Plastic Welding Explaination and Who does it?

[Guest]

Just wondering about plastic welding, how is it done?, how strong is it?(thinkng about hacking a couple of bumpers together)and who does it and how much should it cost?

Looking at finding someone in Auckland or Hamilton possibly...

Cheers

[Guest the_return_of_the_jedi]

Plastic welding is the process of welding plastic parts together. Heat sealing is one of the primary processes of joining or welding plastics.

There are several techniques with which this can be accomplished:

Hot gas welding

This is a plastic welding technique which is analogous to gas welding of metals, though the specific techniques are different. A specially designed heat gun (hot air welder) produces a jet of hot air that softens both the parts to be joined and a plastic filler rod, all of which must be of the same or a very similar plastic. Welding PVC to acrylic is an exception to this rule.

Hot air/gas welding is a common fabrication technique for manufacturing smaller items such as chemical tanks, water tanks (black, grey, fresh & ballast), heat exchangers, and plumbing fittings. Poly family plastics are used for manufacturing cabinets, medical facility chassis, transport assemblies, etc.

Freehand welding

With freehand welding, the jet of hot air from the welder is played on the weld area and the tip of the weld rod at the same time. As the rod softens, it is pushed into the joint and fuses to the parts. Free hand welding is a difficult technique to master, and is slow. However, welds can be made in almost any situation.

Plastic welding rod

This is the extruded rod that is used to weld plastic. Suitable rod materials include ABS, PVC, Polypropylene, polyethylene, PVDF and many other types of thermoplastic. Plastic welding rods are available in a wide range of colors to match a project's color. It is often used for design.[citation needed]

Speed tip welding

With speed welding, the plastic welder, similar to a soldering iron in appearance and wattage, is fitted with a feed tube for the plastic weld rod. The speed tip heats the rod and the substrate, while at the same time it presses the molten weld rod into position. A bead of softened plastic is laid into the joint, and the parts and weld rod fuse. With some types of plastic such as polypropylene, the melted welding rod must be "mixed" with the semi-melted base material being fabricated or repaired. These welding techniques have been perfected over time and have been utilised for over 50 years by professional plastic fabricators and repairers internationally. Speed tip welding method is a much faster welding technique and with practice can be used in tight corners.

Extrusion welding

Extrusion welding allows the application of bigger welds in a single weld pass. It is the preferred technique for joining material over 6 mm thick. Welding rod is drawn into a miniature hand held plastic extruder, plasticized, and forced out of the extruder against the parts being joined, which are softened with a jet of hot air to allow bonding to take place.

[edit] Contact welding

This is the same as spot welding except that heat is supplied with convection of the pincher tips instead of electrical conduction. Two plastic parts are brought together where heated tips pinch them, melting and joining the parts in the process.

[edit] Hot plate welding

Related to contact welding, this technique is used to weld larger parts, or parts that have a complex weld joint geometry. The two parts to be welded are placed in the tooling attached to the two opposing platens of a press. A hot plate, with a shape that matches the weld joint geometry of the parts to be welded, is moved in position between the two parts. The two opposing platens move the parts into contact with the hot plate until the heat softens the interfaces to the melting point of the plastic. When this condition is achieved the hot plate is removed, and the parts are pressed together and held until the weld joint cools and re solidifies to create a permanent bond.

[edit] High frequency welding

Certain plastics with chemical dipoles, such as polyvinyl chloride (PVC), polyamides (PA) and acetates can be heated with high frequency electromagnetic waves. High frequency welding uses this property to soften the plastics for joining. The heating can be localized, and the process can be continuous. Also known as Dielectric Sealing, R.F. (Radio Frequency) Heat Sealing.

In a ferromagnetic work piece, plastics can be induction-welded by formulating them with metallic or ferromagnetic compounds, called susceptors. These susceptors absorb electromagnetic energy from an induction coil, become hot, and lose their heat energy to the surrounding material by thermal conduction. [1]

[edit] Ultrasonic welding

In ultrasonic welding, high frequency (15 kHz to 40 kHz ) low amplitude vibration is used to create heat by way of friction between the materials to be joined. The interface of the two parts is specially designed to concentrate the energy for the maximum weld strength.

[edit] Vibration or friction welding

In vibration or friction welding, the two parts to be assembled are rubbed together at a lower frequency (typically 100-300 Hz) and higher amplitude (typically 1-2 mm) than ultrasonic welding. The friction caused by the vibration motion combined with the clamping pressure between the two parts creates the heat which begins to melt the contact areas between the two parts. At this point, the plasticized materials begin to form layers that intertwine with one another, which therefore results in a strong weld. At the completion of the vibration motion, the parts remain held together until the weld joint cools and the melted plastic re-solidifies. The friction movement can be linear or orbital, and the joint design of the two parts has to allow this movement.

[edit] Spin welding

Spin welding is another form of frictional welding. With this process, one part is held stationary, while the other one is rotated at high velocity. The rotating part is then pressed against the fixed part with significant force. This welding process is related to Vibration Welding.

[edit] Laser welding

This technique requires one part to be transmissive to a laser beam and either the other part absorptive or a coating at the interface to be absorptive to the beam. The two parts are put under pressure while the laser beam moves along the joining line. The beam passes through the first part and is absorbed by the other one or the coating to generate enough heat to soften the interface creating a permanent weld.

Semiconductor diode lasers are typically used in plastic welding. Wavelengths in the range of 808 nm to 980 nm can be used to join various plastic material combinations. Power levels from less than 1W to 100W are needed depending on the materials, thickness and desired process speed. [2]

Diode laser systems have the following advantages in joining of plastic materials:

• Cleaner than adhesive bonding • No micro-nozzles to get clogged • No liquid or fumes to affect surface finish • No consumables • Higher throughput • Can access work-piece in challenging geometry • High level of process control

Requirements for high strength joints include:

• Adequate transmission through upper layer • Absorption by lower layer • Material compatibility – wetting • Good joint design – clamping pressure, joint area • Lower power density

Materials that can be joined include:

• Polypropylene • Polycarbonate • Acrylic • Nylon • ABS

Specific applications include sealing / welding / joining of: catheter bags, medical containers, automobile remote control keys, heart pacemaker casings, syringe tamper evident joints, headlight or tail-light assemblies, pump housings, and cellular phone parts.

[edit] Solvent welding

In solvent welding, a solvent is applied which can temporarily dissolve the polymer at room temperature. When this occurs, the polymer chains are free to move in the liquid and can mingle with other similarly dissolved chains in the other component. Given sufficient time, the solvent will permeate through the polymer and out into the environment, so that the chains lose their mobility. This leaves a solid mass of entangled polymer chains which constitutes a solvent weld.

This technique is commonly used for connecting PVC pipe, as in household plumbing.

Dichloromethane (methylene chloride), which is obtainable in paint stripper, can solvent weld polycarbonate.

[Guest]

were did you manage to copy and past that lot from, damn some one did there research

good sh*t

-smurff

[Guest the_return_of_the_jedi]

 smurff said:

were did you manage to copy and past that lot from, damn some one did there research

good sh*t

-smurff

good ol wikipedia

[Guest]

hahaha, nice

-smurff

[Koom]

 smurff said:

were did you manage to copy and past that lot from, damn some one did there research

good sh*t

-smurff

You type "plastic welding" into google, and its the first non-sponsored link that comes up.................

Now if people would just use that method instead of getting someone else to do it, then the internet wouldn't need to be filled with copied and pasted pages from wikipedia and someone could then give personal opinions on methods they've actually used themselves and have real world experience with i.e. fixing a hole in their bumper using a heat gun and "welding it" compared to the pro's and con's of taking it to a professional and the quality of their workmanship.

And fyi, the heat gun method works and once I bogged it and repainted, can't tell that there used to be a giant slit in the front of my bumper.

[Guest]

i did the heat gun way to redo the cracked mounts on my head lights. . . not pretty but it worked

-smurff

[Guest]

yeah I was a little surprised by what paul posted up lol, All I was looking for was what have people had experience with and would it be suitable for what I'm planning (cutting and merging a Foz bumper with a wRX one)

[Guest the_return_of_the_jedi]

 matdaymon said:

yeah I was a little surprised by what paul posted up lol, All I was looking for was what have people had experience with and would it be suitable for what I'm planning (cutting and merging a Foz bumper with a wRX one)

doesnt take much to suprise u mathieu lol

if u stopped trying to drive through trees and learned to drive around them you wouldnt need to plastic weld

[Guest]

 the_return_of_the_jedi']

[quote name='matdaymon said:

yeah I was a little surprised by what paul posted up lol, All I was looking for was what have people had experience with and would it be suitable for what I'm planning (cutting and merging a Foz bumper with a wRX one)

/quote]

doesnt take much to suprise u mathieu lol

if u stopped trying to drive through trees and learned to drive around them you wouldnt need to plastic weld

Shhh you! I've only hit 2 trees and a rental van! not a whole forest

[Guest the_return_of_the_jedi]

lol, what u waiting for.. get out there man!

there are plenty of trees for you to hit..

do i need to post the pic of u off the side of the road?

[Shale]

Heat gun good for minor cracks et al, eh...

*strokes chin*

[DRFVDR]

 Shale said:

Heat gun good for minor cracks et al, eh...

*strokes chin*

Only really works if u have whiskas

which I hope u dont

[Shale]

Or, if you're an evil scientist. Then it doesn't matter