Dip coating of Glue on a Nylon - Need help with design

[83118898]

hi,

My company requires me to design a mechanism to dip a chord of nylon (about 1 m long) into a container filled with glue. The glue has similar viscoscity as oil although we have not finalised the glue properties yet. It is either a thermal cured or UV cured glue.

The proposed design is:

Dip the nylon chord vertically into and out of a sealed container with the help of one or two rollers. After the chord is out of the container, either a thermal or UV source will be there to cure it. I am not an expert in dipping mechanism so I need your help.

The chord is probably around 0.4 mm to 0.8 mm thick and we need a glue thickness of around 200 microns on the nylon.

1) May I know what are some standard designs available in the industry in glue coating?

2) How do I control the thickness of glue? And, is there some standard equipment that can measure the glue thickness, give feedbacks and adjust the thickness accordingly? I need the glue coating on the chord to be as uniform as possible.

3) Where or How should I design the rollers? At what distance apart and how big should the rollers be?

4) At what optimal speed is best for pulling the chord?

I am thinking of setting up some simple experiment to test the various parameters.. But I'll like to hear expert's opinions first, esp on the roller design...

If there's any company whom you can recommend me, feel free to...

Thanks.
Your help is kindly appreciated.

 

[83118898]

In addition,

I would like to know for vertical dipping,

(chord dips down into the bucket and then move vertically upwards)

Are there some empirical relations that I could use to do calculation about the thickness of the glue?

Thickness of glue coating related to viscoscity of glue and draining time.. (but I do not know if there are any more parameters and the order of their relation?)

Thanks

 

[83118898]

Any expert to provide some tips?

Thanks...

 

[aspearin1]

It sounds like you're on the right track in your experimental thoughts. For references on how to coat cords, you may wish to do a search on coated wire and candle making. Patent searches on such processes would direct you toward companies that may specialize in such equipment. Try

http://www.uspto.gov/patft/index.html

Your critical inputs will likely be as you say, viscosity, line speed, cord wetability, temperature, depth, cure time, dry time... etc.

Aaron A. Spearin
ASQ CSSBB
Engineering Six-S'$

http://www.Engineering6ss.com

"The only constant in life is change." -Bruce Lee

 

[Compositepro]

The details of the coating process depend on what you want to achieve. Do you want the cord coated on the outside only or fully saturated and impregnated. Complete impregnation is much more difficult that mostly impregnated. Remember that for liquid to move into the cord, air must come out somewhere. Slow dipping allows air to come out to the surface through the center of the cord. Faster dipping will entrain air in the cord which will remain as dry spots or can be worked out of the cord in the form of bubbles in the bath. This can lead to frothing of the glue. There are many details to consider.

 

[83118898]

Thanks for all the advices.

As designing this new coating is something new for me, I would like to hear more advices and details that are needed to be considered... i wouldn't want to miss out any detail.. so if anyone has any good advice, feel free to let me know and I'll appreciate your help.

The objective is simple- to coat around 200 microns thick of glue on a nylon chord.

The thickness needs to be as uniform as possible.

And, after dipping the nylon chord with glue, we need it to glue this chord to something else, which is confidential.

so, there are many possibilities that we are still exploring such as the type of glue, dipping method etc...

Thanks

 

[Compositepro]

If you want only an external coating the glue viscosity must be high so it does not wick into the cord. A hole through a rubber diaphagm that is smaller than the cord will squegee the coating on the surface and accommodate irregularities in the cord. Increasing the speed of the cord will increase the coating thickness. Ideally you would use a hot glue with lower viscosity during coating that becomes very high viscosity when it cools so the coating becomes stable.