Post Curing Composites

[[email protected]]

I am looking for some advise regarding "Post Curing of Epoxy Composites".

The sailplane composite repairs have been completed regarding my salvaged ASW-27. The tail boom has a new 3'long intermediate section that has been scarfed and glassed into position. The fuselage pod had some radial cracks and the seat pan had some fractures that were all scarfed and glassed. All of the composite repairs were done at room temperature using OEM materials and MGS epoxy.

What temperature is recommended and for what duration should I be using for post curing the repaired areas. Is there a temperature ramp up and ramp down time that I need to work with. I plan to build a foam insulation box around the repair areas and use a fan with a number of light bulbs to regulate the temperature.

Any advise is greatly appreciated,
Thanks,
Chris

[[email protected]]

If my memory is correct. It is 55 C for 15 hours. I’ll confirm when I get back home this week. It is on most Schemp fiber plans.

[[email protected]]

On Monday, December 31, 2018 at 3:45:51 PM UTC-5, wrote:
> I am looking for some advise regarding "Post Curing of Epoxy Composites".
>
> The sailplane composite repairs have been completed regarding my salvaged ASW-27. The tail boom has a new 3'long intermediate section that has been scarfed and glassed into position. The fuselage pod had some radial cracks and the seat pan had some fractures that were all scarfed and glassed. All of the composite repairs were done at room temperature using OEM materials and MGS epoxy.
>
> What temperature is recommended and for what duration should I be using for post curing the repaired areas. Is there a temperature ramp up and ramp down time that I need to work with. I plan to build a foam insulation box around the repair areas and use a fan with a number of light bulbs to regulate the temperature.
>
> Any advise is greatly appreciated,
> Thanks,
> Chris

The manual calls for 60 degrees C for minimum of 12 hours. You won't go wrong by going longer. It takes a couple hours for the structure to come up to temperature. Longer curing also helps reduce future shrinks showing up.
Make sure you monitor the temperature in a couple of spots.
I usually have a couple blankets to throw over everything if temp doesn't quite come up to target.
Good Luck
UH

[Per Carlin]

It all depends om what Epoxysystem is used. I would be very carfull of post curing with heat without knowing what epoxies that is used. You can ruin the whole glider by overheating the structure.

[Paula]

Am 02.01.2019 um 13:42 schrieb Per Carlin:
> It all depends om what Epoxysystem is used. I would be very carfull of post curing with heat without knowing what epoxies that is used. You can ruin the whole glider by overheating the structure.
>


Yes, it depents on the Epoxy Systems (and all other materials in the
area). To make sure please refer to the data sheet of the systems in use.

As a guideline composite gliders are certified to temperatures up to 54
deg C.
Without specific background info of all materials in use I would post
cure at 50 deg C for 15-24h. You may ramp up the temperature to avoid
problems with only paritial cured epoxy (10h 30 deg C + 15h 50 deg C).

Paula

[Craig Lowrie]

Hi Chris,

I build a cellotex box (building insulation material) and then use a
small bar heater placed low in the box. The Control is achieved using
a commercial Kiln controller which achieves the required temperature
from a thermocouple placed somewhere appropriate in the heat box,
and then controls the temperature to +/- about 1 degree by turning
the bar heater on and off. You can program the cure time and it cuts
it off at the end. I use a separate USB temperature monitor to get
the date to support the cure. Done about 25 cures with this system
now and no problems.... I have done most cures at temperatures of
55C but also done some specialist cures as high as 80C....

I think a fan approach might struggle into a sealed box....

Craig

At 20:45 31 December 2018, wrote:
>I am looking for some advise regarding "Post Curing of Epoxy
Composites".=
>=20
>
>The sailplane composite repairs have been completed regarding my
salvaged
>A=
>SW-27. The tail boom has a new 3'long intermediate section that
has been
>s=
>carfed and glassed into position. The fuselage pod had some radial
cracks
>=
>and the seat pan had some fractures that were all scarfed and
glassed. All
>=
>of the composite repairs were done at room temperature using OEM
materials
>=
>and MGS epoxy.=20
>
>What temperature is recommended and for what duration should I
be using
>for=
> post curing the repaired areas. Is there a temperature ramp up
and ramp
>do=
>wn time that I need to work with. I plan to build a foam insulation
box
>ar=
>ound the repair areas and use a fan with a number of light bulbs to
>regulat=
>e the temperature.=20
>
>Any advise is greatly appreciated,
>Thanks,
>Chris
>

[[email protected]]

On Wednesday, January 2, 2019 at 11:00:06 AM UTC-6, Craig Lowrie wrote:
> Hi Chris,
>
> I build a cellotex box (building insulation material) and then use a
> small bar heater placed low in the box. The Control is achieved using
> a commercial Kiln controller which achieves the required temperature
> from a thermocouple placed somewhere appropriate in the heat box,
> and then controls the temperature to +/- about 1 degree by turning
> the bar heater on and off. You can program the cure time and it cuts
> it off at the end. I use a separate USB temperature monitor to get
> the date to support the cure. Done about 25 cures with this system
> now and no problems.... I have done most cures at temperatures of
> 55C but also done some specialist cures as high as 80C....
>
> I think a fan approach might struggle into a sealed box....
>
> Craig
>
> At 20:45 31 December 2018, wrote:
> >I am looking for some advise regarding "Post Curing of Epoxy
> Composites".=
> >=20
> >
> >The sailplane composite repairs have been completed regarding my
> salvaged
> >A=
> >SW-27. The tail boom has a new 3'long intermediate section that
> has been
> >s=
> >carfed and glassed into position. The fuselage pod had some radial
> cracks
> >=
> >and the seat pan had some fractures that were all scarfed and
> glassed. All
> >=
> >of the composite repairs were done at room temperature using OEM
> materials
> >=
> >and MGS epoxy.=20
> >
> >What temperature is recommended and for what duration should I
> be using
> >for=
> > post curing the repaired areas. Is there a temperature ramp up
> and ramp
> >do=
> >wn time that I need to work with. I plan to build a foam insulation
> box
> >ar=
> >ound the repair areas and use a fan with a number of light bulbs to
> >regulat=
> >e the temperature.=20
> >
> >Any advise is greatly appreciated,
> >Thanks,
> >Chris
> >

Craig,

Are you using an infrared bar heater or something different. What size and type has been working for you. Have you had any problems with the overheat cut off protection.

Thanks,
Chris

[[email protected]]

Hi Chris - you can find some technical date sheets that show the T-glass, E, and strengths that are available as a pull down in most of the MGS supplier sites (AC spruce, Wicks, etc). There can see the material changes when cured at both elevated temperatures and for different time durations. Really, do go with what a few others have said - the manufactures temp. At some point - refer to graphs, the increase in time will have very little effect at a constant temp. What you should pay attention to is not going to the extreme cure temps that the resin is capable of - then you could end up with a section of the boom with strengths and flex characteristics that vary from the original build. Basically a very stiff section between the original boom sections that will cause stress problems. And then it is a repair - easy to make stronger without much effort! I assume you have it in an alignment jig - it would be wise to keep it aligned as repaired and supported during the cure time.
Regards, Mark

[Craig Lowrie]

Hi Chris,

I use an inexpensive bar heater... it has two bars... each about 6-8"
long... I
only use one unless the box is very large. It doesn't have an overheat
protection, but I did have to disable an orientation interlock so it can
lie flat...
open face up..!... The kiln controller is highly recommended to keep the

temperature under control.. but not cheap..!..

Craig

At 20:47 02 January 2019, wrote:
>On Wednesday, January 2, 2019 at 11:00:06 AM UTC-6, Craig Lowrie
wrote:
>> Hi Chris,
>>
>> I build a cellotex box (building insulation material) and then use a
>> small bar heater placed low in the box. The Control is achieved using
>> a commercial Kiln controller which achieves the required temperature
>> from a thermocouple placed somewhere appropriate in the heat box,
>> and then controls the temperature to +/- about 1 degree by turning
>> the bar heater on and off. You can program the cure time and it cuts
>> it off at the end. I use a separate USB temperature monitor to get
>> the date to support the cure. Done about 25 cures with this system
>> now and no problems.... I have done most cures at temperatures of
>> 55C but also done some specialist cures as high as 80C....
>>
>> I think a fan approach might struggle into a sealed box....
>>
>> Craig
>>
>> At 20:45 31 December 2018, wrote:
>> >I am looking for some advise regarding "Post Curing of Epoxy
>> Composites".=
>> >=20
>> >
>> >The sailplane composite repairs have been completed regarding my
>> salvaged
>> >A=
>> >SW-27. The tail boom has a new 3'long intermediate section that
>> has been
>> >s=
>> >carfed and glassed into position. The fuselage pod had some radial
>> cracks
>> >=
>> >and the seat pan had some fractures that were all scarfed and
>> glassed. All
>> >=
>> >of the composite repairs were done at room temperature using OEM
>> materials
>> >=
>> >and MGS epoxy.=20
>> >
>> >What temperature is recommended and for what duration should I
>> be using
>> >for=
>> > post curing the repaired areas. Is there a temperature ramp up
>> and ramp
>> >do=
>> >wn time that I need to work with. I plan to build a foam insulation
>> box
>> >ar=
>> >ound the repair areas and use a fan with a number of light bulbs to
>> >regulat=
>> >e the temperature.=20
>> >
>> >Any advise is greatly appreciated,
>> >Thanks,
>> >Chris
>> >
>
>Craig,
>
>Are you using an infrared bar heater or something different. What size
and
>type has been working for you. Have you had any problems with the
overheat
>cut off protection.
>
>Thanks,
>Chris
>

[SF]

I've spent a lot of my career either heating things up or trying to cool them off. Go with a low watt density heater, not anything that glows red. Maybe a milk house heater on low, at 60C you will have to disable the internal thermostat. Temperature distribution is going to be an issue, small circulation fans will help with that, you need some air movement, you don't need a lot. separate the fan and the heating element on the milk house heater and you get both in one package. TC's are cheap if you just buy the wire and make them your self, put a few extras on the structure you are heating, you can then spot check your temperature differences there will be more than you think. Sort things out at 40C, take it up to 60C after you are comfortable with what you have, including an automatic high temperature cutoff tested at a lower temperature. Automation direct has some pretty good $100 temperature controllers. This is one of those cases when Mo' ain't better. A well sealed foam board box with a few blankets over it isn't going to take a lot.

[[email protected]]

On Monday, December 31, 2018 at 2:45:51 PM UTC-6, wrote:
> I am looking for some advise regarding "Post Curing of Epoxy Composites".
>
> The sailplane composite repairs have been completed regarding my salvaged ASW-27. The tail boom has a new 3'long intermediate section that has been scarfed and glassed into position. The fuselage pod had some radial cracks and the seat pan had some fractures that were all scarfed and glassed. All of the composite repairs were done at room temperature using OEM materials and MGS epoxy.
>
> What temperature is recommended and for what duration should I be using for post curing the repaired areas. Is there a temperature ramp up and ramp down time that I need to work with. I plan to build a foam insulation box around the repair areas and use a fan with a number of light bulbs to regulate the temperature.
>
> Any advise is greatly appreciated,
> Thanks,
> Chris

Thanks for all of the assistance and advice. This is such a great group with experienced an knowledgeable contributors.

Much appreciated,
Chris

[[email protected]]

On Thursday, January 3, 2019 at 11:05:08 AM UTC-5, wrote:
> On Monday, December 31, 2018 at 2:45:51 PM UTC-6, wrote:
> > I am looking for some advise regarding "Post Curing of Epoxy Composites".
> >
> > The sailplane composite repairs have been completed regarding my salvaged ASW-27. The tail boom has a new 3'long intermediate section that has been scarfed and glassed into position. The fuselage pod had some radial cracks and the seat pan had some fractures that were all scarfed and glassed. All of the composite repairs were done at room temperature using OEM materials and MGS epoxy.
> >
> > What temperature is recommended and for what duration should I be using for post curing the repaired areas. Is there a temperature ramp up and ramp down time that I need to work with. I plan to build a foam insulation box around the repair areas and use a fan with a number of light bulbs to regulate the temperature.
> >
> > Any advise is greatly appreciated,
> > Thanks,
> > Chris
>
> Thanks for all of the assistance and advice. This is such a great group with experienced an knowledgeable contributors.
>
> Much appreciated,
> Chris

My response assumed that you are using the MGS system the glider was built with and specified in the repair manual. That is where my info previously came from. This task is not rocket science and does not require much technology.
For the area of your tail boom repair a closed box of foam insulation or even a cardboard box will do fine. Make sure there is a good amount of space between the enclosure and the structure. For that size you can get enough heating with three 100 watt light bulbs if you put a few blankets around the box. Adjust the temperature by adding or removing a bit of insulation. You do need a reliable temperature measuring tool. I use a thermocouple on a meter but a simple calibrated oven thermometer pushed into the box will do in a pinch. Make sure it is remote from the heat source. I put the lights in the bottom at least 8 inches from the part, with a shield to avoid direct exposure.
It will take about 3 hours or so to come to equilibrium.
Gentle heating makes for an easily controlled system.
Curing for longer allows soak and does no harm.
UH

[[email protected]]

On Friday, January 4, 2019 at 8:02:31 AM UTC-6, wrote:
> On Thursday, January 3, 2019 at 11:05:08 AM UTC-5, wrote:
> > On Monday, December 31, 2018 at 2:45:51 PM UTC-6, wrote:
> > > I am looking for some advise regarding "Post Curing of Epoxy Composites".
> > >
> > > The sailplane composite repairs have been completed regarding my salvaged ASW-27. The tail boom has a new 3'long intermediate section that has been scarfed and glassed into position. The fuselage pod had some radial cracks and the seat pan had some fractures that were all scarfed and glassed.. All of the composite repairs were done at room temperature using OEM materials and MGS epoxy.
> > >
> > > What temperature is recommended and for what duration should I be using for post curing the repaired areas. Is there a temperature ramp up and ramp down time that I need to work with. I plan to build a foam insulation box around the repair areas and use a fan with a number of light bulbs to regulate the temperature.
> > >
> > > Any advise is greatly appreciated,
> > > Thanks,
> > > Chris
> >
> > Thanks for all of the assistance and advice. This is such a great group with experienced an knowledgeable contributors.
> >
> > Much appreciated,
> > Chris
>
> My response assumed that you are using the MGS system the glider was built with and specified in the repair manual. That is where my info previously came from. This task is not rocket science and does not require much technology.
> For the area of your tail boom repair a closed box of foam insulation or even a cardboard box will do fine. Make sure there is a good amount of space between the enclosure and the structure. For that size you can get enough heating with three 100 watt light bulbs if you put a few blankets around the box. Adjust the temperature by adding or removing a bit of insulation. You do need a reliable temperature measuring tool. I use a thermocouple on a meter but a simple calibrated oven thermometer pushed into the box will do in a pinch. Make sure it is remote from the heat source. I put the lights in the bottom at least 8 inches from the part, with a shield to avoid direct exposure.
> It will take about 3 hours or so to come to equilibrium.
> Gentle heating makes for an easily controlled system.
> Curing for longer allows soak and does no harm.
> UH

Thanks Hank,

Your details really help out.

Much appreciated,
Chris

[Bret Hess]

Here's a temperature controller and probe for $30, and a version of the same for $15 if you can scrounge up your own cords:

https://smile.amazon.com/Inkbird-Electronic-Temperature-Germination-Controlling/dp/B01486LZ50/ref=sr_1_4?ie=UTF8&qid=1546983554&sr=8-4&keywords=inkbird+temperature+controller

https://smile.amazon.com/gp/slredirect/picassoRedirect.html/ref=pa_sp_atf_aps_sr_pg1_2?ie=UTF8&adId=A02927671UI46I5AKTV1Y&url=https%3A%2F%2Fsmile.amazon.com%2FInkbird-All-Purpose-Temperature-Controller-ITC-1000%2Fdp%2FB00OXPE8U6%2Fref%3Dsr_1_2_sspa%3Fie%3D UTF8%26qid%3D1546983554%26sr%3D8-2-spons%26keywords%3Dinkbird%2Btemperature%2Bcontrol ler%26psc%3D1&qualifier=1546983553&id=6639836400413390&widgetName=sp_atf

[Bret Hess]

Jim Marske's advice is to limit the T rise to about 1 deg F per minute, so I interpret that as every 5 min or so raise the temperature by 5 degrees.

[Guy Palmer]

At 21:43 08 January 2019, Bret Hess wrote:
>Here's a temperature controller and probe for $30, and a version
of the
>sa=
>me for $15 if you can scrounge up your own cords:
>
>https://smile.amazon.com/Inkbird-Electronic-Temperature-
Germination-Control=
>ling/dp/B01486LZ50/ref=3Dsr_1_4?
ie=3DUTF8&qid=3D1546983554&sr=3D8-4&keyword=
>s=3Dinkbird+temperature+controller
>
>https://smile.amazon.com/gp/slredirect/picassoRedirect.html/ref=
3Dpa_sp_atf=
>_aps_sr_pg1_2?
ie=3DUTF8&adId=3DA02927671UI46I5AKTV1Y&url=3Dhttps%3A%
2F%2Fsm=
>ile.amazon.com%2FInkbird-All-Purpose-Temperature-Controller-
ITC-1000%2Fdp%2=
>FB00OXPE8U6%2Fref%3Dsr_1_2_sspa%3Fie%3DUTF8%26qid% 3
D1546983554%26sr%3D8-2-s=
>pons%26keywords%3Dinkbird%2Btemperature%2Bcontroll er%26
psc%3D1&qualifier=3D=
>1546983553&id=3D6639836400413390&widgetName=3Dsp_atf
>

This is the temperature controller I use for £7.42 inc postage! Works
very well:

AC 90V-250V MH1210W Digital Temperature Controller screen H2M6

can be found at:

https://www.ebay.co.uk/itm/AC-90V-250V-MH1210W-Digital-
Temperature-Controller-screen-H2M6/253816032413?
epid=1869137394&hash=item3b189d4c9d:g:HhsAAOSwRiNbdA4R

[Miroslaw Pitorak]

At 20:45 31 December 2018, wrote:
>I am looking for some advise regarding "Post Curing of Epoxy
Composites".=
>=20
>
>The sailplane composite repairs have been completed regarding my salvaged
>A=
>SW-27. The tail boom has a new 3'long intermediate section that has been
>s=
>carfed and glassed into position. The fuselage pod had some radial
cracks
>=
>and the seat pan had some fractures that were all scarfed and glassed.
All
>=
>of the composite repairs were done at room temperature using OEM
materials
>=
>and MGS epoxy.=20
>
>What temperature is recommended and for what duration should I be using
>for=
> post curing the repaired areas. Is there a temperature ramp up and ramp
>do=
>wn time that I need to work with. I plan to build a foam insulation box
>ar=
>ound the repair areas and use a fan with a number of light bulbs to
>regulat=
>e the temperature.=20
>
>Any advise is greatly appreciated,
>Thanks,
>Chris
>


Just ask glider manufacturer - this is the best source of such information.
They should tell you what temperature and for how long have to be kept and
very likely heat up and cooling down procedure.
I can dig out such data for PW-6U (supplied by ZS Jezow when we did front
wheel repair) but they my not be relevant for your glider/epoxy used.

Regards,
Mirek P.