Pick the right welding equipment

Picking the right welding equipments

Picking the right welding equipment in todays modern panel beating shop is important if you want to thrive in tough economic and competitive conditions.

What welding equipment should a bodyshop buy when starting up in business or re-equipping? Jeff Cranza is an industry expert and provides an insight, The first thing that has to be ascertained is the level of throughput the bodyshop is anticipating. This, in turn, determines the best spot welding unit for the bodyshop. Never buy a spot welder that is too small for the job. The second consideration is the type of vehicles that will be repaired. Older cars have far fewer high strength steel (HSS) panels compared with the newer models. Newer cars also have certain areas of boron steel and aluminium, so the tools required must be able to cope with these materials as well. The electrical power requirements must be three phase and the trip switch must be at least 40-amp slow blow. A suitable compressor, capable of supplying the correct volume of air to the different tools and equipment is also essential. For the purpose of this article we will assume the bodyshop intends to repair newer cars and has intentions to grow as a business.

SPOT WELDER The very first piece of equipment required for any bodyshop is a spot welder. With the advent of the latest HSS (Boron, ZstE, bake-hardened dual phased etc), the spot welder must be an inverter welder. Non-inverter welders will not do the job and therefore should not be considered.

WHY INVERTER? The new HSS require a minimum 8,000amps (rms) of welding power through the complete welding cycle and this is only possible with inverter 1000hz to 2000hz mid-frequency welders. In addition to the power requirements, the clamping force at the tips of the twin sided gun must be in excess of 300daN (decanewtons) and in some cases as much as 450daN. This clamping force will hold the molten nugget in place during the weld and prevent it from sparking. Welders with less clamping force produce weak welds. A water-cooled welder that cools the cables, arms and tips is also highly recommended. Without water-cooling the cables and tips become very hot. The hotter the cables become the less efficient the welder becomes, producing poor welds into the bargain. Water-cooling ensures all welds are constant and 100 per cent correct. The InvertaSpot ATMw ensures all these requirements are met but in addition the water-cooling system is refrigerated which allows the welder to be used all day if necessary.

MIG/MAG WELDING The new HSS should be MIG brazed where MIG welding is required instead of being welded with MIG steel wire. The reason for this is the steel wire melts at 1500°C and this excessive temperature will damage the zinc coating on the panel whilst changing the molecular structure of the steel to make it brittle, weak and susceptible to rusting. In contrast, MIG brazing wire melts at 900°C, flowing between the gaps, thus ensuring a proper repair that is stronger than the metal around it. The zinc coating is retained and the panels are not damaged. Furthermore, many cars nowadays have certain sections of aluminium panels, which also will need repair when damaged. An inverter MIG welder would easily cope with welding aluminium once the wire and torch have been changed. To be able to weld all types of metal correctly, only inverter MIG/MAG units should be used.

WHY INVERTER MIG/MAG? A stepped MIG welder normally has seven fixed power control settings (amps and volts), which range between 30, 50, 70, 90, 110,130 and 150 amps. These steps vary slightly between different manufacturers. The only adjustments are made to the wire speed. When MIG brazing a piece of quarter panel for example, the exact welding requirement may be 43 amps with 11.4 volts. A MIG welder with fixed settings would not be able to match this requirement and the repair would be unsatisfactory. The only way to split the volts and amps and to satisfy this requirement would be by using inverter technology. The InvertaPuls IP8 or IP10 digital welder, for example, has a power range from 30-300amps and with 45 different welding parameters is able to MIG steel, MIG Braze and Aluminium weld. The car manufacturers use several types of HSS on their cars, all requiring slightly different volts and amp settings, especially when being MIG brazed. Without inverter technology it is impossible to get the correct settings.

TRAINING The rule of thumb here is: 60 per cent the machine, 40 per cent the man. MIG brazing is a process that is easy to master, provided the user has received proper training. The welding unit can do the job, but if the operator does not understand the welding process, the results will be poor. Training is not only given so that the operator understands torch control, amps, volts, wire speed, wire selection and Tedac, but also in appreciating welding safety, choice of welding helmet, safety gloves, and protective clothing. The choice of welding helmet is vital. Some eye protectors make it impossible for the operator to see where the line is during welding. It is best to choose a helmet that has an automatic darkening eye shield that is designed to cope with both aluminium welding and MIG brazing.

PLASMA CUTTER There are sections on many of the newer cars that have boron steel incorporated in their design. This steel is so hard it is unable to be cut using the conventional saw or air chisel. Trying to remove panels without using the proper equipment will take hours instead of minutes. This is unproductive and unprofitable. The answer is a plasma cutter.

WHY INVERTER PLASMA CUTTER? The problem with plasma cutters in the past has been the lack of control of the power. With the inverter technology this power is very controlled, allowing top skins of steel to be cut without damaging the inner skins. When cutting ultra hard steel like boron, the cut is effortless and very clean. No bodyshop should consider open for business without such a tool.

IN SUMMARY Buying the wrong equipment is costly and very unprofitable. If the equipment is underpowered or if it slows down the operator, the knock-on effect is massive. The painter is held up and the oven is under utilised. The repair times rise and if you have a fixed time to do the job in, the financial result will invariable end up as a loss. Always buy the correct equipment and fund it through leasing as a fixed monthly cost. The end result will be a busy, profitable repair business.
When he became involved in the UK car repair industry in 1985, most bodyshops were still using MIG welders. He launched the first proper single sided spot welding system in 1986, pioneering the concept and changing the mindset of the repairer in the process. In 2001 he awoke the repair industry to the importance of using inverter technology, not only for spot welding but for MIG brazing and plasma cutting.
What about power?

In an effort to maximise sales by some equipment suppliers, bodyshops are being given some very misleading information with regard to power requirements for the new inverter technology and it is very likely the wrong equipment is being purchased as a result. The only measurement that is a true gauge of power is the number of amps being produced at the tips. For inverter welders this must be above 8,000amps (rms). It must be constant and it must not fluctuate. If there is fluctuation, the welds will be poor. The minimum output of 8,000 amps is the average number of amps produced for welding through the whole of the weld cycle (i.e. from the moment the tips clamp up to the moment they are released, including all peaks and troughs.) and the average is shown as (rms). The welding unit creates spot welds only at the welding tips and therefore it is vital the welding measurement is recorded at this point. What is being said? The misleading information being used in the market place is ? the higher the kVA the more powerful the machine?. This is totally wrong and misleading. The kVA rating is not an indication of power, it is simply an indication of expense. The higher the kVA the more expensive the welder is to run. It is a bit like a car. One travelling 35mpg is cheaper to run than another travelling 30mpg. The mpg has nothing at all to do with the power of the car, purely the cost of running it. So what is a kVA? This is the measurement (Volts x Amps/1000). Three-phase current (Volts) in all workshops in Australia is normally 415V. This is fairly constant. If the welding unit draws 135 Amps, the result is (415V x 135A = 56,000VA). Divided by 1,000 is 56kVA. If the welding unit draws 145 Amps, the result is (415V x 145A = 60,000VA). Divided by 1,000 is 60kVA.The more amps drawn by the machine increases the electricity bill.

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2 comments on “Pick the right welding equipment”

  1. Alan

    Apart from the above mentioned tips, one should make sure that working capacity of the welding machine that you are planning to buy matches with the work load you have. Overloading machines reduce their lifetime to a great extent.

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