Technology

FLAT-BED CUTTING FOR BLANKETS AND RUBBER VARNISH PLATES

Company
Valiani, srl
Matteo Muto, Sales and Marketing Manager, Valiani srl
Author
Matteo Muto
Further Information
Published
14th May 2024
Matteo Muti, of Valiani, outlines the advantages of the flat-bed cutting machine in the cutting of coating blankets and rubber varnish plates in offset printing

The complex world of printing is composed of two phases – pre- and post-press. The post-press stage involves a high number of finishing devices, including cutting and creasing. Prepress is a fundamental part of the graphic-printing process, with a strong focus on offset printing. 

Varnish plate transferring the ink from plate to paper
Varnish plate transferring the ink from plate to paper
OFFSET PRINTING

Offset printing is a traditional, but still widely used printing method. It involves the transfer of ink from a metal plate to a rubber blanket which is then placed onto the substrate – typically paper. Composed of rubber or rubber-like material, the offset blanket receives the inked image from the printing plate and transfers it with precision onto the paper. The ink must be removed quickly from the plate and applied with equal speed onto the surface of the substrate. This indirect method ensures that the printing surface remains free of direct contact with the inked plate. As a result, it contributes to the consistent and high-quality reproduction of text and images. 

“The 40° bevel is more suited to intricate curves and shapes”

Offset printing is based on a mechanism consisting of three cylinders – a plate (matrix), blanket and pressure cylinder. The second cylinder is coated with a caoutchouc rubber, which receives the ink from the first plate cylinder and impresses it onto the substrate (paper or cardboard), with the help of the third pressure cylinder. 

STRIPPABLE COATING PLATES WITH MULTIPLE LAYERS

The main advantages of printing-press blankets are precision and high-quality print, longevity, waste reduction and adaptability. However, the perfect cut is an essential part of the process. The offset market offers a complete line of strippable plates for in-line coating. The most popular, range from 1.15–1.35mm. Both polyurethane/polyester and rubber surface-coating plates are available to meet all printers’ coating requirements. The film can be bonded to an aluminium plate or polyester foil as required. The transparent film makes it easy to trace the relevant shape for cut-outs. For example, when placed on a copy of an offset plate, the shapes will be clearly visible. For this, a cutting table with a half-cut tool is needed. The customer makes a file so that the top layer of the coating plate remains only where the varnish has to be printed.

File preview of a job
File preview of a job
40° bevel cut vs 90° straight cut
40° bevel cut vs 90° straight cut
DIFFERENT TYPES OF HALF CUTS

When it comes to cutting, some companies offer a two-fold solution – a 90° straight cut or a 40° bevel. The 40° bevel is more suited to intricate curves and shapes. In addition, it results in longevity of the adhesive glue. Both options can be fruitful. Whether the plates are rubberised or polyester based, these tools are necessary to get a smooth finish, including a final stripping process.

“A lot of offset printing presses benefit from digital cutting”

It is becoming more and more common to use any flat-bed cutting machine for samples for cutting varnish blankets. This process used to be manual, but now a lot of offset printing presses benefit from digital cutting when it comes to rubber blankets.

FLAT-BED CUTTING PLOTTER FOR VARNISH PLATES

Digital cutting reduces the blanket’s preparation time, which means no more outsourcing and reduced downtime. To carry out this process in-house means a better overall control over the quality of the plates. 
If the plate is well cut, it can be used more than once. Beyond the intrinsic reasons for the cutting itself, another advantageous aspect is that cutting tables are generally very compact. Additionally, there is no need for another operator, because the same person can run the cutting and printing machine.

Flat-bed cutting machines also help to achieve a more precise cut. The plotter also cuts faster and more accurately on any shape. These include designs, circles and half circles which are difficult to cut manually.

Corrugated board packaging
Corrugated board packaging
Stripping tool to complete the liner removal
Stripping tool to complete the liner removal
PERSONALISED PACKAGING AND SAMPLES

Cutting tables are often positioned in the prepress stage. This makes it possible to create in-house packaging and mock ups. Thus, the printing presses can further amortise a company’s investment of the machinery. These boxes can be printed or not. In the first scenario, a camera recognises the crop. In the second, the cardboard or paper are neutral where 100% precision is achieved by means of the zero point. This is the intersection of the x and y axis. In this way, the operator can make no mistake in placing the plate onto the cutting table.

“Digital cutting reduces the blanket’s preparation time”

Creating custom packaging and high-end box mock-ups is consistent with the offset-printing market. Many times, printing companies need to design well-made packaging before sending it for large-volume production. A small and compact flat-bed cutting machine allows for all of the jobs revolving around the creation of a packaging box. From cutting to creasing on a neutral cardboard and half-cutting the coating blanket to be applied on the offset press. 

CUSTOM CORRUGATED PACKAGING

In the offset-printing market, custom corrugated packaging plays a major role. Not only does it protect the products, but also reflects the essence of the brand. These features can be used as part of the company’s marketing of its product. Offset printing often specialises in the design in food, cosmetics, perfume, chemical and pharmaceutical packaging. The packaging design must take into account the functionality and protection of the product. While at the same time, highlighting the product, the brand and the message to be conveyed. 

Companies study, conceive and design customised packs capable of being both functional and stylish. This creates a positive, purchasing experience for the customer. 
A tailor-made packaging service can boost the perception and lure of products.

Zero-point on the table for absolute precision
Zero-point on the table for absolute precision
STRIPPING TOOL

The quality of the cutting of the varnish plate contributes to the attributes of the packaging. The very last part of well-made blanket cutting is the stripping tool. The polymer needs to be clean cut and stripped easily, without residues. After proper half cutting on the blanket, the operator is required to precisely peel off the top layer of the plate by means of a stripping tool.

Half cut on polyester-based coating plate
Half cut on polyester-based coating plate

“The quality of the cutting of the varnish plate contributes to the attributes of the packaging”

CONCLUSION

In the intricate journey of the ink – from plates to paper – passing through the coating blanket and printing varnish plates ensures harmony and precision. Their role in achieving high-quality prints cannot be overstated. The benefits they bring to the printing process are multifaceted. From precision and consistency to reduced waste and extended equipment lifespan, these blankets are an indispensable part of the modern printing industry. They silently contribute to the visual allure of the printed page. Correctly cutting and stripping the cut plate is an essential key to the overall image of the final packaging. It allows for the smooth running of the printing process and safeguards quality and colour transfer.