The art of Welding your Car
With the increased use of plastic protective moldings, galvanizing and improved coatings on modern vehicles, corrosion is nowhere near as common as it was in past decades. However, rust can still bite hard into bodywork, as CM’s recent Ford Ka project demonstrated so adeptly. Welding is often the only answer to corroded or bent body panels.
Falling market values and the higher costs associated with repairing accident damage mean that many salvageable cars are deemed uneconomical to repair and are written-off as Category C or D by insurance companies. Additionally, fewer garages offer welding services these days, not helped by body repair shops finding it harder to work on modern cars that are becoming increasingly complex to repair.
If you have the necessary skills and tools, a canny DIYer can take advantage of this gap in the market; either prolonging the life of an existing car or buying a vehicle that requires welding repairs at a knockdown rate. If purchased from a breakers yard, it might be possible to acquire sections from a donor vehicle as part of the deal as well.
Welding Types Explained
Welding joins metals together with heat. Both brazing and soldering are also used to join metal materials, but they do not apply high enough temperatures to provide both fusion and a structurally-strong joint, which is why those methods are unsuitable for effective structural mild-steel repairs. Methods that fuse the metals together (including MIG/MAG, TIG and MMA, or ‘stick ‘welding) are more structurally sound, but most types require a joining filler material.
Manual Metal Arc (MMA) or ‘stick’ welding is more suited to heavy-duty repairs and, as such, tends to be too aggressive for the thin steel sheets that form a typical monocoque car body, although the method can be considered for separate chassis repairs, where the metal is much thicker. The user feeds the metal-cored stick into the work area manually, which requires both patience and experience to achieve a result that is strong and neat.
While Tungsten Inert Gas (TIG) welding is more common when working with metal alloys, it can be used for steel repairs. It consists of a negatively charged (although the polarity can be reversed) tungsten-tipped torch, which helps to create the metal arc. As the tungsten electrode is not consumed, the user needs to feed a jointing material rod with the other hand, while pure Argon gas is used to shield the weld and surrounding area. TIG welding is a slow process but can produce very neat results.
Due to it being more cost effective and notably easier to use, Metal Inert Gas (MIG), or Metal Active Gas (MAG), welding tends to be the preferred method for the DIY car repairer. A MIG welder’s biggest enemy is the atmosphere, which can oxidize the hot metals and create a very weak joint. To remedy this, an inert-based shielding gas is blown over the weld and repair area to keep natural air away from the molten metal. As with TIG, MIG welding requires argon gas, but a small percentage of carbon dioxide is added (the British Oxygen Company’s trade name for this is Argoshield), which allows for superior fusion, while the argon provides a calm atmosphere and less spatter. It may still be possible to obtain pure carbon dioxide gas, used by publicans to pressurize their bar drinks dispensers (hence the term ‘pub gas’), but using CO2 alone produces a fierce arc and a greater chance of metal particles, or spatter, exiting the work area.
Essential kit
Many trade and retail outlets will be able to provide the necessary welding hardware, whether you are looking to buy, or rent. If buying, your choice of welder specification will depend on your expected usage and budget. Should you be welding thin steel occasionally and not embarking on a full restoration (car bodywork thickness tends to be around 0.8mm), you are unlikely to require more than a basic-spec unit. However, the quality of the wire-feed mechanism is crucial and you should always pay more for a decent clamping mechanism. Welding wire is wound under tension into various sized spools, with 0.6mm and 0.8mm diameter wire preferred for car bodywork, and remembers that you must match the wire diameter with that of the torch tip.
You will also require welding gas. For occasional use, it might be best to pay a one-off fee of around £60-£100 to retain the bottle indefinitely, and then exchange it for a replenished replacement for around £40-£50, when your gas is depleted. A reliable regulator, preferably a twin-gauge unit, is critical. The regulator shows not only how much pressure remains within the cylinder but also allows accurate metering to ensure a strong, sound, defect-free weld, while avoiding wastage.
Instead of buying gas, you might consider gas-less wire, where the flux core of the wire, when exposed to the arc, forms a protective gas shield over the work area. However, gas-less wire is not only expensive but also harder to control.
Consider consumables, too. These relate to not only safety equipment, such as gauntlets and welding helmets, but also the essential tools needed to prepare the metal before and after welding, including an angle-grinder and metal cutting, grinding and flap discs.
Techniques
MIG (Metal Inert Gas) welding should really be called MAG (Metal Active Gas) welding, because an active shielding gas mixture of argon and CO2 is used, rather than fully inert Argon alone.
MIG welding is extremely user-friendly. Being a semi-automatic process, it is unnecessary for the operator to feed the wire manually into the work area. The machine also adjusts the current automatically to allow for any discrepancies in both operator movement and the position of the torch, making the process very forgiving.
The wire is wound onto a replaceable spool, housed usually within the welding plant itself, and fed into the torch’s liner by an electric motor and feed rollers. As the welding torch is positively charged, most of the heat generated originates from the wire as it melts. The metalwork is negatively charged by the user attaching the welder’s negative earth clamp as close to the working area as possible.
According to both Steven Hall, welding lecturer at Exeter College, and associate lecturer Richard Dines, the most common misconception among their students is that higher heat results in a stronger weld.
“One of the worse things a novice can do,” says Steven, “is to penetrate right through the thickness of the steel plate completely, unless a gap exists between the plates that is designed specifically for full penetration, such as an open butt weld. Having too high a setting, or welding too slowly, causes the weld and surrounding parent metal to overheat and bulge through the opposite side of the plate, which creates a weakness.”
For the strongest and neatest welds, Steven and Richard advise that you should ensure not only that the steel surfaces are clean, but also that the MIG welder is also set-up correctly before you begin.
Know Your Materials
While this feature focuses on welding mild steel, which remains a major material used for car bodies, the need to reduce weight and improve crash resistance has seen other materials being used, including aluminum. In less exotic mass-produced vehicles, various types and grades of both High Strength Steel (HSS) and Ultra High Strength Steel (UHSS) are employed in critical locations, such as door pillars and even bumper mounts. In general, the greater the steel’s strength, the harder it is to weld, and introducing heat could change its composition, or even cause it to crack. This will affect the crash resistance properties of a car in the future.
Should you be considering buying and repairing a modern crash-damaged vehicle, it may be worth consulting the manufacturer about the material and construction methods used in the damaged area, because this will determine whether, or not, an economical DIY MIG-welded repair is feasible.
Should vehicle-specific data be unobtainable, Thatcham Research specializes in model-specific crash repair methods, but its data tends to be available only to professional body shops, a local branch of which might be willing to share this information with you. Attempting to MIG-weld two steel sections with incompatible tensile strengths may be almost impossible and the most common advice is to drill-out the original spot-welds and replace the complete panel. However, even this may require more specialist hardware, such as a spot-welder or even a pulse MIG welder, both of which tend to be beyond the reach of a DIY mechanic.
Consider also that manufacturers have found ingenious ways of bonding different materials, such as joining aluminum and steel using structural adhesives. Therefore, be wary that MIG-welding an adjoining panel might introduce heat that causes further damage.
Health and Safety
Although MIG/MAG is one of the safest forms of arc fusion type welding, it presents a number of risks. Electric shocks should be minimized if your welder is stored, maintained and set-up correctly, but your car may not be so lucky. In most cases, disconnecting the battery will suffice, but some vehicles require their ECUs to be removed, to avoid damage from the magnetic fields that welding generates.
For this reason, you should seek medical advice before attempting welding, if you are fitted with a pacemaker. Additionally, aim to have the welder’s negative cable as close as you can to your work area, so that the electrical circuit is kept as short as possible.
Keeping your surroundings clear reduces the risk of fire. This includes ensuring that any trim, soundproofing material, cavity wax, etc. cannot ignite within the car. Wear flame-retardant overalls, arm sleeves, gauntlets and even an apron. Keep an appropriate fire extinguisher handy and be aware that fabrics can smolder for hours before igniting.
Welding vaporizes the base metal, filler and gas, creating weld fumes, which present a further, unseen hazard. Fume fever, which has flu-like symptoms, can be quite serious, so weld in a well-ventilated area. If you are welding galvanized metal (even lightly galvanized steel, such as Zintec), remove the thin protective coating with a flap-disc so that you do not breathe the vapor. The argon/CO2 gas mixture is mainly inert but it can displace oxygen, so asphyxiation can be a risk if you are working in a pit and a gas bottle is leaking. While heavy gas cylinders pose a hazard by virtue of their weight, the pressure within them can be up to 2500psi. If they fall over and break their necks, the cylinder can have sufficient thrust to punch through a brick wall. Always ensure that the cylinders are chained up, secured and cannot fall.
While welding will not harm your ears, it can cause serious damage to your eyes and skin. Never look directly at the bright arc, as both ultraviolet (UV) and infrared (IR) lights are generated. Keep your skin covered with thick clothing and use leather gauntlets to protect your hands from the rays. You will feel IR as heat, which can cause burns to the skin. You can neither see, nor feel, UV but it can result in the short term and deeply uncomfortable ‘arc-eye’, a condition that can cause permanent retina damage in the long term.
Falling market values and the higher costs associated with repairing accident damage mean that many salvageable cars are deemed uneconomical to repair and are written-off as Category C or D by insurance companies. Additionally, fewer garages offer welding services these days, not helped by body repair shops finding it harder to work on modern cars that are becoming increasingly complex to repair.
If you have the necessary skills and tools, a canny DIYer can take advantage of this gap in the market; either prolonging the life of an existing car or buying a vehicle that requires welding repairs at a knockdown rate. If purchased from a breakers yard, it might be possible to acquire sections from a donor vehicle as part of the deal as well.
Welding Types Explained
Welding joins metals together with heat. Both brazing and soldering are also used to join metal materials, but they do not apply high enough temperatures to provide both fusion and a structurally-strong joint, which is why those methods are unsuitable for effective structural mild-steel repairs. Methods that fuse the metals together (including MIG/MAG, TIG and MMA, or ‘stick ‘welding) are more structurally sound, but most types require a joining filler material.
Manual Metal Arc (MMA) or ‘stick’ welding is more suited to heavy-duty repairs and, as such, tends to be too aggressive for the thin steel sheets that form a typical monocoque car body, although the method can be considered for separate chassis repairs, where the metal is much thicker. The user feeds the metal-cored stick into the work area manually, which requires both patience and experience to achieve a result that is strong and neat.
While Tungsten Inert Gas (TIG) welding is more common when working with metal alloys, it can be used for steel repairs. It consists of a negatively charged (although the polarity can be reversed) tungsten-tipped torch, which helps to create the metal arc. As the tungsten electrode is not consumed, the user needs to feed a jointing material rod with the other hand, while pure Argon gas is used to shield the weld and surrounding area. TIG welding is a slow process but can produce very neat results.
Due to it being more cost effective and notably easier to use, Metal Inert Gas (MIG), or Metal Active Gas (MAG), welding tends to be the preferred method for the DIY car repairer. A MIG welder’s biggest enemy is the atmosphere, which can oxidize the hot metals and create a very weak joint. To remedy this, an inert-based shielding gas is blown over the weld and repair area to keep natural air away from the molten metal. As with TIG, MIG welding requires argon gas, but a small percentage of carbon dioxide is added (the British Oxygen Company’s trade name for this is Argoshield), which allows for superior fusion, while the argon provides a calm atmosphere and less spatter. It may still be possible to obtain pure carbon dioxide gas, used by publicans to pressurize their bar drinks dispensers (hence the term ‘pub gas’), but using CO2 alone produces a fierce arc and a greater chance of metal particles, or spatter, exiting the work area.
Essential kit
Many trade and retail outlets will be able to provide the necessary welding hardware, whether you are looking to buy, or rent. If buying, your choice of welder specification will depend on your expected usage and budget. Should you be welding thin steel occasionally and not embarking on a full restoration (car bodywork thickness tends to be around 0.8mm), you are unlikely to require more than a basic-spec unit. However, the quality of the wire-feed mechanism is crucial and you should always pay more for a decent clamping mechanism. Welding wire is wound under tension into various sized spools, with 0.6mm and 0.8mm diameter wire preferred for car bodywork, and remembers that you must match the wire diameter with that of the torch tip.
You will also require welding gas. For occasional use, it might be best to pay a one-off fee of around £60-£100 to retain the bottle indefinitely, and then exchange it for a replenished replacement for around £40-£50, when your gas is depleted. A reliable regulator, preferably a twin-gauge unit, is critical. The regulator shows not only how much pressure remains within the cylinder but also allows accurate metering to ensure a strong, sound, defect-free weld, while avoiding wastage.
Instead of buying gas, you might consider gas-less wire, where the flux core of the wire, when exposed to the arc, forms a protective gas shield over the work area. However, gas-less wire is not only expensive but also harder to control.
Consider consumables, too. These relate to not only safety equipment, such as gauntlets and welding helmets, but also the essential tools needed to prepare the metal before and after welding, including an angle-grinder and metal cutting, grinding and flap discs.
Techniques
MIG (Metal Inert Gas) welding should really be called MAG (Metal Active Gas) welding, because an active shielding gas mixture of argon and CO2 is used, rather than fully inert Argon alone.
MIG welding is extremely user-friendly. Being a semi-automatic process, it is unnecessary for the operator to feed the wire manually into the work area. The machine also adjusts the current automatically to allow for any discrepancies in both operator movement and the position of the torch, making the process very forgiving.
The wire is wound onto a replaceable spool, housed usually within the welding plant itself, and fed into the torch’s liner by an electric motor and feed rollers. As the welding torch is positively charged, most of the heat generated originates from the wire as it melts. The metalwork is negatively charged by the user attaching the welder’s negative earth clamp as close to the working area as possible.
According to both Steven Hall, welding lecturer at Exeter College, and associate lecturer Richard Dines, the most common misconception among their students is that higher heat results in a stronger weld.
“One of the worse things a novice can do,” says Steven, “is to penetrate right through the thickness of the steel plate completely, unless a gap exists between the plates that is designed specifically for full penetration, such as an open butt weld. Having too high a setting, or welding too slowly, causes the weld and surrounding parent metal to overheat and bulge through the opposite side of the plate, which creates a weakness.”
For the strongest and neatest welds, Steven and Richard advise that you should ensure not only that the steel surfaces are clean, but also that the MIG welder is also set-up correctly before you begin.
Know Your Materials
While this feature focuses on welding mild steel, which remains a major material used for car bodies, the need to reduce weight and improve crash resistance has seen other materials being used, including aluminum. In less exotic mass-produced vehicles, various types and grades of both High Strength Steel (HSS) and Ultra High Strength Steel (UHSS) are employed in critical locations, such as door pillars and even bumper mounts. In general, the greater the steel’s strength, the harder it is to weld, and introducing heat could change its composition, or even cause it to crack. This will affect the crash resistance properties of a car in the future.
Should you be considering buying and repairing a modern crash-damaged vehicle, it may be worth consulting the manufacturer about the material and construction methods used in the damaged area, because this will determine whether, or not, an economical DIY MIG-welded repair is feasible.
Should vehicle-specific data be unobtainable, Thatcham Research specializes in model-specific crash repair methods, but its data tends to be available only to professional body shops, a local branch of which might be willing to share this information with you. Attempting to MIG-weld two steel sections with incompatible tensile strengths may be almost impossible and the most common advice is to drill-out the original spot-welds and replace the complete panel. However, even this may require more specialist hardware, such as a spot-welder or even a pulse MIG welder, both of which tend to be beyond the reach of a DIY mechanic.
Consider also that manufacturers have found ingenious ways of bonding different materials, such as joining aluminum and steel using structural adhesives. Therefore, be wary that MIG-welding an adjoining panel might introduce heat that causes further damage.
Health and Safety
Although MIG/MAG is one of the safest forms of arc fusion type welding, it presents a number of risks. Electric shocks should be minimized if your welder is stored, maintained and set-up correctly, but your car may not be so lucky. In most cases, disconnecting the battery will suffice, but some vehicles require their ECUs to be removed, to avoid damage from the magnetic fields that welding generates.
For this reason, you should seek medical advice before attempting welding, if you are fitted with a pacemaker. Additionally, aim to have the welder’s negative cable as close as you can to your work area, so that the electrical circuit is kept as short as possible.
Keeping your surroundings clear reduces the risk of fire. This includes ensuring that any trim, soundproofing material, cavity wax, etc. cannot ignite within the car. Wear flame-retardant overalls, arm sleeves, gauntlets and even an apron. Keep an appropriate fire extinguisher handy and be aware that fabrics can smolder for hours before igniting.
Welding vaporizes the base metal, filler and gas, creating weld fumes, which present a further, unseen hazard. Fume fever, which has flu-like symptoms, can be quite serious, so weld in a well-ventilated area. If you are welding galvanized metal (even lightly galvanized steel, such as Zintec), remove the thin protective coating with a flap-disc so that you do not breathe the vapor. The argon/CO2 gas mixture is mainly inert but it can displace oxygen, so asphyxiation can be a risk if you are working in a pit and a gas bottle is leaking. While heavy gas cylinders pose a hazard by virtue of their weight, the pressure within them can be up to 2500psi. If they fall over and break their necks, the cylinder can have sufficient thrust to punch through a brick wall. Always ensure that the cylinders are chained up, secured and cannot fall.
While welding will not harm your ears, it can cause serious damage to your eyes and skin. Never look directly at the bright arc, as both ultraviolet (UV) and infrared (IR) lights are generated. Keep your skin covered with thick clothing and use leather gauntlets to protect your hands from the rays. You will feel IR as heat, which can cause burns to the skin. You can neither see, nor feel, UV but it can result in the short term and deeply uncomfortable ‘arc-eye’, a condition that can cause permanent retina damage in the long term.
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