The flexible manufacturing system consists of a unified information control system, material storage and transportation system and a set of digitally controlled processing equipment.

Flexible Manufacturing System

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.

Development

In 1967, the British company Molins developed the “system 24” for the first time based on 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.

Process basis

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.

System composition

Processing equipment

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 based on the shape of the chips, the amount of removal, and the processing requirements.

Information control

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.

System type

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:

  1. 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.

  1. 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.

  1. 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.