Welding Plastic (soldando Pl�sticos)





Introduction: Welding Plastic (soldando Pl�sticos)

About: I am leaving Instructables, soon. I am very upset with the turnaround that has the page to post the manufacture of a dildo. Me llamo Osvaldo Julio Schiavoni I speak Spanish, not English. I use automatic tr...

No todos los plásticos se pueden soldar, y algunos de ellos sueldan mejor que otros, pero la mayoría de los de uso habitual en el hogar sueldan bien. Es una lástima tirar a la basura algo que puede ser reparado con muy poco esfuerzo y sin costo. Además es poco amigable con el medio ambiente.

Muchas veces se puede utilizar algún adhesivo para solucionar una rotura en un plástico, y suele ser una buena solución. Yo les presento acá una alternativa gratis, ustedes deberán evaluar la conveniencia de usarla en cada caso particular.

Not all plastics can be weld, and some of them weld better than others,but most commonly used at home do it well. It is a pity to throw away something that can be repaired with little effort and no cost. It is also unfriendly to the environment.

Many times you can use some glue to fix a broken plastic, and is often a good solution. I am presenting here a free alternative, you should assess the appropriateness of use in each particular case.

Step 1: Decide (decidir)

Como dije antes, es necesario evaluar si conviene usar un adhesivo o una soldadura. Eso dependerá de varios factores, entre los cuales no es menor el de la estética. La accesibilidad de la pieza a reparar también importa: si está dentro de un hueco difícil de acceder, tal vez lo mejor sea usar adhesivo. La robustez de la reparación también importa.

En mi caso, arreglaré una banqueta plástica, que presenta dos fracturas que obligan a descartarla o repararla. No me interesa demasiado la estética, porque la utilizaré principalmente en mi taller, pero sí la solidez de la reparación, porque es muy peligroso para una persona de mi edad estar parado sobre una banqueta que se desbarata súbitamente por la rotura de una pata.

La accesibilidad de la rotura era excelente, así que no dudé ni un segundo en inclinarme a usar soldadura plástica.

As I said before, it is necessary to evaluate whether to use an adhesive or welding. That depends on several factors, including not least of aesthetics. The accessibility of the repair piece also matters: if it is within a gap difficult to access, may be best to use adhesive. The strength of the repair also matters.

In my case, I will fix a plastic stool, having two fractures requiring disposal or repair. I'm not too interested in aesthetics, because I will use it mainly in my workshop, but the strength of the repair, because it is very dangerous for a person my age standing on a stool that suddenly breaks down by a broken leg.

The accessibility of the break was excellent, so I did not hesitate a second to myself to use plastic welding.

Step 2: Welding (soldar)

Saqué mi soldador de estaño, y comencé a fundir con su punta caliente las orillas de la grieta, haciendo que el plástico fundido se mezclara y produjera una soldadura.

I took my tin solder, and began to melt with its hot tip the crack edges, causing the molten plastic mix and produce a weld.

Step 3: Adding More Plastic (agregar M�s Pl�stico)

Para reforzar la soldadura, corté tiras delgadas de polietileno duro de un envase vacío, y lo utilicé como material de aporte, es decir como si fuera estaño.

To strengthen the weld, cut thin strips of a hard polyethylene desused bottle, and used it as filler, ie like pewter (tin).

Step 4: Optional (opcional)

Dado que en este caso la seguridad es muy importante, como expliqué en el paso 1, quise asegurarme de que la rotura no volvería a producirse, o al menos disminuir la probabilidad de que se repita. A tal efecto hice con la punta del soldador una serie de agujeritos a ambos lados de la soldadura, luego corté trozos de aproximadamente una pulgada de alambre galvanizado de mediano grosor, e hice algunas grapas que pasé por los agujeritos como si fueran broches para papeles, y los cerré. En este caso es importante señalar que los agujeritos no debe estar muy cerca de la soldadura, porque deben agarrar suficiente material como para que no se parta el plástico entre el agujero y la soldadura.

También usé tanza de nylon, de la que usa la bordeadora, pero me tropecé con la dificultad de hacer un nudo eficaz al final. De todas maneras, no creo que se vaya a salir de su lugar.

Since in this case the security is very important, as explained in step 1, I made sure that the break does not occur again, or at least reduce the likelihood of recurrence. To this effect I made with the solder tip a series of holes on both sides of the weld, then cut pieces about an inch of galvanized wire of medium thickness, and did some staples that went through the holes like paper clips, and closed them. In this case it is important to note that the holes should not be too near the weld, because they must hold enough material to avoid cracking of the plastic between the hole and the welding.

I also used my line of nylon, which uses the edger, but I ran into the difficulty of making the final effective knot. Anyway, I do not think that will be out of place.

Step 5: Others (otros)

Esta caja de herramientas tiene muchos años, pero la arreglo cada vez que se rompe.

This toolbox is many years old, but I fix it each time it breaks.



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    Very innovative. A friend of mine put an ATV body back together with cable ties similar to your nylon string idea. I will have to try this some time.

    1 reply

    Thanks for comment, guicarlorobelli. Sometimes I used cable too, instead of nylon.

    Great instructable! Thank you. And to "pretty up" the piece, how about the
    finishing touch - acrylic nail product from any beauty supply or drugstore?

    1 reply

    Yes, it is possible there are many alternatives to enhance the aspect. It depends on each case. Thanks for your comment.

    Nice Instructable very well done, rimar2000. I like the way you think. I don't like throwing things away either. I have tried welding plastic and the best method I've used is a flat tipped screwdriver and a propane torch. I get the torch going and put it on a level, stable surface. I then introduce the screwdriver tip to the flame just long enough to melt the plastic without burning. It takes some practice but Welding at a colder temperature enables better control of the weld. Of course it all depends on which method you are most comfortable. Your method works well with most plastics. I found it quite tricky with some plastics, though. It might be good to mention here there are many different kinds of plastic some of which lend themselves better to welding than others. Again, very nicely written with good photos. Thank you.

    9 replies

    Thanks, SharpyWarpy. My English is precarious, "yes bwana type". Google helps a lot.

    In Introduction I say "not all plastic can be welded", but you are right, is better to add "and some of them weld better than others". I will edit the instructable.

    The use of the tin solder ensures you will not apply too heat, or at least greatly diminishes the possibility of that happening.

    Your English is better and better all of the time.

    Many years ago my mother had a plastic water pitcher. It touched the corner of a hot electric fry pan and got a hole in the side. I used a soldering gun like you have and plastic from a bottle of dish washing soap to make a patch. It required several tweaks before I fixed every leak, but it worked for many years. It was very ugly, but she did not mind.


    Interesting, thanks.

    Thanks, Phil. Google translator is better and better all of the time ;)

    Maybe somebody among Instructables readers can contribute with an easy method to enhance the aesthetics of plastic welds... I tried using sandpaper, it is a little solution, but not fix the problem.

    You know those fingernail tools that have the multiple sides with varying grits of sandpaper glued to them? They are numbered from most coarse grit up to the finest grit. I've used those with good results. You wind up with a sheen like a polished fingernail. I wouldn't bother unless the repair is in a place that's highly visible and might embarrass somebody.

    Thanks newly, SharpyWarpy. I will try that next time. In this case it not worth.

    I understand. I had to come up with something when I was building custom headphone amplifiers that were in plastic enclosures. Sometimes modification was necessary to implement all the features my customers wanted which left an ugly spot. I used the aforementioned method to clean it up.

    Yes indeed, right there in the first sentence "Not all plastics can be welded". Sorry about that. You are very kind. Thank you for the tip on using tin solder. By the way, I thought your comment in the second photo pointing out the other break showing up in the shadow was pretty cool. Took me a while to understand that was a shadow and the light coming through the crack. Maybe I should change my alias!

    Nice, logical solution that I bet we've all considered briefly - just not done anything about it...

    The staples idea, harking back to the methods used to repair pots, is a good one for strengthening the weld.

    If you're careful, nylon line can be melted/welded by putting a match flame to it for no more than half-a-second or so (maybe not even that long). It won't look pretty, but as it's hidden away anyway, that won't matter.

    1 reply

    Thanks for your comment, karlpinturr.

    I tried to weld the nylon line using the solder, but it is not easy. I will try your suggest.