Inkjet printheads, commonly known as "printheads", are the core components of digital inkjet equipment. Digital inkjet was first used in indoor and outdoor advertising printing, but with the breakthroughs in technology development in recent years, digital inkjet has long jumped out of the scope of advertising printing and is turning more to industrial applications, such as ceramic printing, digital textile printing, label printing, packaging printing, PCB inkjet applications, industrial building materials printing, 3D printing, etc. In the past, the application requirements of inkjet in large-format photography and printing were relatively low, and printers tended to be used for workshop-style production purposes, and the requirements for printheads were not high. With the industrialization of inkjet applications, the demand for industrial printheads naturally emerged. Although there were many industrial printheads in the market in the past, few people could clearly explain what industrial printheads were.
What are industrial-grade products?
For most products, including electronic and electrical components and products, they can be roughly classified into consumer, commercial, industrial, and military grades. The main differences are product use environment, stability and reliability, production efficiency, workload, and operating life.
What are industrial printheads?
If you understand the characteristics of industrial products, this question is not difficult to answer. Only printheads that meet the industrial production environment, adapt to industrial inks, can operate continuously at high loads, and have a long life can be called industrial printheads. In this regard, industrial printheads should at least meet the following characteristics:
Ultra-long life
The life of the printhead is mainly reflected in the fatigue life of the piezoelectric ceramic, which refers to the number of times the printhead works when the standard test liquid (ink) is continuously sprayed until the piezoelectric ceramic is fatigued and damaged. It is usually calculated in billions of times.
Schematic diagram of the PZT working of the shear-type piezoelectric technology printhead. The PZT is stimulated by voltage to produce shear deformation, squeezing the ink cavity so that the ink droplets are ejected from the nozzle
The working life of the printhead can be estimated by calculating according to the production workload. For example, the official data of a company's printhead states that the fatigue life of the nozzle PZT reaches 30 billion times. If the industrial production load life is about 6 to 12 months, such a printhead naturally cannot be called an industrial-grade printhead. For industrial equipment, a minimum working life of 3 to 5 years is required, and the fatigue life of the corresponding printhead piezoelectric ceramic is not less than 150 billion times.
Schematic diagram of the PZT working of the push rod piezoelectric technology printhead. The PZT is stimulated by voltage to produce telescopic deformation, pushing the ink cavity so that the ink droplets are ejected from the nozzle
Stable and reliable
Industrial-grade equipment requires the ability to work continuously and stably. An industrial-grade inkjet printer is often equipped with dozens of printheads. Nozzle failure and maintenance suspension lead to reduced production efficiency and even huge losses caused by production interruption and shutdown. The stability and reliability of the printhead is not only reflected in the solid material and precision manufacturing, but also in the maintenance-free performance such as continuous printing without ink, long standby time, and immediate use.
Ink compatibility and evaluation and certification services
If the printhead is likened to a car engine, then the ink is like gasoline. First, in order to meet the special needs of industrial applications, the performance requirements for inks are getting higher and higher, such as high viscosity, large pigment particles, fast drying, and even special functional liquids, which also brings more challenges to the compatibility of the printhead to inks. For example, some printheads on the market cannot print high-viscosity inks, or cannot be compatible with temperature changes, so they cannot be called industrial printheads. Second, ink is the most critical factor affecting the fatigue life of the piezoelectric ceramics of the printhead, and inferior ink will directly corrode the glue and coating inside the printhead and even clog the printhead, causing damage.
Advantages of industrial printheads with internal circulation
In recent years, many industrial applications have adopted the single-pass method for efficient production, and special inks or functional liquids are also required to meet application performance. In this case, in order to meet the stable, efficient, high-load, and long-life production, higher requirements are placed on inks and printheads. In this context, internal circulation printheads are favored by more and more applications. In recent years, various printhead manufacturers have been actively developing internal circulation nozzles, because internal circulation printheads just solve the pain points of printheads in industrial applications. After years of application, internal circulation printheads have also been proven to have some unique advantages in practice:
1) Stability, ink circulation takes away bubbles and impurities in the ink chamber to ensure the stability of continuous printing
2) Moisture retention, greatly extending the standby time, starting the machine and spraying, reducing the maintenance and cleaning frequency
3) Long life, the internal circulation has a self-repairing function, greatly reducing UV reflection, oblique spraying, and blocking holes caused by ink precipitation, and extending the service life of the nozzle
4) Ink adaptability, internal circulation prevents the precipitation of large-particle color ink, and adapts to a wider range of ink applications, such as UV white ink, coating ink, ceramic/glass inorganic ink, high viscosity ink, and special functional liquids.
With the industrialization of digital inkjet, it is believed that more and more printheads adapted to industrial applications will be developed, promoting more and more digital inkjet application innovations.
