by Cassandra Balentine
Manufacturing equipment is rarely turnkey. From concept through production and decoration, items require unique steps to compose a final product. Therefore, when it comes to printing, bespoke solutions are often commissioned to ensure production success. UV LED curing systems are frequently customized to support specific manufacturing goals.
Above: GEW UV systems are engineered and built custom to each customer’s needs.
Duncan Smith, corporate communications, GEW (EC Limited), notes that for common digital inkjet applications, such as marking and coding, wide format signs and banners, direct mail, and digital labels, it is possible to purchase off-the-shelf, fully integrated UV digital inkjet printers from established original equipment manufacturers (OEMs). In other cases a custom machine is built by the end user or a digital inkjet system integrator to accommodate greater parts complexity or specific printing needs.
Depending on the machine being commissioned or retrofitted, the process can take anywhere from two weeks to a few months.
Installation typically takes a few to several days.
How to Start
For manufacturers considering a bespoke UV LED curing solution, the first step is determining its specific needs and whether or not the technology makes sense to implement.
“When looking to specify any UV LED curing system, the first step is to define what you are trying to achieve,” states Ken Reynolds, business and technology manager, Prophotonix. He points out that the project objective of delivering superior performance or competitive advantage versus one focused on achieving cost reductions will likely take different paths.
It is important to establish the needs of the end user and the scope of the project. “The end user and/or OEM should identify the range of parts or substrates to be printed, the type of inks to be used, whether the end user prefers a single-pass, inline print process or a multi-pass process that relies on either a scanning light or surfaces that rotate in front of the lamp and the targeted range of production speeds,” says Smith.
These responses dictate the set up of the UV LED lamp head and the energy the curing system must deliver to the print surface to achieve successful curing. “The output of the UV curing system must always be matched to the needs of the ink as well as the material handling process. Incorrectly matched systems will leave the ink soft, sticky, tacky, or greasy following cure,” continues Smith.
“For a bespoke solution, a clear understanding of the limitations of existing equipment for the application will contribute significantly to the specification,” offers Reynolds.
Criteria may include wavelength, intensity, dose, uniformity, illumination area, beam angle, or form factor as well as compatible consumables, desired print speeds, and intended use and lifetime of the final product.
Several questions to ask before investing in a LED UV system include compatible inks and coatings, changes that need to happen in order to convert a machine to UV, how many lamps and positions, the system’s energy consumption, how long installation takes, whether or not training is offered, the system guaranty, and the price, shares Enca Plaza Bonilla, sales manager, Benford UV.
“It is also important to know if there are any integration constraints for the line. What is the available space for mounting? Are there restrictions on working distance or airflow clearance? What will be the operating temperature/humidity? Defining these factors helps to determine the equipment, feasibility, and process parameters for the print solution,” suggests Pamela Lee, senior product manager, OmniCure UV LED Curing Solutions, Excelitas Technologies Corp.
Mike Higgins, director of sales, Americas, Phoseon, recommends taking a close look at the UV LED curing technology company’s capabilities and reputation of the UV LED supplier. “It is also important to compare the performance differences of the various UV LED based systems. After learning all the facts you can quantitatively determine that not all UV LED curing suppliers or systems are created equally.”
Once it is determined that a UV LED system is the right choice, and a suitable vendor is selected, the next phase in the process can commence.
According to Reynolds, the key to a successful UV LED curing system development is a detailed, mutually agreed specification. From there, the parties can work together to develop a concept in the form of a proposal that includes technical and commercial aspects, deliverables, and key dates for the project.
Lee says once parameters of the bespoke printing solution are defined, manufacturers should then engage with formulators to ensure that a UV LED curable ink is available for their application, as existing inks for mercury or microwave lamps will unlikely be compatible with LEDs. “Only after a suitable formulation is found should curing solutions be pursued,” she stresses.
Higgins suggests manufacturers identify what curing lamp system is ideally suited for application and schedule a trial to work with the chemistry supplier and receive samples of LED curable version of product as well as substrates. “Upon successful testing an official quote is generated based on all required components including LED curing lamp, power supplies, cable lengths, controls, chiller, and bracketing.”
After consideration of the integration constraints and requirements of the print solution, a lab scale trial—or replication of the process—should be run to confirm that the formulation, equipment, operating conditions, and substrates will perform as expected. “Conducting this evaluation is an iterative process and may require multiple tests and subsequent tweaks to the formulation or set-up to find a suitable solution,” explains Lee.
Based on these experiments, the efficacy of the print solution is validated, and the manufacturer will be ready to move to the next stage of the process—pilot or production line trials. “Pilot trials allow parts to be run at speed and operating conditions that mimic production and validate the efficacy of the lab scale process. Then, finalization of the UV LED curing solution, integration parameters, and process windows for the line can be completed. This ensures that the print quality and performance can be reliably reproduced,” shares Lee.
From here, Bonilla says the steps and timing involved in the installation are communicated. “Once we get the order, the first thing is visiting the factory to survey the press that will be retrofitted with the system or check CAD drawings of the press if it is new.” She explains that manufacturing happens on the Benford site, it ships, and installation time varies based on the size of the project. This is typically two to five days and one to two extra days for commissioning.
Smith says the installation is normally carried out by the OEM machine builder or the UV LED supplier. “In either case, the end user is assured the curing system will be seamlessly integrated into the printer.”
Lee points out that the installation process varies from customer to customer, depending on how they choose to implement the integration. Many have in-house experts to install systems while others employ third-party integrators to help. It is common for UV LED suppliers to provide information for mechanical, electrical, as well as control interfaces to support the integration.
Cost estimates are typically given at assessment. However, it is not always a final representation.
“While there can be price targets and high-level estimates earlier in the process of integration, it isn’t until the solution is confirmed to meet customer expectations through trial runs and testing, that a more accurate cost assessment can be made. Since changes to equipment or formulations can result from pilot runs, there can be an impact on which systems make the most sense to integrate,” explains Lee.
Collaboration and Integration
As previously stated, when commissioning a UV cure system, many components are involved. In addition to the UV LED machine, substrates and inks must be vetted. Collaborating with system integrators is an essential part of the process and should happen before installation and finalized machinery plans.
Reynolds explains that UV LED curing lamps form part of a system and it is extremely useful to work with other partners in advance to answer specific questions and collaborate to provide the best end result. “Ink or adhesive manufacturers or accessory suppliers such as printhead or substrate manufacturers can provide important insights,” he offers.
Smith says critical integration components include surface pretreaters; the digital print engine—including printheads, fluid delivery system, and mounting apparatus; inks and coatings; the material handling equipment; and the curing system. The curing system can be air- or liquid-cooled. If it is liquid cooled, a chiller is required along with the associated piping and flow regulators. A mounting bracket for the lamp head as well as appropriate shielding to block stray UV light from the operator and printheads must also be provided.
He believes the part, substrate, or construction suppliers should be involved to the extent that surface energy varies by material make up as well as the grades and ages of plastics. “Some materials will need to be cleaned, coated, primed, or surface treated prior to digital printing in order to improve adhesion,” he advises.
Collaboration between suppliers is crucial, as there are dependencies on one another to successfully implement a fully functional system. “In fact, it is not uncommon for UV LED suppliers to work closely with formulators to ensure materials will be compatible with various curing solutions. In some cases, the relationships between companies may already exist, and in others, introductions are made through the customer,” says Lee.
Smith adds it’s always best that the project manager—which is typically the OEM, integrator, or end users—coordinate activity amongst all suppliers. “That said, many industry suppliers work closely on a regular basis and often have conversations with each other to ensure that technically correct solutions are developed.”
We’ve outlined the process for inquiring, preparing for, and installing a bespoke UV curing system. UV curing technology providers feel there are several aspects of the process that can’t be overlooked and phases that shouldn’t be rushed.
Bonilla says the most important thing is to ensure that the customer really needs LED UV. “Some customers are driven by the excitement of getting the latest technology without realizing that maybe this is not what they really need. It is imperative to assess the customer requirements and advise them for the best UV option for the jobs they want to do. We say it is crucial to apply the right technology to the correct application. This will save customers money, time, and frustration afterward.”
Smith stresses that the consultation and design process is the most important stage. “When this step is managed correctly and thoroughly, it avoids technical and operational issues later.” The UV LED curing system must be designed such that it not only integrates into the allowable printer space, but that it also delivers the correct UV output to produce the desired image quality with the full care under the given process conditions.
“Unfortunately, in cases where this step is not fully appreciated by individuals tasked with sourcing equipment or building the printer, end users are often unable to run the full range of intended parts at the desired process speeds.”
Smith adds that not all UV LED curing systems are intended for the same applications. An under-powered as well as an over-powered UV LED solution for a given application will leave the end user frustrated. “When the consultation and design process is executed correctly by experienced suppliers, however, the end user is ultimately more satisfied with his or her new UV LED digital inkjet printer.”
Higgins feels that the most important aspect of purchasing a UV LED curing system is to ensure the product has proven reliability. “Significant reliability testing needs to be done during product development to ensure products are rugged and reliable in even the harshest environments. Make sure you work with a company that offers reliable products.”
Lee says the testing stage is critical as paper specifications and requirements are no match for real-life validation. “Without conducting trials to verify a process or materials and equipment compatibility, it is impossible to truly assess the quality of print and the performance of a solution. Moreover, specifications—of inks as well as equipment—are best confirmed when tested under conditions representative of the final product.”
Further, Lee explains that selecting components for a print system using only theoretical specifications rarely translates to a successful realization of the product. “As an example, the metrics of UV curing systems may be defined differently from one manufacturer to the next, so while it may appear on the surface that one LED solution should outperform another, it may not be the case in practice. It is also during this part of the process that tweaks can be made to fine-tune the print solution.”
Clearly defined project objectives including developing a detailed product specification and good communication of budgets and timelines is the most critical step in delivering the optimum solution for the application, according to Reynolds. “Working only to a UV LED lamp specification without fully understanding the application or the wider context can mean that the final product is not fully optimized and as a result system performance is not maximized. As a consequence, the upfront effort and planning of the project plan and specification are critical and will advance the development in the fastest possible manner.”
Inkjet is a versatile technology. However, outside of common application environments where turnkey solutions are available, bespoke equipment is often required. It is important to determine your needs upfront and do research on not only UV LED solutions providers, but also treatments, inks, and substrates that support the process to ensure production success. IPM
Sep2020, Industrial Print Magazine