PRINTHEADS IN MANUFACTURING

For the purposes of this article, ‘manufacturing’ and ‘industry’ refer to anything outside of the usual digital-printing applications. A printhead’s purpose is to place a volume of liquid in the right place, at the right time. That fluid does not have to be ink. If the fluid can be jetted, a printhead can be used as a ‘digital-deposition device’, opening possibilities across industries where fluid deposition is critical. Advances in materials and technology have expanded the properties and applications of jettable fluids.

Printheads can now jet coatings, adhesives, controlled dosing (drug delivery) and others in specific patterns or block layers. Improvements in viscosity, particle size, particle per cent volume and even material choice, lead to a wider range of materials that are able to be jetted. As a result, an increase can occur in the number of applications served.

If the fluid can be jetted, a printhead can be used as a ‘digital-deposition device’

Manufacturing accepts that the materials can perform the job required. In this way, the priority in manufacturing is quality – making the same thing, the same way, for the lowest cost possible. For products where the part cost is high – semiconductors, displays, lenses, 3D, batteries, solar panels and glass – this is essential. Nevertheless, if the printhead stops working – especially at unpredictable intervals – all the resolution, functionality, productivity and sustainability advantages of printheads are wasted. The cost of this waste is simply too high.

Reliability must be proven, experienced and understood as a benefit to total cost of ownership to the customer. The reasons for poor reliability can be complex and have many causes. This also makes reliability an easier metric to argue against and to promote resolution, frequency and productivity. 

Redundancy, over printing and other strategies can combat reliability. On the other hand, more printheads can combat resolution and frequency. Additionally, at a higher product value, the balance of trade-offs moves towards production-line reliability and away from production-line costs. In this way, return on investment (ROI) can be better with a higher cost production line. Hence, the reason cars are built by robots.

Printheads can, in fact, be extremely reliable if maintenance and an understanding of the systems type and complexity are prioritised. This can be difficult to justify in the machine cost for printing an inexpensive label. But a high-value semiconductor silicon wafer or elements of car production could make predicted/preventative maintenance or an increased line cost an acceptable compromise. 

In paint spraying alone, a reduction of 20–50% waste is possible. This could save a disposal cost of more than €160,000/year (Guray Salihoglu*, 2015). Printheads produce minimal overspray. So, any use of a printhead will result in a waste reduction alongside other benefits to film thickness, graphics and edges. 

Logos, badges, patterns and text can be applied at the same time as a two-tone roof. This enables huge amounts of extra value for minimal time and material cost. The reduction in atomised fluid also leads to health and safety improvements, cleaning schedule reductions and, ultimately, less liquid consumption. These advantages can be extended to other applications, such as lubricants, adhesives and food flavourings. Ever-tightening legislation on material use and hazardous environments is driving this in several industries.

For semiconductor applications, improvements in viscosity capabilities allow materials to be used with uniform and optimal resist deposition. This allows for technologies such as nanoimprint lithography (very discreet droplet). In turn, this translates well to display, electronic, solar panel, energy, additive manufacturing (single and multi-material) amongst others.

The manufacturing capabilities of printheads are not well known in this field, nor is the technology to use them. The established knowledge is that printheads print pictures using only very low viscosity fluids. This means that the number of companies actively and capably buying printheads is relatively small. The development cycle for a technology within industry is afoot and needs growth, exposure and understanding.

System control is another obstacle. Price pressure on print systems means that the balance of trade-offs within a technology is often limited by the value of the product printed. With high-value manufacturing, this is not the case. For example, a poor print can be far more costly to a manufacturing customer than extra pumps, pipes and sensors in a fluid-delivery system. 

In a 10,000 label run there might be defects, but they can easily be re-printed. In 3D, the entire build is ruined – all the time and cost of opportunity lost. As a result, the reliability metrics start to drive that balance of trade-offs. A drop being reliably printed at a lower resolution is better than one being there, or not, at a higher resolution. Reliability can be achieved through fluid-batch control, fluid-delivery system stability and printhead uniformity (across head and head-to-head). Furthermore, printhead type and manufacturer – all of which have different features. Finally, newer printheads are coming available that expand capabilities, high viscosity and very low drop volume. 

Fluidic control and system monitoring has become something that 3D and advanced manufacturing (AM) technologies have needed to understand and implement. Software and hardware now exist to monitor, react and control these systems automatically. Machine Learning and AI can now manage complex interactions. It is possible to create a system with the right printhead(s), fluid-delivery system, machine architecture, materials and software platforms to make use of the full capabilities of a printhead. 

Machine Learning and AI will only improve this control and create efficiencies where not currently seen as important. Cost and time pressures mean that this will start to appear in 2D text and graphics systems. AM will also begin to drive development of 2D printing as the technology translates across markets.

It is only a matter of time before large manufacturing companies realise that the tools are now available. Material jetting is set to become a key manufacturing technology.