Print and Apply Labelling
PALM – Print and Apply Labelling Machine
A Print and Apply Labelling machine (PALM) is designed to be used online and automatically print and apply labels to products as they move along a production line or within a warehouse or logistics facility.
The PALM consist of 3 main elements – Printer, Applicator and Controller .
The Printer includes a print engine and label or media handling system.
The M-Series print engine uses a thermal print head to create the image on the label. Either directly (Direct Thermal) or by transferring ink from a ribbon onto the label material (Thermal Transfer). The printers are capable of printing text, including dates, serial numbers, use by information, as well as logos, graphics and all types of barcodes.
Direct Thermal Labels
The label material contains a heat sensitive chemical which changes colour when heat is applied. This means that no ribbon is required to create an image on the label.
Direct thermal labels are more sensitive to light, heat and abrasion, which reduces the life of the printed material.
The printer uses a normal label media (e.g. paper) and a ribbon. The ribbon is coated with an ink, which is typically wax or wax/resin. By applying heat to ribbon the ink is melted and transferred onto the label and the image is created. With Thermal Transfer different label materials can be used, with the appropriate ribbons and it will last longer and is more heat and scratch resistant.
As the label or label and ribbon are driven beneath the printhead, tiny pixels or thermal pads, across the width of the printhead, are heated and cooled to create the image in the Direct Thermal Labels; or melt the "ink" off the polyester film and onto the plain label material with Thermal Transfer. This process happens very quickly and accounts for the fast speed of the printers and is dry instantly. Thermal print heads are often 200 dots per inch (8 dots per mm) or 300 dpi (12 dots per mm).
Labels are supplied on a liner or backing paper, after the label has been automatically dispensed this is rewound for disposal.
The printed label is dispensed on to the applicator. There are various applicator types that can be used depending on the application it is being used for.
The most common applicator is the Tamp. The label is held via a vacuum onto a pad and then the pad is extended out, by use of pneumatic cylinder, to meet the product being labeled. The pad physically touches the product and applies the label. Sometimes air is also blown through the pad at the point of contact with the product, to assist with the label’s placement. This is referred to as a Tamp-Blow applicator.
A blow applicator simply blows the label onto a product without the applicator making contact with the product. Again a vacuum holds the label onto the applicator and at the point when the label needs to be applied a blast of air blows the label onto the product as it passes.
If long labels are to be applied, either to the side of a carton or more commonly around a corner, then a wipe applicator can be used. A large pad is used to accept the label as it is dispensed from the printer and held in place with a vacuum. As the box approaches the applicator, the pad is tilted out to meet the box and the label is wiped onto the side of it. If the label is to be applied to a rounded corner, then the label is positioned on the box so that half of the label is left hanging beyond the back of the box and the label is then rubbed or brushed onto the back face of the box.
Other applicators are available for applying labels to the front and rear of products, for high speed applications, very small labels or precision placement applications.
The M-Series Printer Control Unit (PCU) controls all aspects of the printer, The label handling – positioning and image creation, the applicator – timings and speed, Error messaging – media out, inputs and outputs – Label data, PLC and line signals, remote control and networking.