Mechanical Systems - Basics of Engineering Materials and Mechanical Principles

Comprehensive vocabulary flashcards covering engineering materials, fasteners, shaft couplings, mechanical power principles, gear drives, belt drives, chain drives, bearings, and lubrication from the MEC110 Mechanical Systems lecture series.

Ferrous Metals

Metals mainly composed of iron with small amounts of other elements added, almost all of which are magnetic and subject to rusting or oxidising if left untreated.

Non-Ferrous Metals

Metals that do not contain iron, are not magnetic, and do not oxidise from iron content, such as aluminium, copper, lead, zinc, and tin.

Pure Metal

A metal consisting of a single chemical element containing only one type of atom, such as pure aluminium, copper, iron, lead, zinc, tin, silver, or gold.

Alloy

A metallic mixture of two or more pure elements combined together to produce specific properties that individual pure metals lack.

Mild Steel

The most common metal alloy used in school workshops and engineering, containing $0.1 - 0.3\%$ carbon and $99.9 - 99.7\%$ iron, offering tough, high strength but rusting very easily.

Thermoplastics

Plastics that can be repeatedly melted and remolded multiple times, including materials like polyethylene, PVC, acrylic, nylon, and ABS.

Thermosets

Thermosetting plastics that, once set or cured, cannot be re-melted or remolded again, such as phenolic, epoxies, and polyester.

Elastomers

Polymers possessing high elastic properties that allow them to deform under stress and return to their original shape, such as rubber, polyurethane, and silicone.

Machine Screws

Fasteners designed for joining metal parts by being driven into tapped (threaded) holes rather than drawn tight with nuts, typically fully threaded up to the head.

Screw Thread Geometry

The primary dimensions that define screw threads, including the major diameter, pitch diameter, minor diameter, thread pitch, and thread depth.

Helical Spring Washers

Lock washers made of tough spring steel that are split with one end bent up to bite into both the nut and the fastened part when tightened to resist vibration.

Center Punch

A hand tool used to strike a divot into a surface, providing an indented starting point that allows a drill bit to grip without slipping.

Drilling Oil

A specialized fluid lubricant applied during drilling to prevent the drill bit from overheating and to facilitate smooth metal cutting.

T-handle

A device used to clamp onto a thread-cutting tap, providing manual leverage to rotate the tap straight into a drilled hole and create internal threads.

Shaft Coupling

A mechanical component used to connect two rotating shafts together to transmit power, absorb misalignment, dampen vibrations, or block thermal transfer.

Flexible Jaw Coupling

A coupling type that uses a flexible elastomeric insert (spider or cushion) between coupling halves to tolerate minor shaft misalignment and reduce vibration.

Rigid Coupling

A sleeve coupling made of heavy-walled pipe secured with set screws or keys that requires precise axial and radial shaft alignment.

Force

A push or pull exerted on an object, measured in pounds ($lbs$), that can cause an object to move, stop, or alter its direction.

Friction

A force that opposes the relative sliding or rolling motion of two contacting surfaces.

Static Friction

The resistive friction force that keeps a stationary object at rest and prevents it from initiating movement when an external force is applied.

Kinetic Friction

The frictional force acting between two solid surfaces as they actively slide across each other.

Torque

A twisting or rotational force produced by a force acting at a perpendicular distance from a pivot axis, defined mathematically as $\text{Torque} = \text{Force} \times \text{Distance}$.

Mechanical Work

The product of a force applied to an object and the displacement distance moved in the direction of that force ($W = f \times d$).

Mechanical Power

The rate at which mechanical work is performed over a specified time interval, calculated as $\text{Power} = \frac{\text{work done}}{\text{time interval}}$.

Spur Gears

Gears with straight teeth parallel to the axis of rotation, commonly used to transfer rotational motion, alter speed, and change torque between parallel shafts.

Gear Pitch (Module)

The physical size and spacing of gear teeth; two meshing gears must have identical pitch or module values to engage correctly without jamming.

Pressure Angle

The angle between the line of action between meshing gear teeth and the tangent to the pitch circle, with standard values being $20^\circ$ and $14.5^\circ$.

Helical Gears

Gears with teeth cut at an angle (helix angle) to the axis of rotation, offering smoother, quieter operation and higher load capacities than spur gears.

Bevel Gears

Conically shaped gears used to transmit power and rotational movement across intersecting shaft angles.

Miter Gears

A specific type of bevel gear set mounted on shafts intersecting at a $90^\circ$ angle, typically designed to provide a 1:1 speed ratio.

Worm Gear Set

A high-reduction gear set consisting of a threaded worm screw meshing with a worm gear wheel at a $90^\circ$ non-intersecting orientation, frequently featuring self-locking functionality.

V-Belt

A wedge-shaped friction drive belt that relies on tension to wedge itself into pulley grooves, generating friction on the sidewalls to transmit power.

Synchronous Belt

Also known as a timing belt, a positive-drive belt featuring molded teeth that mesh directly into matching sprocket grooves to eliminate slippage.

Roller Chain

An engagement-type mechanical drive chain containing free-turning rollers over bushings that make rolling contact with sprocket teeth to transmit motion with minimal slip.

Roller Chain Components

The individual parts constituting a standard roller chain assembly, including the pin, pin link, bushing, roller, and roller link.

Radial and Axial Loads

Radial load is a force acting perpendicularly to the shaft center line (such as shaft weight), while axial (thrust) load is a force acting parallel along the length of the shaft axis.

Bearing

A mechanical support element positioned around a rotating shaft to hold it in alignment, support applied loads, and minimize rotational friction.

Thrust Ball Bearing

A type of ball bearing designed specifically to withstand pure axial (thrust) loads parallel to the shaft at lower operating speeds.