HOW TO PROPERLY SELECT YOUR WELDING EQUIPMENT.

In a material joining process, it is essential to know the variables to be used, and the welding equipment is the main tool for carrying out quality work. On the market, there are different types of machines and different brands, making the purchase of a machine a not-so-easy selection task. That is why there are a number of elements that must be considered when selecting a good power source. For example:

• Working amperage. (the amount of current required to melt an electrode or a wire). It is important to know which electrode will be used in order to choose the power source that supplies the appropriate amperage.
• Open circuit voltage (OCV). (It is the working voltage that allows electrodes to operate properly.) This voltage results from the reduction of the input voltage as it passes through a transformer that steps it down to a level suitable for welding, where it takes the name of OCV or open circuit voltage. Normally, this open circuit voltage ranges from 45 to 95 volts. If you are going to use E 6010 type electrodes, keep in mind that you need a power source with an open circuit voltage above 75 volts, or check whether the equipment has some type of technology that improves arc stability for any electrode, to avoid issues at the time of application.
• Duty cycle (The duty cycle refers to the amount of time the equipment can operate at its full capacity and the time it needs to rest). Keep in mind that if the equipment is rated at 200 amperes and has a duty cycle of 60%, this means that when operating at full capacity (200 A), it can only run for 6 minutes and must rest for 4 minutes. The reference period is always 10 minutes according to the NEMA standard (National Electrical Manufacturers Association). The duty cycle varies depending on the required amperage range, and to calculate the appropriate amperage, the electrode diameter and coating type must be known. For example: if welding with a 1/8-inch diameter electrode, it should be clear that for every thousandth of an inch of the electrode diameter, 1 ampere is required for proper melting. This means that a 1/8-inch diameter electrode has 125 thousandths of an inch, and therefore requires 125 amperes to operate. This rule applies to rutile-type electrodes; for cellulosic electrodes, 10% should be subtracted, and for basic electrodes, 15% should be added. This ensures that the required amperage is determined according to the job, allowing for the proper selection of welding equipment.

Another determining factor when choosing a power source or welding equipment is analyzing what type of technology the brand has developed. Let us review the types of power sources according to their technology.

Transformer machines: they are called this way because they reduce the voltage from the main power supply and increase the amperage through devices that stabilize the current flow to a voltage that allows welding. They consist of two coils — a primary and a secondary — on a magnetic metal core built from silicon steel laminations. However, welding with a transformer-based machine does not produce a very good finish, since the current it supplies is unstable, generating a great deal of spatter. Not all electrodes work with this type of current, and energy consumption is very high in these machines — a variable to consider at the time of selection.

Rectifier machines: they operate on the same principle as an alternating current power source, with one difference: these machines include a component called a rectifier bridge that converts the incoming alternating current (AC) into direct current (DC). In this way, the current is rectified so that it flows in an orderly manner from the negative to the positive terminal. This generates a higher concentration of heat at the positive terminal — theoretically around 70% — and 30% at the negative terminal. The vast majority of electrodes work with this type of current. These machines also have high energy consumption.

Engine-driven welders: these are power sources driven by a combustion engine. These engines convert mechanical energy into electrical energy, which provides an advantage when performing welding applications where no electrical supply is available and power must be generated on-site. Their field of use includes pipeline installation for gas and hydrocarbon transport, as well as industrial construction and assembly work.

Inverter machines: these are state-of-the-art equipment in which the current rectification process is carried out more efficiently through an electronic circuit board and various components that make the welding arc much more stable and efficient. Some equipment manufacturers have developed several technological features that make inverters the equipment of the future. The advantages of this type of equipment are: versatility, portability, and energy savings — a very good option for a purchase. You just need to make sure it meets the required duty cycles and verify that its open circuit voltage is not too low if the work involves E-6010 type electrodes.

These elements are the basic and fundamental factors when choosing your welding equipment. Also review the technical and commercial support that guarantees proper performance according to your investment.

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