Aluminum makes an excellent stud welding material and can be joined using Capacitive Discharge (CD) and drawn arc processes. When welding aluminum studs together, specific accessories like ceramic ferrules and foot pieces to distribute and hold shielding gas are necessary.
Surface preparation is of utmost importance as aluminum surfaces quickly develop oxide deposits that impede quality welding. To remove any oxide build-up prior to welding, stainless steel brushes should be utilized in order to brush away any oxide deposits using stainless steel bristles.
Welding
Aluminum stud welding is an increasingly popular fastening method across industries. Unlike bolts with peripheral welds or “clinch” fasteners that must be pressed in, stud welding produces a full cross-sectional weld that outshouts both itself and its mating substrate, producing stronger attachment than either one alone could alone. Two main stud welding processes – capacitor discharge (CD) and drawn arc – exist for aluminum stud welding applications, though both must be altered accordingly in order to work effectively with this material. Both methods must be modified accordingly for best results when used on aluminum materials like this.
Before commencing with the stud welding process, the workpiece surface must be thoroughly prepared and cleaned. Aluminum surfaces quickly build up oxides which must be removed with a stainless steel brush in order for successful welding to take place. Contamination from other sources may interfere with proper weld quality or decrease its load bearing capabilities; surface contamination must therefore be thoroughly removed prior to commencing actual welding operations.
Shielding gas is essential when performing drawn arc welding on aluminum because it helps ensure that the weld point doesn’t become exposed to too much heat, given that aluminum conducts heat more efficiently than other alloys like steel and other types of alloy. Argon or its mixture with other gases (helium for example) is ideal as this ensures enough heat remains at the weld point to produce quality welds.
Preparation
Aluminium surfaces designed for welding must be clean, dry and free from paints and anodizations unsuitable for welding; otherwise they could obstruct the ability of the stud to light, an essential step in drawing an arc and producing welds. Surfaces left without proper cleaning often develop oxide build-up that leaves visible dark circles surrounding welded areas if left too long without care being taken to eliminate this problem.
Capacitor Discharge (CD) welding can be an ideal method for joining aluminum materials, as it allows small diameter studs and works effectively against irregularities in its parent metals. Unfortunately, CD welding doesn’t accept imperfections as readily as other forms of welding do, however.
CD welding can be particularly sensitive to heat usage, making it essential to control both time and temperature during welding sessions. This is especially true when joining dissimilar materials like aluminum to steel that could potentially result in warping or burn-through.
Finally, the welding area must be enclosed by gas to avoid air contamination and minimize oxidation. A popular choice is 100% Argon; however a mixture containing 25% to 75% He may prove more efficient for aluminum stud welding due to increasing arc ionization energy and heat availability in the weld zone.
Calibration
Aluminum welding and stud welding require different skills than working with steel, requiring extensive experience and training in order to produce reliable results. Due to aluminum’s higher conductivity surface drawing heat away from weld point and making achieving strong connections more challenging; therefore it is imperative that qualified welding professional oversee the aluminum stud welding process.
Calibration of the welding process is crucial in producing high quality aluminum weld studs, including using an AC inverter, programming the stud gun for specific stud types and sizes, connecting all accessories correctly, and setting timers according to weld time requirements. Furthermore, using quality studs and ferrules should also help guarantee successful welding results.
Furthermore, accurate positioning and orientation of weld studs must be achieved to maintain joint integrity. Unfortunately, due to an ineffective and slow method for measuring pose parameters this remains an obstacle for success.
One manufacturer of popcorn machines, conveyor ovens and toasters sought an effective testing solution to address its costly warranty claims and rework costs related to defective welds on threaded studs that cost them over $5,000 every day in warranty claims and rework costs. They found Mountz’s Weld Stud Test Tool which allowed them to test and calibrate these threaded studs prior to assembly which helped eliminate warranty claims while saving thousands every day in warranty claims and rework costs.
Testing
Stud welding is usually associated with fastening steel bodies together, but can also be applied to other metals. Stud welding forms a strong weld by connecting a stud to its base material using an electric arc that melts both together – then plunging the stud into a pool of molten metal to cool, leaving behind an unshakable bond capable of withstanding loads.
Aluminium stud welding is still relatively new but quickly gaining in popularity for various applications. Like any welding technique, aluminum weld studs require extensive surface preparation prior to applying welding energy in order to produce positive results.
First step to producing quality welds is removing surface oxides that could interfere with fusion. Oxides must be cleaned off by brushing or wiping using non-VOC cleaner, while drawn arc stud welding on aluminum requires using shielding gas – in general an Ar/He mix is preferable as He has greater arc ionization power and conductivity than pure Ar.
As it is essential that weld ports of stud welds don’t leak, a common way of checking for leakage is a bend test – at least 30 times should be performed to ensure that it will withstand loads without becoming deformed or fractured.