MMAW NC II key terms

A safety procedure that isolates energy sources and locks them out to prevent accidental startup during maintenance. Each worker applies a personal lock and tag, and only the person who applied it removes it.

Gear such as safety glasses, gloves, and hearing protection worn to reduce exposure to workplace hazards. It is the last line of defense after engineering and administrative controls.

The process of identifying hazards, evaluating the likelihood and severity of harm, and deciding on controls. It is performed before work begins and reviewed when conditions change.

A workplace organization method with five steps: sort, set in order, shine, standardize, and sustain. It reduces waste and improves safety by keeping tools and materials in defined locations.

Using labels, floor markings, and color coding to make normal and abnormal conditions easy to see at a glance. It supports 5S and helps prevent errors in assembly and maintenance.

A documented, repeatable method for a task that specifies sequence, timing, and key points. It provides a baseline for training and for identifying improvements.

Any activity that consumes resources without adding value to the product or service. Common types include waiting, overproduction, defects, and unnecessary motion.

A drawing method that shows multiple views of an object, such as front, top, and side, arranged in a standard layout. Each view represents the object as seen from one direction, with hidden lines for obscured features.

A drawing convention where the view is placed on the side of the object from which it is seen. Common in North America, it is identified by a truncated cone symbol on the drawing.

A drawing view that shows the interior of an object as if it were cut by a plane. Hatching lines indicate solid material, and the cutting plane is marked on another view.

The allowable variation in a dimension, expressed as an upper and lower limit. It defines the range within which a feature is acceptable for assembly and function.

The relationship between the sizes of two mating parts, such as a shaft and a hole. Clearance, interference, and transition fits determine how easily parts assemble and how they transmit force.

A symbolic language on drawings that specifies allowable variation in form, orientation, location, and profile. It uses feature control frames and datums to define requirements precisely.

A theoretically exact point, axis, or plane from which dimensions and tolerances are measured. Datums establish the reference frame for inspection and assembly.

A measuring tool with a main scale and a sliding vernier scale used to measure outside, inside, and depth dimensions. The vernier scale provides a reading resolution of typically 0.02 mm or 0.001 in.

A precision measuring instrument that uses a calibrated screw to measure small dimensions, typically with 0.01 mm or 0.001 in resolution. It is read by combining the barrel and thimble scales.

The range of values within which the true measurement is expected to lie, considering instrument accuracy, resolution, and environmental factors. It is stated with the measurement result to indicate reliability.

The relationship that voltage equals current times resistance in a linear circuit. It is used to calculate unknown values and to verify circuit operation.

Two rules for circuit analysis: the sum of currents at a node is zero, and the sum of voltages around a closed loop is zero. They apply to any lumped circuit regardless of component type.

Series circuits have one path for current, so current is the same through all components. Parallel circuits have multiple paths, so voltage is the same across each branch.

A semiconductor device that allows current to flow mainly in one direction, from anode to cathode. It is used for rectification, protection, and signal clamping.

A three-terminal semiconductor device used for switching or amplification. In mechatronics, it often drives relays or small motors from a control signal.

A circuit that converts alternating current to direct current, often using diodes. A bridge rectifier uses four diodes to produce full-wave rectification.

A device that provides electrical energy to a circuit at a required voltage and current. It may convert AC to DC and regulate the output.

An electromechanical switch that uses a coil to operate contacts. It allows a low-power control signal to switch a higher-power load and provides isolation.

A heavy-duty relay designed for switching high-power loads such as motors. It often includes overload protection and is controlled by a pushbutton or PLC output.

A system that uses compressed air to transmit power through components such as compressors, valves, and cylinders. It is known for fast, clean operation but limited force.

A system that uses pressurized fluid to transmit power through pumps, valves, and actuators. It provides high force and precise control but requires careful sealing and maintenance.

A valve that directs or blocks flow in a fluid power circuit. It is described by the number of ports and positions, such as a 5/2 valve.

A linear actuator that converts fluid pressure into force and motion. It is specified by bore, stroke, and mounting style.

A device that detects a physical property, such as position, temperature, or pressure, and converts it into a signal. Sensors provide feedback for control systems.

A device that converts a control signal into physical motion or action, such as a motor, cylinder, or solenoid. It is the final element in a control loop.

An electromagnetic device that converts electrical current into linear motion. It is often used to operate valves in pneumatic and hydraulic systems.

An industrial digital computer that controls machinery by executing a stored program. It reads inputs, executes logic, and drives outputs in a deterministic cycle.

A graphical programming language for PLCs that resembles electrical relay circuits. It uses contacts, coils, and function blocks to implement control logic.

A screen or panel that allows an operator to monitor and control a machine or process. It displays status and accepts commands, often communicating with a PLC.

The process of adjusting the relative position of machine components, such as shafts or couplings, so they operate on a common centerline. Proper alignment reduces vibration and wear.

Scheduled inspection and servicing of equipment to prevent failures before they occur. It includes lubrication, cleaning, and replacement of wear parts based on time or usage.

A component that supports a rotating shaft and reduces friction between moving parts. Proper lubrication and alignment extend its service life.

The process of testing and verifying that a system or machine operates according to specifications before it is put into service. It includes checks of safety, functionality, and performance.

The systematic process of identifying the cause of a malfunction by observing symptoms, testing, and eliminating possibilities. It often uses a structured troubleshooting flowchart.

A documented sequence of steps to verify the performance or safety of a system. It specifies the equipment, conditions, and acceptance criteria for each test.