Secondary Processes
SECONDARY MANUFACTURING PROCESSES
The actual changing of the form of material is referred to as material
processing.
Changing the form of materials takes three major steps:
1. obtaining natural resources
2. producing industrial materials, and
3. making finished products
These steps can be divided into two areas:
1. primary manufacturing processes
a. obtaining raw materials
b. producing useable industrial materials
2. secondary manufacturing processes
a. casting and molding
b. forming
c. separating
d. conditioning
e. assembling
f. finishing
Casting and Molding Processes
Casting and molding are a family of processes in which an industrial
material is poured into a mold or forced to take the shape of a mold.
Casting and molding are really terms that describe the same process.
casting usually applies to metals and ceramics
molding usually applies to plastics
All casting processes have five basic steps:
a mold is prepared
the mold is a replica of the finished casting
types of molds
*expendable (used only once)
*permanent (used more than once)
The industrial material is prepared for casting.
may be a liquid or semi-liquid
*heated
*room temperature
The industrial material is poured or forced into the mold.
poured (gravity)
*sand molds
*slip casting molds
*non-pressure permanent molds
forced
*die casting
*injection
The industrial material is allowed or caused to solidify.
the method used depends upon the industrial material
*air/forced air
*liquids
*chemical
The finished item is extracted from the mold.
expendable molds – mold is broken
permanent molds – mold is opened and part removed
Forming Processes
Forming processes utilize a force to cause a material to permanently
reshape without breaking.
All forming practices have three major things in common:
1. a shaping device
a. dies
*open dies
*die sets
*shaped dies or molds
b. rollers
*smoothed
*formed
2. a material forming temperature is determined
a. hot forming (above point of recrystallization)
*material is heated, formed, and allowed to cool
b. cold forming (below point of recrystallization)
3. a method for apply the required force
examples include: hammers, presses, roll formers, a draw benches
IV. Separating Processes
A. Separating processes remove excess material to change the size,
shape, or surface of a part.
B. There are two major groups of separating processes:
1. machining (chip or particle removal)
2. shearing (fracturing the material)
C. Every separating process has three elements:
1. a tool or cutting element
a. single point (chisel, plane, gouge, boring tool, etc.)
b. multiple point (drill, saw blade, milling cutter, etc.)
c. misc. (flame, water, chemicals, electrical, light, etc.)
2. movement between the work piece and the cutting element
a. cutting motion (action of tool or cutting element)
*rotating
*reciprocating
*linear
b. feed motion (movement of tool into material or vice versa)
3. clamping or holding of the tool and the work piece
a. fixtures
b. jigs
c. clamps
d. vices
e. magnetic tables
f. chucks
g. collets
D. There are seven basic types of separating machines:
1. turning
2. drilling
3. milling and sawing
4. shaping and planing
5. grinding and abrasive
6. shearing
7. special or dedicated (flame, electrical, chemical, etc)
V. Conditioning Processes
A. Conditioning processes change the “structure” of a material.
B. The “structure” of a material refers to the:
1. physical properties (size, weight, and condition)
a. describe what the material is like when no external
forces are making changes in the material
2. mechanical properties (ability of material to support a load)
a. strength
b. elasticity
c. plasticity
d. hardness
e. toughness
f. fatigue resistance
C. A material’s conditioning characteristics include:
1. property desired
2. internal structure required
3. process(es) to be used
D. There are three types of conditioning processes:
1. thermal - uses heat to change the physical or mechanical
properties of a material
a. drying
b. heat treating
c. firing
2. chemical – uses chemicals to change the physical or mechanical
properties of a material
a. examples include:
*water --- plaster of paris / cement
*animal hides + chemicals --- workable leather
*catalyst + liquid polyesters --- solid material
3. mechanical – uses physical force to modify the internal structure
of a material
a. cold forming
b. abrasive blasting
c. forging
VI. Assembly Processes
The action of putting things together is termed assembling.
1. This requires a minimum of two pieces.
B. Assembling is the manufacturing process that permanently or
temporarily fastens parts together.
C. There are two major ways to assemble parts into products:
1. bonding (uses heat, pressure, and/or a bonding agent)
a. bonding agent
*self-bonding (spot welding, oxyacetylene puddle, etc.)
*bonding materials (epoxy, glue, etc.)
b. method used to create the bond
*heat (thermal)
-arc welding, oxy-acetylene welding,
brazing, soldering, shrink wrap, etc.
*heat and pressure
-resistance (spot) welding, impulse sealing, etc.
*pressure
-joining of gold, aluminum, copper, etc.
*solvent
-many plastics, some ceramics (slip)
*adhesive
-glue, epoxy, contact cement
c. kind of joint at the bonding point
*most common - T, corner, butt, and lap
2. mechanical fasteners (hold two or more parts in a specific position)
a. permanent (are not removed)
*rivets
b. semi-permanent (can be removed and rejoined over and over)
*threaded fasteners (nuts/bolts, screws, etc.)
*wire fasteners (nails and staples)
c. temporary (quick and easy removal)
*wing nuts
*cotter pins
VII. Finishing Processes
A. Finishing is a surface treatment that protects or decorates a material.
B. Finishing involves three steps:
1. selecting a finishing material
a. converted finishes – chemical treatment of the surface
& no new material is added
*anodizing (aluminum)
*oxidizing (gun bluing, stainless steel)
*phosphate coating (primer for organic coatings)
*chromatic coating (primer for painted surfaces)
b. surface coatings – a new material is added which helps
seal the surface from the environment
*organic (paint, varnish, enamel, lacquer, urethane, etc.)
*inorganic (chrome, galvanizing, tin, ceramic, etc.)
2. preparing the surface to accept the finish
a. mechanical cleaning
*abrasives
*wire brushes
*sand blasting
*tumbling
b. chemical cleaning (liquids and vapors)
*kerosene
*acetone
*pickling
3. applying the finish
a. conversion finishing
*exposing the surface to chemicals
b. surface finishing
*brushing
*dipping
*rolling
*spraying
*electroplating
IV. Conclusion
A. Industrial materials must be processed in order to produce products.
B. This is accomplished using the secondary manufacturing processes.
1. casting and molding
2. forming
3. separating
4. conditioning
5. assembling
6. finishing
C. Often the manufacture of a product will utilize several of these processes