Bonding Nylon 6 to Nylon Rope Fiber End

[Confab]

I am having difficulties bonding a machined end cap (nylon 6) over the end of 19mm double braided nylon rope. I am unable to determine if the rope fibers are Nylon 6 or 6-6. The epoxy used is an off–the-shelf hardware store “lock tight” epoxy plastic bonder. Our goal is to get a minimum of 150lb of direct pull to remove the end cap.


Failed methods tried:
1 We filled the end cap with epoxy and placed it over a seared end of the rope and allowed full cure. At 8lb of pull, the end cap lost bond and was removed.
2 We lightly frayed and opened the rope and filled it with epoxy then placed the rope end into the cap filled with additional end epoxy, and cured. The results were much better, but still failed at 30lb of pull. The epoxy broke free from the nylon cap and was a very messy process.
3 We lightly frayed and opened the rope and filled it with epoxy then placed the rope end into a Teflon mold with compression and cured. We then placed the cap filled with additional end epoxy onto the rope and cured once more. The results increased though failed at 65lb of pull. The epoxy separated or failed at the bond joint of both the rope and cap and was also a very messy process.

Planned Changes:
1 We have started researching “Structural Plastic Adhesive for low surface energy plastics” as a replacement for our off the shelf plastic epoxy. This is our need, we are lost in the number of acrylic adhesives to choose from that would be best suited for this application, or even if acrylic-based adhesive is the best option. We are also wondering if there is a way to “weld” the joint. We don’t have any plastic weld knowledge be it mechanical, chemical, or ultrasonic applicable for this use of nylon and nylon fibers.

2 The second planned change is to machine a square ring groove inside or knurl the inner surface of the cap to try and get more surface area to bond with or create a pegging effect.
3 Seek much needed guidance in: What are the best bonding options? Of those options, what achieves the goal most cost effectively? What can we do mechanically to best improve the parts?

I am unsure if I provided enough or the correct information needed to help, I’ll try to provide more if needed, I really appreciate your advice and time offered.

 

[MikeHalloran]

Thread the rope through the cap and knot it on the other side.
A figure-8 knot should work fine.
If you want to hide the knot, make the cap bigger, seat the knot in a counterbore, and cap or plug the counterbore.

OR

If you really must use a blind hole, put a back taper on it, put a cone in the cup, shove the rope in so it spreads over the cone, and vacuum pot the assembly with epoxy.

OR

See if you find some wire rope terminators, especially the ones filled with molten zinc at assembly, and copy them, making adjustments for different geometries and materials.





Mike Halloran
Pembroke Pines, FL, USA

 

[MikeHalloran]

OR

You can bond nylon to nylon with phenol, but study the MSDS first and take extreme precautions; it's really super nasty stuff.



Mike Halloran
Pembroke Pines, FL, USA

 

[Confab]

Mike
The knot was our first thought though a figure8 with 3/4" rope get large and the client preferred a different idea. The end cap is sealed and has an external thread for linking testing devices to the rope. I am looking into the swage connectors. Thank you

 

[Confab]

We are looking into Formic and will consider carbolic as well

 

[MikeHalloran]

Oh, wait. It's braided rope. This should be easy.

Make the cap longer, bore a hole up most of the way, and mill a side slot, and an expanded cavity adjacent the slot. See if you can do a back-countersink of the bottom of the slot.

Feed the rope up through the central hole, out the side slot, and stuff a bearing ball into the end of the rope, maybe a rope diameter or so. Then pull the rope back into the cavity and down. Just like a monkey trap.

You may need to make the cap from metal, or at least reinforce the area around the back-countersink to take the hoop stress.







Mike Halloran
Pembroke Pines, FL, USA

 

[CoryPad]

I recommend you contact the adhesive manufacturers: 3M, Henkel/Loctite, Reltek, and Devcon. They have products that can be used for your application. Here is a nice page from Reltek:

http://www.reltekllc.com/adhesives-for-nylon.html

Polymers can be welded by a variety of methods including hot air, friction, hot plates, and ultrasound.

 

[Confab]

After reviewing the post I have instructed my staff to call salespersons with in manufacturing. Wish us the best. We hope to work for (ipo) pubic funded companies one day also, until then we will invent and hope china can only copy.
But I know they are waiting on me to send them a drawning… Thankfully The counter man at National Plastics in Irving Texas helped us beyond tying a knot in the end.
also Travis at RelTek solved the bond issue. Best of thoughts to ever one. I hope a entrepreneur still remained in your company.

 

[Demon3]

If they are both the same kind of nylon perhaps you can melt them together so no solvent needed.

I've vibration welded nylons but not sure whether that would work with a rope unless you can hold it rigid.

Maybe you can find a low melting nylon hot melt adhesive. I think Henkel have some.

Chris DeArmitt - PhD FRSC

Plastics & Materials Consulting

http://www.phantomplastics.com

Plastic Training Seminars

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