3D print metal at home

And then I thought, what if I spray metal in the place I need, gradually increasing the thickness? I looked for information about whether someone did this - I did not find it.

Registered on a forum where sprayers gather together and began to disturb them with questions like: is it possible to build up a “film” with a thickness of 1 or more millimeters. To which I caught a lot of misunderstanding what it was for, but received a positive answer.

General information received, you can begin to prepare for experiments.

It is known from various articles and documents that a vacuum of no more than 10⁻² Pa is required. For comparison, the order of magnitude - the pressure that gives a household vacuum pump (Value and others) - about 4 Pa ​​(measured value), i.e. pressure is 400 times greater than necessary. How to deal with it and what to do? To achieve low pressures, turbomolecular vacuum pumps are used, they work in parallel with the foreline pump and, literally by molecules, capture the remaining air from the chamber. The process is not fast. The pump looks like this.

We installed a pump, it pumps out air and everything seems to be fine, but how to find out the pressure? For this I chose an ionization vacuum gauge.

In fact, nothing else is needed, except for the chamber and evaporator. I did not find a ready-made affordable (in terms of finances) camera, therefore, I decided to make my own. It is of a small volume (about 8-10 liters) in order for the air to be pumped out faster. Usually, the chambers have a spherical shape, in my case it is, on the contrary, elongated, in order to be able to set the “target” (the place where the metal is deposited) at different distances from the evaporator. In addition, the camera has a lot of flanges for connecting all kinds of inputs/outputs and sensors. I modeled the camera in a well-known CAD program, drew drawings and transferred it to production.

Current leads and conductors I made from a brass bar and a brass rod, bought on the local market. (Juno, who is from St. Petersburg).

In the photo below, a tungsten boat is fixed between two conductors.

The bottom part looks like this. The photo shows the cooling tubes of the current leads. Subsequently, I abandoned them, due to the simplification of the system.

Assembling the camera did not take much effort and complexity. It is much more difficult to achieve vacuum retention in this chamber. To do this, I polished the flanges and all mating surfaces to avoid the slightest leakage through the rubber seal (in the photo below, I processed only the top flange).

As it turned out later, the weld is not airtight at all (meaning for low vacuum). I, out of inexperience, assumed that by pumping a pressure of 300 kPa into the chamber and immersing it in a bath of water, I would carefully find all the leaks and eliminate them. Yes, at the first stage I did just that, but the pressure in the chamber did not fall below 10-2 Pa, there were leaks. Interestingly, before the start of the test, at a pressure in the chamber of 300 kPa, bubbles emerged from the welds with an intensity of approximately 1 bubble (diameter 2-3 mm) in 30-40 seconds. And those were big losses that I eliminated. But what to do with minimal vacuum losses that cannot be tracked in "kitchen" conditions?

The solution was close. To do this, all you need is a mass spectrometer.

The idea is simple – the investigated chamber or container is connected to the vacuum chamber of the spectrometer. Air is pumped out, on the graph they look for extraneous peaks of any gases. After that, helium is supplied locally, to the places of possible leakage. It is helium, because its penetrating power is higher and the helium peak can be easily tracked on the spectrum. As soon as helium enters the chamber through a micro-hole, it is immediately visible on the spectrum.

I drove twice and looked for leaks twice. Now the chamber with the installed pump is hermetic and it is possible to carry out experiments further, having previously assembled all the components of the system on the rack.

General view of the incredible installation.

Starting up the plant and checking it comes down to maintaining the lowest possible pressure. The foreline pump is started first.

The pressure after the operation of the foreline pump can be seen in the picture below.

After the pressure is established (does not change). You can launch "heavy artillery" - a turbomolecular pump. It reduces the pressure by another 3 orders of magnitude.

The time has come for experiments, what I have been going for so long and what I have been waiting for so long.

First experiment.

Place a small amount of silver into the boat fixed between the conductors. Above the boat I install a steam conduit - a soldered tin cylinder, which, as I thought, should limit the spread of metal through the chamber. Above the steam conduit there is a lid with a hole of 2 mm, behind the lid there is a target on which the metal should condense. It is a pity that there are no photos left, but the vacuum chamber was completely dusty. There was not a single place where there was no applied layer of metal. In the photo below, it’s not a different planet at all, but silver sprayed onto the inner surface of the wall.

Second experiment.

I thought it was because of the large gaps between the boat and the steam line. The solution was born immediately and quickly. I took two boats and combined them so that a shell was obtained. I placed silver inside, and cut a hole with a diameter of 2 mm in the upper half.

And he began to heat up the whole thing. But, I did not take into account the rigidity of the boats and the rigidity of the current leads. The shells parted a little and a gap formed between them, through which steam also flew in all directions.

As a result - spraying in the entire volume of the chamber. In the photo below there is a viewing window, the boat in which was slightly above half, but the window was completely dusty.

Third experiment.

After a little thought and grief, I thought that the container with the evaporated metal should be airtight and with only one outlet, but how and what to make it. From tungsten - very expensive and difficult to process. The way out has been found! Graphite is an excellent material for making a crucible, let's call it that. On the ad site, I found an ad for the sale of graphite bars from the contact whiskers of a trolleybus, cut out a bar with a hole in the center and made a cover for it. In the photo below - just a bar with a hole for the material (without a cover).

And in this photo already in the chamber with the lid installed (the hole in the lid is 1 mm in diameter).

Under the spoiler are a few photos with a short period of time, from which you can see how dusty the viewing window is.

Loss of transparency

It is obvious that in this case, too, there was no success, to my great regret. All three experiments were carried out with a gradual increase in temperature from the state when evaporation does not occur.

A small video in which the information is presented in a slightly different way, in a different form and volume.

Video link

www.youtube.com/watch?v=4yWQOWIG1qw

Unfortunately, it was not possible to get what was intended, but, on the other hand, invaluable experience was gained in the design and manufacture of vacuum equipment. Most of this experience I have shared with you and I would be very grateful if you express your opinion on this issue.

Thank you all and good luck.

technologies, equipment, materials and new opportunities

There is no hotter trend in 3D printing today than metal. We will talk about metal printing at home, how it is done on an industrial scale, about technologies, applications, printers, processes, prices and materials. Over the past few years, 3D metal printing has been actively gaining popularity. And this is quite natural: each material offers a unique combination of practical and aesthetic qualities, can be suitable for a wide range of products, prototypes, miniatures, decorations, functional details and even kitchen utensils. The reason metal 3D printing has become so popular is because the printed objects can be mass-produced.

In fact, some of the printed parts are just as good (if not better) than those made by traditional methods. In traditional production, working with plastic and metal can be quite wasteful - there is a lot of waste, a lot of excess material is used. When an aircraft manufacturer makes metal parts, up to 90% of the material is simply cut off. 3D printed metal parts require less energy and waste is reduced to a minimum. It is also important that the final 3D printed product is up to 60% lighter than a traditional part. Billions of dollars could be saved in the aviation industry alone—mainly through weight savings and fuel savings. So, what do we need to know about metal 3D printing?

3D metal printing at home

If you want to make objects at home that will look like metal, your best bet is to look at metalized PLA filaments (Photo: colorFabb)

Where to start if you want to print metal objects at home? Given the extreme heat required for true metal 3D printing, a conventional FDM 3D printer will not be able to do this.

It is unlikely that in this decade it will be possible to print with liquid metal at home. Until 2020, you probably will not have a printer specialized for this purpose at home. But in a few years, as nanotechnology advances, we may see significant developments in new applications. This can be 3D printed with conductive silver, which will emit in much the same way as it does in 2D home printers. It will even be possible to mix different materials like plastic and metal in one object.

Materials for Metal 3D Printing at Home

Even though you can't print actual metal objects at home, you can turn to plastic filament that has been infused with metal powders. Bestfilament, ColorFabb, ProtoPasta and TreeD Filaments offer interesting metal-PLA composite filaments. These filaments, containing a significant percentage of metal powders, remain pliable enough to be printed at low temperatures (200 to 300 Celsius) on virtually any 3D printer. At the same time, they contain enough metal to make the final object look, feel, and even weigh like metal. Iron-based filaments even rust under certain conditions.

But you can go further. Typically, up to 50 percent metal powder is added to 3D printing filament. Dutch company Formfutura says they have achieved 85 percent metal powder with 15 percent PLA. These filaments are called MetalFil Ancient Bronze and Metalfil Classic Copper. They can be printed even at "moderate" temperatures from 190 to 200 degrees Celsius.

Metallic 3D Printing Filament Spools, in this case by SteelFill and CopperFill colorFabb (Steel and Bronze), Ancient Bronze by Formfutura

Here are the key points about metal printing at home

• Get a unique metal surface and look
• Ideal for jewelry, figurines, household utensils, replicas
• Durability
• Objects are not flexible (structural dependent)
• Objects do not dissolve
• Not considered food safe
• Typical print temperature: 195 - 220°C
• Extremely low shrinkage on cooling
• Table heating not required
• Printing complexity is high, requires fine tuning of nozzle temperature, feed rate, post-processing

Preparing Your Home Printer for Metal 3D Printing

Since getting metal 3D prints is more difficult than usual, you may need to upgrade your 3D printer nozzle, especially if you are an entry-level printer. The metal filament wears it out quickly. There are hard-wearing hot-ends (like the E3D V6) that are themselves made of metal. They can withstand high temperatures and fit most printers. Be prepared for the fact that the nozzles will have to be changed frequently, because the metal filament is very abrasive.

You will also need to take care of the final finishing of the surface (cleaning, grinding, oiling, waxing or priming) so that the printed metal object shines as it should.

How much is metal filament for 3D printing?

And what about metal filament for 3D printing? - you ask. Here are some examples:

• A 500-gram BFSteel and BFBronse coil from Bestfilament costs 1600–1800 ₽
• ColorFabb's 750 gram Bronzefill spool is $56.36
• ColorFabb's 750 gram Copperfill spool is $56.36
• Protopasta's Polishable Stainless Steel PLA Composite is $56 for 56 grams
• Protopasta's Rustable Magnetic Iron PLA Composite is $34.99 for 500 grams

Industrial Metal 3D Printing

But what if you want better results or even full metal 3D printing? Should a real "metal" 3D printer be purchased for business needs? We wouldn't recommend it - unless you're going to be doing it every day. A professional metal 3D printer is expensive: EOS or Stratasys devices will cost you 100-500 thousand dollars. In addition, the costs will be even greater, since you will have to hire an operator, a worker to maintain the machine, as well as to finalize the printouts (polishing, for example). Just a note: In 2016, an affordable metal 3D printer didn't exist.

Reducing Metal 3D Printing Costs

If you are not going to open a metal 3D printing business, but you still need a professionally 3D printed metal part, it is better to contact the appropriate company that provides such services. 3D printing services like Shapeways, Sculpteo and iMaterialise offer direct metal printing. They currently work with the following metal materials in 3D printing:

• aluminum
• steel
• brass
• copper
• bronze
• sterling silver
• gold
• platinum
• titanium

If you are a jeweler, you can also order wax models for casting in precious metals. If we talk about wax models, then in most cases it is they (with subsequent melting) that are used when printing with metals (including gold and silver). Not all orders are carried out directly by these firms. They usually turn to other metal 3D printing companies to complete the order. However, the number of such services around the world is growing rapidly. In addition, metal 3D printing techniques are becoming more and more common in companies that offer such services.

The reason big companies love 3D printing so much is that it can be used to build fully automated lines that produce "topologically optimized" parts. This means that it is possible to fine-tune the raw materials and make the components thicker only if they must withstand heavy loads. In general, the mass of parts is significantly reduced, while their structural integrity is preserved. And this is not the only advantage of this technology. In some cases, the product turns out to be significantly cheaper and affordable for almost everyone.

Please note that metal 3D printing requires special CAD programs for modeling. It is worth paying attention to the recommendations of Shapeways - 3D printing metal guidelines. To delve further into the topic, check out Statasys’ information on related 3D printers and the nuances of metal 3D printing.

Here are some examples of the Benchy test model price for metal 3D printing:

• Metal plastic: $22.44 (former alumide, PLA with aluminum)
• Stainless steel: $83.75 (plated, polished)
• Bronze: $299.91 (solid, polished)
• Silver: $713.47 (solid, mirror polished)
• Gold: $87.75 (gold plated, polished)
• Gold: $12,540 (solid, 18K gold)
• Platinum: $27,314 (solid, polished)

As you might expect, solid metal 3D printing prices are quite high.

Metal 3D printing. Applications

GE LEAP aircraft engine parts 3D printed at Avio Aero (Photo: GE)

There are several industries already using 3D printers to make everyday objects - you may not even know that these objects are printed.

• The most common case is surgical and dental implants, which in this design are now considered the best option for patients. Reason: they can be tailored to individual needs.
• Another industry is jewelry. Here, most manufacturers have abandoned resin 3D printing and wax casting, switching directly to metal 3D printing.
• In addition, the aerospace industry is becoming more and more dependent on 3D printed metal objects. The Italian company Ge-AvioAero was the first to do all-metal 3D printing. It manufactures components for LEAP aircraft engines.
• Another industry targeting metal 3D printing is the automotive industry. BMW, Audi, FCA are seriously considering this technology, not only for prototyping (3D printing has been used for this for quite some time), but also for making real parts.

Before metal 3D printing really takes off, however, there are some hurdles to overcome. And first of all, this is a high price, which cannot be made lower than during molding. Another problem is the low production speed.

3D metal printing.

Most metal 3D printing processes start with an “atomized” powder

You can talk a lot about “metal” 3D printers, but their main problems remain the same as any other 3D – printers: software and hardware limitations, material optimization and multimateriality. We won't talk too much about the software, we'll just say that most of the major specialized software companies, such as Autodesk, SolidWorks and solidThinking, try to emphasize as much as possible the fact that as a result of the 3D metal printing process, you can get any shape you want.

In general, printed metal parts can be as strong as parts made by traditional processes. Parts made using DMLS technology have mechanical properties equivalent to casting. In addition, the porosity of objects made on a good "metal" 3D printer can reach 99.5%. In fact, manufacturer Stratasys claims that 3D printed metal parts perform above industry standards when tested for density.

3D printed metal can have different resolutions. At the highest resolution, layer thickness is 0.0008 - 0.0012" and X/Y resolution is 0.012 - 0.016". The minimum hole diameter is 0.035 - 0.045″. Let's, however, consider what metal 3D printing technologies are.

Metal 3D Printing Process #1:

Powder Bed Fusion

The metal 3D printing process that most relevant large companies use today is called Powder Bed Fusion. This name indicates that some source of energy (a laser or other energy beam) melts an "atomized" powder (i.e., a metal powder that is carefully ground into spherical particles), resulting in layers of a printed object.

There are eight major manufacturers of metal 3D printers in the world that already use this technology; while we are talking here, there are more and more such companies. Most of them are in Germany. Their technologies are called SLM (Selective Laser Melting - selective laser fusion) or DMLS (Direct Metal Laser Sintering - direct metal laser sintering).

Metal 3D printing process #2:

Binder Jetting