helpful hints to basic welding

helpful hints to basic welding 

Welding is an efficient and easy way to cut down on maintenance or repair costs associated with metal equipment around the house or farm. Through welding, you can repair a wide variety

of things including:

Home Improvement

• Lawnmower decks and handles

• Ductwork

• Fencing

• Steel patio furniture

• Garage door tracks and brackets

• Wheelbarrows

Recreation

• Basketball rims and posts

• Swing sets

• Trampolines

• Wagons

• Snowmobile skis and skags

• Bicycles and tricycles

Agricultural

• Combines

• Grain wagons

• Balers

• Farm equipment frames

• Tractors and trailers

• Galvanized roofing

• Trailer hitches

• Trailer frames and sides

Automotive

• Tailpipes

• Motorcycles

• Bumpers

• Trailer hitches

• Auto bodies and door brackets
industries 
•  oil piping
•  refineries
•  power plants
• structures 
etc  ........

hint 1 : be sure you read carefully about welding safety

Always remember…welding is serious business! Make sure you protect yourself Set up protective screens or barriers to protect other persons from flash and glare

Stick or Wire… Which is Your Welding Preference?

There are several different welding processes that are ideal for projects around the house or farm:

• Stick welding – properly known as SMAW (Shielded Metal Arc Welding)

• Wire welding – properly known as GMAW (Gas Metal Arc Welding) or FCAW (Flux-cored Arc         Welding)

All of these processes involve the joining of metals by means of an electric arc. This electric arc, at a temperature of about 10,000° F, melts both the metal electrode and the base metal

(the metal being welded) together, producing a molten weld puddle that quickly solidifies to form the weld.

Although these processes depend on the use of an electric arc, they differ in technique, including the type of electrode and equipment required. Stick welding is a manual arc welding process in which a covered metal stick electrode is used as the filler metal for making the weld. Wire welding is considered as a semi-automatic process, using a wire electrode that’s conveniently fed through a welding gun. Stick welding requires you to have more skill because you have to consistently concentrate on the electrode while you are welding,keeping it in the proper welding position and

manually maintaining the proper arc length as the electrode gets shorter Wire welding is considered to be somewhat easier than stick welding because the welding gun continuously feeds the wire while you weld, allowing you to focus on gun position for maintaining the proper arc length. Plus,

you don’t have to worry about the electrode getting shorter

Whether you prefer stick welding or wire welding… the welding process you use is most likely the one you have the most experience with or have the equipment for.

Basic Stick Welding –A Quick Review

Stick Electrode

Stick welding (properly known as Shielded Metal Arc Welding or SMAW) requires use of a covered stick electrode, a metal rod that’s coated with a material called flux. An electrode holder is used to hold and supply

current to the stick electrode, causing it to melt and deposit molten metal. As the electrode melts, the flux coating breaks down to perform several functions: 
1) form a gas shielding to protect the weld puddle from the air, 
2) keep the weld puddle clean from contaminants, and 
3) produce a light, protective coating, called slag, over the weld. The slag is removed by tapping the weld with a chipping hammer or chisel and cleaned off with a wire brush

Equipment and Tools

In stick welding, the equipment and tools that are required are:

• power source welding machine –complete with welding cable,electrode holder, and ground cable

   and clamp

• chipping hammer or chisel, and a wire brush (for removing slag)

• protective clothing including helmet and gloves

hint 2 :If you have to use an extension cord to get power to your welding equipment, make sure the cord is the correct size to carry the current from the outlet to the power supply!

Techniques

To produce a good quality weld, it is important to master the following stick welding techniques. The first thing you should do before you start welding is make sure the workpiece – the item you are welding – is as clean as possible. Use a clean cloth, wire brush or sandpaper to remove any rust, dirt,

paint, grease, oil or other contaminant. Do not use cleaning solvents because you run the risk of an explosion or fire, or illness from toxic vapors. Be sure to connect the ground clamp of your welding

equipment to the workpiece before you start welding!

hint 3: Be sure to connect the ground clamp of your welding equipment to the workpiece before you start welding!

Setting the Amperage

Select the proper amperage based on the specifications of the stick electrode. Sometimes, you may find that you have to “fine tune” the setting so that the electrode melts properly. The best way to check this is to perform some test welds on some scrap metal and look at the weld. If you notice that the weld is…

• piling up or you see signs of burn-through (holes in the base metal), then the amperage is probably       set too high;

• not penetrating the joint (little depth) or not fusing to the workpiece (doesn’t cover joint walls)             properly, then the amperage is probably set too low.

Striking an Arc

To strike an electric arc, bring the tip of the stick electrode near where you want to start the weld.

Almost like striking a match, strike the stick electrode slightly across the workpiece until you

have established an arc. Once you have an arc, be sure to keep the electrode slightly above the workpiece, otherwise, it will stick and you will have to break the electrode free from the workpiece. If you have trouble striking an arc, you may be lifting the electrode too high off of the workpiece, causing the arc to go out.

The most important thing you want to do after you’ve initiated the arc is to maintain proper position of the electrode and arc.This involves three key factors, namely

• electrode angles

• arc length

• travel speed
hint 4 :Position the ground clamp on the workpiece so that you will be welding away from the     clamp. This will help keeparc blow (interference from magnetic fields) to a minimum.

Electrode Angles

Electrode angles are the angles at which you should hold the stick electrode in relation to the workpiece while welding. These angles differ depending on the type of weld you intend

to make.

For instance, when doing a lap weld (one piece of metal overlaps another) or a T-weld (joining  two metals to form a ‘T’), hold the electrode so that it points into the weld joint at an angleof 45°. When you start welding, angle it 10-15° toward the direction of travel until you

complete the weld and terminate the arc.

For a butt weld (joining two pieces of metal butted together), first hold the electrode so that it is pointing into the joint of the workpiece at an angle of 90°. Then, as you start welding, angle the electrode so that it is pointing 10-15° in the direction of travel (see illustrations above). When completing theweld, bring the electrode back to 90° and lift it to terminate the arc.

Arc Length

Maintaining the proper arc length is another key factor in producing a good quality weld.The arc length is the distance from the end of the stick electrode to the surface of the molten weld puddle. Be careful to watch the stick electrode as you weld because as it becomes shorter and shorter, you have to keep moving the electrode toward the weld joint to maintain theproper arc length.

A good rule of thumb to follow is: try to keep the end of the electrode at a distance from the joint that’s approximately equal to the diameter of the stick electrode. For example, if the stick electrode you are using is 1/8" in diameter, then keep the end of the electrode about 1/8" from the molten weld puddle.

Keep in mind that an arc length that is too long makes a coarse, uneven cracking sound and will often go out. You will also see an excessive amount of spatter (metal particles outside the weld) and the weld will be too wide.

A short arc makes a soft buzzing noise and produces a weld that is too narrow. In some cases, the stick electrode will stick to the workpiece. If this happens, move the stick electrode side to side

and pull it to free it from the workpiece.

hint 5 : Arc re-starts are much more effective when the flux covering at the end of the stick electrode is flush with the metal rod.

Travel Speed

Travel speed is the rate at which you weld. A good travel speed produces a uniform weld that is slightly convex in appearance. However, if you travel too slow, the weld will pile up, wasting

filler metal. If you go too fast, the weld will be narrow and lack proper penetration and fusion.

Factors to Consider in Selecting Arc Welding Electrodes

1. Base Metal Strength Properties

Know and match mechanical properties. Mild steel – generally E-60XX or E-70XX electrodes match base metal. Low alloy steel – select electrodes that match base metal properties.

2. Base Metal Composition

Know and match composition. Mild steel – any E-60XX or E-70XX electrode is satisfactory. Low alloy steel – select electrode that most closely matches base metal composition.

3. Welding Position

Match electrode to welding position encountered.

4. Welding Current

Match power supply available. Some electrodes are designed for direct current (DC); others, alternating current (AC); some, either.Observe correct polarity.

5. Joint Design and Fit-up

Select for penetration characteristic – digging, medium, or light. No beveling or tight fit-up – use digging. Thin material or wide root opening – light, soft arc.

6. Thickness and Shape of Base Metal

To avoid weld cracking on thick and heavy material of complicated design, select electrode with maximum ductility. Low hydrogen processes or electrodes are recommended.

7. Service Condition and/or Specifications

Determine service conditions – low temperature, high temperature, shock loading – match base metal composition, ductility and impact resistance. Use low hydrogen process. Also, check welding

procedure or specification for electrode type.

Hint 6 : For examples of good and bad welds, along with descriptions and illustrations of common stick welding defects

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