Engineering Glossary: H
39 definitions in plain language.
39 terms beginning with H. Use the filter to narrow the list, or the letters to jump to another part of the glossary.
39 terms
- Hardenability #
- How deeply a steel can be hardened by quenching. Materials, manufacturing and measurement
- Hardening #
- Heating steel and quenching it to form a hard structure, usually martensite. Materials, manufacturing and measurement
- Hardness #
- A material's resistance to being dented or scratched, measured by tests such as Rockwell, Brinell and Vickers. Mechanical design and mechanics
- Harmonic motion #
- A repeating back-and-forth motion whose displacement follows a sine wave. Mechanical design and mechanics
- Harmonics #
- Currents or voltages at whole-number multiples of the supply frequency, produced by non-linear loads. Electrical power and machines
- Hash function #
- A function that turns data of any size into a fixed-size value, used to check integrity. Programming, data and computing
- Hazard #
- Anything that has the potential to cause harm. Math, units, quality and workshop
- Head #
- Energy per unit weight of fluid, expressed as a height of fluid column, used for pumps and pipes. Fluids, heat and thermodynamics
- Header (connector) #
- A row of pins on a board that a cable or another board can plug onto. Electronics
- Heap #
- A region of memory used for dynamic allocation. Programming, data and computing
- Heat #
- Energy that flows from a hot body to a cooler one because of a temperature difference. Fluids, heat and thermodynamics
- Heat affected zone #
- The area next to a weld whose properties were changed by the heat without melting. Mechanical design and mechanics
- Heat capacity #
- The energy needed to raise the temperature of a whole body by one degree. Fluids, heat and thermodynamics
- Heat capacity ratio #
- The specific heat at constant pressure divided by that at constant volume, written γ; 1.4 for air. Fluids, heat and thermodynamics
- Heat dissipation #
- The heat that a component gives off, which must be removed to keep it within its temperature limit. Electronics
- Heat engine #
- A device that converts heat into work by running a thermodynamic cycle. Fluids, heat and thermodynamics
- Heat exchanger #
- A device that transfers heat between two fluids without mixing them. Fluids, heat and thermodynamics Read more: Heat Transfer
- Heat sink #
- A part that draws heat from a component and passes it to the surroundings. Fluids, heat and thermodynamics Read more: Heat Sink and Thermal Resistance Calculator
- Heat transfer coefficient #
- The heat flow per unit area per degree of temperature difference between a surface and a fluid, in W/m²·K. Fluids, heat and thermodynamics
- Helical gear #
- A gear with teeth cut at an angle, running more quietly than a spur gear but producing axial thrust. Mechanical design and mechanics
- Henry #
- The SI unit of inductance: one volt second per ampere. Electrical power and machines
- Hertz #
- The SI unit of frequency: one cycle per second. Electrical power and machines
- Hexadecimal #
- A number system with base 16, using the digits 0 to 9 and letters A to F; a compact way to write binary values. Programming, data and computing Read more: ASCII Table
- Hierarchy of controls #
- The order of preference for reducing risk: eliminate, substitute, use engineering controls, use administrative controls, then use protective equipment. Math, units, quality and workshop
- High-pass filter #
- A filter that passes high frequencies and attenuates low ones. Electronics
- High-speed steel #
- A tool steel that keeps its hardness at the high temperatures reached in cutting; used for drills and taps. Materials, manufacturing and measurement
- HMI #
- Human-machine interface: a screen or panel that shows the state of a machine and lets an operator control it. Automation, controls and robotics
- Hole basis system #
- A fit system in which the hole size is kept constant (H) and the shaft size is varied to give the fit. Materials, manufacturing and measurement
- Homing #
- Moving an axis to a known reference position at startup. Automation, controls and robotics
- Humidity ratio #
- The mass of water vapor per unit mass of dry air. Fluids, heat and thermodynamics
- HVAC #
- Heating, ventilation and air conditioning. Fluids, heat and thermodynamics Read more: HVAC and Psychrometrics
- Hydraulic cylinder #
- An actuator that turns hydraulic pressure into straight-line force. Fluids, heat and thermodynamics Read more: Pneumatic and Hydraulic Cylinder Force and Speed Calculator
- Hydraulic diameter #
- Four times the flow area divided by the wetted perimeter; used for non-circular ducts. Fluids, heat and thermodynamics
- Hydraulics #
- The use of liquid under pressure to transmit power. Fluids, heat and thermodynamics Read more: Hydraulics and Pneumatics
- Hydrogen embrittlement #
- Loss of ductility of a metal, especially high-strength steel, caused by absorbed hydrogen. Materials, manufacturing and measurement
- Hydrostatic pressure #
- The pressure in a fluid at rest due to its weight: density times gravity times depth. Fluids, heat and thermodynamics
- Hypothesis test #
- A procedure for deciding, from data, whether a claim about a population is supported. Math, units, quality and workshop
- Hysteresis #
- The difference between the switching thresholds for rising and falling inputs, which prevents chatter. Electronics
- Hysteresis (mechanical) #
- The difference in a system's response depending on whether the input is rising or falling. Math, units, quality and workshop