Enhancing resin infusion with peel ply resin breaks and segmented perimeter vacuum lines
When using the resin infusion process to make a composite part, the combination of a peel ply resin break (although maybe it should be called a resin brake?) and a segmented vacuum line around the perimeter of the laminate can deliver the following benefits:
[ol]
[li]Improved control over the resin distribution pattern
[/li][li]Reduced resin wastage
[/li][li]Reduced risk of resin trap overflows
[/li][li]Less vacuum tubing wastage and reduced resin trap cleaning.
[/li][/ol]
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I feel another post coming up…
:rolleyes:
Better, use MTI hose. Combines all benefits and no resin trap is needed. Also no brake zone needed, no resin waste, better laminate quality…
Is that what you ment herman:)
Hello,
Our post regarding peel ply breaks and segmented perimeter vacuum lines was intended to help laminators obtain better infusion results from peel ply and low cost spiral cut tubing. We are most definitely not trying to inhibit innovation, but have some reservations about the use of the MTI hose for all infusions. These are:
-
It would appear easy to over-feed resin into the part – especially one-off parts. We understand that excess resin can be withdrawn from the resin feed side of the part after the laminate has been filled, but having to do this negates one of the benefits of the MTI hose. Feeding resin into the laminate from a partially evacuated resin feed pot would avoid the risk of over-filling, but this could be more of a complication than a resin trap for many laminators. -
We would also be concerned using the MTI hose on a complicated one-off part where the flow pattern of the resin front is not completely predictable. If the resin flow front should encircle an air pocket, we don’t see how the MTI hose will allow the air pocket to be moved to the perimeter vacuum line. While it may result in resin wastage, using peel ply and spiral cut vacuum tubing does allow some manipulation of the resin front. We don’t see how the same degree of flow front manipulation can be achieved with MTI hose. The MTI hose may be fine for repetition parts, but we are not sure it’s the ideal solution for one-offs. -
From the published prices, the MTI hose seems to be considerably more expensive than spiral cut tubing.
Regards,
Tri
Hello,
Our post regarding peel ply breaks and segmented perimeter vacuum lines was intended to help laminators obtain better infusion results from peel ply and low cost spiral cut tubing. We are most definitely not trying to inhibit innovation, but have some reservations about the use of the MTI hose for all infusions. These are:
-
It would appear easy to over-feed resin into the part – especially one-off parts. We understand that excess resin can be withdrawn from the resin feed side of the part after the laminate has been filled, but having to do this negates one of the benefits of the MTI hose. Feeding resin into the laminate from a partially evacuated resin feed pot would avoid the risk of over-filling, but this could be more of a complication than a resin trap for many laminators. -
We would also be concerned using the MTI hose on a complicated one-off part where the flow pattern of the resin front is not completely predictable. If the resin flow front should encircle an air pocket, we don’t see how the MTI hose will allow the air pocket to be moved to the perimeter vacuum line. While it may result in resin wastage, using peel ply and spiral cut vacuum tubing does allow some manipulation of the resin front. We don’t see how the same degree of flow front manipulation can be achieved with MTI hose. The MTI hose may be fine for repetition parts, but we are not sure it’s the ideal solution for one-offs. -
From the published prices, the MTI hose seems to be considerably more expensive than spiral cut tubing.
Regards,
Tri
maybe we could think of this resin break setup also with mti hose. Or would this be nonsense?
First I want to say that I often recommend your product to several customer. So I didn’t want to say that your product is bad or useless.
It is als possible to get good results without the MTI hose, but you need years of experience and it is easier and you have a higher process stability when using the MTI hose.
Resin overfeed can be eliminated by placing the resin pot below the part or clamping the resin feed before the part is filled. That’s quite easy and caneven be realized by a newbe.
The MTI hose was also made for one off parts for people with less experiance and for complicated parts. The MTI hose was made to make sure that the part will be filled complete.
You are right, a air pocket can not be removed if no MTI hose is placed where the pocket might be expected. But the airpocket can also not be removed in a classic infusion setup. You can let some extra resin travel through the part. That may help to prevent a dryspot, but therefore you have allotted the air and created a pourous laminate with many voids. In both cases you have a technical and optical not perfect part.
Than I prefer to work with a perfekt vacuum and a degased resin so that the vacuum in the “air pocket” will do the job to saturate the fabrics in the pocket.
Of course the MTI hose is more expensive than a spiral tube. It is made from spiral tube, a non wooven, a fabric and a membrane. But it saves a lot of money in the process.
I have worked and often work with your product and it is one of the best combined resin traps on the market. Have you worked with the MTI hose?
Hello
I apologise if you think my previous comments were unfairly critical of MTI hose. However, since it seemed to me that you were suggesting that MTI hose renders our peel ply recommendations (and our resin traps) redundant, I don’t think it was unreasonable of me to look for possible downsides to the use of MTI hose. Most innovations usually have some limitations in their early life and I don’t think it was inappropriate to raise my concerns.
We have not worked with MTI hose. However, as well as manufacturing vacuum systems for composites, you may want to note that we are a significant distributor of spiral cut tubing, both in New Zealand and to export customers. If we could be satisfied that MTI hose is insensitive to resin feed positioning, eliminates the need for resin flow simulations, generally improves the infusion process and is cost effective for large/complex parts, perhaps we should be discussing the arrangement of a trial with a laminator such as a New Zealand boat builder? If the MTI hose clearly improves infusion, without any significant disadvantages, we could find it worthwhile complementing our vacuum systems with your MTI hose. If cooperation is of potential interest, please email us via info@vacmobiles.com.
I would certainly try the MTI hose.
Yes, it will make your resin traps redundant. (not obsolete).
Even when using MTI hose I still feel more comfortable using a resin trap, although I never actually needed it. But it makes me feel comfortable.
You basicly never need seat belts in your car either.
Maybe, a segmented MTI hose perimetral vac line would give the best of both worlds: control of the resin front and the other advantages the MTI hose has …
If you segment the MTI hose there is no need for it. Than you kill the advantages of the hose. The MTI hose has to be undamaged and sealed and not open.
If you just want to use it in critical areas you can do that and use the effect that it is resin impermeable, but that is not what is was made for.
For you and your part size a boat I would reccomend to use a resin trap just for backup. Sometimes someone forgetts to clöose the end ofthe MTI hose, opens the box with a cutter and damages the MTI hose…
For these cases I would use a Resin catch pot as backup. Too much resin that can escape at such a big part.
No real need for segmentation.
I usually did segment into 2-3 meter stretches, so I was able to shut off a segment when the infusion was complete at that segment, but with MTI it shuts off itself. So for your boat in theory you can use an MTI hose all way round, mix enough resin for the infusion, open the resin valve, and go home. Next day everything is infused and cured. No real need to be present. (although I still would not dare walking away)
Edit:
Today I should be the one typing faster… 
Edit2: after reading DD Compounds reply:
Indeed I would still use a resin trap, just to be sure. However, all the infusions I did with MTI I did not spill a single drop of resin into the vacuum lines. But better safe than sorry…
Another nice thing about MTI is that you can use it in areas where you suspect there might be a large void. Sometimes, with larger structures, you cannot avoid that. Just place a small stretch of MTI hose (can be 10 cm long) attached to a vacuum hose, roughly onthe spot where a void might develop. This “set it and forget it” operation will take care of any void that might develop there.
Wet bagging:
prewet the fabric, either by laminating in the mould, or prelaminating, then placing in the mould, then apply bagging consumables peelply, perf film, bleeder, bag and apply a vacuum.
Infusion:
place fabrics dry, apply infusion consumables peelply, perf film, infusion mesh, runner system, bag, apply vacuum, mix resin and let it suck in.
These are the very basics, there are variations on both themes.