Continuous ultrasonic welding without anvil 1

[maxpcc]

Hello all, I'm Max and this is my first post in this forum.
I'm having my first experiences in ultrasonic welding. My need is to weld an ABS (or PVC or PP) band on another thick piece of plastic, so that I can't use an anvil. Being the band so long, the weld must be continuous.
Can anyone give me some suggestion?
TY
Max

 

[MikeHalloran]

Look at thermal bonding.

Without an anvil, ultrasonic can't develop enough heat to make a bond.



Mike Halloran
Pembroke Pines, FL, USA

 

[Demon3]

Vibrational welding is the same as ultrasonic welding just with a lower frequency and greater amplitude of motion. An advantage is that it requires no special configuration so it could be better suited to your needs.

Note that you will only get adhesion between similar polymers so nylon will not stick to PP. Adhesion between any two of the polymers you mention is likely to be poor.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[dwightdixon]

I basically agree with Demon but I would change the word from "similar" to "compatible". To get a bond of any sort the polymers must be compatible.

The more easily accomplished process would to have a hot melt adhesive that is dispensed between the two strata and then brought together through a set of pinch rolls or other means of holding the bond under pressure till solidified. Another possibility is a film of hot melt that is activated (melted) by a process (like Emabond) using magnetic or RF heating and the bond held under pressure until the hot melt becomes a solid again.

 

[Demon3]

By similar, I mean compatible and by compatible I mean, having like polarity and by that I mean a close propinquity of their solubility parameters and consequently their cohesive energy densities.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[maxpcc]

Thanks to all!
And what about welding wood and thermoplastic? I know that wood has lignin, that is compatible with thermoplastic. But in this case I read somewhere on the internet that USW is worst than vibration welding. I think I'll make a try. When ready I'll inform you. Thanks to all.

Max

 

[Demon3]

You can ultrasonic or vibration weld wood right onto nylon because they are both high polarity / compatible. I've done it myself and it works great.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[btrueblood]

Never knew that Chris. LPS for that one.

 

[Demon3]

Thanks btrueblood!

BTW, I developed a way to ultrasonically or vibration weld wood onto wood as well. Now that is not trivial.

Cheers,

Chris

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[MacGyverS2000]

Weld wood to plastic? No kidding? That's slick! I'll have to remember that one, may need it sometime in the future...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[maxpcc]

Sure! You can do better: weld wood to wood:

http://fractals-ibois.epfl.ch/httpdocs/carnet_ibois_2007.pdf

page 16

 

[Demon3]

Yes, as I mentioned above, I have already vibration welded wood to wood. The link you gave mentions a project where they modified some vibration welding machine to try and get a weld. Nowhere does it say that they achieved adhesion.

What normally happens without modification is that you get lots of smoke and burning. That's what they saw and what I saw too. We had to open the windows to stop the fire alarm from going off. Embarrassing because there were visitors passing through from Scania and they smelled the burning.

Anyway, I was able to get very good adhesion with no smoke or burning and without modifying the machine in any way.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry