Why Joining?

Joining is a process to fasten or join two or more components to form a single material.

One might ask what is the reason for joining them together? Well, basically there are few reasons for doing so. First, joining enables the material to preform the desired function (e.g. to improve its thermal conductivity). Second reason is to join small parts together to form a large model because manufacturing a large object might be very expensive (e.g. moulding or casting a large piece might cost a few thousands). Hence, joining is a cheaper alternative in the industry. Lastly, it can improve the beauty of the product.

However it doesn't mean that there is no drawback for this process. Joining might alter the mechanical properties of the parts being fastened together (e.g. heat affected zone might reduce the strength of material). If mechanical joining is used, it might induce stress concentration around the pre-drilled hole. Joining is considered as an additional step in manufacturing process, which means it add cost to the production. As we know, joining rarely occurs at the beginning of the process but instead at the end phase. A failure in the joining process will ruin the production and incur higher loss to the company because it can be rarely fix. Joining assembly such as bolt and nut can be accidentally removed or dropped off during its service life.  

There are different types of joining technology available such as welding, mechanical joining and adhesive bonding. Welding includes fusion welding, non-fusion welding and solid state welding. Fusion welding is the process where the materials are being heated and melted to form a single piece. Non-fusion welding includes soldering and brazing. In non-fusion welding, the materials are heated but not melted. Instead, the filler material is melted to fill the gap and form the bonds. Solid state welding happens at low temperature (not reaching the melting point of the material) but high pressure. There is no filler metal being used in the latter.