Defining Thermal Manufacturing Defining Thermal Manufacturing Thermal manufacturing relies on heat-driven processes like drying, smelting, heat treating, and curing to produce materials such as metals, glass, and ceramics, as well as downstream products such as electronics, vehicles, and machinery. As a result of its far reach, thermal manufacturing is estimated to directly and indirectly impact the employment of an estimated 5.4 million people in the United States at more than 101,000 establishments (U.S. Census Bureau 2009, 2012). These companies—97% of which are small and medium enterprises—annually produce $2.9 trillion in total value of shipments (U.S. Census Bureau 2009, 2012). Figure 1 provides an overview of thermal manufacturing and the industries it impacts. Figure 1: U.S. Thermal Manufacturing Overview Thermal Manufacturing Equipment The type of equipment used for thermal manufacturing ultimately depends on the material undergoing thermal treatment and the desired properties of the final product. These factors determine the required thermal manufacturing process and the associated process atmosphere and temperature. Different 1
15
Embed
Defining Thermal Manufacturing - ASM International
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Defining Thermal Manufacturing
Defining Thermal Manufacturing Thermal manufacturing relies on heat-driven processes like drying, smelting, heat treating, and curing to produce materials such as metals, glass, and ceramics, as well as downstream products such as electronics, vehicles, and machinery. As a result of its far reach, thermal manufacturing is estimated to directly and indirectly impact the employment of an estimated 5.4 million people in the United States at more than 101,000 establishments (U.S. Census Bureau 2009, 2012). These companies—97% of which are small and medium enterprises—annually produce $2.9 trillion in total value of shipments (U.S. Census Bureau 2009, 2012). Figure 1 provides an overview of thermal manufacturing and the industries it impacts.
Figure 1: U.S. Thermal Manufacturing Overview
Thermal Manufacturing Equipment The type of equipment used for thermal manufacturing ultimately depends on the material undergoing thermal treatment and the desired properties of the final product. These factors determine the required thermal manufacturing process and the associated process atmosphere and temperature. Different
1
Defining Thermal Manufacturing
types of equipment can best achieve the desired properties of the final product based on varying atmospheres and temperature ranges, modes of operation (batch vs continuous), heat-producing energy sources, and heating methods (direct-fired vs indirect-fired). While some equipment is best suited for a single process, multiple thermal manufacturing processes can be conducted in some equipment designs. The following sections, organized by thermal manufacturing process, indicate the processes that are conducted in each thermal manufacturing equipment type.
The following types of equipment are used in thermal manufacturing:• Arc furnace • Autoclave oven • Conveyor furnace/kiln • Cupola furnace • Crucible furnace • Fixed-bed reactor • Fluid heaters/boilers • Fluidized bed reactor • Induction furnace
Thermal Manufacturing Process Atmospheres and Temperatures Manufacturers must ensure that their thermal manufacturing processes adhere to specific atmospheric conditions, including air composition and pressure, that directly impact the quality and properties of a product. They must also determine and maintain the optimal thermal processing temperatures, which range from room temperature to over 4,000°F depending on the material and process, and the processing duration, which can also affect temperature. These processing conditions are chosen after a manufacturer determines the type of material undergoing treatment and the thermal process needed to achieve the desired properties of the product. Using this criteria, a manufacturer or process implementer can make an informed decision about the required or preferred types of process heating equipment.
Thermal manufacturing processes are conducted in the following types of atmospheres:• Air/ambient • Ammonia • Carbon-based • Dry steam/air • Inert gas • Helium • Hydrogen • Hydrocarbon
The following sections include figures that outline the process atmospheres and temperatures based on thermal manufacturing subprocesses.
Industry Input Encouraged As we do not have access to all process information, we welcome industry input to ensure the completeness and accuracy of these figures.
2
Defining Thermal Manufacturing
Curing & Forming Curing is the crosslinking of polymer chains in polymer-based materials. Crosslinking causes an exothermic reaction (generation of heat) that is further accelerated with the application of thermal energy. Curing is commonly applied in the fabrication of composites and ceramic coatings.
Forming is a process that shapes plastic resin, polymers, glass, or rubber into a variety of configurations (e.g., rolls, containers, automotive parts). In thermoforming, a thermoplastic is heated and forced against a mold until cooled. Curing & forming processes include Curing/Postcuring, Glass forming, and Thermoforming. The equipment and conditions for each of these processes is outlined in the following figures.
Drying Drying is the removal of water that is not chemically bound to a material. It is most commonly used to reduce the moisture content of raw sand materials like clay, stone, and glass. Examples of drying include the use of direct-fired heaters to dry pulp at paper mills and the use of conveyer-type dryers to remove water from powder compounds in chemical and pharmaceutical manufacturing. Drying is also used during petroleum refining, textile manufacturing, and food production. The equipment and conditions for drying are outlined in the following tables.
Extractive Processing Extractive processing involves the conversion of mineral ores or inorganic materials to metals or other intermediate products. Three key extractive processes include calcining, smelting, and agglomeration. Agglomeration, also called sintering, is the grouping of smaller particles into a large cluster by applying pressure or heat below the melting temperature. Calcination is a thermal treatment performed in the presence of air or oxygen to remove chemically-bound water from a material (as opposed to free water removal, which is known as drying); this process is commonly used in the production of petroleum coke, lime, cement, wallboard, and pulp and paper. Smelting is a thermal or chemical treatment used to extract metal from ore; common smelting processes include steel, aluminum, and magnesium smelting. The equipment and conditions for Extractive Metallurgy are outlined in the following tables.
Fluid Heating Fluid heating is the application of heat to a gas or liquid (i.e., thermal fluid) within a closed-loop system. These systems often rely on a series of heat exchangers, blowers, and pumps to apply thermal processing heat to a variety of products and materials. Examples of fluid heating include distillation of crude oil into separate components and heating of fluids in chemical manufacturing to achieve ideal processing conditions. Fluid heating processes include Air Heating, Catalytic/Thermal Cracking, Distillation, Hydrotreating, Liquid Heating, Quenching, and Steam/Catalytic Reforming. The equipment and conditions for each of these processes is outlined in the following tables.
Table 7: Fluid Heating Equipment
Arc F
urna
ce
Autoc
lave o
ven
Conv
eyor
furn
ace/k
iln
Cupo
la fur
nace
Cruc
ible f
urna
ce
Fixed
-bed
reac
tor
Fluid
heate
rs/ bo
ilers
Fluidi
zed b
ed re
actor
Induc
tion f
urna
ce
Infra
red o
ven
Pack
ed be
d rea
ctor
Quen
ch fu
rnac
e
Radia
nt tub
e/coil
furn
ace
Rotar
y hea
rth ki
ln/fur
nace
Vacu
um fu
rnac
e
Vertic
al sh
aft/bl
ast fu
rnac
e
Walk
ing be
am fu
rnac
e
Air Heating • Catalytic/Thermal
Cracking • Distillation •
Hydrotreating • Liquid Heating • •
Quenching • Steam/Catalytic
Reforming •
Figure 8: Fluid heating columns at petrochemical plant
Heat Treating Heat treating is the application of thermal energy to change the microstructure of a material. This alteration then changes the material’s mechanical properties—strength, ductility, hardness, toughness, and elasticity. Heat treating processes include Aluminizing (Hot Dipping), Annealing, Bluing, Carburizing, Decarburizing, Homogenization, Nitriding, Precipitation Hardening, Solution Heat Treating, and Tempering. The equipment and conditions for each of these processes is outlined in the following tables.
Metal Heating In contrast to heat treating, metal heating primarily refers to the heating of metals to establish ideal fabrication conditions in shaping processes. This application of heat increases the malleability of metals to prevent them from fracturing during cold- and hot-working processes such as forging, extraction, and rolling. In addition to shaping metals, metal heating is required in coating processes such as galvanization and chemical vapor deposition (CVD). The equipment and conditions for each of these processes is outlined in the following tables.
Table 11: Metal Heating Equipment
Arc F
urna
ce
Autoc
lave o
ven
Conv
eyor
furn
ace/k
iln
Cupo
la fur
nace
Cruc
ible f
urna
ce
Fixed
-bed
reac
tor
Fluid
heate
rs/ bo
ilers
Fluidi
zed b
ed re
actor
Induc
tion f
urna
ce
Infra
red o
ven
Pack
ed be
d rea
ctor
Quen
ch fu
rnac
e
Radia
nt tub
e/coil
furn
ace
Rotar
y hea
rth ki
ln/fur
nace
Vacu
um fu
rnac
e
Vertic
al sh
aft/bl
ast fu
rnac
e
Walk
ing be
am fu
rnac
e
CVD Coating • Cold-
Working • • Galvanizing Hot-Working • •
Figure 12: Sheet of metal being heated prior to shaping
Metal & Non-Metal Melting Melting is a standard procedure used to convert a material from a solid to a liquid by applying heat (also known as “molten”). It is commonly used in the metals industry to convert bulk ingots to finished or semi-finished castings. Non-metal melting is also used in the production of glass. Metal and Non-Metal Melting processes include Casting, Enameling, Glass Production, Joining, and Sintering (Powder Metallurgy). The equipment and conditions for each of these processes is outlined in the following tables.
Table 13: Metal & Non-Metal Melting Equipment
Arc F
urna
ce
Autoc
lave o
ven
Conv
eyor
furn
ace/k
iln
Cupo
la fur
nace
Cruc
ible f
urna
ce
Fixed
-bed
reac
tor
Fluid
heate
rs/ bo
ilers
Fluidi
zed b
ed re
actor
Induc
tion f
urna
ce
Infra
red o
ven
Pack
ed be
d rea
ctor
Quen
ch fu
rnac
e
Radia
nt tub
e/coil
furn
ace
Rotar
y hea
rth ki
ln/fur
nace
Vacu
um fu
rnac
e
Vertic
al sh
aft/bl
ast fu
rnac
e
Walk
ing be
am fu
rnac
e
Casting • • • • Enameling
Glass Production •
Joining • • • Sintering (Powder
Metallurgy) • • •
Figure 14: Molten metal being poured into mold
14
Defining Thermal Manufacturing
Table 14: Metal & Non-Metal Melting Process Atmospheres
Air/A
mbien
t
Ammo
nia
Carb
on-b
ased
Dry s
team/
air
Inert
gas
Heliu
m
Hydr
ogen
Hydr
ocar
bon
Oxyg
en
Partic
le-Fr
ee
Pres
suriz
ed
Redu
cing
Salt B
ath
Sulfu
r-bas
ed
Vacu
um
Casting • • Enameling •
Glass Production • Joining • • •
Sintering (Powder
Metallurgy)
• •
Figure 15: Metal & Non-Metal Melting Process Temperatures