Principle of cutting out foam by hot wire

Fundamental principle

The fundamental principle of foam (polystyrene, eps) cutting is similar to that of a plotting table, or the cutting of adhesives. This is done by the combined movement of two (or more) axes, allowing the hot wire to melt the material as it moves along, thus making the desired shape.

The essential difference is that we cannot physically proceed as with a pen, where the pen can be raised, as is the case with a plotting table, to draw non-contiguous shapes. To do this would mean stopping the machine, disconnecting the hot wire, passing it somehow through a hole in the material, reconnecting it and restarting the machine. This method would be long and tiresome.

To solve this problem, we have to indicate the joints (or junctions) of the various shapes (or outlines) to be cut by the machine. In this way, there will be a movement of the hot wire all along the outlines. We shall see later how to make these junctions.

Cutting

Cutting polystyrene (or any other thermofusible material) with a hot wire is not in fact a direct mechanical action of the wire on the material, but rather the action of the layer of hot air surrounding the wire. Thus, there is normally no direct contact between the wire and the material. A good quality cut requires the correct adjustment of the temperature of the wire and its speed of movement. These parameters depend on the type of material used.

The temperature of the wire has to be regulated according to its metallurgical characteristics in order to maintain its mechanical strength. Too low a temperature will result in a cutting speed that is too low, whereas too high a temperature will very quickly burn out the hot wire.

The speed of movement is regulated according to the type of material and its density. Too low a speed will result in low productivity, but not inevitably loss of quality, whereas too high a speed produces drags, indicating that the power of the wire is insufficient for this speed setting.

The Shape

The shape to be cut out is created in a vectorial graphic file using your preferred drawing software. This file is processed in our software, and is converted into machine movement. Drawing conventions require the outlines to be drawn in black, while the junctions (joints between outlines) must be drawn in pure colour, green for example.

Our software calculates the path of the hot wire, in such a way as not to omit any outline to be cut.

Please consult the Software heading for further information about our software.

The Finish

When the shape has been cut out, there remains a vital phase that has a big effect on the quality of the result, this is the finish.

From among the wide range of products suitable for decoration, we can choose mastics, paints, varnishes, resins, etc., depending on the type of application and the customer's requirements. The most widely used products are generally water-based acrylics. There are also professional quick-setting polyurethane-based products, requiring considerable resources and equipment but which give results justifying the investment.

Please visit our links for further information about these products.

Summary

Cutting polystyrene by hot wire is an easily accessible and economic solution for volume production of any object. It consists of moving a wire heated to the correct temperature through a block of material; in this case polystyrene.

Your composition is created in a vectorial file. Then the shape to be cut out is calculated and processed in the JiPers software to have a minimum number of actions required by the operator. Imbricated shapes are cut out by means of a simple line drawn freehand or created automatically in our JiPers software.

The file thus obtained is transferred to the machine and stored in memory, ready for the cutout. The cutting parameters are easily accessible, and vary according to the characteristics of the materials.

We can obtain an infinity of colours and textures using a wide range of products suitable for decoration and compatible with polystyrene. Please visit our links for an informed choice of finishing products.

Jipers