Material handling involves short-distance movement within the confines of a building or between a building and a transportation vehicle.[1] It uses a wide range of manual, semi-automated, and automated equipment and includes consideration of the protection, storage, and control of materials throughout their manufacturing, warehousing, distribution, consumption, and disposal.[2] Material handling can be used to create time and place utility through the handling, storage, and control of waste, as distinct from manufacturing, which creates form utility by changing the shape, form, and makeup of material.[3]
Material handling plays an important role in manufacturing and logistics. Almost every item of physical commerce has been transported on a conveyor or lift truck or another type of material handling equipment in manufacturing plants, warehouses, and retail stores. While material handling is usually required as part of every production worker's job, over 650,000 people in the U.S. work as dedicated "material moving machine operators" and have a median annual wage of $31,530 (May 2012).[4] These operators use material handling equipment to transport various goods in a variety of industrial settings including moving construction materials around building sites or moving goods onto ships.
Design of material handling systems
Material flow diagram between activities in a layout
Material handling is integral to the design of most production systems since the efficient flow of material between the activities of a production system is heavily dependent on the arrangement (or layout) of the activities. If two activities are adjacent to each other, then material might easily be handed from one activity to another. If activities are in sequence, a conveyor can move the material at low cost. If activities are separated, more expensive industrial trucks or overhead conveyors are required for transport. The high cost of using an industrial truck for material transport is due to both the labor costs of the operator and the negative impact on the performance of a production system (e.g., increased work in process) when multiple units of material are combined into a single transfer batch in order to reduce the number of trips required for transport.[5]
The unit load concept
Production batch can be split into a smaller transfer batch containing several unit loads, each of which can contain multiple parts
A unit load is either a single unit of an item, or multiple units so arranged or restricted that they can be handled as a single unit and maintain their integrity. Although granular, liquid, and gaseous materials can be transported in bulk, they can also be contained into unit loads using bags, drums, and cylinders.[6] Advantages of unit loads are that more items can be handled at the same time (thereby reducing the number of trips required, and potentially reducing handling costs, loading and unloading times, and product damage) and that it enables the use of standardized material handling equipment. Disadvantages of unit loads include the negative impact of batching on production system performance, and the cost of returning empty containers/pallets to their point of origin.[7]
Stretch-wrapping machine used to form a unit load
In-process handling
Unit loads can be used both for in-process handling and for distribution (receiving, storing, and shipping). Unit load design involves determining the type, size, weight, and configuration of the load; the equipment and method used to handle the load; and the methods of forming (or building) and breaking down the load. For in-process handling, unit loads should not be larger than the production batch size of parts in process. Large production batches (used to increase the utilization of bottleneck activities) can be split into smaller transfer batches for handling purposes, where each transfer batch contains one or more unit loads, and small unit loads can be combined into a larger transfer batch to allow more efficient transport.[8]
Distribution
Narrow-aisle lift truck used in distribution
Selecting a unit load size for distribution can be difficult because containers/pallets are usually available only in standard sizes and configurations; truck trailers, rail boxcars, and airplane cargo bays are limited in width, length, and height; and the number of feasible container/pallet sizes for a load may be limited due to the existing warehouse layout and storage rack configurations and customer package/carton size and retail store shelf restrictions. Also, the practical size of a unit load may be limited by the equipment and aisle space available and the need for safe material handling.[9]
Manual material handling work contributes to a large percentage of the over half a million cases of musculoskeletal disorders reported annually in the United States. Musculoskeletal disorders often involve strains and sprains to the lower back, shoulders, and upper limbs. They can result in protracted pain, disability, medical treatment, and financial stress for those afflicted with them, and employers often find themselves paying the bill, either directly or through workers’ compensation insurance, at the same time they must cope with the loss of the full capacity of their workers.[10][11]
Scientific evidence shows that effective ergonomic interventions can lower the physical demands of MMH work tasks, thereby lowering the incidence and severity of the musculoskeletal injuries they can cause. Their potential for reducing injury related costs alone make ergonomic interventions a useful tool for improving a company’s productivity, product quality, and overall business competitiveness. But very often productivity gets an additional and solid shot in the arm when managers and workers take a fresh look at how best to use energy, equipment, and exertion to get the job done in the most efficient, effective, and effortless way possible. Planning that applies these principles can result in big wins for all concerned.[10][11]
Types
Manual handling
NIOSH Lifting Equation applied to loading punch press stock task
Manual handling refers to the use of a worker’s hands to move individual containers by lifting, lowering, filling, emptying, or carrying them. It can expose workers to physical dangers that can lead to injuries: a large percentage of the over half a million cases of musculoskeletal disorders reported in the U.S. each year arise from manual handling, and often involve strains and sprains to a person's lower back, shoulders and upper limbs.[12]
Ergonomic improvements can be used to modify manual handling tasks to reduce injury. These improvements can include reconfiguring the task and using positioning equipment like lift/tilt/turn tables, hoists, balancers, and manipulators to reduce reaching and bending.[13] The NIOSH (National Institute for Occupational Safety and Health) 1991 Revised Lifting Equation[14] can be used to evaluate manual lifting tasks. Under ideal circumstances, the maximum recommended weight for manual lifting to avoid back injuries is 51lb (23.13kg). Using the exact conditions of the lift (height, distance lifted, weight, position of weight relative to body, asymmetrical lifts, and objects that are difficult to grasp), six multipliers are used to reduce the maximum recommended weight for less than ideal lifting tasks.
Automated handling
Industrial robot
Whenever technically and economically feasible, equipment can be used to reduce and sometimes replace the need to manually handle material. Most existing material handling equipment is only semi-automated because a human operator is needed for tasks like loading/unloading and driving that are difficult and/or too costly to fully automate. However, ongoing advances in sensing, machine intelligence, and robotics have made it possible to fully automate an increasing number of handling tasks.[15] A rough guide to determine how much can be spent for automated equipment that would replace one material handler is to consider that, with benefits, the median moving machine operator costs a company $45,432 per year.[16] Assuming a real interest rate of 1.7%[17] and a service life of 5 years[18] with no adoption/adaptation cost, no learning cost, no training cost, and no operating cost for equipment with no salvage value,[19] a company should be willing to pay up to
to purchase automated equipment to replace one worker.[20] In many cases, automated equipment is not as flexible as a human operator, both with respect to not being able to do a particular task as well as a human and not being able to be as easily redeployed to do other tasks as needs change.
Benefits of materials handling
Better efficiency: Material handling equipment helps streamline the movement of products. Compared to manual handling, materials handling equipment greatly saves time and effort.[21]
Improved safety: When manually handling goods, there are a lot of risks of injuries experienced e.g fall from heights. When unit load formation equipment is factored in, all these risks are reduced to almost zero.[22]
Cost savings: Materials handling equipment is designed to handle materials and products in a specific way, minimizing the risk of damage, therefore, saving costs that could have been spent on damaged goods.
Flexibility: Materials handling is customizable to meet the specific needs of different industries and operations, therefore offering a high degree of flexibility and versatility.
↑ $31,530 median wage divided by 0.694, where wages represent 69.4% and benefits 30.6% of total labor cost ( "Employer Costs for Employee Compensation". BLS. December 2014. Retrieved 2015-05-15.).
↑ Average U.S. rate from 2005-2009 ( "Real interest rate". The World Bank. Retrieved 2015-05-15.).
↑ Average service life of Custom Software ( "BEA Depreciation Estimates"(PDF). BEA. 2004. Retrieved 2015-05-15.), conservative assumption since software is a major component of automated equipment and has the shortest service life compared to other components.
↑ Conservative assumption that simplifies the analysis since any positive salvage value would increase the purchase cost estimate.
Logistics is the part of supply chain management that deals with the efficient forward and reverse flow of goods, services, and related information from the point of origin to the point of consumption according to the needs of customers. Logistics management is a component that holds the supply chain together. The resources managed in logistics may include tangible goods such as materials, equipment, and supplies, as well as food and other consumable items.
A forklift is a powered industrial truck used to lift and move materials over short distances. The forklift was developed in the early 20th century by various companies, including Clark, which made transmissions, and Yale & Towne Manufacturing, which made hoists. Since World War II, the use and development of the forklift truck have greatly expanded worldwide. Forklifts have become an indispensable piece of equipment in manufacturing and warehousing. In 2013, the top 20 manufacturers worldwide posted sales of $30.4 billion, with 944,405 machines sold.
Logistics automation is the application of computer software or automated machinery to improve the efficiency of logistics operations. Typically this refers to operations within a warehouse or distribution center, with broader tasks undertaken by supply chain engineering systems and enterprise resource planning systems.
A warehouse is a building for storing goods. Warehouses are used by manufacturers, importers, exporters, wholesalers, transport businesses, customs, etc. They are usually large plain buildings in industrial parks on the outskirts of cities, towns, or villages.
A lift table is a device that employs a scissors mechanism to raise or lower goods and/or persons. Typically lift tables are used to raise large, heavy loads through relatively small distances. Common applications include pallet handling, vehicle loading and work positioning. Lift tables are a recommended way to help reduce incidents of musculoskeletal disorders by correctly re-positioning work at a suitable height for operators. Lift tables lend themselves to being easily adapted to a specific use. They can work in hostile environments, be manufactured in stainless steel and have equipment like conveyors, turn-tables, barriers and gates easily added to their deckplates.
A distribution center for a set of products is a warehouse or other specialized building, often with refrigeration or air conditioning, which is stocked with products (goods) to be redistributed to retailers, to wholesalers, or directly to consumers. A distribution center is a principal part, the order processing element, of the entire order fulfillment process. Distribution centers are usually thought of as being demand driven. A distribution center can also be called a warehouse, a DC, a fulfillment center, a cross-dock facility, a bulk break center, and a package handling center. The name by which the distribution center is known is commonly based on the purpose of the operation. For example, a "retail distribution center" normally distributes goods to retail stores, an "order fulfillment center" commonly distributes goods directly to consumers, and a cross-dock facility stores little or no product but distributes goods to other destinations.
A waste collector, also known as a garbage man, garbage collector, trashman, binman or dustman, is a person employed by a public or private enterprise to collect and dispose of municipal solid waste (refuse) and recyclables from residential, commercial, industrial or other collection sites for further processing and waste disposal. Specialised waste collection vehicles featuring an array of automated functions are often deployed to assist waste collectors in reducing collection and transport time and for protection from exposure. Waste and recycling pickup work is physically demanding and usually exposes workers to an occupational hazard.
An automated guided vehicle (AGV), different from an autonomous mobile robot (AMR), is a portable robot that follows along marked long lines or wires on the floor, or uses radio waves, vision cameras, magnets, or lasers for navigation. They are most often used in industrial applications to transport heavy materials around a large industrial building, such as a factory or warehouse. Application of the automatic guided vehicle broadened during the late 20th century.
An automated storage and retrieval system consists of a variety of computer-controlled systems for automatically placing and retrieving loads from defined storage locations. Automated storage and retrieval systems (AS/RS) are typically used in applications where:
Automated Truck Loading Systems - ATLS has been commonly used in the material handling industry to refer to the automation of loading or unloading trucks and trailers with product either on or without pallets, slip sheets, racks, containers, using several different types of automated guided vehicle systems (AGV) or engineered conveyor belt systems that are integrated into vehicles, automating the shipping / receiving and logistics operations.
Musculoskeletal disorders (MSDs) are injuries or pain in the human musculoskeletal system, including the joints, ligaments, muscles, nerves, tendons, and structures that support limbs, neck and back. MSDs can arise from a sudden exertion, or they can arise from making the same motions repeatedly repetitive strain, or from repeated exposure to force, vibration, or awkward posture. Injuries and pain in the musculoskeletal system caused by acute traumatic events like a car accident or fall are not considered musculoskeletal disorders. MSDs can affect many different parts of the body including upper and lower back, neck, shoulders and extremities. Examples of MSDs include carpal tunnel syndrome, epicondylitis, tendinitis, back pain, tension neck syndrome, and hand-arm vibration syndrome.
Manual handling of loads (MHL) or manual material handling (MMH) involves the use of the human body to lift, lower, carry or transfer loads. The average person is exposed to manual lifting of loads in the work place, in recreational atmospheres, and even in the home. To properly protect one from injuring themselves, it can help to understand general body mechanics.
Material handling equipment (MHE) is mechanical equipment used for the movement, storage, control, and protection of materials, goods and products throughout the process of manufacturing, distribution, consumption, and disposal. The different types of equipment can be classified into four major categories: transport equipment, positioning equipment, unit load formation equipment, and storage equipment.
A conveyor system is a common piece of mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transport of heavy or bulky materials. Conveyor systems allow quick and efficient transport for a wide variety of materials, which make them very popular in the material handling and packaging industries. They also have popular consumer applications, as they are often found in supermarkets and airports, constituting the final leg of item/ bag delivery to customers. Many kinds of conveying systems are available and are used according to the various needs of different industries. There are chain conveyors as well. Chain conveyors consist of enclosed tracks, I-Beam, towline, power & free, and hand pushed trolleys.
Order processing is the process or work-flow associated with the picking, packing, and delivery of the packed items to a shipping carrier and is a key element of order fulfillment. Order processing operations or facilities are commonly called “distribution centers” or “DC 's”. There are wide variances in the level of automation associating to the “pick-pack-and-ship” process, ranging from completely manual and paper-driven to highly automated and completely mechanized; computer systems overseeing this process are generally referred to as Warehouse Management Systems or “WMS”.
Packaging machinery is used throughout all packaging operations, involving primary packages to distribution packs. This includes many packaging processes: fabrication, cleaning, filling, sealing, combining, labeling, overwrapping, palletizing.
Warehouse execution systems (WES) are computerized systems used in warehouses and distribution centers to manage and orchestrate the physical flow of products from receiving through shipping. Warehouses are storage facilities for raw materials and parts used in manufacturing operations; distribution centers (DCs) are facilities that store and distribute finished goods to retail locations, consumers, and other end customers.
Ergonomic hazards are physical conditions that may pose a risk of injury to the musculoskeletal system due to poor ergonomics. These hazards include awkward or static postures, high forces, repetitive motion, or short intervals between activities. The risk of injury is often magnified when multiple factors are present.
Engineering controls are strategies designed to protect workers from hazardous conditions by placing a barrier between the worker and the hazard or by removing a hazardous substance through air ventilation. Engineering controls involve a physical change to the workplace itself, rather than relying on workers' behavior or requiring workers to wear protective clothing.
Manual material handling (MMH) work contributes to a large percentage of the over half a million cases of musculoskeletal disorders reported annually in the United States. Musculoskeletal disorders often involve strains and sprains to the lower back, shoulders, and upper limbs. They can result in protracted pain, disability, medical treatment, and financial stress for those afflicted with them, and employers often fi nd themselves paying the bill, either directly or through workers’ compensation insurance, at the same time they must cope with the loss of the full capacity of their workers.
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