Why You Should Try Acrylic PMMA Filament – And How to Print it

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Are you looking to expand the horizons of your 3D printing? Do you feel that your usual go-to 3D printing filaments are constricting the creativity of your designs?

Maybe you simply need a stronger material that can withstand higher temperatures and produce results that range from translucent to nearly transparent. 

If so, PMMA filament may be the solution that you’re looking for.

Let’s take a look at PMMA 3D printing filament, what it is, its benefits and stats, and how it compares with similar transparent 3D printing filament. Then we’ll cover some of the best ways to get great results when printing with it.

What is PMMA Filament?

PMMA, or polymethyl methacrylate, is a strong, lightweight and transparent thermoplastic.

Also known as acrylic, PMMA filament is used commercially as a shatter-resistant alternative to glass under the trade names Plexiglas, Lucite and Perspex.

It has good impact strength, significantly higher than glass, but lower than some stronger and more expensive materials like polycarbonate.

PMMA Filament Material

It has less than half the density of glass, but has comparable clarity and UV absorption properties. It finds commercial applications as a glass substitute when extremely high impact strength isn’t necessary, but weight, transparency and cost are issues.

As a result, you’ll find PMMA in automobile headlights, commercial aquariums, ice rink protective glass and more.

We feel it’s definitely an underrated material. 

There are several important benefits to using PMMA as a 3D printing material. To begin with, it has a high impact resistance which makes it tough and durable. It’s also extremely rigid with very little flexibility.

So, if you’re going to need to print an object that will stand up to a certain amount of stress without bending or deforming, then PMMA 3D printer filaments are a strong contender.  

Its high impact strength means that anything that you print using PMMA will not as likely break if dropped or handled roughly. Think glass, only stronger and less fragile.

Additionally, once printed, PMMA diffuses light wonderfully. Treated right, it can give marvelous results that range from translucent to nearly transparent filament.

In short, here are the main PMMA 3D filament properties:

  • Clear, thermoplastic acrylic
  • Strong, rigid, lightweight, impact resistant
  • Available in several colors, including neutral, red, blue and green
  • Acetone soluble
  • Generally, not food safe
  • PMMA filament temperature prints from 245C to 255C
  • Recommended printing bed temperature: from 100C to 120C

A look at the data stats confirms the strength of PMMA. PMMA has a specific gravity of 1.20 g/cm³. This makes it comparable in density to PLA and about one-fifth denser than ABS.

PMMA has a Rockwell hardness of R 105, making it comparable in hardness to ABS and significantly harder than PLA.

However, strength is where PMMA really shines over plastic filament materials. It has a maximum tensile strength of 12,100 psi (83.42 MPa). Compare that to 6500 psi (44.81 MPa) for ABS and 8383 psi (57.8 MPa) for PLA. It also has a maximum compression strength of 17,000 psi (117.21 MPa). By way of comparison, the maximum compression strength of ABS is 6750 psi (46.54 MPA).

With PMMA you have a dense, hard printing material that gives you some significant advantages in the area of strength. Specifically, PMMA is able to handle various stress forces better than plastic filament. This makes it a natural fit for any application that calls for rigidity and inflexibility.

Additionally, the translucency/transparency of PMMA makes it the perfect solution where a clear part or object is desired. Clarity and strength in one package make PMMA a filament that can be a great contender in your 3D printing arsenal.

PMMA 3D Printer Filament
Rigid Ink 1.75mm PMMA Filament spool

If you’re looking for translucent or clear materials, the ones that are available are PETG, Polycarbonate, Natural PLA and ‘Clear’ ABS. Although, clear ABS uses an additive so it’s more likely translucent filament when printed. 

Now, before we go on to take a look at some of the best practices to use when 3D printing with PMMA, we need quickly talk about the use of PMMA in investment casting.

PMMA in Investment Casting

Investment casting, as you may know, is a process where a pattern of a part or object is made out of an easily melted material, traditionally wax, and surrounded by a ceramic mixture to create a mold. Molten alloy metal is then poured into the mold, melting and displacing the wax. This forms a perfect metal replica of the wax part or object.

Lost Wax Casting With PMMA

The problem with wax patterns is that they are formed using injection molding and typically carry a five-figure price tag and require a two-month lead time to produce. 3D printing has revolutionized the investment casting process by slashing the time and cost of producing patterns.

Read more: lost wax casting in 3D printing

Using a 3D printer and a material like PMMA, a pattern of an object can be completed in under a week for a couple of hundred dollars or pounds, and with potentially greater detail than is available using wax.

Upon contact with the molten metal, the PMMA burns to ash, leaving very little residue behind. If you do any type of metal casting using a mold, you owe it to yourself to try PMMA as a pattern material.

How to 3D print with PMMA filament

If you’re wondering how to 3D print with PMMA, it all comes down to keeping an eye on a couple of things.

Temperature

PMMA will print anywhere from 245°C to 255°C. However, at lower temperatures, the flow can be inconsistent with blobbing occurring.

At higher temperatures, at or near 250°C, the flow becomes consistent and printing is easier.

You’ll want to heat your printing bed to prevent warping. A temperature of around 100°C is optimal. There can be some shrinkage with PMMA during cooling. Because of this, you might want to consider enclosing the printing chamber to better regulate cooling speed with transparent 3D printer filament.

Speed

If you’re looking to maximize the transparency of PMMA, then you want to keep an eye on your printing speed and printing temperature.

Play around with your PMMA filament settings to get the clearest results. As we discussed, PMMA can flow inconsistently and blob at lower temperatures. These inconsistencies can produce bubbling and unevenness in the print line.

These inconsistencies, as they layer throughout the object being printed, eventually begin to reduce the clarity of the material, turning it from transparent to translucent. In extreme cases, the object being produced can even become opaque. Higher printing temperatures reduce inconsistent flow.

Optimal PMMA filament print speeds are:

Slower printing speeds, 30 mm/sec or less, and ensuring your printer’s belts are tight and there’s no vibration on the printer allow for proper material alignment. All of these things lead to increased clarity in the object you are printing.

We want to make sure that your printing jobs come out right the first time, every time. After all, ruined print jobs waste time and materials. That’s why low-quality print filament is a false economy. It may cost you less up-front, but ends up costing you much more in time and the material you lose from failed prints.

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