A key skill in manufacturing is welding and ensuring a good weld is vital for the integrity of a product. A brittle or porous weld presents a serious safety concern for industrial applications and the vast majority of manufacturers have rigorous procedures in place to ensure welds meet quality standards.
Here’s a guide to factors that will ensure a good weld.
Ensure a clean surface
Metal surfaces need to be thoroughly cleaned of impurities like water, oil, and flux before they are welded while aluminium needs to have the outside layer of oxide removed before welding commences. The presence of impurities will cause porosity in the weld – that is tiny holes that weaken the join.
Mind the gap
A factor that often results in welds failing is an incorrect gap or poor edge preparation between the two parts being joined. If the gap is too big there is a danger the weld bead will simply burn away the edges of the two parts, insufficient gap when joining thicker materials will result in lack of weld penetration. To ensure a good weld, you need to pay particular attention to the edge preparation and correct required gap.
Know the best process
There are a number of weld processes, such as MIG, TIG, Stick (MMA) and Flux-cored, and knowing when to use each technique is an important factor in getting a good weld.
MIG, or metal inert gas, is a type of wire welding that is suited to production welding of mild steel sheet and plate, it uses an inert gas to protect the molten weld pool, which sometimes makes it difficult to use outdoors in windy conditions. Another type of wire welding is flux-cored welding, which takes place without gas and is therefore more suitable for outdoor work. Stick welding is typically the best choice for quick onsite repairs while TIG, or tungsten inert gas, welding works well on stainless steel and aluminum where the look and presentation of the weld is important.
Inspect the weld
Once a weld is in place, it is important to check its quality. There are several ways of doing this. The simplest way is to check it by eye for cracks or inclusions in the weld and other problems. Welders also use a number of other so-called non-destructive testing (NDT) processes to inspect their work, such as liquid penetration and X-ray inspections. No matter what inspection is used, ensuring welds are strong and durable is an important step in the process and a vital part of quality assurance.
Typical weld defects
Designing the correct weld joint is important for cost, strength and visual appearance. The welding engineer has a number of options available, and selecting the correct joint and welding process for the job, along with accessibility is critical when designing a welded product.