Usually, there are a few ways to assemble metal components:
- Welding
- Brazing
- Soldering
- Mechanical Fasteners
- Adhesives
Mechanical fasteners and adhesives are not difficult to understand:
Mechanical fasteners provide advantages over welding in that they are not necessarily permanent allowing for assembly with relatively simple and common tools. Mechanical fasteners may also allow for movement at the point of connection. Examples of mechanical fasteners are: screws, bolts, rivets etc.
Adhesives (probably the least common method of joining metals) are used for very specific applications and should be considered carefully before use.
Due to the wide range of adhesives available, the adhesives properties such as; hardness, durability, ease of use, health hazards etc. should be considered for their appropriateness in the given application.
People are easily confused on Welding, Brazing and Soldering. So, what are they and how could you distinguish them?
Welding: The process of joining two pieces of metal together in such a way that material from both sides of the original boundary surface flows together to form one piece of contiguous metal. Welding may be accomplished by the use
of heat and/or pressure, with or without the use of a filler metal.
Brazing: The process of joining
two pieces of metal together using a nonferrous filler metal with a relatively high melting point (but still lower than the
melting point of the metals to be joined), where the original boundary surface of the metals to be joined is not disturbed.
Soldering: The same as brazing,
but filler metal with a relatively low melting point is used.
This is a picture I found on Quora. It lists the differences and commons of welding, brazing and soldering in a chart, which I think is quite straight forward to look at.
Some background info you may want to know:
In the early years of the 20th century oxygen acetylene welding practices were rapidly replacing the craft of forging metal together. This technology greatly improved the quality
and the efficiency of welding, while simultaneously providing a quick and easy method for cutting thick pieces of metal.
Today, gas welding has been replaced by other welding methods to a great extent but is still used to cut thick metal and braze or silver solder very efficiently.
So, what are the main components of welding?
Below is a basic oxygen acetylene setup used for most gas welding, cutting and heating applications:
Several pieces of safety equipment are required when using the oxy acetylene set-up, these include:
1.Shaded goggles (#5 shade)
2.Welding gloves
3.Leather-welding jacket
As with most forms of welding, the light produced can damage unprotected eyes, so one should never look at an oxygen acetylene flame with the naked eye.In addition to the general safety guidelines, one should keep the following in mind when using the oxygen acetylene torch:
1. Make sure the work area is free of combustibles (paper, wood, cloth etc.
2. Pant legs should not be tucked into shoes (to avoid bits of hot metal from falling into your shoes)
3. No“V”neck shirts
4. Remove contact lenses
5. Know where you are pointing the torch (never point it at
someone, or leave it unattended while lit). If you need to set the torch down while lit, place it on the stand, and secure it with a spring clamp so that it will not fall.
6. Never direct the flame at a gas cylinder, or hoses.
7. Follow all cylinder safety procedures.
Oxy/ Acet Start-up:
1. Fully open the main oxygen valve. Pressure in the oxygen cylinder will register on the cylinder pressure gauge in pounds per square inch (psi).
2. Open the main acetylene valve 1/4 turn. As you open the valve, there will be some “slop” to take up before the handle begins to lift the disc from the seat, so when you feel a bit of resistance, continue to open 1/4 turn. Pressure in the acetylene cylinder will register on the cylinder pressure gauge in psi. Acetylene is highly
explosive, by opening the valve only 1/4 of one turn; one may quickly close the valve in the event of an emergency.
3. Adjust the line pressure of the acetylene. Use the acetylene regulator “T” handle to control the flow rate of the acetylene to
the mixing chamber of the torch body as indicated on the working pressure gauge (psi desired is dependent on the application).
4. Adjust the line pressure of the oxygen. Use the oxygen regulator “T”handle to control the flow rate of the oxygen to the mixing chamber of the torch body as indicated on the working pressure gauge (psi desired is dependent on
the application).
5. Partially open the torch
acetylene valve (on the torch
body) and ignite the torch using a striker. Adjust to
medium flame.
6. Slowly open the torch oxygen valve (on the torch body). Adjust to a neutral flame.
Oxy/ Acet Shutdown:
1. Shut torch oxygen valve.
2. Shut torch acetylene valve.
3. Shut main acetylene valve and re-open torch acetylene valve. Leave torch acetylene valve open until cylinder pressure registers 0 psi at the cylinder pressure gauge
（working pressure gauge should also indicate 0 psi).
4. Shut torch acetylene valve.
5. Shut main oxygen valve and re-open torch oxygen valve. Leave torch oxygen valve open until cylinder pressure registers 0 psi at
the cylinder pressure gauge
（working pressure gauge should also indicate 0 psi).
6. Shut torch oxygen valve.
7. Back out regulator “T” handles for both the oxygen and acetylene regulators. “T”
handle should feel loose, but still be engaged in the body of the regulator. Please ensure that this step is completed, for if the“T” handle is left engaged, it prematurely wears the diaphragm in the regulator shortening regulator life.
8.Return torch to tray on back of cart, coil hose neatly and hang from cart handle.
T.I.G. is short for Tungsten Inert Gas welding. It is a type of electric welding very similar in technique to gas welding.
The primary differences are:
- electricity is the source of heat energy (instead of a flame).
- a shield gas (frequently Argon, provided at the cup) reduces fouling of the weld.
Several pieces of safety equipment are required when using the T.I.G. welder (Proper Personal Protective Equipment), these include:
- Welding helmet(#10 shade)
- Welding gloves
- Leather-welding jacket
- Spats and leggings (if necessary) to cover exposed skin or synthetic materials in clothing or shoes
Below is a basic T.I.G. set-up used for welding:
For the torch, I also attached a picture below.
Some tips for the torch components selection:
- For 16 awg. Steel, 3/32″ components will be the most versatile (collet, collet body and electrode).
- When purchasing an electrode, make sure it is a lanthana tungsten electrode if you will be welding steel (brown tip).
Set Up:
- Assemble the torch.
- Check the settings
a. Output selector switch to “electrode negative”.
b. Process push button selected to“TIG”
c.Power/Coolant cable connected to TIG power supply - Turn power switch to “ON”.
- Set amperage to desired level by turning the encoder wheel when amperage is selected (70 amps is generally a good starting point when welding 16 awg. Steel)
- Fully open main argon valve.
- Set line pressure to 15-20 lbs (using either the flow meter adjustment knob, or regulator “T” handle).
- Make sure ground is attached to welding table or the piece that you are welding (if that piece is not directly on the welding table).
Shut Down:
- Close main argon valve
- Depress pedal and drain gas pressure from the line. Both the cylinder pressure gauge and the working pressure gauge should indicate 0 psi (for a unit equipped with a regulator). For a unit equipped with a flow meter, the cylinder pressure gauge should indicate 0 psi and the sight glass should indicate 0 cubic feet per
hour. - If using a TIG welder equipped with a regulator, back off the “T” handle until it feels loose in your fingertips, but is still within the body of the regulator. If using a TIG welder equipped with a flow meter, the adjustment knob need not be moved at this time.
- Place the power switch in the “OFF” position.
- Break down torch and take your consumables with you (Cup, collet, collet body and electrode). Make sure to give sufficient time for the torch components to cool down before touching with your bare hands or placing next to combustible materials.
Bibliography:
- RISD《Metal Shop Safety Procedural Guidelines For Monitors》. 04 January 2017.
