A 4-station rotary indexing machine for an automated assembly cell — indexing torque, shaft and bearing selection, and drive sizing worked from the table's own inertia.
The project brief: a 36 in diameter, 4-station rotary indexing machine carrying an 800 lb payload of fixtures and in-process parts, indexing 90° every 3-second cycle (a 0.5-second index, 2.5-second dwell) at 20 cycles/min. Unlike the other real projects in this program, the challenge here isn't a fluid or electrical system feeding a piece of equipment — it's the machine's own internal mechanism, and every downstream selection (shaft, bearing, drive motor) traces back to a single number: the table's mass moment of inertia.
This module walks the whole project the way a real machine design engineer would: a fully worked indexing-torque calculation from the table and payload's combined inertia, cam-indexer selection and the reasoning behind choosing a mechanical indexer over a direct servo-driven table, servo motor sizing through the indexer's internal ratio, a worked output-shaft sizing and bearing L10-versus-static-capacity selection, and the safety guarding and maintenance plan a machine indexing 20 times a minute actually needs. The full worked numbers, complete bill of materials, and finished design reasoning are part of the unlocked module below.