Selecting a manufacturing mode for a machining task — manual operation on an ordinary machine, use of a jig or fixture, or a fully automatic single-purpose machine — is governed by technological feasibility, resource/technical availability, and economic viability, the last determined by comparing total production cost (fixed/initial cost plus per-piece variable cost, following the linear relation CT = CI + Q·M) across modes as a function of production volume, with break-even points marking the volume ranges where each mode is most economical. A jig or fixture is warranted when its added fixed cost is offset by reduced variable (labor/material) cost per piece over the expected production volume; this belongs to manufacturing/production engineering, specifically the design methodology for work-holding and tool-guidance devices (jigs and fixtures) used in machine-shop operations.
Selecting a manufacturing mode for a machining task — manual operation on an ordinary machine, use of a jig or fixture, or a fully automatic single-purpose machine — is governed by technological feas…