The best of both worlds

The best of both worlds - Why UV flexo printing technology plays a significant role in a digital age

On-demand printing of blister foils delivers significant benefits including increased flexibility, reduced inventory and waste as well as accelerated time to market. On-demand is often thought to encompass only print solutions that are exclusively digital, “this creates an impression that is simply not correct in an absolute sense,” says a long-standing Hapa employee who advises pharmaceutical companies in diverse markets. “For my part, however, I remain a big fan of digital solutions. Hapa is a pacesetter and pioneer in digital drop-on-demand (DOD) inkjet technology. Fully digital solutions allow for advances that were simply inconceivable 15 years ago. I wouldn’t want to turn back the clock,” insists the expert.

Nevertheless, the ability of digital solutions to open up new perspectives doesn't mean that they are the only option that makes sense. The best technology choice depends on the requirements and production complexity. Among the determining parameters are batch size, number of SKU’s, substrate selection, artwork and the available investment resources.

A strong argument can be made for operating UV flexographic, digital and hybrid printing technologies alongside each other, and that’s not going to change in the near future. In fact, anyone who wants to optimize processes would be well advised not to commit to a specific printing technology right from the start. It makes better sense instead to start with an analysis focusing on three key questions: What are the specific challenges I need to resolve? What are the advantages of each printing technology in my application? Where do I get the best return on investment?

A long success story

There’s no doubt that the technology with the longest track record of success is UV flexo. When Hapa first presented solutions for print-on-demand almost 50 years ago, it was akin to a revolution. Suddenly, printing foils for blisters could be held off until the last minute, which represented a major step towards increasing flexibility and agility. It was the beginning of the success story that everyone now calls on-demand printing.

UV flexo is the preferred technology for printing invariable information, such as dosage and product names. The same print mats can be used across multiple batches, but of course they still need to be procured or produced. In the interests of speed and flexibility, Hapa was an early investor in its own precision facility for print mats and continues to offer a production service that many customers value highly. For pharmaceutical manufacturers who require especially large quantities of print mats, investing in their own Hapa laser engraving system can prove worthwhile.

UV flexo printing solutions can quickly reach their limits, however, when variable data come into the picture. “Embossing technology is still widely used to apply batch numbers or expiration dates to blister packs, but there’s no denying that readability is often sub-optimal, even though widely accepted," says the Hapa expert.

Where variable data are to be applied to each unit dose of a blister pack and the individual batches are small, a digital DOD print solution is generally the best option. This applies in particular when many different colors are required. Using all-digital systems, customers can print CMYK. Although UV flexo printing can also be used for up to four colors, these can only be defined and pre-mixed spot colors, not process colors.

Another key criterion is the substrate. As long as the printing takes place on compatible substrates as is the case for the vast majority of pharmaceutical blisters, UV flexo and DOD systems achieve virtually the same level of print quality.

Best of both worlds

Digital printing has a certain benefit when batch sizes become smaller and smaller. Since artwork can be selected at the push of a button, and no print mats need to be exchanged, set-up times are extremely short, which improves OEE. Even with UV flexo printing systems, however, actuators and state-of-the-art HMI allow users to perform changeovers conveniently and quickly.

But what is the smallest batch size at which UV flexo printing continues to make sense? At what point do the benefits of digital printing outweigh those of flexo? "Unfortunately, there’s no simple rule of thumb,” says Hapa’s expert. "We recently had a situation involving only a few different SKUs and very large batch sizes, so that the customer needed only a small number of print mats. In such cases, flexo printing can be an economical and sensible decision. But we also have many customers with large numbers of SKUs and small batch sizes. The advantages of an all-digital solution are immediately obvious in these cases. Then again, for those who have a lot of SKUs and highly fluctuating batch sizes, including some that are only medium or small, there’s a strong case to be made for hybrid solutions."

These combine the best of both worlds: a UV flexo printing system with up to three colors on the one hand, and a digital printer for one additional color on the other. The print modules can be operated together or separately as necessary. The UV flexo unit prints invariable text while the digital module applies serialized codes, lot numbers and expiration date, though the digital unit can be employed to print the entire artwork when small batch sizes are required.

Hapa invests in both these printing technologies and in hybrid solutions equally. "This is a claim that no other manufacturer can make, anywhere in the world,” remarks the Hapa expert. "In consequence, we can provide customers with unbiased advice on the available technologies and then work together on developing the solution that suits them best from a business perspective. No matter which technology they select, customers always get a state-of-the-art solution and a sound, sustainable investment.”

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