Chapter 2 : Automated Production System

Transcription

1 Chapter 2 : Automated Production System Work Cell Automation : Single Station Automated Cells System Automated Production Line Automated Assembly System Industrial Robotic Application Automated Material Transfer & AS/RS: Conveyor System Rotary Indexing Table X-Y Table AGV AS/RS

2 Single Station Automated Cells System Introduction Most common manufacturing system in industry Operation is independent of other stations Perform either processing or assembly operations Can be designed for: 1. Single model production 2. Batch production 3. Mixed model production Classification of Single-Station Manufacturing Cells

3 Single Station Automated Cells System Single-Station Manned Cell One worker tending one production machine (most common model) Most widely used production method, especially in job shop and batch production Reasons for popularity: 1. Shortest time to implement 2. Requires least capital investment 3. Easiest to install and operate 4. Typically, the lowest unit cost for low production 5. Most flexible for product or part changeovers Example: Worker operating a standard machine tool Worker loads & unloads parts, operates machine Machine is manually operated Worker operating semi-automatic machine Worker loads & unloads parts, starts semi-automatic work cycle Worker attention not required continuously during entire work cycle Worker using hand tools or portable power tools at one location

4 Single Station Automated Cells System Single-Station Automated Cell Fully automated production machine capable of operating unattended for longer than one work cycle Worker not required except for periodic tending Reasons why it is important: 1. Labor cost is reduced 2. Easiest and least expensive automated system to implement 3. Production rates usually higher than manned cell 4. First step in implementing an integrated multi-station automated system

5 Single Station Automated Cells System Enablers for Unattended Cell Operation a) For single model and batch model production: Programmed operation for all steps in work cycle Parts storage subsystem Automatic loading, unloading, and transfer between parts storage subsystem and machine Periodic attention of worker for removal of finished work units, re-supply of starting work units, and other machine tending Built-in safeguards to avoid self-destructive operation or damage to work units b) For mixed model production: All of the preceding enablers, plus: Work unit identification: Automatic identification (e.g., bar codes) or sensors that recognize alternative features of starting units If starting units are the same, work unit identification is unnecessary Capability to download programs for each work unit style (programs prepared in advance) Capability for quick changeover of physical setup

6 Single Station Automated Cells System Applications of Single Station Automated Cells CNC MC with Automated Pallet Changer (APC) and parts storage subsystem CNC TC with robot and parts storage carousel Cluster of ten CNC TCs, each with robot and parts storage carousel, and time sharing of one worker to load/unload the carousels Plastic injection molding on automatic cycle with robot arm to unload molding, sprue, and runner Electronics assembly station with automated insertion machine inserting components into PCBs Stamping press stamps parts from long coil

7 Single Station Automated Cells System Example of Single Station Automated Cells 1) CNC Machining Center Machine tool capable of performing multiple operations that use rotating tools on a workpart in one setup under NC control Typical operations: milling, drilling, and related operations Typical features to reduce nonproductive time: 1. Automatic tool changer 2. Automatic workpart positioning 3. Automatic pallet changer

8 Single Station Automated Cells System Analysis of Single Station System The number of workstation required Number of machine cluster Number of work station required Workload (WL) for process and machine cycle time for each work WL = Q Tc WL = workload schedule for a given period work/hour or work/week etc Q = quantity to be produced during the period Tc = cycle time required per piece Workload using work-rate (Wr) with scrap (Sp) WL = Q / Wr (1- Sc) Available time for one station in period (year), AT AT = total operating hour - set up hour Number of workstation n = WL/AT AT = available time on one station in period

9 Single Station Automated Cells System Example 1

10 Single Station Automated Cells System Example 2 (based on no. of setup)

11 Single Station Automated Cells System Number of machine cluster for no machine idle is allowed n = (Tm + Ts) / (Ts + Tr) n = number of machine Tm = machine semi automatic cycle time, Ts = worker service time Tr = worker repositioning time between machine Corresponding numbers of machine to assign the worker n1 = maximum integer (Tm + Ts) / (Ts + Tr) Machine cluster production rate per hour Rc = n (60/Tc) where Tc is cycle time required per piece in minute

12 Single Station Automated Cells System Example 1:

13 Automated Production Lines Automated Production Lines High production of parts requiring multiple processing operations Fixed automation Applications: Transfer lines used for machining Robotic spot welding lines in automotive final assembly Sheet metal stamping Electroplating of metals Where to Use Automated Production Lines High product demand - requires large production quantities Stable product design -difficult to change the sequence and content of processing operations once the line is built Long product life -at least several years Multiple operations required on product -the different operations are assigned to different workstations in the line

14 Automated Production Lines Benefits of Automated Production Lines Low direct labor content Low product cost High production rates Production lead time and work-in-process are minimized Factory floor space is minimized Automated Production Line Defined Fixed-routing manufacturing system that consists of multiple workstations linked together by a material handling system to transfer parts from one station to the next. Slowest workstation sets the pace of the line Work part transfer: Palletized transfer line - uses pallet fixtures to hold and move work parts between stations Free transfer line - part geometry allows transfer without pallet fixtures

15 Automated Production Lines General configuration of an automated production line consisting of n automated workstations that perform processing operations System Configurations 1. In-line - straight line arrangement of workstations 2. Segmented in-line two or more straight line segments, usually perpendicular to each other 3. Rotary indexing machine (e.g., dial indexing machine)

16 Automated Production Lines 2) Segmented In-Line Configurations L shape layout U shape layout Rectangular configuration

17 Automated Production Lines Example: Two machine transfer line. Locate the in-line and segmented transfer line in this figure?

18 Automated Production Lines 3) Rotary Indexing Machine Part is attach to fixture around the periphery of circular worktable Table is rotate at fixed angle Commonly limited to smaller workparts and fewer workstation and cannot accommodate buffer storage capacity Benefit - less expensive and less floor space

19 Automated Production Lines Workpart Transfer Mechanisms 1.Linear transfer systems: Continuous motion not common for automated systems Synchronous motion intermittent motion, all parts move simultaneously Asynchronous motion intermittent motion, parts move independently 2.Rotary indexing mechanisms: Geneva mechanism Others Belt-Driven Linear Transfer System

20 Automated Production Lines Geneva Mechanism with Six Slots Cam Mechanism to Drive Dial Indexing Table

21 Automated Production Lines Storage Buffers in Production Lines A location in the sequence of workstations where parts can be collected and temporarily stored before proceeding to subsequent downstream stations Reasons for using storage buffers: 1. To reduce effect of station breakdowns 2. To provide a bank of parts to supply the line 3. To provide a place to put the output of the line 4. To allow curing time or other required delay 5. To smooth cycle time variations 6. To store parts between stages with different production rates Example : Storage buffer between two stages of a production line

22 Automated Production Lines Control Functions in an Automated Production Line 1) Sequence control - to coordinate the sequence of actions of the transfer system and workstations 2)Safety monitoring -to avoid hazardous operation for workers and equipment 3)Quality control - to detect and possibly reject defective work units produced on the line Data collection in Automated Production Line - Manual operator write down the reject part/product -RFID the pallet using to transfer the product is equip with RFID tag. Every time the pallet past each station RFID sensor will trigger and past the data to dedicated data collection system or PC -Barcode each product have own dedicated barcode number that store product id (location, date or batch etc..). Normally bar code scanner are installed at each critical process to detect product condition either pass or reject.

23 Automated Assembly Systems Definition The use of mechanized and automated devices to perform the various assembly tasks in an assembly line or cell Fixed automation usually - most automated assembly systems are designed to perform a fixed sequence of assembly steps on a specific product that is produced in very large quantities Automated Assembly -Application Characteristics Where is automated assembly appropriate: High product demand Stable product design The assembly consists of no more than a limited number of components The product is designed for automated assembly

24 Automated Assembly Systems Assembly Processes in Automated Assembly Adhesive bonding Snap fitting Insertion of components Soldering Placement of components Spot welding Riveting Stapling Screw fastening Stitching System Configurations In-line assembly machine Dial indexing machine Carousel assembly system Single-station assembly cell

25 Automated Assembly Systems In-Line Assembly Machine A series of automatic workstations located along and in-line transfer system Either synchronous or asynchronous work transfer used

26 Automated Assembly Systems Dial Indexing Machine Base parts are loaded onto fixtures or nests attached to a circular dial table, and components are added at workstations located around the periphery of the dial as it indexes from station to station

27 Automated Assembly Systems Carousel Assembly System A hybrid between circular work flow of dial indexing machine and straight work flow of in-line system

28 Automated Assembly Systems Single-Station Assembly Cell Assembly operations are performed on a base part at a single location A robot is sometimes used as the assembly machine

29 Automated Assembly Systems Multi-Station vs. Single-Station Multi-station assembly machine or line Faster cycle rate High production quantities More operations possible More components per assembly Single-station assembly cell Suited to robotic assembly Intended for lower production quantities Parts Delivery at Workstations Typical parts delivery system at a workstation consists of the following hardware components: 1. Hopper - container for parts 2. Parts feeder - removes parts from hopper 3. Selector and/or orientor - to assure part is in proper orientation for assembly at workhead 4. Feed track - moves parts to assembly workhead 5. Escapement and placement device - removes parts from feed track and places them at station

30 Automated Assembly Systems Hopper - container for parts

31 Automated Assembly Systems Vibratory Bowl Feeder Most versatile of hopper feeders for small parts Consists of bowl and helical track Parts are poured into bowl Helical track moves part from bottom of bowl to outlet Vibration applied by electromagnetic base Oscillation of bowl is constrained so that parts climb upward along helical track

32 Automated Assembly Systems Selector and/or Orientor Purpose - to establish the proper orientation of the components for the assembly workhead Selector -Acts as a filter -Only parts in proper orientation are allowed to pass through to feed track Orientor Allows properly oriented parts to pass Reorients parts that are not properly oriented

33 Automated Assembly Systems Feed Track Moves parts from hopper to assembly workhead Categories: Gravity - hopper and feeder are located at higher elevation than workhead Powered - uses air or vibration to move parts toward workhead Escapement and Placement Devices Escapement device Removes parts from feed track at time intervals that are consistent with the cycle time of the assembly workhead Placement device Physically places the parts in the correct location at the assembly workstation Escapement and placement devices are sometimes the same device, sometimes different devices

34 Automated Assembly Systems (a) Horizontal and (b) vertical devices for placement of parts onto dial-indexing table Escapement of rivet-shaped parts actuated by work carriers

35 Automated Assembly Systems Two types of pick-and-place mechanisms for transferring base parts from feeders to work carriers

36 Automated Assembly Systems Quantitative Analysis of Assembly Systems Parts delivery system at workstations The parts delivery system at each station must deliver components to the assembly operation at a net rate that is greater than or equal to the cycle rate of the assembly work head Otherwise, assembly system performance is limited by the parts delivery system rather than the assembly process technology Component quality has an important effect on system performance - poor quality means - jams at stations that stop the entire assembly system -assembly of defective components in the product Multi-station assembly machines As the number of stations increases, uptime efficiency and production rate are adversely affected due to parts quality and station reliability effects The cycle time of a multi-station assembly system is determined by its slowest station Multi-station assembly systems are appropriate for high production applications and long production runs

37 Industrial Robotic Applications ROBOT APPLICATIONS The important factor of an industrial environment to promote the use of a robot to replace human labour: Work environment hazardous for human beings Repetitive tasks and multi-shift operations Boring, unpleasant task and infrequent changeovers Performing at a steady pace Operating for long hours without rest Responding in automated operations Minimizing variation Industrial robot applications that tend to match these characteristic can be divided into four basic categories: Material handling applications Processing operations Assembly operations Inspection operations

38 Industrial Robotic Applications MATERIAL HANDLING APPLICATION Material handling applications involve the movement of material or parts from one location to another. Materials may be the raw material that goes into production or product ready for shipment. A robot to accomplish the transfer of materials is equipped with a gripper-type end effector. The gripper must be designed to handle the specific part or parts to move in the applications. The robot must have the following features: The manipulator must be able to lift the part safely The robot must have the reach needed The robot must be a cylindrical coordinate type The robot controller must have a large enough memory to store all of the programmed points so that the robot can move from one location to another The robot must have the speed necessary for meeting the transfer cycle of the operation

39 Industrial Robotic Applications Robot Application in material Handling 1) Part Placement Pick and place operation, pick up parts at one location and place them at a new location (transferring a part from one conveyor to another). A low technology robot of cylindrical coordinate type is usually sufficient pneumatically powered robots are often utilized. 2)Palletising and Depalletizing Many material-handling applications require the robot to stack parts one top of the other, that is, palletize them or to unstack parts by removing from the top one by one, that is, depalletize them. Palletising: could be the process of taking parts from an assembly line and stacking them into pallet. Depalletizing is the opposite. It could be the process of taking the parts off the pallet and placing them on the assembly line.

40 Industrial Robotic Applications 3)Machine Loading And Unloading The robot transfer parts into and/or from a production machine. There are three possible cases: Machine loading in which the robot loads parts into a production machine, but the parts are unloaded by some other means. Machine unloading in which the raw materials are fed into machine without robot assistance. The robot unloads the part from the machine assisted by vision or no vision. Machine loading and unloading that involves both loading and unloading of the work parts by the robot. The robot loads a raw part into process and unloads finished parts. Processes involved: Die casting, Plastic molding, metal-machining operations, press working, heat treating 4) Stacking And Insertion Operation It s the process in which the robot places flat parts on top of each other, where the vertical location of the drop-off position is continuously changing with each cycle. The inserting operation is the process where the robot inserts parts into components of divided carton.

41 Industrial Robotic Applications PROCESSING OPERATIONS Processing operations are those in which the robot performs a processing procedure on the part. The robot is equipped with some type of process tooling as its end effector, in order to perform the process, manipulates its tooling relative to the work part during the cycle. Processing operation: Spot welding/continuous arc welding Spray painting Metal cutting and deburring operations Various machining operation like drilling, grinding, laser and water-jet cutting Adhesives and sealants dispensing

42 Industrial Robotic Applications 1) Spot Welding: Spot welding is a metal joining process in which two sheet metal parts are fused together at localized points of contact. Types of robot used are usually large, with sufficient payload capacity to wield the heavy welding gun. Five or six axes needed to achieve the positioning and orientations required. Playback robots with point to point control are used and the programming is accomplished using the powered teach-pendant method. Jointed-arm and polar coordinate robots are the most common anatomies in the automobile spot welding lines.

43 Industrial Robotic Applications 2)Spray Painting The spray painting process makes use of spray gun directed at the object to be painted. Fluid flow through the nozzle of the spray gun to be dispersed and applied over the surface. The robot application: Spray painting for appliances, automobile car bodies, engines. Others including porcelain coatings and bathroom fixtures. The robot must be capable of continuous path control to accomplish the smooth motion sequences required in spray painting. Most convenient programming method is the manual teach-pendant. Most common anatomy: jointed-arm robot. The robot must posses a long reach in order to access of the work part to be painted in the application. Advantages: Human are removed from hostile environment. Less energy is needed for fresh air requirement and the need for protective clothing is reduced. Greater uniformity in paint application. Lower needs for ventilating the work area. The quality of painting is improved, reducing rework and warranty codes. Less paint and other materials are used.

44 Industrial Robotic Applications ASSEMBLY OPERATIONS The application involved both material handling and the manipulation of a tool. Included components to build the product and to perform material handling operation. In some cases, the fastening of the operations requires a special tool to be used by the robot. Robots applications are classified as batch assembly or low volume assembly: 1. In batch assembly, as many as one million products might be assembled, have long run production operation and required the same repetitive assembly routine. 2. In low-volume assembly, a sample run of ten thousand or less product might be made. The design of the parts that can be assembled by the robot need to be concerned: 1. The robot s end effector must be able to easily pick-up and assemble the parts. 2. Minimizing the number of parts required in robotic assembly is a big advantage.

45 Industrial Robotic Applications Small parts assembly generally involves parts weighing no more than a few pounds. Electrically powered robots can handle these small parts very accurate positioning of their manipulators. Using remote sensor compliance (RCC) devices in their grippers AS/RS throughput analysis helps them overcome any minor part misalignment that may occur. Most common configuration: jointed arm, SCARA and Cartesian coordinate. Programming is often dine using a machine programming language, together with a powered teach pendant to teach locations in work cell.

46 Industrial Robotic Applications Accuracy requirement in assembly work are often more demanding than any other robot application, some have repeatability as close as ±0.0001inch. The end effectors may be required to perform multiple functions at a single workstation in order to reduce the number of robots in the production line. INSPECTION OPERATIONS Inspection task can usually be divided into the following techniques: By using feeler gauge or a linear displacement transducer or linear variable differential transformer (LVDT). The part being measured will come in physical contact with the instrument or by means of air pressure, which will cause it to ride above the surface being measured. By utilizing robotic vision, matrix video cameras are used to obtain an image of the area interest, which is digitised and compared to a similar image with specified tolerances. By involving the use of optics and light, usually a laser of infrared source is used to illustrate the area of interest. Reflections are captured by receiving optics, which convert the data into digital code.

47 Automated Material Transfer & AS/RS: Introduction The movement, storage, protection and control of materials throughout the manufacturing and distribution process including their consumption and disposal (The Material Handling Industry of America) Handling of materials must be performed Safely Efficiently At low cost In a timely manner Accurately (the right materials in the right quantities to the right locations, position and orientation) And without damage to the materials

48 Automated Material Transfer & AS/RS: Design Considerations in Material Handling Material characteristics Flow rate, routing, and scheduling Plant layout Unit load principle Flow rate - amount of material moved per unit time (pieces/hr, pallet loads/hr) Whether the material must be moved in individual units, as batches, or continuously Routing - pick-up and drop-off locations, move distances, routing variations, conditions along the route Scheduling - timing of each delivery. Prompt delivery when required. Use of buffer stocks to mitigate against late deliveries Material characteristics : Solid, liquid or gas Size, Weight, Shape - long, flat, bulky Condition - hot, cold, wet, dirty Risk of damage - fragile, brittle, sturdy Safety risk - explosive, flammable, toxic, corrosive

49 Automated Material Transfer & AS/RS: Plan Layout Material handling equipment considerations must be included in the plant layout design problem Correlation between layout type and material handling equipment: Plant layout type Material handling equipment Process Hand trucks, forklift trucks, AGVS Product Conveyors for product flow Unit Load The unit load should be as large as practical for the material handling system that will move and store it. A unit load is the mass that is to be moved or otherwise handled at one time Reasons for using unit loads in material handling: Multiple items handled simultaneously Required number of trips is reduced Loading/unloading times are reduced Product damage is decreased

50 Automated Material Transfer & AS/RS: Material Transfer System There many type of material transfer system. Common material transfer usually using following system. Conveyor system Rotary Index table X-Y table Automated Guided Vehicle (AGV) Pick and Place Robot Material transfer system play very important role to move part or component from magazine to process station (load and unload) or from machine to another machine to perform manufacturing process. Example of Material Transfer Video using conveyor and Gantry Robot

51 Automated Material Transfer & AS/RS: Conveyor system 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 transportation of heavy or bulky materials. Conveyor systems allow quick and efficient transportation for a wide variety of materials, which make them very popular in the material handling and packaging industries. Many kinds of conveying systems are available, and are used according to the various needs of different industries. Conveyors are able to safely transport materials from one level to another, which when done by human labour would be strenuous and expensive. Can be installed almost anywhere, and are much safer than using a forklift or other machine to move materials.

52 Automated Material Transfer & AS/RS: Conveyor system They can move loads of all shapes, sizes and weights. Also, many have advanced safety features that help prevent accidents. There are a variety of options available for running conveying systems, including the hydraulic, mechanical and fully automated systems, which are equipped to fit individual needs. Many factors are important in the accurate selection of a conveyor system. It is important to know how the conveyor system will be used beforehand. Conveyor design consideration Type of transportation, accumulation and sorting, Type of material sizes, weights and shapes Loading and pickup points need to be.

53 Automated Material Transfer & AS/RS: Conveyor system Types of Conveyor System 1. Gravity Roller Conveyor 2. Gravity Skatewheel Conveyor 3. Belt conveyor 4. Plastic Belt 5. Belt Driven Live Roller 6. Chain conveyor 7. Chain Driven Live Roller Conveyor 8. Pneumatic Conveyor 9. Flexible conveyor system Types of motions Continuous - conveyor moves at constant velocity Asynchronous - conveyor moves with stop-and-go motion - They stop at stations, move between stations Another classification of conveyors: Single direction Continuous loop Recirculating

54 Automated Material Transfer & AS/RS: Conveyor system Single-Direction Conveyor and Continuous Loop Conveyor (a) Single direction conveyor (b) Continuous loop conveyor

55 Automated Material Transfer & AS/RS: Conveyor system Belt conveyor A belt conveyor consists of two or more pulleys, with a continuous loop of material - the conveyor belt - that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward.the powered pulley is called the drive pulley while the unpowered pulley is called the idler. There are two main industrial classes of belt conveyors; Those in general material handling such as those moving boxes along inside a factory bulk material handling such as those used to transport industrial and agricultural materials, such as grain, coal, ores, etc. generally in outdoor locations.

56 Automated Material Transfer & AS/RS: Conveyor system Continuous loop with forward path to move loads Belt is made of reinforced elastomer material. Many belts in general material handling have two layers. An under layer of material to provide linear strength and shape called a carcass and an over layer called the cover. The carcass is often a cotton or plastic web or mesh. The cover is often various rubber or plastic compounds specified by use of the belt Support slider or rollers used to support forward loop Two common forms: 1. Flat belt 2. V-shaped for bulk materials

57 Automated Material Transfer & AS/RS: Conveyor system Chain conveyor Chain conveyors utilise a powered continuous chain arrangement, carrying a series of single pendants. The chain arrangement is driven by an a motor, and the material suspended on the pendants are conveyed. Many industry sectors use chain conveyor technology in their production lines. The automotive industry commonly uses chain conveyor systems to convey car parts through paint plants. Chain conveyors also have widespread use in the white and brown goods, metal finishing and distribution industries.

58 Automated Material Transfer & AS/RS: Conveyor system Flexible Conveyor Systems The flexible conveyor is based on a conveyor beam in aluminum or stainless steel, with low friction slide rails guiding a plastic multi-flexing chain. Products to be conveyed travel directly on the conveyor or on pallets/carriers. Standard conveying applications can be specified. This includes 1.Straight conveyors 2.Conveyors with one or two bends 3.Wedge conveyors 4.Conveyor support

59 Automated Material Transfer & AS/RS: Conveyor system Pneumatic Conveyor Systems Pneumatic conveyor system makes use of pipes or ducts called transportation lines that carry mixture of materials and a stream of air. These materials are such as dry pulverised or free flowing or light powdery materials like cement, etc. The materials can be transported conveniently to various destinations by means of a stream of high velocity air through pipe lines. Products are moved through various tubes via air pressure, allowing for extra vertical versatility.

60 Automated Material Transfer & AS/RS: Conveyor system 2 type of pneumatic conveyors: 1. Carrier systems - carrier systems simply push items from one entry point to one exit point 2. Dillute-phase systems - use push/pull pressure to guide materials through various entry and/or exit points. Three basic systems that are used to generate high velocity air stream: 1. Suction or Vacuum systems 2. Pressure Type systems 3. Combination system

61 Automated Material Transfer & AS/RS: Rotary Indexing Table A rotary index table is a device used to convey parts for assembly, machining, packaging, finishing, or other manufacturing operations. This index device conveys the parts in a rotary or dial motion, stopping intermittently in station "to dwell" for a fixed period of time. The dwell time and index time between stations are programmed and variable. The number of index stations of a rotary index table is predetermined and specified at the time of purchase or set-up. Stations range from a minimum of two up to thirty-six in a 360 work circle.

62 Automated Material Transfer & AS/RS: Rotary Indexing Table Stations on a rotary index table are typically set at 20, 40, 60, 120, 180 degree etc. Rotary index tables provide controlled acceleration and deceleration from station to station in a clockwise or counterclockwise mode. Index times can be as low as.20 seconds, and over 150 cycles per minute. Rotary index table diameters range from 5" to 40". Electric motors are the most common drive source, however, rotary index tables can be driven by air and fluid motors. Most rotary index tables are dedicated and installed in automatic machines. Rotary index tables are specified based on inertia load capacity, work circle radius, and speed of index time.

63 Automated Material Transfer & AS/RS: X-Y Table X-Y table is a device used to convey parts for assembly, machining, packaging, finishing, inspection or other manufacturing operations. This X-Y table device conveys the parts in a linear motion in x and y axis for positioning within axis working area. It consist of two rotary actuator (servo motor) and come-with precession motor controller.

64 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) Storage System Function to store materials (e.g., parts, work-in-process, finished goods) for a period of time and permit retrieval when required Used in factories, warehouses, distribution centers, wholesale dealerships, and retail stores Important supply chain component Automation available to improve efficiency Storage performance Storage capacity : 1) Total volumetric spac 2) Total number of storage compartments (e.g., unit loads) Storage density - volumetric space available for storage relative to total volumetric space in facility Accessibility - capability to access any item in storage System throughput - hourly rate of storage/retrieval transactions Utilization and availability (reliability)

65 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) Automated Storage System Mechanized and automated storage equipment to reduce the human resources required to operate a storage facility Significant investment Level of automation varies In mechanized systems, an operator participates in each storage/retrieval transaction In highly automated systems, loads are entered or retrieved under computer control

66 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) Objectives and Reasons for Automating Storage Operations To increase storage capacity To increase storage density To recover factory floor space currently used for WIP To improve security and reduce pilferage To reduce labor cost and/or increase productivity To improve safety To improve inventory control To improve stock rotation To improve customer service To increase throughput

67 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) Types of Automated Storage System Automated Storage/Retrieval System (AS/RS) - Rack system with mechanized or automated crane to store/retrieve loads Carousel Storage System - Oval conveyor system with bins to contain individual items AS/RS Type Unit load AS/RS - large automated system for pallet loads Deep-lane AS/RS - uses flow-through racks and fewer access aisles Miniload AS/RS - handles small loads contained in bins or drawers to perform order picking Man-on-board AS/RS - human operator rides on the carriage to pick individual items from storage Automated item retrieval system - picks individual items Vertical lift storage modules (VLSM) - uses a vertical aisle rather than a horizontal aisle as in other AS/RS types

68 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) Unit load AS/RS with one aisle

69 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS)

70 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) AS/RS Applications Unit load storage and retrieval Warehousing and distribution operations AS/RS types: unit load, deep lane (food industry) Order picking AS/RS types: miniload, man-on-board, item retrieval Work-in-process storage Helps to manage WIP in factory operations Buffer storage between operations with different production rates Supports JIT manufacturing strategy

71 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) Justification for installation of AS/RS for WIP Buffer storage in production buffer storage for two processes whose production rates are significantly different. Support of JIT delivery Kitting of parts for assembly Compatible with automatic ID system barcode or RFID Computer control and tracking materials combine with ID system permits the location, WIP status and product history Support of factory-wide automation

72 Automated Material Transfer & AS/RS: Automated Storage & Retrieval System (AS/RS) AS/RS Component 1. Storage structure rack of framework which support the loads contained in AS/RS and to support the aisle hardware required to align the S/R machine 2. S/R machine to accomplish storage transactions, delivering loads from input stations into storage, retrieving loads from storage and delivering them to output station.3 drive system are required (horizontal, vertical and shuttle transfer) 3. Storage module unit load containers of stored material (pallet, steel wire baskets, tote pans). Generally standard size and can be automatically handled by carrier shuttle 4. Pickup-and-deposit station location where loads are transferred into and out of AS/RS

73 Automated Material Transfer & AS/RS: Carousel Storage Systems There are two types of Carousel Storage Systems Horizontal Operation is similar to overhead conveyor system used in dry cleaning establishments Items are stored in bins suspended from the conveyor Lengths range between 3 m and 30 m Horizontal is most common type Vertical Operates around a vertical conveyor loop Less floor space required, but overhead room must be provided

74 Automated Material Transfer & AS/RS: Carousel Storage Systems Horizontal Vertical

75 Automated Material Transfer & AS/RS: Carousel Storage Systems Horizontal Carousel Storage System 1) Overhead system (top driven unit) 2) Floor mounted system (bottom drive unit) Overhead system-motorized pulley system mounted at the top of framework and drive the overhead trolley system. Bins are suspended from the trolley. Floor mounted system-motorized pulley system mounted at the base of framework. Trolley system rides on a rail in the base. Can carry more load compared to overhead system.

76 Automated Material Transfer & AS/RS: Carousel Storage Systems Carousel Applications Storage and retrieval operations Order picking Kitting of parts for assembly Transport and accumulation Progressive assembly with assembly stations located around carousel Work-in-process WIP applications in electronics industry are common

77 Automated Material Transfer & AS/RS: Carousel Storage Systems Difference between AS/RS and Carousel Storage System Feature AS/RS Carousel Storage System Storage structure Rack system to support pallets or shelf system to support tote bins Baskets suspended from overhead convey or trolleys Motions Linear motion of S/R machine Revolution of overhead conveyor trolley around oval track Storage/retrieval operation Replicable of storage capacity S/R machine travels to compartment in rack structure Multiple aisles, each consisting of rack structure and S/R machine Conveyor revolves to bring baskets to load/unload station Multiple carousels, each consisting of oval track and suspended bins

78 Automated Material Transfer & AS/RS: Engineering Analysis of Automated Storage Systems Automated Storage/Retrieval Systems Sizing the AS/RS AS/RS throughput analysis Carousel storage systems Storage capacity Throughput analysis

79 Automated Material Transfer & AS/RS: Engineering Analysis of Automated Storage Systems Sizing the AS/RS Capacity per aisle = 2nynz ny number of load compartment along length nz number of load compartment that make height of the aisle AS/RS size Width, W = 3 (x + a) Length, L = ny (y +b) Height, H = nz (z + c) a, b and c is allowance in storage compartment to provide clearance for unit load

80 Automated Material Transfer & AS/RS: Engineering Analysis of Automated Storage Systems Example 1:

81 Automated Material Transfer & AS/RS: Engineering Analysis of Automated Storage Systems Example 2:

82 Automated Material Transfer & AS/RS: AS/RS throughput analysis System throughput the hourly rate of AS/RS transactions that the automated storage system can perform. A transaction involves depositing a load into storage or retrieving a load from storage.two type single command and dual command Single command given by: Dual command given by: Tcs cycle time of single command cycle Tcd - cycle time of dual command cycle L & H length and height Vy & Vz velocity along length and height Tpd pickup and deposit time

83 Automated Material Transfer & AS/RS: AS/RS throughput analysis Rcs Tcs + Rcd Tcd= 60 U Rcs number of single command cycle perform per hour Rcd number of dual command cycle perform per hour U system utilization during the hour Total hourly cycle, Total number of transaction per hour Rc = Rcs + Rcd Rt = Rcs + 2Rcd

84 Automated Material Transfer & AS/RS: AS/RS throughput analysis Example 1:

85 Automated Material Transfer & AS/RS: AS/RS throughput analysis Example 2:

86 Automated Material Transfer & AS/RS: Carousel Storage Systems Storage capacity Total number of bins = ncnb Size of carousel system determine by C = 2 (L W) + πw C- circumference of oval conveyor track L and W is length and width of oval track C = ncsc sc carrier spacing S/R cycle time, Tc Tc = C/4Vc + Tpd Vc carousel speed Tpd the average time to pick or deposit in each cycle Hourly Transaction, Rt Rt = 60/Tc

87 Automated Material Transfer & AS/RS: Carousel Storage Systems Example 1: Example 2: