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The quest for the ultimate extrusion screw

This topic contains 91 replies, has 26 voices, and was last updated by  citamrac aurf 9 months ago.

4
Siemen Cuypers siemenc

The quest for the ultimate extrusion screw

15/02/2017 at 10:48

In the plans of the current extrusion machine a basic drill is being used in the barrel to push and melt the plastic to the nozzle. This seems to work, however, in the industry a different type of screw is used which compresses the plastic while it’s melting. These are way less accessible than the drill, for obvious reasons. So Dave had the idea of possibly trying to produce these ourselves. Therefore this topic will be dedicated to the research on trying to design/model/produce this.

I was quickly doing some research on this yesterday and it seems to be a world on its own with different designs of screws, different compression ratios and different “zones”. If there’s anybody that might have some experience or knowledge on this that could help out, let us know here.

I turned the basic idea for the screw design into a quick 3D model, to see if I would be able to model it. Now I need to find the right design requirements to turn that into the eventual 3D model, so we can turn this into a physical prototype.

https://en.wikipedia.org/wiki/Plastics_extrusion#Screw_design

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starter
05/03/2018 at 22:27
0

Hi everyone,
I´ve contacted more than 50 local workshops and everybody told me that they would make the screw I wanted according to the plans I downloaded from the website, so it hot me thinking how to solve that problem, I posted my question to our national machining forum and the answers I got werent very nice 😀 they basically told me that the the blueprint is total trash and that they aren´t surprised nobody wanted to make it for me, they told me I should start over and make a better design, but here is the catch, I´m total amateur, I can´t make new design, but I think that new design is necessary in order to bring the price down so that the screw could be cheaper, which would be really nice right? I can start to study the theory behind the problem but I don´t know how to use any software to make new design. Can someone help us with this? Or what do you think about that? Is that a bad idea?

helper
24/01/2018 at 11:22
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next machine i will build is the extruder
any update on this?

starter
18/01/2018 at 01:28
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Has anyone made a closer tolerance barrel for the industrial screw? The closest U.S. size tubing I could find without having to ream has a nominal ID of 1.031 which is 0.019 larger than the 25.7mm screw. This seems like a lot and I’m worried about plastic leaking from around the edges or not building pressure. Ideas here?

new
16/01/2018 at 15:45
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Hi! Does anybody still have some screws in stock? And from where do you ship?

warrior
10/01/2018 at 10:10
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Looking good @plasticsurfer. Sell them in our bazar, many request for those screws!

helper
08/01/2018 at 14:47
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HI everyone.

For those who want one ultimate screw, i have an offer for 180 usd per piece if we buy 3 pieces.

Someone need one ?

Cheers

Gaetan

starter
25/12/2017 at 01:35
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Can an improved extrusion screw (compared to a wood drill) put more pressure and force on the extruded plastic, to the point that it can be used as an injection machine?

helper
15/12/2017 at 15:01
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Hi @davehakkens,

Jerry say me in an other post you order 20 screw.

Is still on the pipe ?

Definitly need one and it’s boring if i ordered just one in alibaba.

If they still ordered, you know when they arrived ?

Thank’s a lot

Cheers

helper
15/12/2017 at 11:59
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I found this link with a quick google search for someone who sells them from alibaba.com:
https://www.alibaba.com/product-detail/screw-and-barrel-extrusion-for-ppr_60693234451.html?spm=a2700.7724838.2017115.2.13e58a03Aj7wFt&s=p
i don’t know if this has already been mentioned, but it would be an option.

helper
15/12/2017 at 11:51
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I found this link with a quick google search for someone who sells them from alibaba.com:
https://www.alibaba.com/product-detail/screw-and-barrel-extrusion-for-ppr_60693234451.html?spm=a2700.7724838.2017115.2.13e58a03Aj7wFt&s=p
i don’t know if this has already been mentioned, but it would be an option

starter
14/12/2017 at 22:45
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Hello everyone, do you think its a good idea to make the screw out of a soft and easily machined metal, such as aluminum?

warrior
07/12/2017 at 20:14
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@plasticsurfer got them at this company: https://www.alibaba.com/product-detail/Mixing-Type-Screw-plastic-extrusion-screw_60505829299.html?spm=a2700.8443308.0.0.SlLhjl final price depend a lot on the amount and shipping costs.

starter
06/12/2017 at 03:25
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Dave, do you have contact info for this company (Five Star Machinery), and the cost of the finished screw? @davehakkens

Glenn

starter
09/07/2017 at 11:23
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Still would love one of those screws for my extruder @andyn

starter
07/07/2017 at 22:55
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I would love one of those for my extruder. That is a much better than the drill bits hands down.

dedicated
07/07/2017 at 13:55
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@andyn, nice idea, maybe I can test this next week!

warrior
07/07/2017 at 12:49
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@siemenc

Ok, I see what you mean now about the taper! But I really don’t think it matters, I kept my cutting tools parallel to the axis of the screw the whole time, I could have angled them easily, but there’s no need. Yes the compression zone will appear to have steps between each turn when viewed from the side (mine are only about 0.33mm and not really visible) but the channel in the screw is a smooth transition from one end to the other.

In fact if you were to cut the taper at an angle, you would have to blend each end in with the straight parts either side which would be more complicated and give a less smooth transition between zones. I don’t know if @dustintweir still reads this forum, whats the industry standard way of doing this?

@davehakkens

I’m glad you’ve had success with this type of screw. Did you find the plastic chips need to be smaller than with the wood auger bit? I found my first smaller screw needed really fine chips to work consistently, and it took too long to shred and filter them.

helper
07/07/2017 at 07:34
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I think @siemenc is right. It is some kind of nozle-modification to extrude any tube materials.

warrior
06/07/2017 at 23:38
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No for some reason it just works. Get a metal tube and fill it up. That’s all. Super easy. Haha it has enough pressure to fill up the entire 3 meters. Haven’t really pushed it to the limits yet. Think we are currently about 40 mins. @mathijsstroober has been working on this, he knows the details.

hero
21/06/2017 at 03:41
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@davehakkens did they ship you the screw already? 😀

helper
19/06/2017 at 03:51
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I love Alibaba and AliExpress. I hope the prototype works well. They will be getting a bunch more orders if it’s more efficient than the current version!

dedicated
07/06/2017 at 15:21
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I finally got some material… Now just need to find the time to try and mill it out!

Has the Chinese one arrived yet?

dedicated
30/05/2017 at 17:37
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Interesting, looking forward to seeing how this will turn out! (Pun not intended)

I’ve been trying to find a material supplier where I don’t need to buy a 6 meter rod (and them not being able to chop it up into smaller chunks), with little success. But tomorrow I might meet somebody that can help me out.

warrior
29/05/2017 at 08:33
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its been a super slow process but i’ve ordered an extrusion screw from Alibaba a few months ago. Its manufactured according to the 3D model of @siemenc. Now its finally ready and they send a picture! Last part is shipping to the Netherlands then we can test it out 💪

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dedicated
25/04/2017 at 16:14
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Interesting. Maybe I’m missing out on something but how does the plastic get pushed forward then?

new
25/04/2017 at 00:04
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Wanted to toss an idea out there:

In twin-screw extrusion there’s a method where the screw is fabricated from inter-meshing kneading blocks as shown.

Pros: May be cheaper in theory than a machined screw, kneading blocks can be adjusted post-fab, and you get the benefits of twin screw (higher mixing)

Cons: More parts, probably slower extrusion

This definitely isn’t industry standard but could maybe work for this application. I’m new here but have followed the project for a little while now. Also- I’m finishing up a polymer processing course now so I don’t have 20yrs. experience but if anyone wants notes and slides explaining this process better let me know.

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dedicated
24/04/2017 at 17:06
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Cool! I’m curious of the result.
Can’t go wrong with a company called “Five-star machinery manufacturing” 😀

dedicated
12/04/2017 at 18:50
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Until the 4th axis is done, I think we can do it at the Fablab outside of Oslo, they have a 4-axis machine. But we will need to wait until the machine guy is back from holidays so he can explain how the machine works. And I’m afraid by the time he’s back I’ll be out of the country for two weeks. :/ So we’d be talking about at least another month before we can try it out, unfortunately. We’re eager to try it out though! And if it works, I’d be willing to send it for testing, if material and shipping cost would be refund?
I’m also wondering whether aluminium or brass would be strong enough. Is there a lot of force applied to the screw in the extruder?

warrior
12/04/2017 at 17:53
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wow that looks sick @siemenc. Does he also know a place to manufacture it, or is that the reason why he is looking into a 4 axe lathe? 😅

warrior
03/03/2017 at 17:17
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you can post 3D files as .zip @siemenc, or use an external service like grabcad. (we don’t use it yet)

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