CMfgE flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Taylor tool life equation

Empirical relation V·T^n = C linking cutting speed V and tool life T, where n and C depend on tool and workpiece material; higher n means tool life is less sensitive to speed.

Shear plane angle

Angle φ of the primary deformation zone in orthogonal cutting, related to chip thickness ratio r and rake angle α by tan φ = r·cos α/(1 − r·sin α).

Chvorinov's rule

Solidification time equals a mold constant times the square of the volume-to-surface-area ratio (V/A); used to size risers so they freeze after the casting.

Specific cutting energy

Energy required to remove a unit volume of material; it increases as chip thickness decreases because of the size effect, making light finishing cuts less energy-efficient.

Bend allowance

Length of the neutral axis in a bent sheet, calculated as θ(R + K·t), where θ is bend angle in radians, R inside radius, t thickness, and K the neutral-axis factor.

Welding heat input

Heat delivered per unit length of weld, H = ηEI/v, where η is arc efficiency, E voltage, I current, and v travel speed; higher input widens the heat-affected zone.

Forging force estimate

Required force approximated as flow stress times projected area times a shape factor K_f between about 1.0 and 1.5, accounting for friction and redundant deformation.

Castability and fluidity

Ability of molten metal to fill a mold; fluidity decreases with a wide freezing range, low superheat, and high mold thermal conductivity, raising misrun risk.

Little's Law

For any stable system, work in process equals throughput multiplied by flow time; changing any one of the three determines the third.

OEE calculation

Overall Equipment Effectiveness equals Availability times Performance times Quality, each expressed as a fraction; it measures how much planned production time yields good parts.

Takt time

Available production time divided by customer demand rate; it sets the pace a line must meet and is the target for line balancing.

Economic order quantity

Order size minimizing the sum of ordering and holding costs, EOQ = sqrt(2DS/H), where D is annual demand, S order cost, and H holding cost per unit per year.

Kanban sizing

Number of cards or containers equals demand during replenishment lead time times one plus a safety factor, divided by container quantity.

Theory of Constraints

Management approach holding that system throughput is limited by one bottleneck; scheduling and buffering focus on protecting that constraint from starvation and blockage.

Safety stock formula

Buffer inventory equal to the service-level z-factor times the standard deviation of demand during lead time; higher target service level increases required stock.

Cellular layout

Arrangement grouping different machine types into cells dedicated to part families, reducing travel, queue time, and setup compared with a functional process layout.

Cost of quality categories

Four cost buckets: prevention, appraisal, internal failure, and external failure; external failures usually carry the highest cost per defect because they reach the customer.

ASTM 52900 process families

Standard taxonomy of seven additive families: vat photopolymerization, material extrusion, material jetting, binder jetting, powder bed fusion, directed energy deposition, and sheet lamination.

Volumetric energy density

Laser powder bed fusion parameter E = P/(v·h·t), combining power, scan speed, hatch spacing, and layer thickness to indicate energy delivered per unit volume of powder.

Binder jetting green part

Part formed by depositing liquid binder into powder without melting; it must be cured and sintered, and typically shrinks 15–25% linearly during sintering.

Support structures in PBF

Anchors that conduct heat from the melt to the build plate and resist distortion on overhangs; they must be removed after the build.

Anisotropy in additive parts

Direction-dependent properties caused by layer-wise building; the build (Z) direction is usually weakest because interlayer bonding differs from in-plane material structure.

Hatch spacing

Distance between adjacent scan tracks in powder bed fusion; smaller spacing raises density and surface quality but increases build time and energy input per volume.

Topology optimization for AM

Algorithmic material layout that removes mass where loads are low; additive processes can realize the resulting organic geometries that conventional machining cannot.

Layer thickness trade-off

Thinner layers improve surface finish and Z-resolution but increase the number of layers and thus build time roughly in inverse proportion.

ISA-95 levels

Hierarchy from level 0 process through sensing, control, MES at level 3, and ERP at level 4; integration projects typically connect control data to MES and ERP.

OPC UA

Platform-independent industrial communication standard with a structured information model and built-in security; it is not tied to one fieldbus or vendor.

MQTT quality of service

Publish/subscribe messaging with QoS 0 (at most once), 1 (at least once), and 2 (exactly once); higher levels add overhead and delivery assurance.

Digital twin

A synchronized virtual model of a physical asset fed by live data, used for monitoring, simulation, and prediction; without a data link it is only a static model.

IEC 62443 zones and conduits

OT security framework that partitions networks into zones of similar risk connected by controlled conduits, limiting lateral movement of attacks.

Process capability index

Cpk = min(USL − μ, μ − LSL)/(3σ), measuring how well a centered, stable process fits within specification limits; 1.33 is a common minimum target.

Edge versus cloud analytics

Edge computing filters and reacts to data at the machine for low latency, while cloud platforms handle long-term storage, model training, and cross-plant analytics.