selection is critical. In this step, you should provide enough substrate material for ink testing. Testing can determine the proper ink set for adhesion, durability and resistance for your particular industry standards. See more details on ink selection under Printer Selection tab.
Your environment will require some pre-planning before launching into digital print. How much floor space needs to be dedicated to this decoration process? Is the environment clean enough for the digital printing process? Is the environment climate-controlled? What type of labor do I plan on using (manual versus automation)?
Which type of digital printing equipment is right for your application? Ask yourself what type of throughput is needed now and in the future? There are small tabletop printers and large format flatbed printers which can be manually loaded with parts or set up for automatic loading. For much quicker printing output, there are high-speed single pass and custom high-speed printing systems that integrate into the manufacturing process. These systems can be set up for in-line production printing, off-line printing or integrated into work cells. The printing work cells easily can be ramped up for expansion should the work demand increase. Using modular work stations can help assist in growing the digital printing operation as new digital printing advancements are introduced into the marketplace.
A general overview of print heads for ink jet technology. Print head technology is similar to new model cars. Every year there is a new and improved model to test drive. The print head technology is ever-evolving. Print heads are one of the most important and most expensive components of your printer selection. This ranks at the top of the list for one of the most important things to consider in your digital printer selection. Why is that?
- Speed. Evaluate your needs carefully to see if speed is part of your manufacturing process, or just part of the equation. Currently, the higher the speed the more you sacrifice the definition, print quality. The heads become more expensive. You have to determine the critical performance you need out of a print head?
- Print Resolution. Resolution of a print head is determined by the smallest dot it can print.
- Print Head Capabilities. What are the print head capabilities? Is the print head compatible to a variety of ink sets? Can you jet the ink you will need for your product line?
- Service and Warranty. Support at the beginning of your digital printer build is just as critical as support two year down the line when you are running major production. Research the print heads on the market, look carefully at how widely used a print head is in the market, and this will give you an indication of how well the performance is.
The phrase of the day, how to feed the beast? A good ink delivery system is critical. Some things to consider:
- How efficiently is the ink brought to the print head? UV ink Jet ink must be at a certain temperature and viscosity to optimize the print head performance.
- How close is the ink reservoir to the print head? Why is this important? The closer the reservoir is to the print head, the more optimized performance. Also look at the size of the reservoir. The reservoir needs to be large enough for ink passage and small enough so that cleaning; purging will not waste a lot of ink or time.
- It is imperative that the white ink must be agitated in order to prevent settling of the pigment. Settling can cause an anemic white print and clogging in the delivery system.
- Ink delivery system usually includes the alignment of the print heads. It is important that the design should consist of an easy replacement of the head, should it need to be replaced. Using a quick easy alignment configuration will cut down time.
- Your system should also include an automatic cleaning mode that keeps the heads in optimal condition while printing. Simple regular maintenance is required and keeping the heads clean is the most important step.
There are many factors to consider when making the ink selection for your digital printing system.
- Substrate material. Determine all of the substrate materials that you want to decorate with your digital printer.
- Make a list of performance requirements for the digitally decorated product. For example:
- Light fastness, fade resistance
- Does it need to meet any regulatory standards, i.e. FDA, any industry standards, ASTM
- What type of ink to use? Solvent inks, water-based aqueous inks, latex inks, UV inks, and specialized inks to include those that are edible ink.
- Ink testing and sampling. In working with a manufacturer or Digital Integrator, make sure they have the resources to print samples of your substrate material. Then you can put these samples through your initial phase performance testing. In a lot of cases, one ink may not perform for all of your printing applications.
- Pre-treatment and primers. There are instances when a pre-treatment is necessary on the substrate material before jetting ink. Some pre-treatment methods include:
- Coatings or primers. If your product cannot be flame treated or the ink is still not adhering after flame or corona pre-treat, there are primers that are available for a lot of substrates. The downfall of using primers is that it adds and extra cost and process to the printing. This process can be minimized by jetting the primer in-line using a dedicated print head. This ink jet head should be in the first print head position, prior to the ink colors being applied. In Figure 5, below, the primer head would be placed in front of the W (white) print heads.
Most manufacturers and integrators will have the ability to pre-treat or recommend pre-treatment options if needed. It is also possible to work directly with the ink manufacturers. Generally, if working directly with ink manufacturers you may need to be a high potential customer. The ideal situation is to work with a manufacturer of digital equipment or a digital integrator who have a good working relationship with all of the major ink manufacturers. When the printer manufacturers and ink manufacturers are working as a cohesive unit towards recommending and supplying the required ink for your printing needs, your project will run a lot smoother.
UV Ink Curing
The decision to use UV or LED curing, factors to consider:
- UV Curing. UV curing uses a mercury arc to cure.
- Advantages of UV. UV has a wider range of curing capability; it penetrates and cures inks for some substrates better than UV LED. The ink is also a key factor.
LED Ink Curing
Most manufacturers are trying to move to LED curing for following reasons:
- UV LED can be used as a pinning, which is critical in the single pass type printers. (See Figure 5) The part is being jetted with each color in a series. Pinning is used to hold the ink in place until an all printing is complete and a full cure can be applied. Pinning allows for tack and not a complete cure.
- UV LED has less power consumption, instant on – needs no warm up; it does not produce as much heat. If you have a heat sensitive product, this is a real advantage.
- UV LED is mercury free and does not generate ozone. The cost for UV LED is more expensive than the UV Mercury cure. This if offset by the LED bulbs having a much longer shelf life.
Some best solutions use LED to pin the ink and then use UV for a complete cure.
Software Considerations for Industrial Workflow
Software selection is also an integral part of the decision making process. Things to consider are the:
- Easy to operate
- Upgradable. Will the software package grow with your business?
- Who will be using the software? Is it an advantage to have your line operator interface with the software? Or do you prefer to keep control of all software in a separate location with limited access by line operators. Keeping it simple on the shop floor.
- Base operating system. Know your requirements when looking for software, the proper RIP (Raster Image Processing) for hardware and software that converts graphics.
Digital manufacturers are offering more sophisticated software that allows:
Multiple File Capabilities
- Multiple file capabilities. This option will automate the process and merge files when applying graphic art or text decoration to the product. This software application is valuable when separating white and clear files.
- Variable data. This function allows for merging text files with custom colors, sizes and fonts, merge images such as photo in photo, photo and text. When using the variable data software you have the ability to print a different image on every part, one up and custom printing using only software to make the changes. No expensive plate charges, clichés, rollers, etc. Printing custom orders rapidly.
- Bar code. The ability to scan a bar code, which initiates the proper art to be printed on a given product, is a necessary tool in certain industrial markets. This software option provides efficient throughput. Here is a brief example:
- Purchase Order is placed. Inventory part is scanned. Identifies the part to be printed.
- The scan then pulls together the print image files automatically to the printer, in sequence to be printed.
- A second bar code can be printed to identify the finished product, send to shipping and ordering tracking information.
- Serialization. Software options can be set up to allow each image to be serialized. Serializing each image easily with flexibility allowing for printing of limited series or where product identification is critical as an extra level of security of each unit printed (i.e. pharmaceutical).
- Template Formatting. Base software can be enhanced to offer a template format and recognize templates or trays of product (See Figure 6) showing a part template layout. This is to help in fixturing parts and registering them to the printer. Allowing for automatic fixture registration and to correct for fixture inaccuracies.
- Multiple Printers. Software enhancements will manage multiple printer operations.
- Remote Data. Print operations can be handled at the printer location by the print operator. Software is also available to allow for remote data being sent to a printer as opposed to operator interface. This can cut down on possible human error, free the operator to handle more print and packaging functions. Ultimately, it allows for tighter control of printing operations by management.
It is important to address the real software advantages. If you don’t select the appropriate software, you will not be able to benefit from all the print advantages of digital printing.
The Time is Now
Digital printing is growing by leaps and bounds, with numerous advantages over traditional product decorating options. However, the industrial aspect of digital printing must be carefully mapped out, with consideration given to all of the variables.
Chris Lynn, XAAR
Paul McGovern, Mimaki USA