Why striking an arc is important?

Why striking an arc is important?

Why is it important to strike the arc only in the weld joint? Striking the arc accurately in the weld joint is necessary step. It needs lot of practice to develop the speed and skill needed to prevent the electrode from sticking to the plate.

What is arc Strike in welding?

Arc strike This is a defect caused by instantaneously striking an arc on the base material. In other words, an arc strike is a spot of failed arc ignition which was not fused by subsequent welding and remained on the base material. Arc strike may be the cause of cracking in the base material.

Why is arc length important in welding?

Arc length is the distance between the welding nozzle and the metal you’re welding. A shorter arc length will keep an adequate amount of shield gas around your weld but will result in more spatter on the nozzle.

Why are arc strikes outside the weld bad?

Arc Strikes result in localized base metal heating and very rapid cooling. When located outside the intended weld area, they may result on hardening or localized cracking, and may serve as potential sites for initiating fracture.

What are 2 ways to strike an arc?

There are two general methods of striking the arc:

  1. Scratching.
  2. Tapping.

When you do the striking the arc length should?

The correct arc length is 1/8 in. long. As the electrode burns off and gets shorter, the arc will get long. To compensate for this burn-off you will have to move your hand gradually toward the work-piece.

How do I get rid of arc strike?

All arc strikes should be removed by grinding. Grinding to a depth of 1/8 inch below the original surface should remove all traces of arc strikes and their hardened heat-affected zones. In locations where the arc strikes have been removed should have magnetic-particle inspection and hardness testing performed.

What happens when the arc is too short?

Arc Length Too Short The surface of the weld is uneven where it has been dragged along by the rod, and the weld will be low on power and contain slag inclusions.

How do you start an arc?

The arc is started by touching the electrode momentarily against the work to complete the electrical circuit before raising the electrode to establish the arc. This needs to happen quickly to avoid welding the rod to the work. “Tap Starting” and “Scratch Starting” are the two common methods of starting the arc.

How is an arc maintained in a welding machine?

A welding arc is maintained when the welding current is forced across a gap between the electrode tip and the base metal. A welder must be able to strike and establish the correct arc easily and quickly. The scratching method is easier for beginners and when using an AC machine.

Why are arc strikes outside the welding zone considered a problem on pipe?

Likewise, a slight arc strike outside the weld zone most likely will have absolutely no effect on the performance of the pipe unless it’s some very severe defect. – MarkKw Originally Answered: why are arc strikes outside the welding zone considered a problem on pipe ?

Why is it so hard to strike an arc?

The principal difficulty encountered in striking the arc is “freezing,” or when the electrode sticks or fuses to the work. This is caused by the current melting the electrode tip and sticking it to the cold base metal before it is withdrawn from contact.

Do you need to use slag in arc welding?

Arc welding may or may not require filler metal. In spot welding, there is no need for filler metal. Because of the flux used in arc welding, slag is formed on the weld bead which has to be removed while finishing operations. There is no slag formation in spot welding.