Body Shop
Choosing a Spot Welder 101 By Shawn Hart
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n today’s modern body shop, quite a few pieces of capital equipment are necessary to stay on top of the vehicle repair game. Every facility in the market will have a repair bench, paint booth and a wire feed welder, but many are lacking Squeeze Type Resistance Spot Welding (STRSW) equipment. This is typically because STRSW equipment is very expensive and most don’t see the benefit it would bring to their shop. There are many factors to consider when purchasing STRSW equipment. Yes, cost is a big factor to consider when making an equipment purchase, but what good is a piece of equipment, whether expensive or not, if it doesn’t do what you want or need it to do? Before you simply review prices and choose the lowest priced machine, you should also consider these criteria: • Specifications • Service • Ease of Use/Efficiency • Approvals Specifications Look at the specifications of the machines you’re considering; don’t just rely on the sales representative’s opinion that “it can do it all”. Compare the specifications to the requirements of the vehicle manufacturers for the cars your shop works on. Many of these specs result from advancements in vehicle body construction, like the use of High and Ultra High Strength Steels, and affect how the welder operates when welding on each of the different manufacturer’s vehicles.
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What specifications should you look for? You want to look at things like: • Air Pressure/Squeeze Pressure (at the tips) • Power output (amps at the tips) • Power input (what’s necessary to run the machine) Air pressure is pretty simple. I don’t know of any collision shop that doesn’t have air. However, if there’s not enough air coming into the machine, it will not produce the necessary squeeze pressure between the tips. Many manufacturers specify how much pressure is necessary to produce a proper spot weld; typically between 75 and 120 psi.
Power input is one of the specs that gets overlooked the most, but is probably one of the most important. Even if you get a machine that meets all of the vehicle manufacturer’s specifications, if you cannot make it work due to inadequate power, then it’s worthless. I know a number of shops that spent a fair amount of money on STRSW equipment only to discover they couldn’t run it in their shop because they didn’t have the right power. This is something that should be checked out by the representative of the STRSW company and taken into consideration before anything is purchased.
“Look at the specifications of the machines you’re considering.” Power output is very important, especially when working with newer vehicles that incorporate High and Ultra High Strength Steels. These types of steels require a high amount of amperage output between the contact tips in order to produce a quality weld. Most manufacturers will specify this; typically they are looking for a minimum of 10,000 amps output.
May / June 2012
Fixed Ops Magazine