Screw Conveyor Demonstration Model

Screw conveyors move grain, cement, plastic granules and food powders through thousands of plants, yet mechanical students usually meet them only as a formula — throughput equals a constant times diameter squared times pitch times speed. This project makes the formula tangible: a bench-scale screw conveyor with a fabricated helical screw in a sheet-metal trough (transparent acrylic top so the material flow is visible), an inlet hopper, a discharge chute and a geared DC motor with a speed controller. The student loads wheat, rice or plastic granules, runs timed conveying trials at several speeds and two inclinations, weighs the discharged material, and compares the measured throughput with the theoretical capacity calculated from the screw's geometry. The gap between theory and measurement — slip, fill efficiency, inclination losses — becomes the most viva-worthy part of the report, and every number in it is the student's own.

1. Fill the hopper with the test material (wheat, rice or granules) and set the trough to horizontal.
2. Set a screw speed on the controller and measure the actual RPM with the tachometer sticker reading.
3. Start the conveyor and, once flow is steady, collect the discharge in the bin for a timed 60-second interval.
4. Weigh the collected material and compute throughput in kg/h for that speed.
5. Repeat across the speed range, then repeat the series at an inclined trough setting.
6. Compute the theoretical capacity from the screw diameter, pitch, RPM and the material's bulk density, with the standard fill-factor and inclination corrections.
7. Plot measured vs theoretical throughput, and discuss fill efficiency, slip and inclination losses from your own data.

Tech stack:

• Fabricated helical screw on shaft
• Sheet-metal trough with acrylic top cover
• Inlet hopper and discharge chute
• Geared DC motor with PWM speed controller
• Adjustable-inclination support frame
• Digital weighing scale and stopwatch
• Tachometer sticker for RPM check
• Test materials: wheat, rice, plastic granules

• [Fabricated helical screw] A true helical flight wound on a shaft — the defining component — sized to the trough with proper clearance for smooth conveying.
• [Transparent trough cover] An acrylic top on the sheet-metal trough makes the material bed and its movement visible during every trial.
• [Inlet hopper and discharge chute] A sheet-metal hopper gives uniform feed and the chute delivers into a weighing collection bin.
• [Geared motor with speed control] A geared DC motor with a PWM speed controller lets the student run the full speed range for the throughput trials.
• [Adjustable inclination] The trough tilts from horizontal to about 20°, so the student measures and reports the inclination penalty themselves.
• [Timed weighing procedure] A digital weighing scale and stopwatch turn each trial into a measured throughput point — no estimated figures.
• [Theory-vs-measured comparison] The report template computes theoretical capacity from screw geometry and places the student's measured points beside it.
• [Multiple test materials] Trials run on wheat, rice or plastic granules, showing how bulk density and particle shape shift the results.

• Fabricated screw conveyor: screw, trough, hopper, chute, frame
• Geared DC motor with PWM speed controller and power supply
• Digital weighing scale and stopwatch
• Collection bins
• Test material starter pack (grain/granules)
• Trial procedure and observation sheets (blank, for your readings)
• Project report PDF (bulk-handling theory, design, procedure)
• PPT presentation for final review
• Viva Q&A preparation document

• Throughput figures are entirely student-measured; the theoretical capacity is a design calculation, and the report presents both without claiming either as the other.
• Fill efficiency and slip depend on the material — the student's wheat results will not match their granule results, which is the point of the comparison.
• The model handles dry, free-flowing granular materials only; sticky, wet or fibrous materials jam the screw.
• Capacity falls with inclination; the 20° setting is for demonstrating the penalty, not for rated duty.
• Screw-to-trough clearance is a fabrication tolerance — excessive clearance raises slip and the student reports it as a build observation.