Lec 27: Material handling systems

Lecture 3: Material Handling Systems in Automation

Overview of Material Handling Systems

• The lecture introduces various material handling systems used in automation within manufacturing, outlining the key topics to be covered.

• It emphasizes the importance of moving, storing, and tracking materials, parts, and products on a shop floor or industrial setting.

Understanding Logistics

• Logistics is defined as the acquisition of materials and activities related to their movement, storage, and distribution within an enterprise.

• External logistics involves transporting goods outside a facility to market destinations using various transport systems like rail, truck, air, ship, or pipeline.

• Internal logistics focuses on moving or storing materials within a facility while maintaining records of these operations.

Importance of Material Handling Equipment

• Material handling is identified as a crucial element in logistics; it encompasses equipment necessary for various operations such as transportation and positioning.

• Different types of material handling equipment are categorized into transport equipment (e.g., trucks), positioning equipment (e.g., robots), unit load formation equipment (e.g., pallets), storage equipment, and identification/control equipment.

Types of Equipment Used

• Five main types of transport equipment are highlighted: industrial trucks, automated guided vehicles (AGVs), rail-guided vehicles (RGVs), conveyors, hoists, and cranes.

• Positioning equipment is utilized for specific tasks like feeding tools or loading/unloading parts from machines. Industrial robots often perform these functions in automated settings.

Unit Load Formation

• Unit load formation involves creating containers that hold individual items together for easier handling. An example given is using wooden pallets to stack finished products efficiently.

Material Handling Systems Overview

Types of Unit Loads

• A smaller version of a wooden pallet is described as a tote box, which can hold commodities like fruits and vegetables. One tote box of apples is considered a unit load.

• For heavier or larger quantities, pallet boxes are used to store raw materials for sub-assembly or processing operations.

Palletizing Operations

• Palletizing involves automatically shrink-wrapping plastic film around the unit load on a pallet for shipping. This process requires arranging products securely on the pallet before wrapping.

• Depalletizers are necessary for unloading cartons from pallets at distribution centers, automating the depalletization process.

Storage Equipment Methods

• Conventional bulk storage methods involve stacking food grain bags in open floor areas, while rack systems provide more sophisticated storage solutions designed to accommodate pallets.

• Automated storage and retrieval systems (AS/RS) utilize automated racks to streamline the storage process, reducing manual labor compared to traditional methods.

Tracking Technologies

• Barcode technology is employed in material handling to track commodities and equipment on the shop floor, similar to its use in retail markets.

• RFID technology (radio-frequency identification) is also utilized for tracking palletized unit loads within industrial settings.

Design Considerations for Material Handling Systems

• The design of material handling systems depends on factors such as material type (solid, liquid, gas), quantity (low, medium, high), and distance required for transport.

• Additional considerations include production facility requirements and budget constraints when selecting appropriate material handling technologies.

Material Handling Equipment and Plant Layouts

Overview of Material Handling in Automation

• The selection of material handling equipment must consider the plant layout, which can significantly impact transportation costs and efficiency.

• Three primary types of layouts are utilized in industry: process layout, product layout, and fixed position layout.

Process Layout Characteristics

• In a process layout, equipment is arranged based on similar utilization; for example, lathe sections and milling operations are grouped together.

• This arrangement facilitates various machining operations such as grinding, welding, fitting, assembly, testing, inspection, painting, packaging, and pelletization.

Workflow Examples in Process Layout

• Different parts (A, B, C) follow unique processing sequences through various operations like lathe work or milling before moving to inspection and packaging.

• Process layouts cater primarily to low to medium volume production (1 to 100 parts), allowing flexibility for diverse part processing.

Advantages and Challenges of Process Layout

• Flexibility is a key advantage of process layouts; they support batch mode operations effectively.

• However, challenges include potential bottlenecks due to limited equipment availability leading to inefficiencies in material handling.

High Volume Production Scenarios

• For high quantity production scenarios where only one product is manufactured (e.g., screws), specialized machines can be employed for mass production.

• Flow line-based production systems involve multiple workstations arranged sequentially for efficient assembly of sub-systems either produced in-house or outsourced.

Workstation Definition in Flow Line Production

• A workstation consists of necessary equipment along with skilled manpower or robots; it plays a crucial role in flow line production systems by facilitating rapid assembly processes.

Product Layout and Material Handling Systems

Overview of Product Layout

• The product layout involves a sequential flow where raw materials enter at one end, are processed by workstations, and result in semi-finished or finished products at the other end.

• Flexibility in product layout is low; changes in product design often require a complete redesign of the hardware involved.

• While product variety is limited to typically one type of product, efficiency remains high due to mass production capabilities.

Mass Production Systems

• Material handling systems for mass production utilize conveyors, robots, and indexing mechanisms for efficient movement of parts.

• In heavy manufacturing (e.g., airplanes, ships), equipment is arranged around the product itself due to its size and complexity.

Fixed Position Layout

• A fixed position layout is used for complex products that require multiple subsystems; processing occurs at the site rather than moving the product.

• Material handling equipment like forklifts or cranes are essential since conveyors would obstruct movement during assembly.

Unit Load Concept

• The unit load refers to a mass moved or handled simultaneously, which can be a single part or multiple parts on a pallet.

• Efficient management of logistics through unit loads reduces trips needed for material handling and minimizes loading/unloading times.

Transport Equipment in Industry

• Various transport equipment includes industrial trucks (manual/powered), automated guided vehicles, rail-guided vehicles, conveyors, cranes, and hoists.

• Non-powered trucks like hand-operated dollies are commonly used for lighter products; powered options assist in semi-automated industries.

Automated Guided Vehicles and Their Applications

Overview of Equipment for Bulk Handling

• The discussion begins with the necessity of equipment like forklifts to manage bulkier components such as dies, molds, tools, and raw materials in fixed position layouts.

• Forklifts utilize a hydraulic system for lifting heavy loads, which is powered by a robust engine that also operates the hydraulic mechanism.

Introduction to Automated Guided Vehicles (AGVs)

• AGVs are self-propelled vehicles that operate independently, utilizing onboard batteries with a lifespan of 8 to 16 hours.

• There are three primary types of AGVs: towing vehicles, pallet trucks, and unit load carriers. Each type serves specific functions in material handling.

Types and Functions of AGVs

• Towing trucks can be remotely controlled or self-propelled; they transport palletized commodities using forks.

• Unit load carriers have a low height design and handle only one pallet at a time, while pallet carriers can transport multiple dollies arranged sequentially.

Role of AGVs in Automated Storage Systems

• AGVs play an integral role in automated storage and retrieval systems (AS/RS), facilitating the movement of unit loads from receiving docks into storage.

• They efficiently retrieve stored pallets for delivery purposes at distribution centers, showcasing their importance in logistics operations.

Guidance Technologies for Navigation

• Five guidance technologies are utilized for navigating AGVs: embedded wires, paint strips, magnetic tapes, laser-based technology (LGVs), and gyroscopes (inertial navigation).

• Embedded guide wires generate low-frequency signals to create magnetic fields that help navigate AGVs along defined paths.

Advanced Navigation Techniques

• The embedded wire method involves cutting slots into the floor where wires are placed to guide the vehicles based on generated magnetic fields sensed by induction sensors.

• In complex environments with loops or branches, frequency select methods allow different frequencies in guide wires to direct AGV movements effectively.

AGV Navigation Techniques

Frequency-Based Path Selection

• AGVs (Automated Guided Vehicles) follow paths based on programmed frequencies. If the frequency matches the available branch path, the AGV will navigate that route.

• Electrical signals are sent to activate only the chosen path while deactivating all other unnecessary paths, ensuring efficient navigation.

Visual and Magnetic Navigation Methods

• Navigation can be achieved using painted strips with fluorescent particles that reflect ultraviolet light, detected by onboard sensors of the AGV.

• Alternatively, magnetic tapes can be used along defined pathways, allowing for easy reconfiguration without cutting into floor surfaces as required by embedded wire technology. This flexibility enables quick path changes.

Laser-Based Navigation Systems

• Laser-based AGVs do not require physical markers like wires or tapes; they utilize a combination of dead reckoning and reflective beacons for navigation. The laser continuously transmits signals that bounce off beacons to determine position.

• Dead reckoning allows AGVs to navigate without predefined pathways by calculating their location based on wheel rotations and steering angles during movement. This method enhances autonomy in navigating shop floors without physical guides.

Triangulation and Inertial Guidance

• Reflective beacons positioned strategically within factories enable triangulation to ascertain the current location of an AGV through reflected laser signals from multiple sources. This system supports self-sufficient navigation capabilities of AGVs inside manufacturing environments.

• Inertial guidance systems employ gyroscopes and motion sensors to track speed and acceleration changes, providing continuous positional data to ensure accurate navigation similar to technologies used in aircraft and submarines. Additionally, magnetic transponders may assist in verifying correct path adherence.

Crane Types in Manufacturing Automation

• Various cranes are utilized in manufacturing for handling heavy loads: bridge cranes (with horizontal beams supported on fixed rails), gantry cranes, and jib cranes are common types employed for lifting machinery parts or raw materials efficiently within industrial settings.

Bridge and Gantry Cranes: Overview and Applications

Understanding the Bridge Crane

• The hoist can move along the horizontal beam (x-axis), while the vertical movement occurs in the z-direction, allowing for object handling.

• Bridge cranes are essential in manufacturing industries for lifting heavy objects like large machinery and components, utilizing a rail system for horizontal movement.

• Common applications include power generation stations where large turbines and impellers need to be handled efficiently.

Exploring the Gantry Crane

• The gantry crane operates similarly to a bridge crane but has a lower handling capacity, suitable for smaller work parts.

• It features a bridge supported by one end on a runway and another on a gantry leg that moves over rails, making it versatile within warehouses or factory floors.

• Variations of gantry cranes include double gantries with two legs, half gantries with one leg supported by wall-mounted rails, and cantilever types extending beyond their support length.

Jib Crane Functionality

• A jib crane consists of a movable arm pivoted to a fixed column, allowing the hoist to lift items from the floor effectively.

• The arm's rotation around its axis enables coverage of considerable areas within shop floors through circular or semicircular sweeps.

Rail Guided Vehicles: Types and Benefits

Overview of Rail Guided Vehicles

• Rail guided vehicles are motorized units operating on fixed rail systems, driven by electric motors that draw power from electrified rails.

• Two main types exist: overhead monorails suspended from ceilings saving floor space, and parallel fixed rails protruding from the ground for vehicle movement.

Advantages of Rail Systems

• Overhead monorails allow efficient use of ground space as they carry materials above floor level, freeing up room for other operations.

• Parallel rail systems enable asynchronous vehicle movements powered by onboard electrical motors while offering flexibility in routing variations and speed adjustments easily.

Conveyors in Manufacturing Processes

Role of Conveyors

• Conveyors facilitate continuous or intermittent material transport across production lines, crucial for moving raw materials to finished products efficiently.

• They can be powered or non-powered; non-powered systems rely on human intervention or gravity-assisted mechanisms like slopes and rollers to convey materials effectively.

Material Transport Systems Overview

Types of Conveyor Systems

• Power systems are sophisticated methods for conveying commodities, requiring energy to perform work. Various conveyor types include roller, skate wheel, belt, in-floor towline, overhead trolley conveyors, and cart-on-track conveyors.

• The roller conveyor is a basic example of an automation system featuring rollers arranged perpendicular to the direction of travel. It consists of two frames with guideways and rollers connected between them, utilizing rolling friction for movement.

• Overhead trolley conveyors use motorized vehicles on a monorail to convey objects via hooks. This system is particularly effective for transporting dies and molds along the overhead track.

• Belt conveyors consist of a continuous loop driven by a motorized drive roller and supported by an idler roller. They can transport various materials including food grains and cement bags but have limitations as only half the belt length is utilized at any time.

• Variants of belt conveyors include flat belts and troughed belts. These systems are versatile enough to handle both solid and loose commodities as well as flat-bottomed materials like cartons or boxes.

Rotary Indexing Tables

• Rotary indexing tables are essential in assembly operations where raw materials are processed at multiple workstations arranged around a rotating table. The table indexes clockwise to facilitate processing at each station.

• The rotary indexing table functions as a conveyance system itself; it allows parts positioned at each station to undergo various assembly or processing tasks efficiently.

• Common applications for rotary indexing tables include assembling watches, jewelry, electronic circuitry, small molds or dies, and consumer appliances.

Summary of Lecture Content

• This lecture covered material transport systems' definitions and logistics concepts while discussing different variants and applications such as cranes, trucks, rail-guided systems among others.