網上找來的，我個人建議 Arc Stick

個人建議:  http://www.harborfreight.com/welding/arc-welders/70-amp-arc-welder-68888.html

Which welding process is best? That depends on the application. The following is a short description of each:

Arc (Stick) Welding or SMAW (Shielded Metal Arc Welding):

Arc welding is one of the oldest welding processes around. It can be the cheapest to start with as there is not a lot of equipment needed. It is also very versatile as there a lot of specialized electrodes available. Some of the main features and limitations are:

• Inexpensive
• Has specialized electrodes for hardening, high-strength, stainless, mixed, cast iron and other metal alloys
• Uses a flux coating to shield weld.
• Weld will need to have flux cleaned off
• Very difficult on thin metal
• Takes considerable training and practice to master.
• Portable as no need to carry gas or wire feeder.
• Works on AC or DC

Arc welding is nice for its simplicity in the equipment. It takes practice to do consistent and proper welds.

There are dozens of types of rods (electrodes) available. Some of the most common are:

• 6011 - Deep penetration, cellulose
• 6013 - General purpose, easy to use.
• 7014 - Low Penatration, great for thin metal
• 7018 - Low-hydrogen, higher strength. Rods need to be kept dry, usually in an oven. They are also more productive as far as amount of weld per minute.
• Nickel/Silicon - Designed for Cast Iron. Two main types depending on Nickel content. High nickel content is stronger but very hard and cant be machined. Lower nickel content for machinability.
• Stainless -308, 309 and 316 grades available.

Most DIY welders will use 6013 rods as they are widely available and relatively easy to use. Note, the quality of the rods make a big difference on their ease of use.

Electrodes can be purcased in differnt sizes from 1/16" to 1/4". For DIY use 1/8" or less will be used. I find 5/64" or 3/32" rods are the most useful.

Note: thin metal is difficult with arc welding. I found some 1/16" (1.6mm) 7014 rods that work well on 0.040 steel.

MIG Welding

MIG welding (Metal, Inert Gas) welding is also call GMAW (Gas, Metal Arc Welding.) It uses a thin wire as an electrode and filler fed by a wire feeder to the gun. The power source is constant voltage (CV) DC.

There are two main process Gas (MIG) and gasless (flux core.) Below is a comparison of the two:

Gasless MIG (FCAW - Flux Core Arc Welding):

• Does not need shielding gas, saves cost of bottles, regulator.
• Wire is more expensive.
• It is more portable, no gas to transport.
• Uses flux core to shield weld. Causes slag and spatter that must be cleaned up.
• Produces smoke that makes it hard to see weld.
• Has deeper penetration than gas MIG.
• Easier on positional welds (overhead and vertical.)
• Direct-Current, Electrode Negative Polarity (DCEN)
• Smallest wire available is 0.030" (0.8mm); not easy to use on thin metal.

Gas MIG (GMAW):

• Very clean welds with no slag or spatter.
• Uses Argon/CO2 or straight CO2 as a shielding gas.
• Wire is less expensive.
• More complex than Flux Core
• Less portable
• Direct-Current, Electrode Positive polarity (DCEP)
• Wire size down to 0.023: (0.6mm), great for thin metal.

The wire is fed via from a roll wire feeder to the gun. MIG is the easiest process to learn, but requires gas and a wire feeder so it is not as portable. MIG is great for thin metal especially auto body work.

TIG Welding, GTAW (Gas Tungsten Arc Welding):

TIG welding is also very versitile and produces the highest quality welds. It also takes considerable practice and is least productive.

TIG uses an torch with a tungsten electrode. Argon is used as a shielding gas to protect weld and tungsten. An arc is struck between the tungsten and the work and a short gap is maintained. As the weld progresses, filler wire is dipped in the weld pool. Power source is constant-current DC or AC depending on metal used.

Controlling the torch, feeding wire, moving at the right speed and also using the correct current makes it physically more complicated. Using a footpedal, you have 1 foot and both hands busy. It is easier for bench work (I use a barstool .)

TIG can do just about any metal with AC and a DC power source. DC is used on ferrous metals (steels.) AC is used on aluinum. This DIY welder only does DC.

So, Which Do I Use?

As usual, that depends ;)

For building a DIY welder, arc welding is cheapest and simplest. It is a versitile starting point. Great for farm repairs as it is the most portable. Difficult on thin metal.

If you plan on doing bodywork, then gas MIG is best. That will require adding a wire feeder, gun, gas bottle and regulator to the basic arc setup. I prefer MIG for its clean welds. However, if I need to lug the welder out somewhere for a quick fix, I use stick.

If you are building something like a off-road buggy frame, then TIG is preferred as you have the most control over the welds.

I use arc 80% of the time. TIG for aluminum and MIG for thin metal.