Which of the following is NOT a basic method of metal joining?

Thermal cutting is not considered a basic method of metal joining because it involves the process of separating or cutting metal materials rather than joining them together. Processes like welding, brazing, and soldering are all techniques specifically designed to join metal pieces, either through the melting and fusing of materials or through the use of filler materials that bond to the base metals.

Welding involves melting the base materials and typically requires additional filler material, creating a strong bond as the melted metals cool and solidify. Brazing uses a filler metal with a lower melting point than that of the workpieces, allowing the metals to bond without melting those pieces themselves. Soldering is similar to brazing but typically involves even lower melting temperatures and is often used in electronics and plumbing.

Thermal cutting may include processes like oxy-fuel cutting or plasma cutting, which focus on cutting through metals rather than creating a union between them. Thus, it does not fit in the category of methods dedicated to joining metals.