1. Introduction
Material handling involves the movement, protection, storage, and control of materials throughout manufacturing, warehousing, distribution, consumption, and disposal stages. Efficient material handling enhances productivity, reduces costs, ensures safety, and maintains quality. Conveyors and elevators are pivotal in transporting materials across horizontal, inclined, or vertical paths within a facility.
2. Basic Principles of Material Handling Equipment
- Flow of Material: Design systems to follow the natural flow of materials, minimizing unnecessary movement.
- Minimize Handling: Reduce the number of times materials are handled to decrease costs and risks.
- Unit Load: Consolidate materials into standard units to simplify handling.
- Economy of Motion: Ensure smooth and direct movements to enhance efficiency.
- Use of Gravity: Utilize gravity where possible to save energy and simplify design.
- Safety and Protection: Safeguard materials, personnel, and the environment during handling.
- Flexibility and Scalability: Design systems to adapt to changes in load, product types, and volume.
- Balanced Capacity: Match the capacities of handling equipment to avoid bottlenecks.
3. Conveyors: Principles, Types, and Working
3.1 Principle
Conveyors are devices that transport materials continuously over fixed paths. They consist of moving elements (belts, rollers, chains, air) and support structures. Conveyors can handle unit loads (boxes, bags, pallets) or bulk materials (grains, powders, aggregates).
3.2 Types of Conveyors
- Belt Conveyor: A continuous looped belt transports materials between pulleys.
- Roller Conveyor: Materials rest on rollers; movement can be powered or by gravity.
- Screw Conveyor: A helical screw rotates in a trough to move bulk materials.
- Chain Conveyor: Chains move linked plates or slats to carry loads.
- Pneumatic Conveyor: Air flow moves materials through tubes or ducts.
3.3 Working Details
Conveyors operate by moving materials along a fixed path. For instance, in belt conveyors, a belt is tensioned between pulleys; one pulley is driven by a motor, and others are idlers or return pulleys. The belt speed, width, pulley diameters, and bed support are designed based on capacity, distance, inclination, and material properties.
4. Elevators: Principles, Types, and Working
4.1 Principle
Elevators are devices designed to lift materials vertically from one level to another. They utilize belts, chains, buckets, cages, or platforms to transport materials. The key function is vertical lifting with mechanisms to load, lift, discharge, and return the lifting medium.
4.2 Types of Elevators
- Bucket Elevator: Buckets attached to a belt or chain pick up material from a lower level, carry it up, and discharge it at the top.
- Cage or Platform Elevator: Used for unit loads, employing a platform or cage that travels vertically guided by rails.
- Skip or Lift Hoists: Used for heavy materials in skips, often employed in mining or construction.
4.3 Working Details
Bucket elevators collect material in buckets at the bottom (boot), then the buckets travel up (on chain or belt) and at the top (head) discharge — either by gravity, centrifugal action, or mechanical flipping. The belt/chain passes over pulleys or sprockets; tensioning devices maintain belt/chain tension. The elevator shaft may be enclosed to avoid spillage and dust.
