Do-it-yourself extruder for polypropylene

DIY manual welding extruder is no longer a fantasy. With the development of technology, there is a real opportunity to create this unit yourself.

First, let’s figure out what it is and why it is necessary. It is with the help of this unit that polymer products are obtained without length restrictions. It has its uses and applications. Do-it-yourself manual extruder – simplicity and ease of assembly and subsequent operation.

dressing process

The top part, also called the “die head”, moves the fusible polymer to the next chamber, otherwise called the “molding”, with the correct profile for the selected product. The described method is one of the most common methods. It can only be compared with the “injection” method of manufacturing plastics.

Which polymers interact most strongly with extrusion:

Well, the direct process is quite transparent, it is worth taking a closer look at the actual extruder.

Construction and action

The idea itself is already more than sixty years old, it is not surprising that over the past time it has undergone some changes and has become almost ideal. Over time, a large number of machines have appeared that have different methods of influence and are almost identical in the field of the products obtained.

What heats the base of the future product? Everything is quite simple here, the energy from mechanical processes becomes heat, which also helps to heat the plastic. It is also possible external thermal influence. Here, for the most part, there is a dependence on the original design of the extruder.

Changeable elements of plastic processing by extrusion:

  • compound;
  • nature;
  • humidity;
  • intensity;
  • duration;
  • pressure and temperature.

Extruder operation

The extruder is a fairly simple unit, and all technical variations can be divided into three groups. Groups are divided by working moments:

  • cold forming;
  • hot extrusion;
  • heat treatment.

The most demanded element at present is hot forming. This process is accompanied by high pressure and speed. For implementation, an extruder called a screw is required. For such units, the main element is a special type of screw. Here, the molding process is located at the outlet. Raw materials are loaded into a specialized chamber, just like the selected additional components. These units have the ability to equip the screws with special elements at the factory. The mixing of the composition and its movement depend on this.

How an extruder works

The extruder, its working part, can be divided into three:

The process of using an extruder

The grain unit performs its work due to closed-type chambers and grains located in them. Internal pressure increases due to the evaporation of moisture. To increase the volume of the mixture of steam and air, a sharp depressurization is carried out. And depressurization, in turn, increases the volume of grains.

Production

Do-it-yourself manual extruder for polypropylene is one of the easiest ways to purchase such a unit. It should be noted that the assembly process is not as complicated as it might seem, and anyone can do it.

The production of extruders is a rather interesting process, which directly depends on the configuration and purpose of the unit. Production differences:

  • number of working chambers;
  • availability of additional systems;
  • design of the elements.

The only thing that is unchanged is the cylindrical shape. To date, it relies on the most technologically advanced, and therefore remains itself.

Technological differences

The process of creating and operating an extruder is enough to understand. But there are a few important points that need to be highlighted. In particular, lighting is required for the dry extrusion process. Why exactly? Dry extrusion is based on the heat generated by the unit itself, due to the direct process of work. At the same time, it remains possible to introduce steam into the work; for this, it has a special chamber. What is steam for? It is thanks to him that the wear resistance of the unit increases.

A special difference of this method is speed. The process takes only half a minute. During this time, the unit manages to:

  • grind;
  • dehydrate;
  • mix;
  • disinfect;
  • stabilize and increase volume.

A do-it-yourself manual welding extruder requires the purchase of several elements from which the assembly is made. The list of elements required for assembly:

  • auger of the proper configuration;
  • Electrical engine;
  • body of the device;
  • capacity for supply and output capacity;
  • vacuum chamber.

Alternative unit

A manual extruder for polyethylene also belongs to the general cohort of extruders, although it has a slightly different purpose. What is this unit used for? For joining various polymer products. Particularly good in this field is the welding extruder, applicable to various materials. This unit greatly facilitates the work with small and very small plastic products.

I will have to make an extruder for plastic with my own hands for the following reasons. Firstly, I decided to make a 3D printer with my own hands, and I will need a lot of rather expensive rod for a 3D printer, which is many times cheaper to produce myself using a plastic extruder than buying a ready-made ABS or PLA plastic rod for a 3D printer. Secondly, a plastic extruder is one of the components of an injection molding machine (TPA), which I have been dreaming of for a long time. So I am again trying to kill two birds with one stone and save myself a lot of money

Let’s figure out what a plastic extruder consists of and how to make it yourself at minimal cost. A plastic extruder consists of a tube ending in a removable brass nozzle from which molten plastic will come out. Inside the tube, the so-called auger will rotate (such a large screw, as in a meat grinder). This screw will push the plastic granules along the tube. Starting somewhere slightly to the middle, the tube will be heated by a special heating element, due to which the plastic inside the tube will melt and reach the nozzle already in a fairly fluid state.

An ordinary large-sized wood drill, bought at a tool store for 340 rubles, acts as an auger. With the diameter, I messed up a little and took 22mm, which I later regretted a lot, because it turned out to be quite difficult to find a pipe with the same inner diameter. Therefore, my advice to you is to first find a pipe, then look for a suitable drill (auger) for it.

As you can see in the very first photo, the tube is divided into two parts, connected by flanges. This is necessary in order to separate a particularly strongly heated part of the tube from the rest of the mechanism. Later, a heat-resistant heat-insulating gasket will be sandwiched between the flanges. In general, heat will still be transferred through the screw, but a collapsible tube will make the extruder more maintainable, and leave room for experimentation (removed one tube – screwed on another).

I made the flanges on my homemade CNC machine from 5mm steel sheet. As you can see, my machine gnaws quite tolerably on steel, despite its still flimsy and unfinished Z-axis. Two bolted flanges were clamped into the vise at once. We want all the holes to match!

To ensure the parallelism of the two pieces of pipe, I welded the flanges to the frame before sawing it. We twist two flanges together (in one of them I cut an M6 thread, in the other just through holes), and it is necessary to twist through washers, the thickness of which would then allow a hacksaw blade to crawl between these flanges. By the way, do not forget to mark how the flanges should be attached. To do this, at the end, I sawed the mark with a file. The flanges are connected correctly if the marks on them match.

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The next step I made a cut in the short part of the pipe. Granular plastic will enter this slot through a special funnel and be pushed by the screw further along the pipe towards the nozzle. Note that the right side of the loading slot roughly coincides with the start of the screw.

One of the most tedious steps in creating a do-it-yourself plastic extruder is making a heating element for the longest part of the extruder – the one in which the plastic will melt. Here I also decided to save money and make the heating element myself from crushed refractory bricks mixed with liquid glass and nichrome wire, pre-calculated for a given power.

The difficulty is that I do not have carbon dioxide for the rapid hardening of liquid glass. So far, I have not found where in our city you can refuel a cylinder of carbon dioxide. One could, of course, indulge in a carbon dioxide fire extinguisher, but somehow I didn’t want to waste such a responsible device on trifles.

I read a good recipe on the Internet when a little cement is added to the refractory (1/5 or even less). Then liquid glass reacts with cement and hardens literally in a matter of minutes. In the spring, I did well with fresh cement, but now by autumn the cement had already lain down and deteriorated, so the liquid glass did not want to harden properly.

By the way, the cover from my auger, in which it was sold, was very useful as a mold for filling the pipe with refractory. And if I had not forgotten about the special measures for curing liquid glass, then my heating element would have turned out to be just the perfect shape. In fact, I forgot to add cement there, so I had to remove this entire mold and manually coat the pipe with a refractory mixture, and then wrap it all in an ordinary piece of paper to dry. By the way, it helps to speed up the curing process by calcining liquid glass in degrees so at 150-160 C.

Today I unwound this scroll and checked the result. Adhering paper is very easy to remove if moistened with a little water. In general, it turned out well, but you will have to coat it again in some places, closing up holes. The fact is that in some places the refractory solution with liquid glass “floated”, a little behind the extruder pipe. This was easy to detect by running my finger across the entire surface of my extruder heater. Where the refractory did not adhere tightly to the pipe, it crumbled and fell off.

Of course, you will need to work a little on the technology for making heaters for extruders with your own hands from refractory bricks and liquid glass. This calcined ring is especially inspiring – it turned out just superb! (It can be clearly seen on this photo right next to the mounting flange) But for the time being, I am not going to mass-produce heaters for extruders, so we will put this issue on the back burner.

So, we got a heater with a power of about 3 kW. Yes, aluminum can be melted in this – not like plastic. I wonder what extruder performance can be achieved with such a heater?Now it remains to fit the engine and make it a normal driver with synchronization. Keep for updates…

I don’t understand. Let’s say such an extruder worked once. The plastic inside is frozen. How to live on?

We have a hefty 22mm axle, melted plastic will try to climb into all available slots.
After cooling in these slots, it is not a fact that the heater will melt it or melt it completely.
Shagovik will pull out such a wild load?

You can also put toothpaste in there – see how evenly the plastic will be squeezed out. It’s certainly interesting to see what happens.

Well, apparently, you will have to accurately load the required amount of plastic and develop it completely. In any case, you need to squeeze out everything to the last of the screw, and then there will be a small piece in the head itself, which separates quite well (judging by the video of already working extruders on YouTube).

Here, the cracks just need to be made smaller. Well, in theory, the plastic will climb where the extrusion force squeezes it out. The molten ones will not be allowed to climb back fresh granules that have just entered the auger.

As for the engine, I saw projects on steppers, and even on car window lifters. Everything seems to press at least 1mm / sec, which is quite enough for a bar extruder for a 3D printer.

I am also planning an extruder for an injection molding machine, so I want to put in a 500 W asynchronous engine. It would be nice to have a servo, but I don’t have one, but it’s very expensive to buy.

for all types of plastic, be it abs, pla or any other, there is a set of specific physical properties, ranging from pour point, melt viscosity, and so on.

For any extruder there is such a thing as a feed rate. didn’t you read about it? it is again tied tightly to the type of plastic you are processing.

the feed rate is tied to the gearbox, the power of the engine is tied to the type of material and its volume in the cylinder.

What is your working area will be considered?

how many nozzles will you have? you have an unloading chamber, as I understand it, at the output, judging by the size of the cylinder, but the question is why, if you intend to make a bar … and you need at least a kilowatt engine to scroll such a mass … the smaller the diameter of the screw and its length, the lower the engine power … for a screw of 30×300 mm, 500W is no longer enough …

if there is an extruder in one nozzle and without bells and whistles such as a vacuum chamber or unloading at the exit, take a 12 mm screw and a 200 mm long one, this is enough for your eyes … especially for 1.75-3 bars you have more than 20 revolutions per minute = material reverse flow …

I’ll say right away that the working area where the material begins to melt you will have a maximum of 100mm with an 18mm screw

About the types of plastic and the different feed rates depending on the plastic – these are pretty obvious things to read about. To read about everything and count everything – so life is not enough. I prefer the scientific-experimental poke method to this.

I not only planned to make a rod. I also want to build an injection molding machine based on this extruder. I also have a kilowatt engine, if that. By the way, my auger is 22mm (it says in the article).

But, probably, pressing a bar and an injection molding machine are too different tasks to press them all with one extruder. Or, at least, you need to install several heaters and control them separately, depending on the task being solved.

I haven’t even approached the calculations of cameras and zones yet 🙂 I left the theory for later, in case I can’t solve the problem in a hurry

22 mm is a lot, you will have to unload and output to 3-5 nozzles

for thermoplastic you will need a factory screw with a pear, ala 20k at least you will have to pay for it … it’s
better to make a piston-type thermoplastic, less worries, because. hydraulics are easier to adjust in terms of feed rate, and there are no particular problems with the components … and cyclically it’s all the same … but with the auger, I’ll immediately say that the problems will come out with the reverse flow of the material, because the speed is more needed here.

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decide on the volume of casting, more than 8000 cubic meters. cm there is no point in doing something, after 1000 you will need a vacuum chamber or a centrifuge

with the working area, too, not everything is so simple, overheat – the material will begin to decompose, and most of these constituents and by-products are poisonous and you will need a well-ventilated area, work in a gas-dust respirator or even better in a gas mask. do you need it?

therefore, it is better to spend your life on theory than to die from lung cancer, for example, or severe poisoning with compounds in practice

Yes, I thought to do something more productive with the output to several nozzles at once

With 8 liters you turned down, of course! I didn’t even dream of pouring such volumes! And a liter is too much. I would be quite satisfied with small things, equal in volume to the molten volume in the screw. Something like BabyPlast (I watched a video on YouTube once).

And so, I have a vacuum, and a forced hood is planned in the future (I have already bought pipes for it – they are gathering dust).

We will most likely die from cancer anyway 🙁 Almost all my neighbors in the district burn plastic garbage in bonfires. It is useless to explain to people.

volumes … always decided all volumes … for all kinds of profiles it is better to use an extruder by itself, but you still won’t produce a pipe, I’m more than sure, and you won’t be able to, because the screw needs a profile screw, some other power and equipment, and for molding and enough syringe. besides, you will have to resolve the issue with the form itself, because. here gypsum does not roll, aluminum is not desirable, steel is needed, because. in any case, you will have to heat the form. let’s say abs 200 degrees will have to be kept exactly, LDPE 160. and aluminum will quickly give off heat and the product can go into bubbles ..

ps we return as you see to the theory)))

By the way .. I recommend taking ring heating elements as a heating element. on the same aliexpress, there is also a digital thermostat, nichrome will often overheat, the stage passed will burn everything) I recommend finding ceramic fiber for thermal insulation, a rare, special thing, but consider 2 times the efficiency of your heating elements and most importantly, no harm from asbestos For example.

Yes, it’s a pity for me to spend money on heating elements when there is a nichrome coil right next to it 🙂 I would have bought them a long time ago if not for this coil

Got the thermostat!

Well, one way or another, you will come to the Tens)

Hi, can you somehow make a heater yourself or from something so that you don’t eat a lot of energy?

Energy will be spent with any heater in the same way – exactly as much as is required to melt the plastic of a given amount.
A powerful heater will heat up faster, and a weak heater will heat up more slowly. With a powerful one you will press a bucket in an hour, with a weak one – a glass in a week.

And how will you make sure that the guys have as much energy as you need?

This is physics Plastic itself will take exactly as much as it needs to melt. If you heat it further, then it will simply begin to decompose, so you just need to turn off the heating.

I repeat once again, each substance has a specific melting power, i.e. some kilowatts per kilogram. You will heat either 15 minutes with a kilowatt, or 15 hours with 10 watts. How long do you want to melt the plastic – you choose.

As a result, you just need to choose the right extrusion speed depending on the power of your heater. If your plastic melts quickly, then you need to press it quickly!

And I’ll repeat it again! You CANNOT save energy. Plastic will take exactly as much as it needs to melt. Not less!

build a fire but cheaply

what are the shadows for? why do you need ready-made technology painted from and to? for beauty? you first read the theory, and then talk about practice and ask questions

I want to do the extruder, everything is ready, the heater remains to be done, I want to make it more economical and do something on my own so as not to overpay

in order not to overpay you need to buy ready-made)

This device is more like an extruder for the production of the plastic thread itself – the raw material for a 3D printer!

I studied the topic of what to do in the new year and came across your topic. Tell me, after a year of work (and was there work?), How does your assembly behave?

No, Renat, the project has been frozen for an indefinite time. I have not tried anything with this extruder yet, even from a drill. I was somewhat disappointed with the quality of the mixture of crushed refractory bricks with liquid glass. ZhS from heating bubbles and swells, as a result, the coating cracks and crumbles.
I just recently bought a normal fireplace clay and I want to try making a heater out of it. But while everyone is working on a new CNC …

I wonder if this machine was launched or not, and how does it work?

Dear moderator, I wildly apologize for importunity .. reading your comments, I’m delighted) I need your help) idea, making the extruder for abs and pla threads 1.75 -3mm …. kilowatt so for 7 and 10 with two cooling baths … .. help calculate the screw pair? and heating? (annular heater), (vacuum, filter will be provided) with a head? (you can use a couple of threads), a gearbox, a 380V motor … honestly, I’m already a walking encyclopedia on this matter)) very little information about production lines ((((thanks in advance

There’s more to talk about…

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There’s more to talk about…

Great discussions are happening here on Disqus. You’ll never be bored.

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3 kilowatts for such a tiny one? Isn’t it too much? difficult to follow. only if the PID regulator. with heating is too confused. all these coatings are not practical, not repairable and time consuming. it’s much easier to wind a spiral from an “iron” on top of asbestos and a fum tape. it warms up faster keeps it more stable

Yes, he is not tiddly, like. Well, with a margin and for speed, of course, I bought a PID controller for it.

And about winding – what to wind on? I blinded this coating in order to isolate it from the pipe and to fix the coils so that they would not shorten among themselves. Are you saying that fum tape will keep glowing red hot?

heater from the “iron” in ceramic cups or tubes on top asbestos then a thick fumka

Yes, at first I wanted to use an iron … But it turns out that finding such an iron with cups is a big problem. That’s why I had to fence a garden with my own “ceramics”.

Just imagine that you decide to mass-produce such extruders. Where will you look for so many irons? With coating, of course, is also not an option.

there are a lot of similar heaters of different denominations and sizes. The price is laughter 300 rubles on a market day. Low-voltage ones will be more expensive

In the practice of production activities of small enterprises involved in the packaging of various products, as well as in the laying of plastic pipes, a tool is needed with which it would be possible to reliably connect materials with a low melting point to each other. The class of such materials is large – these are low-pressure polyethylene (HDPE), polyvinyl chloride (PVC), polypropylene, etc. A manual welding extruder handles all these works.

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Design and principle of operation

A manual welding extruder is a thermomechanical device that sequentially performs two processes – heating a low-melting plastic to a viscous state, and then extruding the mass onto the surface in the joint area. There, HDPE, PVC and other low-melting plastics solidify, forming a strong weld.

For compactness and ease of use, the technique in question is usually designed in the form of a pistol with a handle (in which the drive motor is mounted) and an upper nozzle for heating the working mixture. The welding extruder consists of the following units:

  1. Electric motor.
  2. Feeder.
  3. extrusion chamber.
  4. Crushing screw device.
  5. Chambers for melting plastic.
  6. Thermal heater.
  7. welding nozzle.
  8. Control systems.

For operation, the device is pre-filled with a filler rod from the material that will be welded. The process is as follows. On the top panel of the extruder there is a receiving sleeve with a hole through which the filler rod is passed. Filling should be such that the free end of the bar falls into the zone of its capture by the auger. When the electric motor is turned on, two processes take place: heating of the filler rod with a concentrated stream of hot air, and – after some time, which is determined by the sensor of the device – feeding the rod into the zone of its grinding.

There, a rotating screw crushes the plastic rod, turning it into a granular mass. The latter melts when heated, and, moving further, enters the melting zone. In this zone, the granulate is already mechanically and homogeneously homogeneous. Under the influence of pressure from the screw, it passes into the welding zone, enters the welding nozzle and, in the process of pressing against the surface of the workpieces to be welded, is squeezed out in a uniform strip, the width of which depends on the configuration of the nozzle. Since the external temperature is much lower than that created by the thermal heater, the material of the filler rod solidifies instantly, forming a weld.

In less compact, but more productive models of extruders, the filler rod is heated using an external thermal heater, and air is supplied there from a small compressor. Structural differences can also exist in the method of heating the filler material: sometimes heating is performed by annular heating elements coaxially placed in the body of the thermal heater.

The manual welding extruder control system performs the following functions:

  • Pre-set heating temperature, which is determined by the melting point of plastic (as you know, HDPE melts at 120…130ºС, PVC – at 150…220ºС, and polypropylene – at 170…190ºС).
  • Switching on the thermal heater;
  • Starting the screw grinder drive;
  • “Cold start” blocking, when the screw can move still inhomogeneous filler material;
  • Switching off the thermal heater while the auger is still rotating, which eliminates the sticking of granulate residues in the welding chamber.

Operating rules and model selection of manual welding extruder

Before use, it is necessary to fulfill a number of conditions that are common for plastic: clean the surface of the products to be joined from external contaminants and prevent work with wet material.

The success of the work also depends on the difference in the values ​​of the melting points of the materials being joined, if they have different chemical compositions. For example, HDPE with polypropylene can be welded in this way, since their melting temperature ranges completely or partially overlap. On the contrary, welding HDPE with PVC, and even more so with polypropylene, is problematic or impossible at all. In such cases, the welding extruder can only be used to connect products made from the same materials.

The compactness of the manual welding extruder allows its efficient use even without stopping the operation of the connected devices. In particular, when welding polypropylene pipes, it is not necessary to turn off the water supply through them.A number of mandatory checks are preliminarily performed (especially if the extruder has not been used before):

  1. Checking the straightness of the feed of the filler rod in the extruder sleeve: with a high roughness, the generatrix of the rod can move not in a straight line, but along a helical line, which will worsen the operating conditions of the screw crusher and lead to the formation of a granulate that is not uniform in size.
  2. Control check of the effectiveness of the heating temperature of the rod to the state of its viscous flow: material from different manufacturers may have a different range of melting temperatures.
  3. Checking the reliability of pressing the welding nozzle to the surfaces to be joined, especially if they have a complex configuration. Many models of manual welding extruders are equipped with interchangeable nozzles for this purpose.
  4. Checking the possibility of melting the joined materials with heat from a thermal heater, without supplying a filler rod. It is performed in the absence of accurate information about the material of the products connected in this way.

The choice of a suitable model of a manual extruder is made according to the following parameters:

  • By productivity per unit of time;
  • For the convenience of managing process parameters;
  • According to the thickness of the products to be welded;
  • By completing the device with interchangeable accessories
  • According to the range of bar diameters.

It should be noted that most brands are designed to work with filler material from a specific manufacturer (often the same manufacturer that produces extruders).

Theoretically, it is possible to make a household welding extruder with your own hands. To do this, a screw drive is attached to a conventional industrial hair dryer (for example, for grinding feed), and both units are designed in a compact form. Instead of a screw, a more accessible plunger drive is sometimes installed, but this option is unreliable: it all depends on the homogeneity of the material of the original bar. The electric motor for the drive is selected as a collector type, which better tolerates constant changes in torque values.

Manufacturers of welding extruders

The most popular in this market segment are the following devices:

  1. From the Munsch trademark (Germany). Consumer advantages – ease of attachment of all components (which increases maintainability), undemanding to the size of the filler material, the presence of a separate heating function (useful when using the extruder outdoors in the cold season), a convenient set of interchangeable nozzles, a perfect control and monitoring system. Plus – traditionally high German workmanship and assembly.
  2. From the Leister trademark (Switzerland). The manufacturer produces a wide range of standard sizes of welding extruders: from small ones, with a capacity of up to 0.8 … 1.2 kg / h, to professional ones, designed for processing up to 6 kg / h. The devices are equipped with a modern system of control and monitoring of the welding progress, ergonomic in use. The quality is also at a high level. There is a special line of machines for welding linoleum.
  3. From the Dohle trademark (Germany). The company is known as a manufacturer of building hair dryers, but recently it has been actively positioning itself as a manufacturer of manual welding extruders. Unlike the above brands, it uses purchased electric motors to drive. Produces the smallest extruder with a capacity of only 0.5 kg / h, which is completed with a hose and a built-in mini-compressor.
  4. From the brand Stargun (Italy). With a small range of models, the extruders of this company differ in drive power, and are designed for use mainly in professional conditions. The highlight of the devices is the possibility of local illumination of the welding zone.
  5. Domestic extruders of RSE type. They are equipped with a filler material feed drive and include most of the same options that have already been listed above.

Prices for extruders depend on their functionality and performance. On average, the cost of domestic devices ranges from 30,000 to 55,000 rubles, imported – from 50,000 rubles. and more.

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