How and how to cut foam?

Polyfoam – modern material that is used to solve a variety of tasks. Often, when performing different works, it becomes necessary to cut the sheets of the insulation or cut out of it small details of a complex form.

How to cut the material exactly, neatly, with a minimum number of garbage, which tools can be used for this and how to create a thermosaque for foam – you will learn about all this from this article.


Polyfoam is a common name for a large group of modern polymer materials. The most common type of foam – polystyrene (polystyrene foam). According to manufacturing technology, it happens to be prepossible, press and extruded. These species differ in properties, and each of them is additionally divided into brands with different density. For example, there are special types of high density that can be used even to cover airfields. But they are pretty expensive. For ordinary household tasks, as a rule, the material adapted to high loads is not needed.

Most often, the prestickable foam is used here (in marking the first 3 letters – PSB) density from 15 to 35 kg / m³ (PSB-15, PSB-25, PSB-35). It consists of a variety of bonded round plastic cells, inside which is gas (usually – carbon dioxide).

And gas in material 95-98% and only 2-5% – plastics, so the material is very light by weight. Externally, it looks like a plate of many rolled white balls.

All stamps of presticking expanded polystyrene have certain properties. So, this material:

  • Excellent heat and soundproofing;
  • at room temperature non-toxic;
  • It does not come true mold mushrooms and microorganisms;
  • Very light by weight, so convenient in transportation and installation;
  • has a small value compared to other insulating materials (for example, rolled);
  • Most species possess moisture resistance;
  • Does not support open burning, but is light-melting (melting temperature depends on the brand – lighter begin to melt at 60-90 ?, Some – only at 270 ?);
  • High service life – from 10 to 100 years, depending on the brand;
  • easy enough to process.

Such a foam applies for the following tasks:

  • as insulation and soundproofing;
  • for outdoor and interior decoration;
  • for the production of packaging and containers;
  • For interior decor (plinth, finishing ceiling tiles, columns);
  • To create interior statuettes, inscriptions and even toys.

Materials are for sale in sheets that are distinguished by a large variety of sizes: the standard thickness varies from 10 to 500 mm in increments of 1 mm, the length and width – from 1 to 5 meters in increments of 5 mm. But even with such a rich choice often, there is a need to cut foam sheets for their exact fit or to create various decorative elements of an unusual form.

Features of cutting foam

Polystyrene foam has a small density, so it cuts any cutting surface (for example, an ordinary knife). But at the same time, due to its cellular structure, the material will easily crumble, and a lot of garbage can be formed with non-accurate cutting, and the slice itself is often obtained uneven and bug. Therefore, it is important not to just cut foam, but to do it exactly, achieving the most perfect cut and the minimum amount of chips. Make such a cut alone at home is not really so difficult. The main thing is to choose the right tool. It can be “cold” or “hot”.

Cold ways are convenient because the usual tools that are in every home are used:

  • acute thin knife – for example, stationery or shoe;
  • Hoven on a tree or metal;
  • Bulgarian with thin discs;
  • electric jigsaw;
  • Thin metal string.

The thinner the cutting edge ,,.

Nevertheless, with a cold cutting, a certain amount of creaked balls and chips will still inevitably arise. Besides, Only direct cuts can be carried out with such tools.

The more smooth edge and almost complete lack of garbage provide hot cutting methods. They allow you to create objects of any complexity and geometry. Hot cutting professionals use special machines, but their simple analogs can be easily made with their own hands. For a total use:

  • Fine nichrome wire cutter;
  • Solder-based thermal.

Next, consider the features of working with each tool in more detail.

How to use a knife?

For cutting thin sheets of foam plastic (40-50 mm), the simplest tool is perfect – knife. It can be any knife that meets the following criteria:

  • The blade should be as thin as possible – so as not to hurt the neighboring granules;
  • have a very sharp cutting surface – the knife should easily pass through the balls, separating them into pieces, and not to cut the material (since excess friction will lead to the glance of the granules, and the cut will be a bug);
  • The length of the cutting edge should exceed the sheet thickness – so that he can cut the foam sheet through one passage.

Best of all, the usual stationery knife with a thin and wide blade will cope with the task. But you can also use a shoe or even a kitchen knife with a thin blade with small (1-1.5 mm) tooths.

The process of work is as follows.

  • The foam leaf should be horizontally positioned on a solid base (for example, on the table or on the floor), ensuring a sufficient working surface that will not allow the sheet to slip during operation. Cut the thin sheets of polystyrene foam on weight or in a vertical position is not worth it, because at the same time they will be likely to break or get hard and crumble. In addition, it is simply inconvenient.
  • Be sure to make a cutting and marking of the material: with a roulette or ruler, make measurements and make a marker or a pencil to the line, which will be cut. Cut the eye – a very bad idea.
  • Even with a neat cutting, a certain amount of chips and balls will still arise. So the workspace is desirable to be sealed with a film or newspapers so that later it was easy to collect trash.
  • Pre-blade is desirable to additionally sharpen. Also, as it works, a knife is recommended periodically (according to approximately every 200 cm foam blade) to sharpen, as it is quite quickly dulled. You can do this with a polishing circle or grinding stone. To improve cutting, you can warm the blade.
  • So that the material crumble less, moving the knife should be smoothly, without strong push and jerks, slightly pressing the cutting edge to the material (for this knife should be sufficiently sharp).
  • The cut part of the sheet should neatly hold, so that it does not roll and does not slide on the working surface.
  • Specialists are recommended to cut the stationery knife in the direction of “from themselves”, thicker cutting tools (shoe or kitchen knife) – from the far edge “to themselves”, if it allows the leaf area.
  • If the sheet is too wide, then an incision is performed on one side in the direction from the edge to the middle of the sheet, then from the opposite edge lead the cut line to the connection with the already made.
  • Polyfoam cuts and breaks with a characteristic sound that some annoyed. Therefore, headphones can be used for more comfortable work.
  • After cutting the material of its edge, you can be fired with fine-grained sandpaper to perfectly level.

Cutting with baccoon and hacksaw

Cut the foam knife is quite comfortable. But only thin sheets can be cut through quality (up to 50 mm). For cutting thick plates, it is advisable to use the hacksaw, it allows you to work with a thickness of up to 250 mm thick. The process of work is practically similar to working with a knife. You can use the hacksaw of any type (on wood or metal), the main thing is that she has a thin blade and small teeth. Of course, the thickness of the canvas is even thin hacksaw more than the stationery knife, so the slice will be somewhat coarse, and the chips will be more.

Nevertheless, the quality of the cut with due accuracy will still be good. Additionally, to achieve the best smoothness edge, it can be treated with sandpaper. With the help of hacksaw, as well as a knife, it is good not only to cut the insulation slabs, but also cut even large decorative elements with sharp angles (for example, volume letters for any inscription, geometric shapes and so on).

If the material needs to cut a lot (for example, a large number of plates for the insulation of one or more walls of the house), then a lot of time work with a knife or hacksaw. In these cases, it is advisable to use automatic cutting tools – such as Bulgarian or Lobzik. They significantly accelerate the work (if there would be no one day on the cutting knife, then Bulgarian will cope in just a few hours). Although the quality of the cut is obtained somewhat coarse, and the debris is much larger than when working with a knife or hacksaw, since the mechanical impact of automatic power tools is more intense. But when cutting insulation, small irregularities on cuts are not very critical – the surface of the finished parts can be treated with a reference and pollnate by sandpaper, and with the subsequent installation for the ideal docking of the slabs to use construction foam.

The work process with a grinder or jigsaw is also practically similar to working with a knife:

  • Material is horizontally on a flat, comfortable surface;
  • When cutting with a grinder, it is necessary to use a thin saw circle;
  • incision leads smooth movements, without sharp jerks, holding the edge of the material of the material;
  • If, after cutting, the final processing of edges of the plane and sandpaper is expected, then it is necessary to carry out cutting with a small allowance (1-1.5 cm).

Cold strings

As a fine cutting surface that leaves a neat smooth slice on a foam, a conventional steel wire can act. The optimal is the diameter of 0.4-1 mm. To such a wire required length (preferably at 5-8 cm, more than the length of the future cut) on both sides are the handles from any convenient material (for example, wooden or plastic). It turns out a peculiar analogue of the two-handed saw, only with a very thin cutting edge.

It is more convenient to work for such a sawmaker together, as well as a two-handed saw – especially if the cut-down foam plate is large. Colley is carried out due to the progressive movement of the wire on the intended line. When the string is running a bit heats up from friction, which further improves the quality of the edge of parts. In this way, you can cut any number of foam plates.

Their thickness can be any – from very thin (10-50 mm) to very thick (more than 250 mm).

Overview of thermal cutting methods

The quality of the cut can be enhanced, if applied is not cold, but a heated cutting surface. For this, electrical voltage is supplied to it, and the metal is heated. It is this principle that underlies the professional instruments for cutting polystyrene foam. The choice of such devices is huge today: from compact thermal, pistols, portable guillotine machines to smart mechanisms for 3D cutting, special devices with milling heads and CNC laser machines.

Depending on the class and complexity of the equipment, its cost may also differ – from 500 rubles. up to hundreds of thousand rubles. But for household tasks, for one-time application, it is usually no sense to buy expensive devices. Their analogues can be made independently.


The easiest and at the same time very functional device is a special knife with a heated blade. You can buy a ready-made option in the store at a price of 500 rubles. The cost of thermioned with several replaceable blades of different form will be from 1200 rubles. Such a tool is ideal for professional cutting of figured and artistic elements of any complexity. Also, they can also cut the thin sheets of the insulation and, if necessary, make technological openings of any form in them.

If there is no desire to buy a finished device in the store or you need an option with a very non-standard form or blade size, the tool with the necessary parameters can be easily made with your own hands from the usual soldering iron.

ThermoMo is done as follows.

  • Powing the soldering iron take off, spreading the screws on the handle.
  • Instead of sting, the blade of the desired form is fixed and fixed. Its role can be performed, for example, the blade of the usual or stationery knife, a hazardous razor or nozzle made from the end of a screwdriver. Also, an excellent cutting surface can be created if you put a thin wire with high resistance instead of sting – nichrome, tungsten or even copper. Wire can be curbed on figure, this will allow you to cut the details of any complex and non-standard form for the incarnation of the most creative ideas.


Thermonozh is good for cutting small details of non-standard shape. If you just need to smoothly cut into parts a large number of foam plates when installing the insulation, it is more efficient to use a non-compact tool with a small blade, and a special steel guillotine, which is much faster to cope with the task.

As a cutting edge in the machine there is a heated metal wire. This is a more efficient way than cutting cold string. In order to cut a self-made machine with a hot wire sheet of foam 50 mm thick, you need about 10 seconds (with a sheet width of 1 m), the foam almost does not crumble.

The most popular version of the self-made thermosal for foam is made as follows.

  • First, it is necessary to assemble the frame in the form of the letter “H” from the non-conductive electric current of the material – it is better from thin wooden plates, but it is possible from plastic pipes.
  • The bolts are fixed to the ends of the lower legs of the n-shaped frame.
  • The bolts are attached thin (0.4-1 mm) wire made of metal with high resistance to electricity. It is best to use nichrome or tungsten thread. It can be bought in a construction store or get out of the old electrical appliance (for example, an electric kettle, a hair dryer, any heater, except for oil). In the devices, such a wire is twisted into the spiral, it should be obtained, cut off the piece of the desired length and very carefully straighten.
  • Between the upper ends of the frame stretch the spring (or brought to each leg of the loader). It is necessary so that the string, extending when heated, does not start to sign (the heated string is long cold by 2-3 cm), and remained tightly strained and elastic to make a fine material.
  • Next you need a small transformer. It can also be “mined” from old technology (for example, TV). Wires from the transformer are connected to the same bolts on which the wire is attached.

The device is ready for use, it remains only to connect it to the network. You can also power the device from the low-voltage current source – for example, battery. If there is no possibility to connect to the network or the battery, then the device can work even from batteries: three 9-volt “crown” is enough to provide 35-40 minutes of full battery life. When working you need to take into account the next moment. The stronger the healing thread, the faster the machine cuts. However, with a strong overheating, the thread just burst.

Experienced wizards for calculating the optimal parameters of the work are used by special tables, where data is shown in the ratio of the strength of the current current and the parameters of the metal filament.

If there is no possibility to adjust the settings of the equipment or it is difficult for you to understand in technical details, you need to just follow the color of the wire: the red or scarlet color speaks about the optimal heating, if the thread has rolled out something – it needs to be cooled (reduce current strength or give time hardware ).

Rate the article
( No ratings yet )
Add comments

;-) :| :x :twisted: :smile: :shock: :sad: :roll: :razz: :oops: :o :mrgreen: :lol: :idea: :grin: :evil: :cry: :cool: :arrow: :???: :?: :!: