Flexible manufacturing system (FMS) explained


A flexible manufacturing system (FMS) is a highly automated group technology (GT) machine cell consisting of a group of processing workstations interconnected by an automated material handling and storage system and controlled by a distributed computer system.

It’s a collection of numerically controlled machine tools and supporting workstations linked by an automated material handling system and managed by a central computer.

In other words, an FMS is an arrangement of automated processing machines interconnected by conveyors and material handling systems. The manufacturing process in an FMS requires a combination of workstations and possibilities of technological paths provided by the material handling system and inspected by an automatic inspection unit.

The FMS is called flexible because it can process a variety of different part styles at different workstations simultaneously, and the mix of part styles and production quantities can be adjusted to meet changing demands. Flexibility is a quality that both manual and automated systems share. Human workers are frequently the enablers of flexibility in manual systems.

In recent years, FMS has gained a lot of attention in various industrial sectors The hardware components in FMS include equipment from every manufacturing area, including machines, robots, inspection stations, deburring, material handling, chip removal, and manual work areas. Many different parameters must be considered when planning FMS. The main goal is to find enough system capacity to meet a specific production requirement.

An FMS consists of four components: processing stations or workstations, material handling and storage, computer control system, and human labor.

FMS is used to provide a flexible manufacturing facility for pan family components, provide the benefits of grouping the operation in a single location, provide the flexibility in producing small and medium parts, maximize the utilization of facilities, and have good management control.

FMS can be divided into five categories: in-line layout, loop layout, ladder layout, open field layout, and robot-centered cell.

The number of machines in the FMS allows it to be distinguished. The typical categories are as follows:

A single machine cell (SMC) consists of one CNC machining center combined with a parts storage system for unattended operation. A flexible machine cell consists of two or three processing workstations (typically CNC machining or turning centers) plus a part handling system. The part handling system is connected to a load/unload station. Four or more processing workstations are connected mechanically by a common part handling system and electronically by a distributed computer system in a flexible manufacturing system (FMS).

Advantages of FMS

  1. Increased machine utilization with several features such as automatic tool/pallet changing, dynamic scheduling of production, and so on.
  2. Reduced inventory – FMS processes different parts together following the GT concept. This tends to reduce the work-in-process inventory significantly.
  3. Reduced manufacturing lead time – Because of reduced setups and more efficient materials handling, manufacturing lead times are reduced.
  4. Greater flexibility in production scheduling – A FMS has greater responsiveness to change. It means FMS can make adjustments in the production schedule daily to respond to immediate orders and special customer requests.
  5. Reduced direct labor cost – Reduced (manual) material handling and automation control of machines make it possible to operate an FMS with less direct labor in many instances. Thus the direct labor cost is reduced considerably.
  6. Increased labor productivity – Due to higher production rates and reduced direct labor cost, FMS achieves greater productivity per labor hour.
  7. Shorter response time – Setup time is relatively low with FMS as most of the work is done automatically. Production’s lead time is very low, and the response time will be shorter.
  8. Consistent quality – Human error is minimized due to maximum automation. In the absence of a human interface, the quality is consistent.
  9. Reduced factory floor space and reduced number of tools and machines required.
  10. Improved product quality and easy expandability for additional processes or added capacity.

Disadvantages of FMS

  1. Very high capital investment is required to implement an FMS.
  2. Acquiring, training, and maintaining the knowledgeable labor pool requires heavy investment.
  3. Fixtures can sometimes cost much more than FMS, and software development costs could be 12–20% of the total expense.
  4. Tool performance and condition monitoring can also be expensive since tool variety could undermine efficiency.
  5. Complex design estimating methodology requires optimizing the degree of flexibility and finding a trade-off between flexibility and specialization.
  6. Substantial pre-planning activities are required and may have technological problems requiring a long debugging process.

FMS technology is most broadly applied in the machining process. Furthermore, it is applicable in metal press working, forging, and assembly, mostly used in mid-volume and mid-variety production, including metal-cutting machining, metal forming -forging, plastic injection molding, assembly of parts and/or equipment (auto), joining-welding (arc, spot), sheet metal – press working, surface treatment, inspection, and testing.