Class D Fires: Combustible Metals

Powder coating is a dry finishing process where a thermoplastic or thermoset polymer powder is applied to a surface, typically electrostatically, and then cured under heat. The powder particles are charged, causing them to adhere to the grounded substrate. Heating melts the powder, allowing it to flow and form a continuous, durable, and high-quality finish, often superior to conventional paint.

Hot gas welding is a fabrication process that joins thermoplastic materials using a stream of heated gas, typically air, to soften the surfaces. A specialized heat gun directs the hot gas onto the joint area and a plastic filler rod simultaneously. As the base material and the rod melt, they are pressed together, fusing upon cooling to form a continuous, solid bond.

Numerical Control (NC) is the automated control of machining tools using a program composed of precisely coded alphanumeric data. This program dictates the tool's path, feed rate, speed, and other operational parameters. Early NC systems utilized punched paper tape as the input medium, marking a significant technological leap from manual control via handwheels or physical templates.

Spin coating is a procedure for depositing uniform thin films onto flat substrates. An excess of a coating solution is placed on the substrate, which is then rotated at high speed. Centrifugal force spreads the solution, and solvent evaporation or curing solidifies the film, with the final thickness determined by viscosity, concentration, and spin speed.

The Fill Factor (FF) is a key parameter that determines the quality of a solar cell. It is the ratio of the maximum power a cell can produce (\(P_{max}\)) to the theoretical power if it were an ideal voltage and current source (\(V_{oc} \times I_{sc}\)). A higher fill factor indicates lower parasitic resistance losses and a more 'square' I-V curve.

The Toyota Production System is founded on the complete elimination of waste, categorized into 7 types, 3 main being described here: Muda (non-value-adding work), Muri (overburden), and Mura (unevenness). While Muda is the most commonly discussed, TPS recognizes that Muri and Mura are often the root causes of Muda and must be addressed first to achieve a truly lean system.

Kanban, meaning "visual card" or "signboard" in Japanese, is a scheduling system integral to the Toyota Production System. It uses visual cues, typically cards, to trigger action and manage workflow. It is a "pull" system that signals the need to move materials within a manufacturing facility or from an outside supplier into the production facility.

A thermal lance, or thermic lance, is a tool that cuts materials using the intense heat from the oxidation of iron. It consists of a steel tube packed with steel rods. Pressurized oxygen is fed through the tube, and the tip is ignited. The iron in the lance acts as fuel, burning in the oxygen stream to create a high-velocity, high-temperature jet.

Neutron embrittlement is the loss of ductility and toughness in materials subjected to neutron irradiation. In nuclear reactors, high-energy neutrons displace atoms from their lattice sites, creating defects like vacancies and interstitials. These defects accumulate and form clusters that impede dislocation motion, thereby increasing the material's hardness and strength but severely reducing its ability to deform plastically before fracturing.

The United States fire classification system, standardized by NFPA 10, categorizes fires into five main classes based on the type of fuel. Class A includes ordinary combustibles like wood and paper. Class B covers flammable liquids and gases. Class C is for fires involving energized electrical equipment. Class D pertains to combustible metals, and Class K is for cooking oils and fats.

A matrix method of structural analysis fundamental to the finite element method (FEM). It models a structure as an assembly of elements connected at nodes. The method relates nodal forces \({R}\) to nodal displacements \({D}\) through a global stiffness matrix \([K]\), expressed as \([K]{D} = {R}\). Solving this system of linear equations yields the unknown nodal displacements.

A structured methodology for creating new products, typically involving analysis, concept development, and synthesis. It is an iterative cycle where designers research user needs, brainstorm ideas, create prototypes, and test them to refine the final product. This process ensures that the end product is both functional and meets market demands effectively before full-scale production.

Heijunka is the principle of production leveling or smoothing within the Toyota Production System. It involves averaging out the production volume and mix over a fixed period to eliminate peaks and valleys in workload. This creates a predictable and stable manufacturing environment, which is a prerequisite for implementing Just-in-Time (JIT) and standardized work effectively.

Takt time is a theoretical calculation representing the pace of customer demand (\(Available Time \div Demand\)). In contrast, cycle time is an empirical measurement of the actual time taken to complete one unit of work at a specific process step. A core principle of lean manufacturing is to ensure that cycle time is consistently less than or equal to Takt time.