durfill – CNC Router Info https://cncrouterinfo.com Wed, 05 Oct 2022 09:35:04 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.5 https://cncrouterinfo.com/wp-content/uploads/2022/08/favicon.webp durfill – CNC Router Info https://cncrouterinfo.com 32 32 210092132 Revolutionary – Polymer Concrete – Vibration Damping Material for Machine Frames https://cncrouterinfo.com/article/revolutionary-polymer-concrete-vibration-dampening/ https://cncrouterinfo.com/article/revolutionary-polymer-concrete-vibration-dampening/#respond Tue, 04 Oct 2022 14:33:54 +0000 https://cncrouterinfo.com/?p=3984 Polymer concrete also available as a completed product such as UHPC – ultra high performance concrete has interesting properties which are beneficial for vibration dampening in machine frames such as for a diy cnc machine. However, there are some drawbacks to using polymer concrete that you should be aware of before you decide to implement it in your next project.

What is polymer concrete?

Polymer concrete is the composite material made by fully replacing the cement binders of conventional cement concrete with polymer binders or liquid resins, and is a kind of concrete-polymer composite. Replacing these binders allows new and interesting properties which excel above regular cement based concrete.

How is it made?

Polymer concrete (PC) consists of an aggregate mixed with a monomer or resin that is subsequently polymerized in place. The techniques used for mixing and placement are similar to those used for portland cement concrete. After curing, a high strength (greater than 10,000 psi), durable material is produced.

There are various commercial products available in pre-mixed form. Each having their own speciality such as a good basis for molding machine components – Nanodur or for filling hollow areas in machine beds to provide better vibration dampening properties – Durfill .

Increasing vibration dampening properties of machine frames

Polymer concretes – especially UHPC mixes are an increasingly popular material for DIY and professional CNC machines. It allows you to upgrade an steel tube or aluminium tube based machine frame and add beneficial dampening properties to it.

How much improvement can you expect?

Below is an illustration showing los coefficient of materials (dampening performance) vs young’s modulus (stiffness).

loss coefficient modulus
Steel approximately 0.01% loss coefficient; epoxy granite 0.05%, concrete 0.2% durfill UHPC ~0.4%

Epoxy granite for example is approximately 3-5 times better in dampening vs an empty steel tube. But there are other polymer concretes that exceed the improvement by 50 times. source: Durfill – Fraunhofer -IWU .

durfill polymer concrete uhpc machine frame vibration dampening
Excerpt Iwu Fraunhofer vibration dampening of various material sandwiches
MaterialDampening[%]
Steel tube0,070
Steel tube filled with light concrete0,220
Steel tube filled with fine concrete0,180
Steel tube filled with Durfill0,380
Steel tube filled with polymer concrete
UHPC		0,130
Steel tube filled with Epoxy granite0,050
Vibration dampening percentages polymer concrete UHPC

As can be seen in the table and image above there is a big range of performance depending on which filling is used in the machine frame construction.

My personal experiments

I wanted the best performance for my up and coming cnc build so I decided to fill my aluminium extrusion with Durfill.

Coming … Professional DIY CNC Machine
Coming … Professional DIY CNC Machine

Containing the concrete

Durfill aliminium extrusion 8020 80/20

I filled the bottom of my aluminium extrusion with garden sand. With some light compressing it made a good and easily removable spacer. Which afterwards could just be removed by spraying it with water.

Filling the aluminium extrusion

Durfill is easy to mix. Just add 2,3 liters of water to 25kg of pre-mixed UHPC – mix it and pour it into the aluminium extrusion. It is self compacting, removes the bubbles by itself. Therefor it is very easy to use.

aluminium extrusion durfill 8020 80/20 120x120 80x80
Filling aluminium extrusion with Durfull. 120x120mm extrusion (left) , 80x80mm extrusion (right)

Finished product

durfill aluminium extrusion
Dried Durfill in aluminium 120x120mm aluminium extrusion

Conclusion

Polymer concrete is an awesome material and filler for diy and professional CNC machines. Albeit a little bit expensive, it is easy to use and has very beneficial properties for machine frames and other applications.

Its practical use is immediately noticeable when knocking on an empty aluminium extrusion and one that has been filled with a uhpc product such as durfill. It does not ring which an empty extrusion or tube would do. When you knock on it it sounds like a dead knock such on a big piece of granite or concrete wall.

Frequently asked questions – FAQ

Does filling aluminum extrusion with UHPC / Durfill make it stiffer?

Yes filling aluminium extrusion with UHPC – Durfill or any other polymer concrete makes it stiffer. To calculate how much see Durfill Datasheet for an example.

What is the difference between durfill and castings made from reaction resin-bonded mineral cast or polymer concrete?

With both materials, the coarse aggregate and the fine sand are bonded with a binding agent. 
In the case of polymer concrete or mineral casting, epoxy resin is usually used for this. 
It is an excellent adhesive, but it is not easy to process and clean. 
With durfill, the binder is cement paste. 
Due to the further development of concrete technology, the cement-bound mineral casting has sufficient strength and rigidity for applications in mechanical engineering.

Do you absolutely need composite anchors?

If you want steel and grout to work together, you need a swelling agent for all cement-bound grouting because of the shrinkage that occurs technologically. 
Furthermore, compound anchors or shear cams are essential to absorb the shear forces and to prevent the casting compound from sliding towards the steel surface. 
The steel surface may be rusted and wet at the time of backfilling. 
In the case of mineral casting with epoxy resin, one relies on the adhesive effect of the polymer on the steel. 
However, this only applies if the steel surface has been blasted, degreased and dried beforehand. With my aluminum extrusions I did not use any anchors.

What processing temperature do you need?

The warmer it is in summer, for example, the shorter the processing time and the quicker the hardening of the cement-bound mineral cast. 
At temperatures below 5°C, hardening is so slow that it can take several days before the component can be transported. 
In the event of frost, the UHPC that has not yet hardened freezes and the structure is destroyed. 
In cold and very hot temperatures, it is advisable to carry out the backfilling in a hall.

What is the secret behind durfill?

Due to suitable concrete technology measures, durfill is significantly stronger and more fluid than the standard concrete from the hardware store. 
This is achieved by lowering the w/c value with powdered superplasticizers and grading the grain size of the binder down to the micrometer range. 
The ingredients are identical to commercial concrete and durfill can therefore be disposed of like this. 
We will be happy to tell you the waste key number.

Can I process the material myself?

Yes, the ready-to-use dry mix durfill was developed with the aim of being easy for everyone to use.

What is the difference to Nanodur concrete?

As ready-to-use dry concrete, all aggregates must be oven-dried with durfill before mixing. 
The swelling agent and the powdered superplasticizer also make the product more expensive and reduce its performance. 
In short: durfill is twice as expensive and has a significantly lower performance compared to Nanodur concrete. 
No initial investment in a mixing plant is required for this.

Where can you buy Durfill or Nanodur in low quantities?

Moertelshop in germany sells it in small quantities (below one ton) in 25kg bags.

]]> https://cncrouterinfo.com/article/revolutionary-polymer-concrete-vibration-dampening/feed/ 0 3984 How to Build Epoxy Granite Machine Base nonadult Avoid ? Epoxy granite for DIY CNC https://cncrouterinfo.com/article/avoid-epoxy-granite-for-diy-cnc/ https://cncrouterinfo.com/article/avoid-epoxy-granite-for-diy-cnc/#comments Tue, 30 Aug 2022 18:35:15 +0000 https://cncrouterinfo.com/?p=228 Epoxy granite is a material that has been gaining a lot of attention in the DIY CNC community for its ease of use and dampening characteristics. However, there are some drawbacks to using epoxy granite that you should be aware of before you decide to switch to it for your next CNC build.

What is epoxy granite?

Epoxy granite, also known as polymer concrete, is a material made from a mixture of epoxy and granite aggregate. It is often used as a construction material or for making countertops, floors and other surfaces. Epoxy granite is strong and durable, and it can be shaped and molded into nearly any form. It is also resistant to heat, chemicals and impact and has beneficial dampening characteristics.

How is it made?

Epoxy granite is a material that is made by combining epoxy resin with granite powder / aggregate. It is a strong and durable material that is often used in the manufacturing of countertops and other surfaces.

What are the benefits of epoxy granite?

Epoxy granite is an increasingly popular material for DIY CNC machines. It is strong and durable, yet relatively lightweight (vs steel) and easy to work with. In addition, epoxy granite is non-conductive and has excellent vibration damping properties, making it ideal for use in CNC applications.

While it is known for its dampening properties … it is actually not that good vs alternatives. To illustrate see image below:

loss coefficient modulus
Steel approximately 0.01% loss coefficient; epoxy granite 0.05%, concrete 0.2% durfill ~0.4%

So while it is approximately 3-5 times better in dampening vs an empty steel tube. There are other alternatives which exceed that by 50 times. source: Durfill – Fraunhofer -IWU . I will write a post about what is dampening, which materials have which properties etc.

Finally, epoxy granite can be difficult to work with if you don’t have experience. It requires special tools and techniques to ensure good end results.

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What are the alternatives to epoxy granite?

Epoxy granite is a popular material for DIY CNC machines, but it’s not the only option. Other materials like UHPC or other polymer concretes can also be used to build a CNC machine. Each material has its own advantages and disadvantages, so it’s important to choose the right one for your project.

Epoxy granite cnc builds

Which epoxy to buy?

As epoxy granite is a mix between epoxy and generally sand or other additives you generally don’t need a specific epoxy to enable that. It must be noted that which these DIY solutions it is best to experiment with mixtures on a small scale before you make parts out of it or fill cavities on your cnc router or cnc mill. There are various recipes floating around on youtube and for example cncnzone. Best bet is to get your inspiration there.

Experiments in creating the best epoxy granite mixture

If you want a big CNC machine you need a strong, vibration-resistant base. They build bells out of metal, so that might not be the best if you want something that doesn’t shake. Epoxy granite is your best bet, but what epoxy granite is the best? That’s the question [Adam Bender] answered in a series of experiments that resulted in a great-looking CNC machine.

While this is a project that resulted in a completed base for a CNC machine, this is also an experiment to determine the best formula for creating your own epoxy granite. The purpose of the experiment is effectively to determine the best-looking epoxy granite and uses four variables in the composition of this composite. Play sand, gravel, dye (in the form of iron oxide and liquid epoxy dye), and two-part epoxy were used to create seven different samples. Samples using rock didn’t turn out that great and still had trapped air. This was true even if the epoxy was put in a vacuum chamber for degassing. The winning combination turned out to be a mix of 80% sand and 20% epoxy with a bit of black dye, vibrated for 30 minutes on a DIY shaker table.

Hackaday – Adam Bender – Experiments in creating the best epoxy granite

Conclusion

Epoxy granite is an awesome material for making DIY CNC machines. It’s strong, durable and looks great. However, it can be expensive and difficult but in some cases easy to work with. If you’re up for the challenge, though, epoxy granite is definitely worth considering for your next project. Although don’t forget the alternatives such as concrete / UHPC as these also have very promising characteristics.

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