What is a plotter printer

Plotter or printer?

Plotters and large format printers are often used synonymously - in fact, however, both devices differ both in their functionality and in their areas of application. We explain the difference.

What actually is a plotter?

Plotters, sometimes also called curve recorders, are mainly used for the creation of technical drawings and for the precise cutting of materials. A pen plotter has several ink pens that are used to draw lines. So basically the plotter draws like we draw pictures by hand. In contrast, an inkjet printer does not produce images line by line, but pixel by pixel. The plotters that functioned according to the old principle have been increasingly replaced by classic large format printers since the end of the last millennium. In the meantime, the term “plotter” often simply means a large format printer - basically in a high price range and intended exclusively for industrial purposes. These inkjet plotters print line by line and are therefore more similar in their mode of operation to classic printers than actual plotters. Basically, the "inkjet plotter" is an inkjet printer with a very wide print area.

Traditionally, plotters have been and are often used for CAD plots such as those used by architects and engineers. In the meantime, however, large format printers are also being used for this - another reason why they are often equated with classic curve recorders in everyday language. In the meantime, reproplan also almost exclusively uses a large format printer for creating CAD plots: the HP PageWide XL 8000.

Cutting plotter

Because of the way it works, a plotter can also cut. To do this, the pen is simply replaced by a blade. For this reason, plotters are used, for example, for adhesive films, such as those used for some traffic signs and film advertising on buses and shop windows.

A distinction is made between two basic types of function with cutting plotters: the drag knife and the tangential knife.

With a drag knife, the tip of the blade is not in the center of the axis. This offset must be taken into account when calculating the plot path. Drag knives have a simpler structure and are therefore generally cheaper. A tangential knife, on the other hand, has a complex cutting head with an extra motor, by means of which the knife can be lifted, rotated and set down again. Since this takes a short while, a drag knife can be used to plot faster than a tangential knife, as the latter has to be lifted at acute angles. The advantage of the tangential knife, on the other hand, is its wide range of uses. Even thick and difficult-to-cut materials can be processed extremely precisely using a cutting plotter with tangentially controlled knives.

In most cases, the cutting plotter's blade can also be exchanged with a pen, so that these devices usually have several functions.

Flatbed and galvo laser plotters are a special form of cutting plotter, which, as the name suggests, does not cut or engrave the material with a knife, but with a laser. The advantage: Since, unlike with a blade, there is no physical pressure exerted on the material, these machines can cut even finer shapes. Cutting plotters are usually used to display lettering or logos that can easily be cut out of a mostly monochrome film. With multi-colored logos, different, cut-out foils are combined when gluing.

Laser plotters with LED technology, which can be used to print extremely quickly - but "only" in monochrome, have also been around for a few names. The coloring material here is a toner that is applied with the help of heat.

Stickers: Plotted or Digital Printing?

Depending on which motif is to be implemented, advertising stickers can be produced with a plotter or a printer. Multi-colored motifs can be produced with this method, but foils have to be stored on top of each other. Color gradients are not possible. The main advantages of plotted foil stickers are that there is no border or background of the motifs - the shapes can be rasterized extremely precisely and are then free-standing. As a result, they may also be a little more complex to affix than digital print stickers. Pixel graphics also have to be converted into vector graphics first. One-offs are also more economical with plotting than with foil printing. In the case of large quantities, on the other hand, digital print stickers are often more worthwhile. In addition, more complex designs with color gradients or many optical elements do not affect the price.

Flatbed or Roll?

There are two fundamental differences in how pen plotters work. With a flatbed plotter - also called a table plotter - the material to be plotted simply lies flat and is fixed on the work table via a vacuum or an electrical charge. The tool head of a flatbed plotter can take many different forms: Depending on what the material demands, there are special models for textiles, metal, rubber and more. At up to 2 kilograms, the possible penetration pressure with roll plotters is also very high. This variety of possible uses has its price - the costs for a flatbed plotter often start in the five-digit range.

With the roll plotter, on the other hand, the material is moved back and forth on one axis and the cutter moves on a second axis. This means that higher speeds are necessary, and this method is not suitable for every material. Roll plotters are mostly used for foils. They either rest firmly on the axle due to friction or are perforated at the edge and are fixed in this way.

What is a vector graphic?

If a plotter is to be used for printing, a vector graphic is required because the pen or blade can move along the lines defined for the graphic. A vector graphic is an image that is based on image lines, i.e. the connection of points to one another. In contrast to normal pixel graphics, a vector graphic can theoretically be enlarged infinitely without losing sharpness. This type of graphic is therefore often used for logos and simple shapes. When one speaks of vector graphics, a two-dimensional representation is usually also meant.

Photo: © TASPP / Adobe Stock