If “Can you weld magnets?” is a question you have been asking yourself and you have not been able to obtain an answer, you have come to the right place.
To answer the question; yes, it is possible to weld magnets. However, a one-word answer will not suffice in the world of welding as there are numerous terms, conditions and additional factors to be considered when regarding the subject of welding magnets.
Magnets are complex objects and there are several technicalities that must be considered when welding them as minimizing or eliminating magnetic fields during the welding process are dangerous and difficult challenges; even for those who know their way around a welder. Even upon the removal of an external magnetic field, there exists a probability of residual magnetism whereby magnetization remains in ferromagnetic material. The welding temperature and techniques must be carefully considered and controlled according to the magnet’s thermal conductivity, reactivity as well as its propensity to maintain its remnant magnetization throughout the process of welding. The most feasible manner of welding magnets is via arc welding processes wherein gas tungsten arc welding (GTAW), submerged arc welding (SAW), and shielded metal arc welding (SMAW) are utilized with the latter being the most sought out method. However, ‘magnetic arc blow’ is an obstacle that may occur during such processes if the magnet is not sufficiently demagnetized and the conditions are not strictly controlled. This article will further discuss the significance of removing external magnetic fields and diminishing the remanence and tips on ensuring a magnet is suitable to be incorporated in the welding process.
The Importance of Demagnetization Before Welding
Magnetism is caused when the atoms which constitute a magnet align between its two poles. In the event that a magnet is exposed to high levels of heat beyond a point referred to as the ‘Curie temperature’, the motion of the atoms is misaligned and the magnet begins to lose its magnetic fields. This is a critical process when magnet welding is concerned as, if not executed, can cause magnetic arc blow.
Magnetic arc blow is a phenomenon that is caused when there is an imbalance in the conditions of the magnetic field surrounding the arc. This imbalance may occur due to various reasons with the most common ones being the arc forming at varying distances from the joint and workpiece connection or changes in the direction of the current flow to, through, and from the arc.
Magnetic arc blow may result in welding defects such as porosity, lack of fusion, etc. In extreme cases, depending upon the type of magnet, it might even explode. It is recommended for the degree of magnetism to be within 10 Gauss, 20 Gauss and 40 Gauss for GTAW, SMAW and SAW. As magnetic arc blow may be caused by residual magnetism itself, it is essential for external magnetic fields to be removed before commencing the welding procedure.
Tips on Magnet Welding
First and foremost, it is important to research the type of magnet you intend to weld and its respective properties in order to ensure a smooth process of demagnetization as different types of magnets, such as neodymium iron boron, samarium cobalt, alnico, and ferrite magnets, react to heat differently in different ranges.
Once the magnet and its melting properties are identified, the magnet needs to be heated above its Curie temperature and then cooled in a zero field. AC welding is the recommended method for magnet welding as it has the capacity to facilitate higher temperatures of welding and can support higher degrees of magnetism, which better combats arc blows, as compared to DC welding.
A commonly used method to ensure minimized magnetism is by wrapping cables around the object and connect the cables to an AC welder tuned to the highest amperage available to detect any possible arc and break the arc with scrap before tuning the welder by a range of 15 amps. Repeat this process until the lowest amperage is attained. Upon the completion of the process, the remnant magnetization, and subsequently the probability of arc blow, should be minimized and possibly eliminated.
Using an AC yoke to detect and measure the presence of magnetic particles at this point is highly beneficial and is, in fact, ideal equipment in this process. Once the conditions suitable for welding a magnet have been attained, the process may continue as is standard procedure for the method of welding assumed. Always pay keen attention to the weld puddle and if there is any sign of interference, search for the cause immediately.
The art of welding magnets is a challenging skill to master but, as with any other matter of competence, it is attainable with the right amount of practice. Nevertheless, magnet welding is not recommended for those who are beginners in the field of welding to attempt on their own and it is highly advisable that one experiments with it using small-scale magnets in the presence of an experienced welder.
If attempting to weld larger objects with magnetic properties, it is advisable to invest in specialized equipment to ensure that the capacity is maintained and welding defects are minimal.
As magnet welding is a niche area in the field, it is vital to thoroughly research the type of magnet to be welded, its properties, the manners of ensuring the prevention of magnetic arc blow and its compatibility with the method of welding and other materials possibly integrated as the reactions of a particular magnet type may not be applicable to all. Always ensure that your magnet is demagnetized appropriately according to its components and always gradually test its propensity to create an arc blow before kickstarting your welding process.
Due to magnet welding being a field is not as widely pursued as other areas and consequently not having as much coverage as others, do provide inputs of your experience welding magnets on platforms catered to the subject of welding as it may be extremely useful to the next up and coming magnet welder!