Lines for the production of filament used in 3D printing using additive technology.

3D printing technology, often referred to as additive manufacturing, is used in many industries, more and more companies are adopting this future-proof technology. Additive manufacturing has great potential for supply chains, product development and the creation of new business models. Additive manufacturing is a specific 3D printing process. This process builds parts layer by layer by depositing plastic according to 3D digital design data. The term "3D printing" is increasingly used as a synonym for additive manufacturing. However, "additive manufacturing" better reflects a professional manufacturing process that is significantly different from conventional, subtractive manufacturing methods. For example, instead of milling a workpiece from a solid block, additive manufacturing builds the part layer by layer from material supplied as a filament. Various plastics and composite materials can be used in the 3D printing process. Additive manufacturing is used in many fields and industries. Regardless of whether it is used to build visual and functional prototypes, or small and medium series, and increasingly for series production. This method offers convincing advantages that cannot be achieved by conventional methods. Product development and market entry can be significantly accelerated, and agile product customization and functional integration can be achieved faster and at lower cost. In this way, additive manufacturing offers large manufacturers in many different industries the opportunity to differentiate themselves in the market in terms of customer benefits, cost reduction potential and sustainability goals.

The greatest advantage of industrial 3D printing is the freedom to design parts that do not depend on any tool or mold.

The product is created by the 3D printer layer by layer from 3D CAD data This reduces costs, resources and time in many areas beyond high volume production Prototypes can be built quickly and cheaply to optimize designs and accelerate development cycles Components for one-off or series production can be flexibly designed and made to order.

3D printing technology is characterized by almost unlimited design freedom and significantly shortened design, production and delivery times. Development and production costs are also drastically reduced. Parts with less weight and greater complexity become possible to make, and production requires less material and minimal amounts of tools.

With additive manufacturing, design-based manufacturing becomes a reality.

Industrial 3D printing means that the manufacturing process no longer determines the complexity of a component, but rather the desired functionality and appearance of the product. Complex geometries such as 3D structures with undercuts or cavities are usually impossible to produce using conventional technologies such as milling, turning or casting. or are only possible at disproportionately high costs.
Now any shape that can be constructed in a 3D CAD program can be produced using additive manufacturing technology. There are almost no limits even when producing structures with internal voids. This is possible because the material is added by the 3D printer only where it should. Additive manufacturing gives designers unlimited freedom of geometric design, and high complexity plays only a minor role in production costs. By using less materials, you can often even significantly reduce costs.

3D printing with fused plastic deposition (FDM).

The FDM 3D printing process, also known as Fused Filament Fabrication (FFF), consists in unwinding a filament made of plastic from a spool and forcing it through a heated nozzle of the 3D printer head in a horizontal and vertical direction. The item is created immediately after the molten plastic hardens. The 3D printer uses molten plastic extrusion technologies, extrudes the material through the nozzle of the head onto the working platform, layer by layer.

The printing material is a filament made of plastic wound on spools. The filament is fed into the printer head. 3D. The filament in the printer head is heated until it reaches the appropriate fluidity, then it is extruded through the nozzle of the print head. The 3D printer uses information from a digital file. the printer knows exactly where to place the molten plasticThe nozzle of the 3D printer head deposits the molten polymer in thin layers, often 0.1 millimeter thickThe polymer cools quickly, bonding to the layer below Then the 3D printer build plate moves one layer of the printed model and the print head adds another layer of molten plastic Depending on the size and complexity of the object, the entire process can take anywhere from a few minutes to a few days Once the 3D model is finished printing, the object requires a bit of post-processing This can include gluing the object from the working platform, removing supporting structures.

If you are printing with a 3D printer using FDM technology, your 3D printer uses a pre-made filament that is melted and then layered on a build plate You can have one of the best 3D printers on the market, use all the appropriate 3D printer settings, and still end up with a failed print or ugly print Cause of print failure 3D will be using the right filament.The best 3D printing filaments can ensure good adhesion of the material to the substrate and avoid clogging the extruder and, consequently, interrupting the 3D printing process. A good filament allows you to build models with sharp details and high mechanical strength.

The quality of the plastic filament used for 3D printing.

The mechanical and chemical properties of the filament are reflected in the characteristics of the 3D print. There can be no illusions, poor filament properties will have a negative impact on the quality of the printed 3D object. What's more, if a low-quality filament is contaminated, the risk of jamming the 3D printer's extruder and stopping printing increases.

The quality of a 3D printer filament can be measured by the deviation of its diameter and ovality from the required values. If the diameter of the filament changes rapidly over a short linear distance, you will probably notice some inconsistencies in the printed face of the 3D model, such as small bumps and dimples. This can happen because the 3D printer at one moment, it extrudes more molten material (feeding a filament with a larger diameter), and at another moment, when a filament with a smaller diameter is introduced into the head, it extrudes less plastic. In extreme cases, when the diameter of the material is too large, it may not fit in the extruder entrance and the printing will stop. Interrupting the printing of a 3D model is expensive, especially in the case of models printed for many hours or days.
The second important factor affecting the quality of the filament is the presence of a large inclusion, which can lead to blockage of the printer head nozzle and failed printing, while the presence of porosity will lead to the formation of weaker parts, which is important in more advanced applications.

Our added value is a consistent solution: we deliver and implement systems for the production of high-quality filaments for 3D printers. We design and manufacture filament production lines taking into account the experience of our customers. For filaments intended for professional 3D printing, the lines used for their production must meet stringent criteria.

Filament for 3D printers is produced by extruding a molten polymer or composite.
To produce the filament, it is necessary to have the appropriate equipment and knowledge of the extrusion process.

Purpose of the line for the production of filament for 3d printers.

• The line is dedicated to the production of filaments made of hot-melt plastics for use in 3D printers.

• The line can be made as left or right, which allows two lines to be set opposite each other. In this configuration, two lines can be operated by one person.

• The line also allows you to produce filament for other applications than 3D printing, e.g. for welding plastics.

• The line can be supervised and serviced via Ethernet [Internet].

• The line can be controlled wirelessly from a tablet [option].

• The line can be configured and adapted to the customer's needs.

Description of the devices of the filament production line intended for use in 3D printing.

1 Filament extruder.

The filament extruder used in the filament production line must have a high capacity to extrude alloy pellets with high homogeneity without inclusions and bubbles.
Parameters such as the rotational speed of the screw, the temperature of the feeding zone, the temperature of the zones of the plasticizing system and the pressure values should be very stable over long periods.
This requires the use of modern drives in extruders with high stability and allowing to regulate the rotational speed of the extruder screw in a wide range while maintaining a constant torque. The requirements for heating and cooling systems of the extruder cylinder are also high. PLCThe control program should allow for adjusting the thermal profile of the extruder to the ongoing filament extrusion process for 3D printers.
Plastic extruders produced by Zamak Mercator are distinguished by high efficiency, durable construction, low energy consumption, and additionally they take up little valuable space.

Screw drive of filament extruders for 3D printers.

The extruder screw drive motor plays an important role because it must ensure a very stable rotational speed of the screw This is important because stable rotation of the extruder screw ensures stable pressure of the extruded material Pressure stability has a direct impact on the stability of the filament diameter We use modern AC motors to drive extruder screws in filament production lines in 120 Hz technology in the power range up to 22kW Such motors have an extended range of stable rotational speed control, especially in the low rotational speed range, and provide constant maximum torque in the entire range of rotation speed An important element of the extruder screw drive system is the frequency converter [inverter] A well-chosen inverter and appropriate software allows for stable rotation of the extruder screw in the full range Our drives [motor, inverter, control program] ensure stable operation of the extruder or and they save electricity.

Filament extruder screw thrust bearing.

It is a key mechanical element of the construction of the filament extruder. The technical parameters of the thrust bearing determine the maximum operating pressure and the reliability and durability of the device. The thrust bearing must work reliably under heavy load for many years. To ensure reliable operation, the bearing in our extruders is lubricated with oil. The thrust bearing works directly with the gear motor.

Plastic pellet feeding module for the extruder.

An important subassembly of the filament extruder, which affects the efficiency, product quality, reliability, ergonomics of operation. The extruder feeding module, developed and designed in our company, is adapted to work with granules or powder. The body of the hopper module has an efficient system of channels through which the cooling agent flows. Efficient water the cooling system of the extruder's feeding zone prevents premature softening of the plastic granules, ensuring stable feeding of granules Similarly, it prevents powders from sticking Stable feeding of granules or powder is important because it affects the stability of pressure and proper plasticization of the material The feeding module of the extruder enables easy emptying and cleaning of granules or powder The feeding zone of the extruder can be equipped with a port for dispensing liquids and a port for blowing with compressed air It is possible to install gravimetric feeders and a pneumatic grain transport system latuIf a plastic granulate drying system is used, the entire dry granulate supply system is hermetic.This is important to prevent moisture from the air from entering the pellets.

The plasticizing system consists of a cylinder and an extruder screw.

In the process of extrusion of plastics, a very important role is played by the plasticizing system of the extruder, built of a cylinder and a screw, which is a key component of each extruder. The specific type of the plasticizing system of the extruder is selected adequately to the properties of the processed material. The screw of the extruder is responsible for the quality and consistency of the extruded material. the material is transported towards the head. The plastic, moving in the extruder's cylinder, enters the heated zone, where it is melted, and then material and thermally homogenized.

The plasticizing system of the extruder performs four basic functions:

• heating of the material, carried out in order to ensure the desired course of changes in the physical states of the processed material, determined by temperature.

• mechanically compressing the material in order to remove air from between its granules. Next, create a stable pressure in the molten material in order to obtain the desired course of pressure changes.

• mixing, ensuring homogenization, i.e. homogenization of the composition and properties, mainly thermal and mechanical, as well as the structure of the processed material and uniform heating of the alloy to the required temperature

• transporting, enabling the material to be moved through the system, obtaining at its end the required flow rate of the material with a specific intensity and a fixed fluctuation and pulsation.

The quality of the design, workmanship and the appropriate selection of plasticizing system components have a direct impact on the quality of the extruded 3D printing filament.

The cylinder is equipped with a wedge closure that allows easy attachment of the head or the plastic pump.

The key element of the filament extruder's equipment is the rotation mechanism of the plasticizing system [without the need to change the position of the extruder relative to the line] in order to replace the screw or clean it.

Thermoregulation of extruder cylinder zones.

If we want to produce good filament for 3D printers, the extruder should have a good quality plasticizing system, a stable screw drive system and, what is extremely important, a stable and accurate cylinder heating system.

Ecological thermoregulators that we use in our extruders have very good technical parameters and are easy to use. Each zone of the five zones of the cylinder is equipped with a digital system that regulates the temperature in the range of up to 400 ^o C. Each zone of the extruder cylinder is equipped with electric heaters that allow you to obtain set temperature and radiator with a fan, allowing for quick temperature reduction The heaters and the cooling system are simultaneously regulated by a digital PID controller (proportional-integral-derivative) Such a solution allows maintaining the set temperature of the melt with a high accuracy of about 1 ^o C (temperature measurement is made with an accuracy of 0, 1 ^o C).The digital temperature control system allows you to avoid the so-called overloads, i.e. uncontrolled increases or decreases in temperature. The digital temperature regulator developed by our automation department supervises the operation of all extruder zones simultaneously, taking into account their mutual influence.

2 Melt pump.

In the filament production line for 3D printers, a plastic pump with its own precise drive and heating system is installed between the extruder cylinder and the head. The use of the pump allows to improve the stability of the flow and pressure of the material stream supplied to the filament forming head. During the operation of each single-screw extruder, due to the rotation of the screw, a small pressure pulsation and the extruder screw sets the material in rotation The use of a gear plastic pump eliminates these phenomena and allows precise control of the linear speed of the extruded filament.

The use of the pump enables the separation of the filament extrusion process into two independent stages.

• The extruder is responsible for the plasticization of the material, if it is equipped with a plastic pump, it does not need to build pressure, because the pump is responsible for it.

• The plastic pump allows for precise regulation of the plastic stream supplied to the head and the filament extrusion pressure, regardless of the extruder's operating parameters.

The pump is equipped with the same temperature controllers as the extruder. The control system of the extruder and the melt pump is integrated and allows you to control both devices simultaneously from one touch panel.

The plastic pump is mounted in the filament extrusion line in a way that allows the line to work with and without the pump. Changing the line's operating mode is easy and does not require specialized tools.

3Extruder head forming extruded filament.

The extruded filament forming head is the element of the line which, depending on the forming tool, determines the final shape of the extruded filament All parts of the head in contact with the molten plastic are nitrided, which allows for high abrasion resistance The head is heated with band heaters and is placed in it sockets for connecting temperature sensors and a pressure sensor The head is also equipped with the same temperature regulators as the extruder and the pump and is controlled from the extruder's touch panel.

The head is attached to the plastic pump or extruder with an easy-to-use wedge closure
The filament forming head for 3D printers is standard equipped with two tools for producing filament with diameters of 1.75 mm and 2.85 mm The accuracy of the diameter of the extruded filament is not worse than ±0.05 [mm] Tool replacement is easy and does not require the use of specialized tools All head elements in contact with plastic are nitrided to a hardness of 1000 ^o HV and to a depth of not less than 0.5 mm.

4 Extruded filament cooling system for 3d printers.

The extruder used in the filament production line offers a standard operating temperature range from ambient temperature to 400 ^o C. Filaments are most often extruded in the temperature range from about 160 to 300 ^o C, with the exception of high-temperature thermoplastics such as PEEK.

The extruded filament should be cooled to the ambient temperature, or at least to the temperature at which it will not undergo mechanical deformation during the production process. The matter seems simple, we pull the filament through cold water and it's ready.Undoubtedly, most of the produced filaments are cooled with cold water. However, the cooling of molten plastics has technological requirements and limitations that result from the laws of physics and the properties of plastics.

• First of all, plastics have low thermal conductivity. This effect means that the filament takes a long time to cool down, and during cooling there is a large temperature difference between the surface that is in direct contact with water and the inside of the filament. The phenomenon increases with the filament diameter in a non-linear way.

• Secondly, not all plastics tolerate rapid cooling with cold water well. It will be said that gradual cooling is always better because it reduces rapid thermal shrinkage of the extruded material, reducing the negative phenomena associated with it. For this reason, plastics are often extruded into warm or hot water. Moreover, some plastics used for the production of filaments they keep their oval well if they stay in the air, which cools more gently than water, before entering the water.

To reconcile these process requirements, we have designed and manufactured an extruded filament cooling tank, which allows for heating and cooling water in the range of 7 to 80 ^o C.
The tub is equipped with a very precise mechanism for adjusting the distance of the filament entering the water and with a vacuum calibrator of the filament diameter.

Bath for cooling the extruded filament with water cooling and heating.

The filament (string) for 3D printing extruded through the head goes into a tub with warm or hot water. The extruded filament is cooled down there.

The hot tub is made of acid-resistant steel and has a mechanism that allows for its precise movement along the longitudinal axis. the water in the bathtub is maintained thanks to a set of sensors The bathtub works in a closed circuitThe bathtub is approx. 3000 [mm] long, the maximum water temperature is 80 °CThe bathtub can be moved in the range of 200 mmThe bathtub works in a closed water circulation system [ecological solution], which is equipped with a circulation pump with adjustable capacity and an easy-to-use fabric water filter The water in the tank is refilled automatically The water tank is equipped with a water heating system to the required temperature, then this temperature is stabilized All bathtub functions are controlled from the operator panel level.

The key element of the hot tub is the calibrator, which causes the filament to be of one shape and diameter. The calibrator, operating under pressure, stabilizes the dimension of the extruded filament and controls that the diameter deviation does not exceed +/- 0.05 mm. The calibrator has replaceable mouthpieces with different diameters and an adjustment mechanism position in two axes, which ensures the possibility of its precise setting in relation to the extruder head, which is an extremely important factor for the quality of the filament. In addition, the calibrator is equipped with a vacuum pump with the possibility of precise adjustment.

A tub for cooling the extruded filament.

The task of the cold water tub is to cool the filament for 3D printing at the end. Constant, low water temperature allows heat to be removed from the filament in an effective way. The tub works in a closed-circuit water system [ecological solution], which is equipped with a circulation pump with adjustable capacity and an easy-to-use mesh water filterThe water in the tank is refilled automatically.The water tank is equipped with a water cooling system to the required temperature, then the temperature is stabilized. All bathtub functions are controlled from the operator panel. The bathtub is made of acid-resistant steel and in the final part equipped with an air dryer. [mm] The minimum water temperature in the tub depends on the temperature of the water supplying the heat exchanger. In order to achieve high filament cooling efficiency, it is necessary to supply cold water to the tub's heat exchanger system from a cold water generator. The tub is not equipped with cold water generators as standard.

The cold tub is equipped with two mechanical water scrapers and an efficient pressure dryer. The dryer is designed so that it does not make the filament vibrate. The air necessary for the operation of the dryer is supplied by a centrifugal fan. The use of a fan eliminates the need to supply compressed air, which is expensive.

5Laser system for measuring the diameter of the filament.

A laser gauge with an integrated measurement display is used to measure the diameter of the filament in two or three axes. an essential element in the filament production process.

6Crawler exhaust for OG-400 filament.

The lashing has tracks with a length of contact with the extruded profile of 400 mm and a width of 80 mm.
Filament production lines equipped with caterpillar extractors designed for 24/7 continuous operation.

The key issue affecting the quality of the produced filament is stable linear transport Stability of the linear speed of the produced filament is extremely important, because any change in speed will result in a change in the diameter of the filament This is a relationship that cannot be eliminated or limited Stable transport means precisely maintaining the set linear speed of the extruded filament and its diameter .

Tracked lashing is a proven and universal solution, because it allows transport of profiles with different cross-sections. Precise linear speed control allows for very precise adjustment of filament dimensions. Tracked lashing has tracks covered with a layer of material that ensures high friction between the track and the filament. The materials used for covering the tracks are Corex or Linatex - materials with high resistance to abrasive wear.

In order to ensure a stable linear speed of the caterpillar haul-off, we use independent drives for each of the caterpillars.

We use two types of traction track drives:

Gear motors driven by asynchronous AC motors operating in 120 HZ technology equipped with digital encoders min up to 100 m/min or up to 2 m/min up to 200 m/min.

Geared motors driven by AC synchronous motors (servo) Such geared motors in combination with modern inverters allow you to maintain a stable speed while maintaining the nominal pulling force in the range of 1 to 1000 This is an important parameter because it allows you to adjust the speed of the line, e.g. in the range from 0.1 m/min to 100 m/min or up to 0.2 m/min up to 200 m/min. However, these drives are much more expensive.

Our caterpillar extractors are usually equipped with their own digital PLC controller and touchscreen operator panel. The use of our own PLC controller is a convenient solution for operation and allows the extractor to work as an independent device or working in a line producing filament for 3D printing.The lashings are equipped with a safety system that protects against uncontrolled access to the zone of moving parts.

7Extruded filament magazine and compensator for tension changes.

In the filament production process, it is necessary to replace the spools on which the produced filament is wound. Replacing the spool is easy, takes about 10-15 seconds and does not require starting the filament production.

The vertical tension force compensator is in fact an extruded filament magazine that collects the extruded filament when changing the spool on a twin-spindle winder The compensator allows the operator to easily change the spool without interrupting the extrusion process The compensator can store 30 or 40 m of filament The compensator's key equipment is the integrated laser roller position gauge Precise position measurement rollers allows precise cooperation of the magazine with the winder, which eliminates the pulsation of the tension force in the winding process.

This inconspicuous device plays a key role because it allows you to conveniently replace the spools in the filament winder and, what is extremely important, thanks to the use of the laws of physics and laser distance measurement, it allows the winder to maintain a constant programmed filament tension force during spooling.

8Two-spindle filament winder.

Produced filament for 3D printers should be stored Since the filament is packaged on small spools used in 3D printers, it is easiest to store it also on spools with a large capacity The twin-spindle filament winder is a device that allows you to wind the filament in the technological line The winder is adapted to wind the filament on spools with a diameter of up to 400 [mm] and width up to 500 [mm] Large spool capacity reduces the frequency of necessary changes during filament production The spool mounting mechanism is equipped with easy-to-use clamps The winder is equipped with a filament length counter and a tension force meter The winder spools are driven by two modern independent drives To proper placement of the line on the spool, a Uhing GmbH mechanical layer was used, which is coupled with the spool drive. The winder closely cooperates with the filament magazine through a digital control system, ensuring stable filament tension and with storage functions.

All functions of the winder are controlled from an independent touchscreen operator panel equipped with a digital PLC controller. Thanks to this, the device can work independently or in a filament production line. The use of a touchscreen facilitates operation, because the operator is not forced to approach the main operator panel.

9Digital control system for the line for the production of filament for 3D printers.

Based on many years of experience, our automation department has developed software that allows you to manage extruders and filament production lines. Our software allows you to steer, control and manage filament extrusion processes.

Continuous control of extrusion parameters such as: pressure, temperature, rotation, torque, energy consumption, allow you to control and control the process and devices of the filament production line.

You can add to this the ability to save parameters to the database for later analysis and archiving, displaying graphs on-line and working in the plant or even global network.
Our software can be adapted to the expectations of our customers. The process can be controlled from the touch screen on the device console or in the Ethernet network.

10.Additional equipment for the line for the production of filament for 3D printers

• Raw material dryer with pneumatic feeder

Some plastics used for the production of filament for 3D printers require careful drying. Drying of plastics that absorb moisture from the air is necessary to obtain a filament without water vapor bubbles, which will obviously deteriorate the properties of the filament. Dehumidifiers from various manufacturers are used to remove moisture from plastic granules. we can deliver together with our filament production linesIf a plastic granule dryer is used, our extruders are equipped with a vacuum system for transporting granules from the dryer to the extruder's hopper This is a solution that ensures the tightness of the entire extruder feeding system and eliminates the access of moist airIn most cases, the dryer is an essential element filament production lineDrying the material for filament extrusion radically reduces the formation of water vapor bubbles in the extruded filament and has a positive effect on the dimensional stability of the extruded filament.

• Gravimetric or volumetric dispensers

The extruder of the filament production line can be equipped with dosing systems that ensure the feeding of strictly defined, preset amounts of raw materials to the extruder cylinder.

The equipment of the dosing system may include:

Adapter for attaching the dosing system to the extruder barrel, equipped with ports for dispensing liquids directly onto the screws and a port for blowing with air or inert gas.

Static mixer adapted for mounting 2 dispensers on the extruder, 1 pc.

Gravimetric powder feeder with stirrer MCPOWDER 0.2-16.4 kg/h, for bulk density 0.6 kg/dm3, 5L tank

Gravimetric feeder for powders with agitator MCPOWDER 0.4-76.6 kg/h for bulk density 0.6 kg/dm3, 5L tank

Gravimetric feeder for granules 0.72-18 kg/h, 5L tank

Main tank without dispensing 10 L

A unit controlling the operation of dispensers cooperating with a touch screen equipped with an interface for communication with the filament extrusion line.