- Flexible Manufacturing System
- Process basis
- System composition
- Information control
- System type
- Flexible Manufacturing System – Definition, Process and Features
- History of Flexible Manufacturing Systems
- The Process of Flexible Manufacturing Systems
- Key Features of Flexible Manufacturing Systems
- Case Study: Toyota’s Lean Production System
Flexible Manufacturing System
The flexible manufacturing system consists of a unified information control system, material storage and transportation system and a set of digitally controlled processing equipment.
An automated manufacturing system that adapts to the transformation of machining objects.
The English abbreviation is FMS.
A group of machines arranged in sequence, connected by automated loading and unloading machines and integrated by computer systems.
Raw materials and finished parts are loaded and unloaded on the part transfer system.
After the part is processed on one machine, it is passed to the next machine.
Each machine accepts operational instructions and automatically loads and unloads the required tools without manual intervention.
In 1967, the British company Molins developed the “system 24” for the first time the basic concept of FMS proposed by Williamson.
Its main equipment is six multi-process CNC machine tools with modular structure.
The goal is to achieve continuous processing 24 hours a day, under unattended conditions.
However, it was not completed due to economic and technical difficulties.
In 1967, White Sunstone of the United States built the Omniline I system.
It consists of eight machining centers and two multi-axis drilling machines.
The workpieces are placed in a jig on the pallet and transported and machined between the machine tools in a fixed sequence in a fixed cycle.
This flexible automation device is suitable for use in small-volume, high-volume production.
It is similar in form to a traditional automatic production line, so it is also called a flexible automatic line.
Japan, the former Soviet Union, Germany, etc. have also carried out the development of FMS.
In 1976, Japan FANUC exhibited a flexible manufacturing unit (FMC) consisting of a machining center and industrial robots, which provided an important form of equipment for the development of FMS.
The Flexible Manufacturing Unit (FMC) generally consists of 12 CNC machine tools and material transfer devices.
There is a separate workpiece storage station and unit control system that can automatically load and unload workpieces on the machine and even automatically detect the workpiece.
Continuous production of limited processes is possible.
Suitable for multi-variety small batch production applications.
Over time, FMS has developed both technically and quantitatively.
In the practical stage, the FMS consisting of 3-5 devices is the most, but there are also larger systems that are put into use.
In 1982, Japan FANUC built an automated motor processing shop consisting of 60 flexible manufacturing units (including 50 industrial robots) and a three-dimensional warehouse.
Two other automatic guided trolleys convey the blank and the workpiece.
There is also an unmanned motor assembly shop that can run 24 hours a day.
This automated and unmanned workshop is an important step towards an automated factory that implements computer integration.
At the same time, there have been several basic features with only FMS.
However, the economical FMS, which is not fully automated, has made the design ideas and technical achievements of FMS popular.
The process basis of FMS is a group of technologies.
It determines the process according to the group of processing objects, selects the appropriate CNC machining equipment and the storage and transportation system of the workpiece, tools and other materials, and is controlled by the computer.
Therefore, it can automatically adjust and realize the batch and efficient production of a variety of workpieces within a certain range (ie, has “flexibility”), and can change products in time to meet market demand.
FMS combines both manufacturing and partial production management functions, so it can comprehensively improve production efficiency.
FMS’s process range is expanding and can include blank manufacturing, machining, assembly and quality inspection.
Most of the FMS put into use are used for cutting and also for stamping and welding.
The processing equipment mainly uses machining centers and CNC lathes.
The former is used to machine box and plate parts, while the latter is used to machine shaft and disk parts.
The FMS used in the production of medium and large batches of small varieties often uses a machining center with a replaceable headstock for higher production efficiency.
Storage and handling
The materials handled by the storage and handling system are blanks, workpieces, tools, fixtures, gauges and chips.
The method of storing materials has a flat tray warehouse and a large storage warehouse.
The blanks are typically loaded into the fixture on the pallet by the worker and stored in a specific area of the automated warehouse, which is then sent to the designated station by the automated handling system in accordance with the instructions of the material management computer.
The fixed-track trolley and the transfer raceway are suitable for arranging the FMS of the equipment in the order of the process, and the order of automatically guiding the conveyance of the trolley is independent of the arrangement position of the equipment, and has greater flexibility.
Industrial robots can transport and load workpieces from 1-4 machines to a limited extent.
For larger workpieces, the automatic pallet changer (APC) is often used for transport. Robots that travel on the track can also be used to complete the transfer and loading and unloading of the workpiece.
The worn tools can be removed one by one from the magazine, or the spare sub-tools can be used to replace the magazines filled with the tools to be changed.
The jaws of the lathe chuck, special clamps and the headstock of the special machining center can also be replaced automatically.
The chip handling and handling system is a necessary condition to ensure continuous FMS operation.
The economical structural solution is generally selected the shape of the chips, the amount of removal, and the processing requirements.
The FMS information control system has many structural forms, but generally adopts a hierarchical control system.
The first level is the computer numerical control device (CNC) of each process equipment, which realizes the control of each processing process.
The second level is a group control computer, which is responsible for distributing the production plan and numerical control commands from the third-level computer to the numerical control devices of the equipment in the first level, and reporting their operational status information to the upper computer.
The third level is the main computer (control computer) of the FMS. Its function is to formulate production operation plans, implement management of FMS operation status, and manage various data.
The fourth level is the management computer of the whole plant.
Software with complete performance is the foundation for implementing FMS functionality.
In addition to the system software that supports computer work, the number is more specialized application software developed according to the use requirements and user experience.
It generally includes control software (control machine tools, material storage and transportation systems, inspection devices and monitoring systems), planning management software (scheduling management, quality management, inventory management, tooling management, etc.) and data management software (simulation, retrieval and various databases) ), etc.
In order to ensure continuous automatic operation of the FMS, the tool and the cutting process must be monitored. Possible methods are:
- Measuring the current power output from the spindle motor of the machine tool, or the torque of the spindle;
- Using a sensor to pick up a signal that the tool is broken;
- Directly measure the change of the cutting edge size of the tool or the size of the workpiece working surface by means of the contact probe;
- Accumulate the cutting time of the tool for tool life management.
In addition, contact probes can be used to measure machine tool thermal deformation and workpiece mounting errors and compensate for them accordingly.
Flexible manufacturing refers to a manufacturing system that can adapt to changes in processing objects with the support of a computer.
There are three types of flexible manufacturing systems:
- Flexible manufacturing unit
The flexible manufacturing unit consists of one or several CNC machine tools or machining centers.
The unit can automatically change tools and fixtures as needed to machine different workpieces.
The flexible manufacturing unit is suitable for processing parts with complex shapes, simple processing steps, long processing time and small batch size.
It has greater equipment flexibility but low flexibility for personnel and processing.
- Flexible manufacturing system
The flexible manufacturing system is a production system consisting of a CNC machine tool or a machining center with a material conveying device.
The system is automatically controlled by an electronic computer, and can meet a variety of processing without stopping the machine.
The flexible manufacturing system is suitable for machining parts with complex shapes, many processing steps and large batch sizes.
Its processing and material handling are flexible, but the flexibility of personnel is still low.
- Flexible automatic production line
The flexible automatic production line is a production line consisting of a number of adjustable machine tools (mostly dedicated machine tools) combined with automatic transport devices.
The line can process large quantities of different gauge parts.
The flexible automatic production line with low flexibility is close to the automatic production line for mass production in performance.
The flexible automatic production line with high flexibility is close to the flexible manufacturing system for small batch and multi-variety production.
Flexible Manufacturing System – Definition, Process and Features
A Flexible Manufacturing System(FMS) is a manufacturing system in which there is a certain degree of flexibility that allows the system to react in the case of changes, whether predicted or unpredicted. Flexibility is the speed at which a system can react to and accommodate change.
To be considered flexible, the flexibility must exist during the entire life cycle of a product, from design to manufacturing to distribution.
Flexible Manufacturing System is a computer-controlled system that can produce a variety of parts or products in any order, without the time-consuming task of changing machine setups.
The flexibility being talked about is generally considered to fall into two categories, which both contain numerous subcategories.
The first category, Machine Flexibility, covers the system’s ability to be changed to produce new product types, and ability to change the order of operations executed on a part.
The second category is called Routing Flexibility, which consists of the ability to use multiple machines to perform the same operation on a part, as well as the system’s ability to absorb large-scale changes, such as in volume, capacity, or capability.
The main advantage of an Flexible Manufacturing System is its high flexibility in managing manufacturing resources time and effort in order to manufacture a new product. The best application of an FMS is found in the production of small sets of products those from a mass production.
FM systems are supposed to provide the manufacturer with efficient flexible machines that increase productivity and produce quality parts. However, FM systems are not the answer to all manufacturers’ problems. The level of flexibility is limited to the technological abilities of the FM systems.
FM systems are being used all over the manufacturing world and though out industries. A basic knowledge of this kind of technology is very important because FM systems are involved in almost everything that you come in contact with in today’s world.
From the coffee maker to your remote control FM systems are used all over.
History of Flexible Manufacturing Systems
At the turn of the twentieth century, Flexible Manufacturing System did not exist. There was no pressing need for efficiency because the markets were national and there was no foreign competition.
Manufacturers could tell the consumers what to buy. During that period, Henry Ford had been quoted as saying “People can order any color of car as long as it is black.
” All the power remained in the hands of the manufacturer and the consumers hardly had any choices.
However, after the Second World War a new era in manufacturing was to come. The discovery of new materials and production techniques increased quality and productivity. The war led to the emergence of open foreign markets and new competition.
The focus of the market shifted from manufacturer to consumer. The first Flexible Manufacturing System was patented in 1965 by Theo Williamson who made numerically controlled equipment.
Examples of numerically controlled equipment are CNC lathes or mills which are varying types of FM systems.
During the 1970s, with the ever-growing developments in the field of technology, manufacturers started facing difficulties and hence, FM systems became main-stream in manufacturing to accommodate new changes whenever required. During the 1980s for the first time manufacturers had to take in consideration efficiency, quality, and flexibility to stay in business.
The Process of Flexible Manufacturing Systems
A flexible manufacturing system is an integrated manufacturing system of computer-controlled machine tools, transportation and handling systems under the control of a larger computer.
Flexibility is attained by having an overall system of control that directs the functions of both the computer-controlled machine tools and the handling systems.
These computer systems are designed to be programmed or grouped easily with other devices to be able to allow fast and economical changes in manufacturing process, enabling quick responses to the market changes and allowing mass customization of products.
As has been discussed above the flexible manufacturing system can be broadly classified into two types, depending on the nature of flexibility present in the process, Machine Flexibility and Routing Flexibility
Flexible Manufacturing Systems essentially comprise of three main systems.
- The processing stations: These are essentially automated CNC machines.
- The automated material handling and storage system: These connect the work machines to optimize the flow of parts.
- Central control computer: This controls the movement of materials and machine flow.
The Flexible Manufacturing System as a system stands out because it does not follow a fixed set of process steps. The process sequence changes according to requirement to allow maximum efficiency. Sequence of material flow from one tool to another is not fixed nor is the sequence of operations at each tool fixed.
Key Features of Flexible Manufacturing Systems
Some characteristics that differentiate Flexible Manufacturing System from conventional manufacturing systems are their technical flexibility, i.e.
, the ability to quickly change mix, routing, and sequence of operations within the parts envelope and also complexity resulting from the integration, mechanization, and reprogrammable control of operations i.e.
, parts machining, material handling, and tool change. Some key features of the process are discussed below.
Cell: It consists of several groupings of two or more automated machines within a company. Each grouping is called a cell. All the machines present are controlled by a computer. They are programmed to change quickly from one production run to another.
A key feature is the automated flow of materials to the cell and the automated removal of the finish item. Several cells are linked together by means of an automated materials-handling system, and the flow of goods is controlled by a computer.
In this manner a computer-integrated manufacturing process is initiated.
Random bypass capability: The material handling system has a random bypass capability, i.e. a part can be moved from any tool in the interconnected system to another because the transport system can bypass any tool along the path, on demand. This implies:
- Each part can traverse a variable route through the system.
- Again, this flexibility in material handling, in combination with multipurpose tools, makes it possible for a flexible manufacturing system to process a great diversity of parts.
Automation: Computers are the heart of automation. They provide the framework for the information systems which direct action and monitor feedback from machine activities.
As FMS involve a wide variety of components, each with their own type of computer control, many of these computer components are installed as islands of automation, each with a computer control capable of monitoring and directing the action.
Each of the computer controls has its own communication protocol the amount of data needed to control the component. Thus, the task of computer integration is to establish interfaces and information flow between a wide range of computer types and models.
Computer software provides the ability to transmit timely and accurate status information and to utilize information which has been communicated from other computers in FMS.
Component redundancy: In Flexible Manufacturing System as the equipment is highly integrated, the interruptions of one component affect other components. This results in a greater time to trace the problem when compared with isolated components.
In some cases, the interruption might be due to some other integration effect, and greater downtime may result before the actual cause of the problem is found. In this situation, component redundancy provides flexibility with the opportunity for choice, which exists when there are at least two available options.
Flexible manufacturing contains functionally equivalent machinery. So in case of failure of one machine the process flow is directed towards a functionally equivalent machine.
Multiple Paths: A path in flexible manufacturing represents a part sequence and requisite fixtures to complete its required operations. In a conventional machine environment, only one path exists for a part because a single fixture remains at a single machine.
However, this is not the case within flexible manufacturing systems, where there are multiple paths. The number of paths which are present within flexible manufacturing is a measure of the degree of flexibility.
Obviously, the higher the number of paths, higher is the degree of flexibility.
Flexibility ranks high in Japan €²s manufacturing strategy but not in America €²s.
A true flexible factory will not only build different versions of the same car, a coupe or a station wagon, on the same production line, but also a completely different car. This is what the Japanese factories are setting out to do.
The cost of one factory can be spread across five or ten cars. Apart from lower fixed cost, it is also less painful to stop making one of those cars if it fails to sell.
FMS as a system of manufacturing process can be compared to other processes in terms of the product volume it generates and its capacity for creating part variations.
The above depicts the position of FMS vis-Ã -vis that of stand-alone machine and transfer lines. The horizontal axis represents production volume level and the vertical axis shows the variability of parts.
Transfer lines are very efficient when producing parts at a large volume at high output rate, whereas stand-alone machines are ideally suited for variation in workplace configuration and low production rate.
In terms of manufacturing efficiency and productivity, a gap exists between the high production rate transfer machines and the highly flexible machines. FMS, has been regarded as a viable solution to bridge the gap and as a gateway to the automated factory of the future.
The Process: Though the features of this manufacturing innovation process are similar across all types of firms, the manner in which they are adopted and implemented depends on product type, manufacturing, maintenance, process planning and quality control processes. It is also contingent upon the people carrying out these processes; the productive resources being used and the organizational arrangements used to divide and coordinate the processes distinguished.
The description of the lay a company that has adopted the flexible manufacturing system gives a clear idea of how the system works in practical life. It has all the features as mentioned before of a typical FMS.
Case Study: Toyota’s Lean Production System
Toyota is the most efficient auto company in the global industry, thanks to its lean production system, developed in response to problems Toyota’s engineers saw with the long production runs of a mass production system.
The problems included the creation of large and expensive inventories, the production of a large number of defective products if the initial machine settings were wrong, and the system’s inability to accommodate diverse consumer preferences.
Toyota then developed a number of techniques designed to reduce equipment setup times–a major source of fixed costs. This made small production runs economical, which eliminated large inventories, fewer defective products, and better responsiveness to consumer demands for product diversity.
Process innovations enabled Toyota to produce a more diverse product range at a lower unit cost than was possible with conventional mass production.