1. Joining Methods

2. Introduction
every joining technique has particular design requirements,
design for assembly, automation, and fastener selection imposes their own requirements.
mechanical joining (e.g., use of bolt, screws, nails) is a common fastening method, for example, but welding may reduce the weight of an assembly.
naturally, joints and assemblies designed for the two techniques would differ greatly.
all joint designs must consider characteristics such as load conditions, assembly efficiency, operating environment, overhaul and maintenance, and the materials used.

3. Joining is divided into three categories:
Thermal
Chemical
Mechanical

4. THERMAL JOINING PROCESSES
Welding
a joining process where the work pieces are melted and a filler material is added to form a pool of molten material that cools to become a strong joint       
Brazing
a metal-joining process whereby a filler metal is heated above melting point and distributed between two or more close-fitting parts
the filler metal is brought slightly above its melting temperature and flows over the base metal and is then cooled to join the work pieces together. It is similar to soldering, except the temperatures used to melt the filler metal are higher for brazing.    
Soldering
is a joining process that's similar to brazing, except that it is performed at much lower temperatures than brazing
process of joining two work pieces together with a filler metal, such that only this filler metal undergoes melting, i.e., the work pieces do not experience any melting                   

5. CHEMICAL JOINING PROCESSES
Adhesive Bonding
process for joining parts using bonding chemicals or materials known as adhesives. 
typically used to join polymers and composites, as well as polymers to metals, metals to metals, and ceramics to metals. 
adhesive-bonded joints can withstand shear, tensile, and compressive stresses, but they do not exhibit good resistance against peeling
The most common adhesives are:
wood glue (a.k.a. yellow glue, carpenter's wood glue, aliphatic resin)
Elmer's glue (a.k.a. white glue, PVA)
Plastic resin glue
Epoxy
Cyanoacrylate (a.k.a. super glue)
Construction adhesive
Contact cement

6. MECHANICAL JOINING PROCESSES
is a process for joining parts through mechanical methods, which often involve threaded holes
joining parts using screws or nuts and bolts are common examples of mechanical joining