[Kevin_Johnson]

I started the first independant polymer concrete casting company in the US, so I can help anyone interested in this technology. I have made more PC machine castings than any US company.

Although the title of the thread is "epoxy granite", granite is not used. When Studer licensed companies in the US, they had them use granite. I proved that quartz is a much better filler. I also developed the epoxy system used by all US machine base manufacturers.

Let me know how I can help.

http://www.cnczone.com/forums/epoxy_...tml#post277305

Comments?

Also, have you ever looked into using very small particles like Zeospheres and does shape matter at this size level?

[castinite]

Yes, we have looked into using spheres and other fillers, but have not changed to them. We are always seeking new fillers. The most common fine fillers are silica flour or calcium carbonate.

[Kevin_Johnson]

Yes, we have looked into using spheres and other fillers, but have not changed to them. We are always seeking new fillers. The most common fine fillers are silica flour or calcium carbonate.

As I mentioned a bit ago, the background discussion of the Studer patent suggests, by extension, meal grain with as close to cubic shape as possible. You have pushed the technology forward to suggest purer forms of quartz as superior over quartz bearing granite and now mention silica flour as a filler which is, as is quartz, primarily silicon dioxide.

Have you experimented successfully with the polishing grade with median size in the 1.5 to 5 micron range? If so, are you able to share whether your packing densities moved out of the lower than expected densities experienced by Cameron with Zeospheres and silicon carbide?

The characterization of shape is angular but irregular and this would seem to conform to the Studer patent suggestion.

[castinite]

Silicon carbide offers a lot of great properties, but rasies the cost too much. So far, we have not found sufficient justification, cost versus benefits, to use either sc or Zeospheres.

To my knowledge, none of the five Studer licensees in the US were able to successfully cast bases. Hardinge hired a consultant, for 3 years, and developed thier own system. They now use mine.

[Kevin_Johnson]

The delicate art of ellipsis.

[johnohara]

Kevin~

The delicate art of ellipsis.

LOL. Exactly. I suggest reading roach's posts instead. He gave this thread a generous gift of humor, knowledge and insight.

It's all there if you comb through it and give it some thought.

CNCzone.com-The Largest Machinist Community on the net! - Search Results

~John

[Kevin_Johnson]

Have you experimented with cores/layers having dissimilar Poisson ratios?

[Kevin_Johnson]

Kevin~


LOL. Exactly. I suggest reading roach's posts instead. He gave this thread a generous gift of humor, knowledge and insight.

It's all there if you comb through it and give it some thought.

CNCzone.com-The Largest Machinist Community on the net! - Search Results

~John

Thanks, John.

[johnohara]

I like working with Al2 03 as the filler (<.5mm). It's easier to find, blends well, and has very good size consistency. Higher hardness too (9 Mohs), if it matters.

High quality pool filter sand (.45-.50mm).
Washed pea gravel >1mm.

Once the weight of the aggregate mix is known, I use 10%-12% epoxy by total weight.

I understand the importance of trying to reach an optimum ratio free of voids, but there is a lot of other stuff such as mold-making, material preparation, vibration techniques, mold-release ideas, post production surface preparation, cast-in-place inserts and piping, etc., that doesn't get discussed in this thread. It's a shame because those things take a lot of time and are very important to get right.

Terry:
How 'bout kickin' in an old pump base recipe you don't use anymore so Cameron can work his magic and give you some free R&D?

~John

[ckelloug]

Hi Guys,

Roach definitely did teach us a lot of useful information. My own work has been mainly theory although I have been working on catching up in the lab to get sufficient properties. I'll have more data when I get home from my neverending trip.



As for molds, I used machined A-2 or 4140vprehard due to the ease of procurement at the local tool supply. I have also used a williams sonoma brownie pan however the one piece nature of the brownie pan makes samples difficult to demold. Easier ways abound.

As for mold release, I use Mann Ease Release silicone mold release. It's cheap and effective. Placing a one piece mold upsidedown on the vibrating table for a few minutes is a lot more effective than beating the snot out of it with a hammer.

I have no insight at this time about inserts.

I mix smallest particles first and then larger ones because the smallest particles effect the viscosity the most and each additional larger particle has less and less effect. If you added the smallest last, then it is too hard to mix even with a lab mixer. This also tends to maximize the shear applied to the small particles and helps the coupling agents do their best work.


Finally, the rule of thumb I gave about sections large enough to hold small displacements being strong enough for most purposes says nothing about whether something will be durable or make a good base, especially with sliding friction. It only says that a failure of the material used due to externally applied loads is relatively low.

Good Luck folks and glad to see Terry Back.

--Cameron

[Herbertkabi]

hi,
I have not read this thread few months, sorry,
perhaps you have seen this,
CR-900 High Strength Casting Resin, 26 fl. oz.
what is your opinion?
cheers,
herbert

[brunog]

Herbertkabi,
I believe this product is urethane.

I like the product's viscosity

Best regards

Bruno

[lgalla]

Here is another source for inexpensive epoxy and mold materials.
Thin Epoxy Resin- Fast (5 Gallon, 2 1/2 Gallon Hardener) [EPXTHNFST500] - $269.00

[Steven.ji]

Yes, we have looked into using spheres and other fillers, but have not changed to them. We are always seeking new fillers. The most common fine fillers are silica flour or calcium carbonate.

Hi

This is Steven, I always here study knowledge of polymer concrete.

What is calcium carbonate? Do you mean marble? As my knowledge, marble is not the best filler for polymer concrete, I prefer granite particals.

As my knowledge, marble is easy to be corroded by water,acid and alkali. and softer than granite. The most critical problem is that marble will absorb water, which will result in precision lost.

In China, it's easy to get granite particles, I think if the technology can be localized in China, the quality should be better.


It's difficult to get granite paricles in US and Europe?


Regards

Steven

[Steven.ji]

Silicon carbide offers a lot of great properties, but rasies the cost too much. So far, we have not found sufficient justification, cost versus benefits, to use either sc or Zeospheres.

To my knowledge, none of the five Studer licensees in the US were able to successfully cast bases. Hardinge hired a consultant, for 3 years, and developed thier own system. They now use mine.

do you consider cecramic or pottery?

[castinite]

do you consider cecramic or pottery?

Steven,

Quartz aggreagte is as hard or harder and usually less expensive.

Terry

[Steven.ji]

Steven,

Quartz aggreagte is as hard or harder and usually less expensive.

Terry

Presumably, in US, it's that situation.

But in China, you will find good materials like granite, ceramic, pottery etc. Nowadays, the materail is waste in China.


Steven

[jvalger]

I've been following this thread with fascination for a long time now, have gone back and read what I missed coming in. Tremendous level of discussion and amount of effort being expended.

I'm going to pose a few of those annoying engineering manager-type questions. It seems like an appropriate time.

- What are the objectives? Lower cost? Better quality? Specific properties? Business model?

- What are the assumptions, about the fabricator and about the machine being built? e.g., early on this seemed like it was focused on cast-in-place hobbyists, not fabricating parts to be shipped by a manufacturer. Still true?

- How we will know this is done? Or at least, "version 1 ready"? As I look through recent postings, the degree of fine-tuning seems like perhaps it is time to articulate best-known practices for a "version 1", or at least a checkpoint.

- What is the relationship of the EG to the rest of the machine and connecting pieces? Is it providing specific properties like vibration damping and stiffness to an assembly, or is it replacing an assembly with a unitary cast piece? There are issues either way that seem to have dropped off over time in favor of the focus on the material itself and the casting process. I'm not sure anyone reading this thread who "gets" everything about the casting would know enough to deal with machine design, connectors, ....

Jeff

[ckelloug]

Hi Jeff,

I can't speak for everyone here but I'll answer for myself.

I've been following this thread with fascination for a long time now, have gone back and read what I missed coming in. Tremendous level of discussion and amount of effort being expended.

I'm going to pose a few of those annoying engineering manager-type questions. It seems like an appropriate time.

- What are the objectives? Lower cost? Better quality? Specific properties? Business model?

My original objective was to thoroughly understand the science involved in E/G and be able to design materials as I desired. I thus want to develop an open reference formulation based on quartz for all of the folks that helped on this project. My formulations are designed for small cross-section parts and thus tend to use smaller particles than other formulations.

My additional objective was to come up with some ultra high performance materials which won't be open source but will hopefully be profitable for special applications. I might offer various materials for sale depending on how things go.

I'm strictly operating on the "Underpants Gnomes" business model at present. This joke originally came from the far side cartoons but it was co-opted by southpark. My work in E/G has also been a good re-introduction to materials science for some other projects.

- What are the assumptions, about the fabricator and about the machine being built? e.g., early on this seemed like it was focused on cast-in-place hobbyists, not fabricating parts to be shipped by a manufacturer. Still true?

The assumptions define the problem more than the materials at hand. My original goal was to produce a high performance material. Now that I have my models refined, I'd like to produce a reference material that hobbyists can use predictably. But, since I've focused on understanding how it all works, I can develop formulations for multiple purposes.

In general, commercially viable E/G materials need very careful measurements of the components in their construction. They also are likely to require epoxies, hardeners, and additives that are more difficult to procure than just calling up us composites. At the laboratory scale they also appear to require mixing and deairing techniques as well as compaction under large scale vibration that aren't going to be available to most hobbyists.

For hobbyist materials, it is starting to look like it would be wise to trade off some of the ultimate modulus performance for ease of mixing and employment. This will also involve a smaller usage of fine particles than would otherwise be needed and the use of a formulation that is easier to compact.

- How we will know this is done? Or at least, "version 1 ready"? As I look through recent postings, the degree of fine-tuning seems like perhaps it is time to articulate best-known practices for a "version 1", or at least a checkpoint.

I've been working on a math model that generates formulations with given materials and I've been working on the constraints. The key to my recent advances is that in addition to determining the packing of the aggregate, there is also a very thin shell of epoxy around each particle that is essentially bound to the particle and that this shell must be accounted for when optimizing packing density in models. As near as I can tell, this shell is between 0 and 1um.

Given the agsco materials we have previously discussed, here is the recipe for a 200 cc test batch using the current model results which account for epoxy requirement due to small particles. I haven't tested this formula because I am out of most of the components but I have validated the model itself on roughly similarly sized silicon carbide. Based on my silicon carbide results, this should be just mixable. I normally add smallest to largest due to my coupling agents. Your mileage with deairing and coupling agents may vary. Also note that this version uses a lot less of the smaller components than previous versions as I have taught the model that it shoots itself in the foot when it uses too many small particles.

For a 200.000000 cc test batch:
Agsco Number 6 Aluminum Oxide=228.531871 g solids volume_precent 0.342407
Agsco Number 4 quartz=89.688517 g solids volume_precent 0.202837
Agsco Number 2 quartz=58.882351 g solids volume_precent 0.133166
Agsco 2/0 Quartz=64.778319 g solids volume_precent 0.146501
G800 Zeeospheres=60.787552 g solids volume_precent 0.165595
G200 Zeeospheres=3.960579 g solids volume_precent 0.009495
Total aggregate mass is 506.629189g
Total Aggregate Volume is 166.857032ml
Total Epoxy Volume is 33.142968 ml
pph=0.227200 1/pph=4.401408
Epoxy (Hexion 813) mass is 29.500268g
Hardener (Isophorone Diamine) mass is 6.702461

phi=0.871259, phi_m=0.834285, var=0.027647, modulus=3328073.073155

- What is the relationship of the EG to the rest of the machine and connecting pieces? Is it providing specific properties like vibration damping and stiffness to an assembly, or is it replacing an assembly with a unitary cast piece? There are issues either way that seem to have dropped off over time in favor of the focus on the material itself and the casting process. I'm not sure anyone reading this thread who "gets" everything about the casting would know enough to deal with machine design, connectors, ....

Jeff

I've been studying how to make the E/G material itself to replace large parts of an assembly completely. Some pool sand and us composites thin epoxy are perfectly adequate to pour into a structure that just needs damping and weight and this is a far easier process with fewer pitfalls.

Normally, commercial manufacturers use threaded inserts and linear rails when they build machines from E/G. Inserts allow them to precisely place pieces which can accept bolts or screws and then bolt rails to these parts. An insert is pretty much a blind nut ideally with some fins or other modification to get mechanical interlock with the remainder of the structure.

Good Luck and Best Regards,
Cameron

[JohnMcNamara]

Hi All

The semantics of commerce…. or they keep moving the cheese.

Research keywords:

Polymer concrete
Epoxy concrete
Epoxy granite

Maybe the above are becoming outdated.

“Mineral Casting” may be where industry is moving?

Try the following search for "Mineral Casting"
Google

Also here for a large number of pictures of actual examples
mineral casting - Google Search

Cheers

John McNamara