Metal Forming Processes: Hot working Processes, Cold working processes, Joining Processes, Surface Finishing Processes

Metal  Forming Processes

Forming processes encompasses a wide variety
of techniques, which make use of suitable force, pressure or stresses, like
compression, tension and shear or their combination to cause a permanent
deformation of the raw material to impart required shape. These processes
are also
known
as mechanical working
processes
and are mainly classified
into
two major categories i.e.,
hot working processes and cold working processes. In these processes, no
material is removed; however it is deformed and displaced using suitable
stresses like compression, tension, and shear or combined stresses to cause
plastic deformation of the materials to produce required shapes. Such processes
lead to production of directly usable articles which include kitchen utensils,
rods, wires, rails, cold drink bottle caps, collapsible tubes etc. Some of
the important metal forming processes are:

Hot working Processes

(1)  
Forging, (2)
Rolling, (3) Hot spinning, (4) Extrusion, (5) Hot drawing and (6) Hot spinning.

Cold working processes

(1) Cold forging, (2) Cold
rolling, (3) Cold heading, (4) Cold drawing, (5) Wire drawing,
(6) Stretch forming, (7) Sheet metal working processes
such as piercing, punching, lancing, notching, coining, squeezing, deep
drawing, bending etc.

Joining Processes

Many products observed in day-to-day life, are commonly
made by putting
many parts together may be in subassembly. For example, the ball pen consists of a body, refill, barrel, cap, and refill operating mechanism. All these parts are put
together to form the product as a pen. More than 800 parts are put together to
make various subassemblies and final assembly of car or
aero-plane. A complete machine tool may also require to assemble
more than 100 parts in various sub assemble or final
assembly. The process of putting the parts together to form the
product, which performs the desired function, is called
assembly. An assemblage of parts may require some parts to be
joined together using various joining processes. But assembly should not be
confused with the joining process. Most of the products cannot be
manufactured as single unit they are
manufactured as different components using one or more of the above
manufacturing processes, and these components are assembled to get the desired
product. Joining processes are widely used in fabrication and assembly work. In
these process two or more pieces of metal parts are joined together to produce
desired shape and size of
the  product. The joining processes are
carried out by fusing, pressing, rubbing, riveting, screwing or any other means
of assembling. These processes are used for assembling metal parts
and in general fabrication work. Such
requirements usually occur when several pieces are to be
joined together to fabricate a desired
structure
of products. These
processes
are used developing steam
or
water-tight joints. Temporary, semi-permanent or permanent
type of fastening to make a good joint is generally created by these
processes. Temporary joining of components can be achieved by use of nuts, screws
and
bolts. Adhesives are also used
to make temporary joints.
 


Some of the important
and common joining
processes are:

(1) 
Welding  (plastic  or 
fusion)
(2)  Brazing
(3)  Soldering
(4)  Riveting
(5)
Screwing,
(6) Press fitting
(7) Sintering
(8) Adhesive
bonding
(9) Shrink fitting
(10) Explosive welding,
(11) Diffusion welding
(12) Keys and cotters joints
(13)
Coupling and 
(14) Nut and bolt joints.

Surface Finishing Processes

Surface finishing processes are utilized for
imparting intended surface finish on the surface of
a job. By imparting a surface finishing process, dimension of part is not changed
functionally; either a very negligible amount of material is
removed from the certain material is added to the surface of the job. These
processes should not be misunderstood as metal removing processes in any case
as they are primarily intended to provide a good surface finish or a decorative
or protective coating on to the metal surface. Surface cleaning process also
called as
a surface finishing process. Some of the commonly
used surface finishing processes are: 
(1) Honing

(2) Lapping
(3) Super finishing
(4) Belt grinding
(5) Polishing
(6) Tumbling
(7)   
Organic finishes
(8) Sanding
(9)
deburring 
(10) Electroplating
(11) Buffing
(12) Metal spraying
(13) Painting
(14) Inorganic
coating
(15)
Anodizing
(16) Sheradising
(17)
Parkerizing
(18) Galvanizing
(19) Plastic
coating
(20) Metallic coating
(21) Anodizing and 
(22) Sand blasting.

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