While both flexo and offset are popular, they do things differently. It is important to understand what their roles are and how each printing process works.
Here are three differences:
Difference 1: Plates (Printing Matter)
Flexible plates are used in the process of flexo printing, which uses rotary printing. The plates are made from photopolymer nylon or rubber compound and are flexible enough to be wrapped around a printing cylinder. The relief image on the plate is fixed using a laser image-setter, and the polymer in the non-print areas is removed in a processing unit by dissolving it in a solvent or water solution. The ink is transferred to a flexo plate using a rotating 'anilox' roller. For each colour, a separate printing station and flexo plate are required. The image is then printed directly onto the substrate. The printing plates are quite durable and if stored correctly, can be re-used several times, before they eventually need to be replaced.
Flexo Plate Made of Photopolymer Nylon
For offset printing, again as the name suggests, ink is transferred (offset) via a series of rollers onto the printing plate. This can be either a flat-bed or rotary process – depending on the type of offset press. The plate is usually made of aluminium. The complete wet image (either single colour or multicolour) is then transferred onto a ‘blanket’ and in turn onto the substrate, before drying.
Offset Plate
Difference 2: Ink
Offset printing usually consists of four ‘process’ colours: cyan, magenta, yellow and black. Each colour has a dedicated printing station. Any spot colours are made from a combination of the process colours. Ink can be water-based or UV curable.
Although process colours are also used in the flexo process, additional print stations tend to be used for spot colours. Spot colours can be supplied pre-mixed or can be mixed in-house, as required. A flexo printing machine can use different types of inks, like water-based ink and solvent ink. Inks need to be removed from the press when it is not in use – to prevent ink from drying on the rollers & in the ink trays.
Difference 3: Type of Materials to Print on
Offset printing machines can print on materials such as; paper, metal, cardboard, cellophane, and vinyl. The printing surface must be flat and smooth. It is excellent for printing newspapers, books, magazines, stationery, posters, brochures and so on. Generally, printing onto both sides of the substrate will require a second pass. Similarly, any die-cutting, slitting, folding, creasing, laminating, etc is done as a secondary, off-line process.
Flexography is used on both absorbent and non-absorbent materials, for example, PP/HDPE Woven Fabric, paper, aluminium-foil paper, paper board, PET, BOPP, etc. It is mostly used for packaging, like envelopes, retail bags, wallpaper, paper, newspapers, sweet wrappers, and so on.
The main difference between both processes is that offset printing is only done on a flat surface while Flexographic printing can be used on almost any substrate with a flexible surface. Flexo printing can achieve high-speed production and many presses have multiple converting options integrated into the press, enabling a single pass operation.
Making the Right Choice
Advantages of Flexo Printing
Flexo presses have short set-up times with a minimum of waste and guarantee high-quality output
Flexo printing eliminates the need for additional work and cost. The press automates additional tasks in-line that are most commonly needed for labels, such as die-cutting and lamination. Offset printing requires performing these processes on separate machines after completing the printing, which asks for additional time and manpower.
The principle of flexo printing is simpler. It’s a relatively straightforward and more controlled printing process that requires less-trained operators to achieve high-quality output.
Disadvantages of Flexo Printing
The printing plates that are needed to print the image onto the label are more expensive than offset printing plates. (at the other hand, you can use them for repeat orders, whereas in offset you always need to make new plates, also for repeat jobs)
Advantages of Offset Printing
It guarantees high-quality images.
This printing technique allows a lot of flexibility with label material.
It’s suitable for large printing jobs: the price per 1000 labels goes down as the number of labels goes up
Disadvantages of Offset Printing
An offset printing press is expensive; due to the complex print units.
It requires more set-up time and produces more set-up waste, so higher set-up costs.
To keep the quality up to mark, you need skilled operators because the press and offset printing process are very complex. Ink and water balance, pH value, temperature, etc. all influence label quality.
Both Flexographic and Offset machines have their advantages. Flexography is excellent for high-speed production and overall quality. It is great inefficiency in many ways and is generally appropriate for most large-scale printing tasks. In the label printing sector, most businesses prefer flexographic printing machines because of their adaptability and economy of scale. When looking for a printing solution, look for one with the future in mind, and invest in the printing technology of the future. One current trend for flexo is for it to be combined with digital printing technology to produce powerful hybrid solutions that outperform most traditional offset presses.
Flexography beats offset printing in many circumstances because of its flexibility & productivity benefits. A flexographic press is a sound, long-term investment and is adaptable enough to accommodate and integrate a wide range of in-line processes, including new digital technology.
Get to know the difference between Flexographic Printing and Rotogravour Printing here.
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