3D printing support materials

Introduction

At the current level of development of technology and the chemical industry in the world, an insane amount of plastics has been developed and sold, which continues to increase every day. However, most of this diversity is due to slight modifications to the basic compositions, as well as the intrigues of marketers from manufacturing companies who come up with different names for the same products, just to sound good. In this article, we will try to briefly describe different types of plastics, which fundamentally differ from each other in composition and, as a result, properties and characteristics. We describe their strengths and weaknesses, and the preferred areas of application arising from them.

Important note. Plastics of even the same type can differ quite a lot from each other depending on the manufacturer, additives, quality, color, batch, and even on the period and storage conditions. This is especially true for materials such as PLA, they are contraindicated in high and low humidity, high and low temperatures, direct exposure to sunlight (UV in particular), but after a year or two, even under ideal conditions, they become brittle like dry spaghetti and unsuitable for work. Therefore, the information in this article (and other sources) is valid only for average plastics and applies to their original, new state. For the same reason, we will not delve into the variety of technical characteristics, we will only touch on the main ones, since the spread is too large and any figure will be approximate. Information about the more or less exact parameters of each specific plastic on a specific coil should be taken from the manufacturer's specifications.

Note. This article deals only with plastics for FDM printing, liquid polymers and materials for other technologies - a topic for separate articles.

Conditional division into amateur and professional plastics

The word “conditional” in the title is not accidental, there is no clear division of plastic types according to such a criterion as “professionalism”. All of them can be used both at home and at work, but working with some of them places very high demands on the printer, which in most cases are not available to home “favorites”. For example, not all budget printers will be able to provide a nozzle temperature above 250 ℃, and not every nozzle will endure such treatment. A thermal camera is also not a cheap pleasure, especially an active one, capable of maintaining a predetermined temperature in the print working area. And the price of professional / engineering plastics, as a rule, is several times higher than usual ones, which makes them completely uninteresting for home use. However, it is interesting and useful to get acquainted with them, you need to know what FDM technology is capable of, brought to perfection, so we included professional materials in this review too.

Plastic materials

ABS , the full, hard-to-pronounce name is acrylonitrile butadiene styrene. One of the oldest representatives of thermoplastics for FDM printing, he has both an army of old-school fans and modernist deniers, between whom holivars have not subsided for more than a year. We will not join any of the parties, everyone decides for himself what to love and what to hate, as well as change his mind in the course of time, experiments, experienced admiration and disappointment.

ABS is a fully synthetic material, which means it has the following advantages:

strength and impact resistance,

chemical resistance,

long service life,

high temperature resistance,

the possibility of light post-processing, both mechanical (drilling, grinding, cutting, etc.) and chemical (dissolved in acetone),

Individual parts made of ABS are bonded instantly and permanently with acetone,

low price.

Due to its merits, ABS is excellent for printing functional, mechanically stressed products. Parts can work for a long time at temperatures from -40 to +80 degrees Celsius, in damp conditions and even in water, as well as in the environment of some aggressive chemical vapors and liquids. With the help of an “acetone bath”, the surfaces of ABS products are given a pleasant glossy appearance, which makes it possible to successfully use it for artistic and decorative purposes, which, incidentally, is facilitated by the widest color gamut of all plastics on the market. In addition, ABS is one of the most inexpensive materials, which undoubtedly contributes to maintaining its popularity.

ABS is not without flaws, and there are many. The first follows from its chemical origin: when heated, an unpleasantly smelling gas is released, which is far from beneficial to the health of others. This property already imposes a desire to equip the workplace with exhaust ventilation, which is not so easy for living conditions. Some adherents of the ABS sect say with blue lips that there is nothing wrong with that, but not everyone believes them, looking into their honest, but sunken and yellowed eyes.

In addition, ABS is a rather capricious material, large shrinkage breaks and warps products during the printing process at the slightest uneven cooling. Any draft will cause delamination of the part, separation from the table and most likely lead to marriage. And this imposes another expensive wish on the workplace: a closed box, preferably with heating of the internal volume. This is especially true when printing volumetric products and when manufacturing parts with exact dimensions. Scale correction should be done in advance in the model or in the slicer.

For good adhesion to the table, it will need to be heated to at least 90 ℃, and preferably 100-110 ℃, which makes another strict requirement for the printer.

ABS does not tolerate sunlight and exposure to other sources of UV radiation, but this disadvantage can be partially solved by coloring the product, since it is painted well.

Based on the above, ABS can be recommended for:

• printing of functional, mechanically loaded products,
• body prints,
• decorative prints,
• manufacture of vessels, tubes and containers,
• printing plastic parts.

PLA is the full name of polylactide. Also the "old man" in the world of FDM printing, but in contrast to the poisonous ABS, it is almost a natural product. It is based on lactic acid extracted from corn, sugar cane, potatoes and other agricultural products. It does not pose any danger of poisoning during printing, on the contrary, it smells pleasantly like fried potatoes, but it tends to degrade during storage, in other words, biodegrade. This fact must be taken into account. After some time, usually a couple of years (there are a number of studies on this topic with opposite conclusions), the product may begin to actively lose its strength and appearance, which already excludes a number of possible applications. It has a lot of improving modifications from various manufacturers of varying degrees of success

Pros:

material is very easy to print, and therefore especially recommended for beginners,

there is no shrinkage during cooling, the material sticks to the table perfectly even without heating, it is not afraid of drafts, which means that any simple printer will work,

does not require corrections to the dimensions of the part,

strong and hard, practically no springiness, perfectly holds the load in compression, tension and fracture much more than ABS,

non-toxic,

is available in a wide range of colors including metallic, wood, glow in the dark, iridescent and other complex colors,

is well processed mechanically, well painted, and therefore suitable for the manufacture of decorative products.

Cons::

• above degradability over time, especially outdoors. with a difference in temperature and humidity, although the situation can be slightly improved by applying a protective coating to the product,
• very low softening temperature - about 50 ℃, the product will “float” in direct sunlight and even in the shade on a hot summer day,
• brittleness at temperatures below -10℃,
• can sometimes get stuck in hotends when printing, although this does not always happen and infrequently.

PLA is therefore recommended for:

• printing of large items, incl. prototypes and forms,
• printing products with exact geometric dimensions,
• decorative prints, incl. for painting,
• print cases,
• printing of mechanically loaded parts (taking into account the operating time, temperature, etc.),

PETG - polyethylene terephthalate flavored with glycol. A very promising newcomer to 3D printing materials. It successfully combines most of the advantages of PLA and ABS, while devoid of most of the disadvantages of them. Today it can be called a favorite in the general-purpose plastics market for both beginners and experienced printers.

Pros:

• is simple and not capricious in printing,
• does not emit harmful substances and does not smell when heated,
• does not shrink, which means it does not warp, does not come off and is not afraid of drafts and keeps the exact dimensions of the part without the need correction,
• table temperature from room to 80 ℃, which means it can be printed on almost any printer,
• excellent sinterability, almost never delaminate,
• strength is comparable to ABS, while PETG is more flexible, stretchable and resilient,
• is not afraid of water and a number of chemicals, incl. acids, alkalis and solvents,
• UV resistant,
• extremely durable,
• softening point from 80℃,
• non-toxic,
• beautiful glossy surface, gears and other contact parts of medium duty machines,
• high impact resistance,
• wide range of colors, including transparent,
• low price.

Cons:

• requires careful setting of print parameters and some getting used to it after ABS and PLA,
• a little “snot” due to high fluidity,
• low adhesion of the surface, which means it is poorly painted, poorly glued (but it washes well ),
• viscous, poorly processed mechanically and even worse chemically, solvents such as DCE and DCM do not smooth the surface, but soften the part, which only leads to loss of shape.

Thus, PETG can be recommended to any user for the manufacture of almost any product, from artistic to mechanically loaded. The lack of toxicity allows it to be used for dishes, food containers, molds and children's toys.

HIPS is a high strength polystyrene. It was originally meant as an auxiliary plastic for ABS, used as a support. It dissolves quickly and without residue in limonene without affecting the base material. However, it can be used independently, for example, for the manufacture of decorative unloaded products, “high strength” is present here only in the name.

5

Pros:

• low density, light weight,
• softness, very easy to machine,
• matte surface that looks good, visually hides unevenness and layers, can be easily painted if necessary,
• high softening temperature (similar to ABS),
• less shrinkage than ABS, making printing a little easier, especially on large parts,
• non-toxic, odorless, food-safe,
• is durable,
• is not afraid of moisture,
• is a good color range, but not as rich as ABS and PLA.

Cons:

• requires a high table temperature, from 90 ℃,
• is afraid of drafts and uneven cooling, although not as much as ABS, but care should be taken,
• fragility and low strength, not recommended for use for loaded parts,
• is UV resistant but can be overcoated.

HIPS has a rather narrow range of applications, decorative products without load (printed and put on a shelf) and support for printing with ABS plastic.

SBS aka Watson, real name styrene butadiene styrene. The same age as PETG in the world of plastics, that is, it appeared on the market relatively recently. Similar to PETG in many ways: easy to print, non-toxic, shrinkage is present, but insignificant and does not affect quality. Does not tolerate ultraviolet light, avoid sunlight or apply a protective coating. Distinctive features: especially transparent and flexible. SBS produces the best lampshades, shades and other transparent elements for lighting products. Solvent-treated surfaces finally get rid of irregularities, acquire smoothness and even greater transparency, imitating glass.

5

Pros:

• easy to print,
• low shrinkage for easy printing and dimensional accuracy,
• impact and tear resistance,
• non-toxic, food and liquid compatible,
• waterproof,
• frost resistance,
• excellent transparency,
• beautiful color range, especially for transparent rods,
• easy mechanical and chemical processing,
• flexible and resilient, even thin-walled products are very strong.

Cons:

• high flexibility, not suitable for machine parts,
• relatively weak adhesion of layers forces to reduce print speed and/or increase nozzle temperature.
• is degraded by UV light.

Excellent for safety glass-look decorative items. Due to its transparency, it is ideal for printing plafonds of lamps and fixtures.

TPU is a thermopolyurethane, also known as FLEX by some manufacturers, a soft rubber-like plastic. It is used for the manufacture of flexible products: wheels, dampers, gaskets, belts, coasters, toys and even shoes. Extremely tear and impact resistant, heat-resistant, softening point is about 110℃. It cannot boast of ease in printing, it sticks poorly to the table even at a temperature of 80-90 ℃, the layers do not fuse very readily, which limits the printing speed. It is hygroscopic, it is highly recommended to dry the rod before printing, otherwise voids and “pimples” are provided. Doesn't handle retracts well, especially in bowdens, the long flexible bar is very intertwined.

Pros:

• soft and flexible, hardness varies by version and manufacturer,
• impact resistant,
• tear resistant,
• abrasion resistant,
• waterproof,
• oil resistant,
• indifferent to gasoline, can be used for containers, lids and gaskets,
• heat resistant, works at high temperatures.

Cons:

• is not easy to print, requires fiddling with settings and may need to modify the printer, such as the bar feed mechanism,
• slow print speed,
• poor adhesion to the table,
• small selection of colors, mostly white, grey, black.
• Indispensable for the manufacture of flexible "rubber" parts and decorative elements.

NYLON , in Russian nylon, synthetic plastic from the polyamide family. Very durable material on all sides with a very slippery surface and maximum abrasion resistance. Due to this property, it is widely used for the manufacture of mechanical parts operating under high loads and with rubbing surfaces, such as gears, screws, plain bearings, hinges, and so on. At the same time, rubbing surfaces do not need lubrication, which means they do not collect dust and other abrasive, they work even longer than metal ones. Durable, withstands temperatures up to 120 ℃, it would seem an ideal plastic, but no, the pluses are crossed out by a very difficult print. The high degree of shrinkage warps the part when it cools, and the exceptional slip minimizes adhesion to the worktable. As a result, printing something more than a few millimeters in height on consumer printers is very difficult, almost impossible. The edges of the product are bent higher and higher with each layer, come off the table, then the whole workpiece comes off ... Tricks to improve adhesion do not help much: substrate, varnish, glue, thermal adhesive tape, and so on. As if this is not enough - nylon is also extremely hygroscopic, it absorbs moisture from the air quickly and a lot, which makes it cloudy and, when you try to print it in this form, bursts out of the nozzle with explosions of steam with pieces of plastic. It is necessary to dry thoroughly and for a long time before each printing, and print as quickly as possible so that it does not have time to moisten again. In terms of complexity, it can probably be attributed to professional plastics, for printers with improved characteristics.

Pros:

• perhaps the most durable plastic available,
• resilient,
• low slip surface, abrasion resistant,
• heat resistant,
• non-toxic,

  6 90.

Cons:

• very difficult to print, requires printers with an active thermal chamber, nozzle heating up to 260 ℃ and a bed up to 120 ℃, which puts 99% of household printers out of the game,
• high shrinkage, size correction is required,
• need to dry thoroughly before each use,
• elastic, must be taken into account when designing parts,
• high price,
• only two colors: white (translucent) and black.

At the amateur level, you can afford to print several small flat gears or hinges, with a thickness of 5-6 mm, and even then it will not work right away. But unlike rubbing pairs made of other materials, nylon ones will last almost forever and in almost any conditions. Sometimes the pain is worth it.

ASA Acrylonitrile Styrene Acrylate, a more expensive analogue of ABS, is UV and weather resistant. Rigid, resistant to oils, acids, gasoline, diesel fuel and similar liquids. Does not yellow over time. Used for outdoor parts such as cars, outdoor furniture and decor. In terms of printing complexity and in everything else, it is approximately equivalent to ABS with all its pluses and minuses. It has the same shrinkage, so the models need to be sized. With excellent mechanical properties and chemical resistance, it remains a household plastic that can be printed on almost any printer, without forgetting, however, about the specifics.

Pros:

• strong, hard, durable,
• UV resistant,
• operating temperature -40℃ to 90℃,
• can be easily machined and smoothed with an acetone bath,
• stains well.

Cons:

• capricious in printing, warps from uneven cooling, afraid of drafts,
• does not stick well to the table, even heated to 110℃,
• emits harmful gases during printing, which, moreover, smells unpleasant, it is advisable to use a hood.
• small assortment,
• is at least twice as expensive as ABS.

Useful for outdoor products, such as automotive parts, outdoor lighting, decorative products, gardening tools, window and balcony elements, wearable accessories, and so on. It will last for a long time in any conditions without losing its valuable properties.

PP - polypropylene. Strong, wear-resistant, not afraid of water and most chemicals, durable. Due to this, it is often and happily used in industry, but difficult for 3D printing. Problems are poor adhesion to the table and a high degree of shrinkage, which tends to bend inward and tear off the surface when printing. He often succeeds. Requires high table and extruder temperatures. It can be attributed to professional plastics, which are better not to use at home without special need.

Pros:

• high strength,
• low slip, low friction wear,
• chemical resistance,
• non-toxic.

Cons:

• complex printing,
• high requirements for printers (temperature, heat chamber),
• large shrinkage,
• does not tolerate frost, it is better not to use at negative temperatures.

Suitable for functional parts that work indoors (apartment, office, workshop) or outdoors in a warm climate. However, it can be quite successfully replaced by more flexible materials with similar characteristics.

PC - polycarbonate. Controversial plastic. On the one hand, it has high strength, especially impact, does not lose its properties in a wide temperature range from -140 to +150 ℃, which makes it unique in some senses, on the other hand, it does not tolerate ultraviolet and humidity, which nullifies its chic capabilities for outdoor applications. Printing is not easy, it requires temperatures up to 310 ℃ from the nozzle, and up to 120 ℃ from the table, which not every “household” printer can handle. Afraid of drafts, shrinks when cooled, warps and breaks away from glass at the first opportunity. A closed chamber is recommended, preferably an active one. It makes sense to use in cases where extremely high temperature and impact resistance is required. It is well processed mechanically - sharpened, drilled, skinned. Easy to paint, which can partially correct the UV problem..

5

Pros:

• high strength, especially impact,
• huge operating temperature range,
• low slip coefficient, low friction wear,
• easy mechanical post-processing,
• chemical resistance,
90.0

Cons:

• complex printing,
• high requirements for printers (temperature, thermal chamber),
• high shrinkage,
• hygroscopicity,
• is destroyed by exposure to ultraviolet light.

POM - polyacetal. This is a truly professional plastic, nylon at maximum speeds. It outperforms its little brother in every way, including printing difficulty. It requires more temperature for both the nozzle and the table, moreover, those that household printers can very rarely provide: up to 250 and 130 ℃, respectively. Heat shrink is higher than nylon and ABS combined. An active thermal camera is already required, even for printing the smallest details. Hygroscopic, thorough drying before printing is essential. Suffering is justified by the highest strength, low coefficient of friction, high softening point, as much as 135 ℃.

Pros:

• very strong,
• low friction, high wear resistance, excellent for mechanical gears,
• frost resistant, can work at temperatures down to -50 ℃.

Cons:

• is very tricky in printing, requires drying, an active thermal chamber, high temperature of the extruder and table,
• professional printers are required for printing.

Direction of use is the same as nylon, but it makes sense if the strength and other properties of nylon are not enough.

PMMA - polymethyl methacrylate, popularly called plexiglass. Another professional plastic with interesting properties, but difficult to print. It is transparent, resistant to UV, atmosphere, water and many chemicals. It is well processed mechanically, easily and firmly sticks together with itself and with other materials.

Pros:

• transparent, durable outdoors,
• non-toxic,
• is easy to process.

Cons:

• high temperature printing, up to 255℃,
• cures too quickly, requiring high print speed and precision,
• Shrinkage on cooling is not very large, but there is. Can be a problem given the high setting speed.

It is used in the same place as ordinary plexiglass: lamp shades, light panels, plates, housings, pipes and fittings of complex configuration. Can be used in contact with food and in medicine.

PEEK - polyetheretherketone. Professional hard plastic. The high melting point is both its plus and minus: on the one hand, parts made from it can operate at temperatures up to 150 ℃, which is inaccessible to most plastics, on the other hand, the extruder needs to be heated up to 410 ℃, and you can’t look for such household printers. Even a different nozzle is required, the standard bronze one is not good.

Pros:

• very strong, performs well under heavy mechanical loads,
• chemically resistant,
• durable,
• non-toxic,
• very high softening point,
• abrasion resistant, can work in kinematic pairs.

Cons:

• high printing temperature,
• requires an active thermal camera,
• expensive.

It is used in especially critical parts and devices that experience high mechanical loads and high heating temperatures. Printing requires industrial equipment. Due to its high strength, chemical resistance and lack of toxicity, it is used in medicine, in particular for the manufacture of prostheses and frameworks in dentistry.

Ceramo is a ceramic imitating plastic. Similar to ceramics in everything, in feel, in weight, just as hard, but brittle. It is well processed mechanically, you can go through the sandpaper to hide the traces of printing, and then it is almost indistinguishable from real ceramics. Non-toxic, withstands boiling water, Ceramo cups and teapots can be used for their intended purpose. With caution, you can print on household printers, since the print temperature is quite democratic, about 220 ℃. The main thing is not to go too far, that is, a bar, when printing, because it is also almost porcelain in terms of fragility.

Pros:

• almost identical to real ceramics,
• beautiful and pleasant to the touch,
• good layer sinterability,
• heat resistant,
• non-toxic,
• printable on household printers, with some restrictions,
• only white,
• is easy to machine.

Cons:

• is very fragile, however, this is a plus for imitation of ceramics,
• not suitable for printers that bend the bar a lot when printing,
• requires careful handling at all stages, from storage to use of the finished product,
• is quite expensive.

It is used, as the name suggests, for the manufacture of "ceramic" products: cups, teapots, candlesticks, figurines, lamps and other decor. Not intended for mechanical parts under physical stress.

WAX One of the few materials used for the manufacture of intermediate products. Details printed with wax are poured with gypsum, after which it hardens, it is heated and melted out of the mold obtained in this way. In the future, the form can be filled with any material to obtain the final part, including metal. Before pouring, the printed model can be subjected to simple post-processing, for example, removing traces of printing, for which it is enough to gently heat the surface of the product with a hot air gun. Printing with wax is easy and enjoyable, and any 3D printer will do.