JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III INTRODUCTION TO MATERIALS HANDLING Previous Question Paper (November/December - 2020 - R16)

Materials handling systems are categorized based on their operational environment and path constraints. Surface and overhead equipment serve distinct roles in industrial logistics, with specific characteristics defining their application.

General Characteristics of Surface Equipment:

• Floor Dependency: These systems operate primarily on the ground level, utilizing the factory floor space for movement. Examples include forklifts, AGVs (Automated Guided Vehicles), and conveyors.
• Flexibility: Mobile surface equipment like industrial trucks offer high path flexibility, allowing them to navigate around obstacles and adapt to changing production layouts.
• Load Capacity: Designed to handle heavy, bulky, or palletized loads that are impractical to suspend. They are essential for loading and unloading operations at docks.
• Space Utilization: While versatile, they consume valuable floor space, which can lead to congestion if not managed correctly.

General Characteristics of Overhead Equipment:

• Vertical Space Utilization: These systems, such as overhead cranes, hoists, and monorails, utilize the unused vertical space near the ceiling, freeing up the floor for manufacturing processes.
• Fixed Path Operation: Overhead equipment typically follows a predetermined path defined by rails or tracks, which limits flexibility but ensures high repeatability and safety in heavy-duty lifting.
• Safety and Efficiency: By moving loads above the heads of workers and equipment, they reduce the risk of collisions and interference with floor-level activities.
• High Lifting Capacity: They are specifically engineered for lifting and transporting extremely heavy or oversized components in assembly lines or foundries where floor-based transport is impossible.

In summary, surface equipment provides the agility needed for point-to-point distribution and warehouse operations, whereas overhead equipment provides the structural support and space efficiency required for heavy-duty, repetitive manufacturing tasks.

Pneumatic conveying systems transport bulk materials through a pipeline using air or gas as the motive force. They are classified based on the pressure conditions within the conveying line.

1. Positive Pressure (Pressure) Conveying: In this system, a blower or compressor at the inlet creates a pressure higher than atmospheric pressure to push the material through the pipeline. It is ideal for transporting material from a single source to multiple discharge points.

2. Negative Pressure (Vacuum) Conveying: A vacuum pump at the discharge end creates a pressure lower than atmospheric pressure, pulling the material into the pipeline. This system is effective for picking up material from multiple sources and delivering it to a single destination, and it is inherently dust-free because any leaks pull air inward.

3. Combined (Vacuum-Pressure) Conveying: This system integrates both methods, using a vacuum to collect material from various points and a positive pressure blower to deliver it to multiple distant locations. It is used in complex layouts requiring high versatility.

System Components:

• Air Mover: Blower, fan, or compressor providing the necessary airflow.
• Feeding Device: Rotary airlock valve or venturi feeder to introduce material into the airstream without losing pressure.
• Conveying Pipeline: Steel or alloy pipes that transport the material.
• Separation Device: Cyclone separator or bag filter at the discharge end to separate the solid particles from the conveying air.

Sketch Description: A typical layout involves a blower connected to a feeding device at the start of the pipeline. In a pressure system, the blower is at the beginning; in a vacuum system, the blower is placed after the cyclone separator at the end. The material is introduced via a rotary valve, travels through the pipe, and is captured in a cyclone where air is vented and material is discharged through a bottom valve.