GLOSSARY OF HEAT PROCESSING TERMS
Aging (Age Hardening)
A gradual change in the material properties of metals and alloys over time at ambient conditions resulting in the metals increasing in hardness and tensile strength as well as a reduction in ductility.
Alloy
Term commonly pertaining to steel when combined with small amounts of elements other than carbon to increase hardness, strength or chemical resistance properties. Nickel, chromium, silicon, manganese, tungsten, molybdenum and vanadium are typical alloy elements. The addition of chromium results in stainless steel.
Aluminized Steel
Steel that is hot dip coated with an aluminum silicon alloy that has a strong chemical bond between the two metals. Aluminized steel is corrosion resistant and can withstand temperatures up to 800Deg C so it is commonly used in oven construction.
Annealing
A heating and cooling operation with a controlled cooling rate. Annealing is typically used to remove stresses and lower ductility in metals but may be used to alter other physical properties.
ANSI
American National Standards Institute
ASTM
American Society for Testing and Materials
Baking
Heating at a set temperature in order to change the properties or appearance of a substance.
Batch Oven
An oven designed to process a load of product through a thermal heating cycle. Product is loaded prior to and unloaded after the batch is complete. Batch oven designs range from small bench top lab units to extremely large industrial duty machines.
British Thermal Unit (BTU)
The amount of heat energy required to increase the temperature of one pound of water by one degree Fahrenheit. It is equivalent to 1055 Joules. It is roughly the same amount of heat generated from one lighted kitchen match.
Calorie
The amount of thermal energy needed to raise one gram of water 1 Degree C.
Car Bottom
Movable car capable of supporting the weight of the workload into and out of the oven chamber.
CE
A mark that designates compliance with European Union (EU) requirements for products sold in Europe.
Celsius (Centigrade)
A temperature scale with 0 Deg C defined as the freezing point and 100 Deg C as the boiling point of water at sea level.
Ceramic
Hard, brittle material compound comprised of a metallic element and other elements such as oxygen nitogen, carbon or sulfur. The compound is non corrosive, and is a good electrical insulator. Glass is an example of a type of ceramic.
Circulation Fan
The primary air mover in a heat processing zone. The circ fan moves air through the combustion chamber, into the work chamber and back again. Proper sizing of the circ fan is critical for the application.
Combustion
A process where a substance reacts with oxygen to produce a rise in temperature and the emission of light.
Combustion Blower
Combustion blowers provide a sufficient volume of air, which is mixed with natural gas to enable efficient burning of the fuel mixture.
Conduction
Transfer of heat from higher temperature to lower temperature within an object or between objects in direct contact with each other.
Conductivity
Property of a material to convey heat or electricity. Materials with high conductivity are called conductors and materials with low conductivity are called insulators.
Continuous Dryer
A Dryer that has a conveying system to move the product through the oven in a continuous manner.
Continuous Oven
An oven that has a conveying system to move the product through the oven in a continuous manner.
Convection
The transfer of heat from a source or higher temperature area in a gas or liquid by the movement and mixing of the masses.
Convection Oven
An oven designed to circulate heated air into the work chamber.
CSA
Canadian Standards Association, a testing and approval agency.
C-UL
Canadian UL – often accepted by customers who would normally require CSA approval.
Density
The mass of an object divided by its volume – expressed in lbs/cu-ft or kg/cu-m.
Direct Gas Fired
Heat processing system where air is directly heated with the burner and is circulated to the work zone.
Draw Furnace
A particular design of heat treatment oven used for tempering and annealing steel.
Drop Bottom Solution Heat Treatment
A heat processing system designed to provide a heat treatment cycle to a product in an elevated heating chamber. Automatic doors on the bottom of the oven are opened following the heat cycle enabling the product to be dropped into a liquid solution for rapid cooling.
Dryer
A general term for heat processing equipment used in applications that require removal of moisture.
Drying
The removal of moisture from a product using a combination of heat and air movement.
Endothermic
A process that absorbs heat.
Enthalpy
A measure of heat transferred during a heating process. Also known as total heat or heat content. Enthalpy is calculated as the sum of the internal energy of a system plus the product of its volume multiplied by the pressure.
Exhaust Fan
An Exhaust Fan is used in heat processing applications to remove moist air or products of combustion (VOC’s).
Exothermic
A chemical process that generates heat.
Fahrenheit
A Temperature scale with 32 Degree F defined as the freezing point of water and 212 Degree F as the boiling point of water – at sea level.
FM
Factory Mutual – a third party approval agency, which tests and approves equipment for service in various areas and conditions.
Fuel Cell
A device that converts chemical energy into electrical energy. Hydrogen is commonly used to make fuel cells.
Furnace
A general term for industrial heat processing equipment that require operating temperatures greater than 1000 Degrees Fahrenheit.
Galvanized Steel
Steel coated with a layer of Zinc during a process called hot-dip galvanizing. The Zinc will combine with Oxygen and Carbon Dioxide to form Zinc Carbonate a protective substance that prevents further corrosion to the coated steel. Galvanized steel is suitable for temperature applications of up to 392 °F (200 °C) and is not widely used in heat processing applications.
Heat
Thermal energy expressed in Calories, BTU’s or Joules.
Heat Exchanger
A device that allows heat transfer from one medium to another without a physical mixing of the medium. Heat exhchangers are used when it is desirable to separate the combustion gases from the heat process.
Heat Processing System
A machine or series of devices which includes a heat source, a heat or work chamber, heat transfer medium (usually air), loading and unloading systems and a control system.
Heat Transfer
Three different types of thermal energy flowing from one mass to another;
1) Conduction: the transfer of heat within an object via adjacent molecules.
2) Convection: the transfer of heat by mixing warm molecules with cooler molecules, usually via air movement.
3) Radiant: the transfer of heat into an object absorbing radiation energy.
Heat Transfer Medium
The material; solid, liquid or gas, used to transfer heat from the heat source to the desired object.
Heat Treatment
Alternating heating and cooling cycles to metals and alloys to obtain desired material hardness or other characteristics for further processing.
Hybrid Oven
An Industrial oven that incorporates different heating technologies throught the design such as infrared and forced air convection.
Impingement
To strike or collide with. In convection ovens impingement air describes the process of forcing heated air to come in contact with the product. Properly designed air impingement systems reduce temperature differentials within an oven and will generally improve the heat processing process.
Indirect Gas Fired
Heat processing system incorporating a heat exchanger. Combustion air circulates inside of the heat exchanger and is prevented from circulating through the work chamber. The heat exchanger is used to heat the air that is circulated through the work chamber.
Industrial Dryer
A general term for heat processing equipment used in industrial applications that require removal of moisture.
Industrial Furnace
A general term for industrial heat processing equipment that requires operating temperatures greater than 1000 Degrees Fahrenheit.
Industrial Oven
A general term for an enclosed, insulated heated compartment for baking substances, curing epoxies, heat-treating metals, firing ceramics and other industrial heat processing applications.
Infrared
Radiation light energy with wavelengths longer than visible light but shorter than microwaves. Infrared, also known as IR, is used in heating applications when it is desirable to have the work object absorb heat energy instead of heating the air around the work object. Successful Infrared applications match the IR heat source wavelengths to the heat absorbing characteristics of the material to be heated.
Insulation
Material with low heat conducting properities used to reduce heat transfer between materials with high heat conductivity.
Joule
An international unit of thermal energy. One Joule of heat is equivalent to One Watt – Second. It is also equal to one Newton Meter (Nm). The term Joule (J) is named after James Prescott Joule, a scientist who developed the theory of the conservation of energy.
Kelvin
An absolute temperature scale – 0 Kelvin is absolute zero, the point where all molecular activity stops. It is interesting to note that the degree symbol is not used in the Kelvin scale. The freezing point of water is 0 Deg C = 273.15K; the boiling point of water is 100 Deg C = 373.15K.
Kilowatt Hour
An electrical unit of energy – equal to one kilowatt in one hour. Also equal to 3412 BTU per hour.
Knock Down Construction
Ovens that are physically too large to ship from the Lanly factory in Cleveland, OH are sent out in subassemblies and constructed in the field at the user’s Facility. These installations are referred to as “Knock Down Construction” jobs.
LANSCAN
A first event circuit monitoring device developed by The Lanly Company to monitor electrical interlocks in industrial oven and dryer control systems.
Make Up Air
Amount of air required to replace the air that has to be exhausted from the oven.
Mineral Wool
A Fibrous, woollike material made from molten slag and formed into thick sheets. Mineral wool is inserted within floor, side and ceiling panels of ovens for heat insulation.
NEC
National Electrical Code – regulations and specifications for wiring as published by the National Fire Protection Association.
NEMA
National Electrical Manufacturer’s Association
NFPA
National Fire Protection Association – an International Codes and Standards Organization.
NPT
National Pipe Thread
OSHA
US Government agency, Occupational Safety and Health Administration (or Agency). Specifies and enforces safety in the workplace.
Oven
A general term for an enclosed, insulated heated compartment for baking substances, curing epoxies, heat-treating metals, firing ceramics and other industrial heat processing applications.
Pittsburgh Seam
A method of joining the edges of two pieces of sheet metal to form a locking corner seam. The edge of the first piece of sheet metal is formed into a simple 90 degree flange approximately 1/4 inch wide. The edge of the second piece is formed into an “N” shaped pocket with an extended edge. The pocket is deep enough to accomodate the flange from the first piece and the two pieces are joined lengthwise. The extended edge of the second piece is peened back over the first piece to complete the seam.
Pit Oven
A vertical oven constructed below floor level arranged for the loading of parts in a metal basket.
Purge
To remove undesirable gases from the oven and combustion chamber prior to combustion by exhausting the volatile gases and introducing fresh replacement air. Purge cycles are measured in complete volumetric changes of air. A purge circuit includes sensors and timers to ensure the required number of air changes are completed prior to granting permission to the operator to light the burner.
Quenching
Rapid cooling in a liquid of a part immediately after heating.
Ramp
A term used to define the time it takes to raise the temperature from ambient to the soak temperature. Also used as the time it takes to lower from soak temperature to ambient temperature.
Rankine
An absolute temperature scale similar to Kelvin – 0 Degrees is absolute zero – except the Fahrenheit temperature scale is used. The freezing point of water is 491.67 Deg R and the boiling point is 671.64 Deg R and 0 Deg F = 459.67 Deg R.
Reaumur
Temperature scale similar to Celsius where the freezing point of water is set equal to zero and the boiling point of water is set equal to 80.
RTD
Resistance temperature detectors are sensors made of materials that predictably change resistance with temperature. Many RTD’s are made from platinum and are also known as Platinum Resistance Thermometers or PRT’s. RTD’s are considered more accurate than thermocouples.
SAE
Society of Automotive Engineers. An organization that publishes engineering specifications related to the automotive industry.
SAE AMS
Society of Automotive Engineers Aerospace Materials Specification.
Snack Food Dryer
A continuous dryer designed for the specific needs of the snack food industry. Comprised of stainless steel components for corrosion resistance.
Soak
A term used to define the time a product is subjected to a particular temperature within the oven work chamber.
Solution Heat Treatment
Heat treatment thermal cycle of a solid object followed by a rapid cooling in a liquid.
Specific Gravity
Comparison of the mass of an object to the mass of water. Calculated as a ratio greater than, equal to’ or less than 1.0.
Specific Heat
The ratio of the amount of heat required to raise the temperature of a mass of any material one degree to that required to raise the temperature of an equal mass of water one degree. Note, since the measurement is a ratio the temperature scale doesn’t matter as long as it is the same for both measurements.
Stainless Steel
A steel alloy containing a minimum of 10.5% chromium. The chromium content enables stainless steel to resist stains, rust and corrosion longer than ordinary carbon steel. The chromium will combine with oxygen – to form a Chromium Oxide barrier preventing the formation of Iron Oxide (rust) within the metal.
Stress Relieving
Heat treat thermal cycle to remove residual stress in a part.
Tempering
Heat Treat thermal cycle after quench to increase the toughness of the material. Also referred to as drawing or drawing the temper.
Tensile Strength
A measurement of the maximum stress a material can withstand without plastic deformation. Tensile strength is measured in force per unit area – pounds per square inch (PSI ) for example.
Textile
Material used for manufacture of woven or nonwoven fiber, yarn or cloth. Pertaining to textile production or the textile industry.
Thermal Conductivity
Property of a material to convey or conduct heat.
Thermal Expansion
Measurement of the dimensional expansion of an object subjected to an increase in temperature.
Thermal Lag
Time required for a heat processing system to respond to a change in set point temperature.
Thermistor
A sensor that changes resistance as a function of temperature. The device is designed to be placed within the heated work chamber and as the temperature changes the device will alter an electrical voltage signal proportional to the amount of heat sensed.
Thermocouple
A temperature sensor consisting of a circuit of two wires of different metals welded together. Changing temperatures induce a voltage across the dissimilar materials. The voltage is proportional to the temperature change.
Turn Down Ratio
The ratio of the maximum BTUH firing capability to the minimum BTUH firing capability of the burner. Higher turn down ratios are desirable.
UL
Underwriters Laboratories – an approval agency for components and finished products.
Vertical Lift Door
Insulated oven door that is raised open to allow loading and unloading of the work parts. Vertical Lift Doors are typically powered by electric motors and may include counterweights to reduce required HP of the drive. Vertical Lift Doors require less floor space than swing doors but an adequate ceiling height is required.
VOC’s
Volatile Organic Compounds are organic chemical compounds that can be found as products of combustion in heat processing applications. VOC’s are defined and regulated by government agencies such as the Environmental Protection Agency (EPA) in the United States.
Watt
A unit of power that equals one joule per second, named after the Scottish inventor and mechanical engineer, James Watt.