How to select the best printing blanket for rotary or digital textile printing machines
At Habasit, we’ve been working with textile manufacturers and OEMs in the global textile printing industry for decades, so we understand the numerous challenges our customers face. Whether they’re using rotary or digital printing machines, the aim is to achieve the highest printing precision and speeds, with the fastest turn-around times, for an ever-expanding array of fabrics and designs. Central to success is the printing blanket, which I want to focus on in this blog.
What is a printing blanket?
Habasit defines printing blankets, whether for screen or digital printing machines, as conveyor belts that fabric (or substrate) is adhered to in order to be conveyed forward and have colors applied. Printing blankets typically have a one-, two-, or three-ply construction, with TPU on the conveying side, a PET or aramid traction layer, and impregnated fabric on the running side.
Why are printing blankets so crucial?
The printing blanket is the heart of every screen or digital inkjet printing machine. Since textiles do not have the stability on their own to provide an accurate run through the printing machine, they are glued to a stable conveyor belt (the printing blanket) which provides the correct positioning throughout the printing process, which can involve up to 24 different colour screens or printing stations.
Precision is everything
Since every drop of color must be exactly positioned in all types of textile printing, printing blankets must meet very high standards. Uniform thickness and surface flatness, as well as uniformity of internal construction (the ‘neutral line’) are the key drivers of printing accuracy. I’ll be looking in more depth at the neutral line in my next blog.
Digital printing has particularly high precision requirements. A typical printing precision goal of our customers is a few thousandths of a millimeter over a printing area that often exceeds several meters. On top of this, the number of colors used is constantly growing, and fabrics are increasingly becoming lighter and thinner. Meeting these challenges calls for a faultlessly even surface, perfect joining technology, and uniform thickness across the entire printing blanket.
Key differences between a printing blanket for rotary and digital printing machines
Traditional flatbed and rotary printing machines are generally longer than digital machines. This means that above a certain length, they need the strength of a printing blanket with an aramid traction layer to ensure optimal repeat accuracy. Another difference: rotary printing machines usually run at faster speeds than digital machines.
In digital printing, the flatness and lateral stiffness of the printing blanket are of the upmost importance to ensure that the printheads can be placed up close to the textile conveyed through the machine. Multi-pass digital printing machines also have to be able to cope with frequent starts and stops. Another point: roller (pulley) diameters on digital printing machines are smaller, which results in different designs for printing blankets to take account of this.
Vital design features
Printing blankets share an array of design features necessary for all printing machines. These include: homogenous thickness, dimensional stability, chemical resistance, high abrasion- and scratch resistance, temperature resistance, and the absence of marking or aging of the joining area. The presence of these features is essential to providing high printing repeat accuracy, reliable processes, high machine output, and a long belt service life.
How to select the right printing blanket
The exact specifications of the printing blanket will depend in every case on the machine and application it is intended to serve. Our team has extensive experience of advising customers on selecting the right belt. It’s vital to understand the entire machine system. For example, the highest performance printing blanket could be too demanding in terms of machine construction if matched with an entry-level machine. The most expensive printing blanket is not necessarily the best, or even necessary.
For short digital scanning printing machines, it is important to find a belt with a low tensile force for elongation, which will minimize belt load and save costs on cylinders and bearings.
In general, wider and longer applications will require different belt features from narrower and shorter ones.
Habasit’s proven range of printing blankets is optimized for every kind of digital textile printing machine, from plotter types to high-productivity and high-precision multi- or single-pass printing machines, as well as for traditional flat-bed and rotary screen printing machines. Very wide printing blankets can also be accommodated.
Finding the right design and cost:performance position for the printing blanket and machine is a challenge that the Habasit team is glad to help with. Please contact me for assistance and advice, or leave a comment below. And if you’re interested to learn more about textile printing and our solutions, listen to the podcast where I discuss the trends and challenges in the textile industry.