Group technology in flexible manufacturing

Current engineering production is characterised by rapid changes. These changes arise due to the shortening of product life cycles. Manufacturers are forced to introduce upgraded products at shorter intervals based on customer requirements. In this paper, we focus on the possibilities of production upgrading by using a group technology in the flexible manufacturing system. The production capabilities of one of the production machines in the manufacturing system will be analysed. This production machine is a lathe that produces one of the essential parts of a finished product. Determine what variations of this part can be produced without changing the physical configuration of the machine.


Introduction
Digital manufacturing, intelligent manufacturing systems, group technology and CNC manufacturing are four key technologies changing modern engineering and manufacturing.
CNC, or Computer Numerical Control, is a technology that enables the automation and control of manufacturing equipment using computers that execute pre-programmed sequences of machine instructions.These machines can perform various machining operations with high precision and consistency, reducing errors and increasing production efficiency.Nowadays, such equipment is usually supplemented with robotic operators, which further increases the efficiency of these machines work.Such automated production workstations are often combined into entire production lines controlled by a master production planning and control system.Such complex production systems have recently been supplemented with certain intelligence features (the ability to learn, recognise and react to specific external influences, etc.).
Digital manufacturing, in turn, uses digital technologies to plan, design and manufacture products.These technologies may include CAD (Computer Aided Design) and CAM (Computer Aided Manufacturing) systems, which allow engineers to develop and test products in a digital environment before they are physically manufactured.A possible solution is to generate production data directly from the CAD model and place it in the model in a generic format.Manufacturers can transform this data from the 3D CAD model into a format specific to their facility and upload it into the control system of a flexible manufacturing system.
Intelligent manufacturing systems use artificial intelligence and machine learning to monitor and optimise manufacturing processes.These systems can, for example, predict the need for machine maintenance, preventing unplanned downtime and increasing production efficiency.
The need for flexible manufacturing systems (FMS) has become particularly important in recent years due to fierce competition in the manufacturing industry.These systems allow us to react quickly to change, but this flexibility costs time and money.
Flexible Manufacturing Systems (FMS) has been developed with the hope that they will be able to address these new challenges and strike a balance between product standardisation and production flexibility.A competitive FMS is expected to be flexible enough to respond to small batches of customer demand.Given that the construction of each new production line represents a significant investment, existing production lines must be able to be reconfigured to keep pace with the increased frequency of new product introductions.This new kind of system we must study in a formal framework, which is a challenge if we consider that in each FMS, we find important characteristics that we must model: sequential relationships and concurrent relationships, events that must occur asynchronously and others that require synchronisation, as well as resources that we must use in mutual exclusion to avoid conflicts, such as a robot.We must also ensure that deadlocks are not created.
Group technology is a method of organising production that groups similar parts into 'families', which are then produced together.This method makes more efficient use of production resources, reduces the time required to set up machines and increases overall production productivity.Group technology is a process that allows a manufacturer to create products with a high level of precision and quality.It is a manufacturing process that uses a classification system to group parts that are similar in shape, function, or other characteristics.This system allows for the efficient production of parts in batches, which can reduce costs and improve quality.The working base of group technology is to reduce setup time and cost by using common tooling and fixtures for similar parts.This system also helps to reduce inventory costs by allowing parts to be produced in batches.
Together, these four technologies represent a new era in engineering, characterised by greater efficiency, flexibility and precision in production.These technologies also allow the manufacturer to better adapt to changing market needs and respond quickly to new opportunities.

Flexible production system
In 2008, our institute started to develop a project called "Flexible Manufacturing Systems Laboratory with Robotic Manipulation for a Drawing-Free Environment".
The main objective of this project is to build a laboratory equipped with a flexible manufacturing system that will be directly connected to our CAD laboratory.The direct link between the two laboratories will allow the implementation of a coupled design and manufacturing system.The main benefit of this system is the possibility of rapid production response to design changes without paperbased production documentation.This is a model for new 'digital' manufacturing [1].The iCIM3000 system from Festo is a complex production system with several vital stations.These stations are designed to simulate fundamental industrial manufacturing processes and provide users with hands-on experience with modern manufacturing technologies.1. Storage system: This station stores raw materials and finished products.It has an automated storage system that automatically moves materials between the shelves and the transport system.The warehouse system is controlled using computer software that tracks the quantity and location of all materials in the warehouse.2. Assembly station: At this station, raw materials and components are grouped and assembled into finished products.The station has various assembly tools and equipment, including robotic arms that automatically assemble components according to predefined instructions.The assembly station is also equipped with sensors and cameras that monitor the quality of the assembly and detect any errors.3. Testing station: After assembly, the products are moved to the testing station and subjected to various quality tests.This station can have multiple testing devices that check product parameters, such as dimensions, weight or functionality.If it is found that the product does not meet the specified specifications, it is moved to the repair station.4. Production-turning station: This station is designed to provide hands-on experience with CNC turning, an essential part of modern production processes.
Concept Turn 105 is a compact CNC lathe designed for teaching and research.This lathe is equipped with a high-precision control system that automatically turns components with high accuracy and consistency.The lathe also has an automatic tool feeder to hold different turning tools for various operations, such as rough or fine turning, axial drilling or tapping.At this station, the raw materials are fed into the lathe, where they are automatically turned to the desired shape and size.
After turning, the finished components are automatically removed from the lathe and moved to the next station for further processing or testing.If a component does not meet specified specifications, it may be returned to the lathe for additional machining or repair.
The Concept Turn 105 lathe station is an integral part of the iCIM3000 system, as it provides users with hands-on experience with one of the most critical technologies in modern engineering.This station is also ideal for study and research in CNC turning and automated manufacturing.
5. Station production -milling: This station is designed to provide practical experience with CNC milling, a fundamental part of modern production processes.
The Concept Mill 105 is a compact CNC milling machine suitable for teaching and research.This machine is equipped with a high-precision control system that enables automatic milling of components with high accuracy and consistency.The device also has an automated tool feeder to hold different milling tools for various operations, such as rough or fine milling and drilling.
At this station, the raw materials are fed into the milling machine, where they are automatically machined to the desired shape and size.
After the milling, the finished components are automatically removed from the machine and moved to the next station for further processing or testing.A piece may be returned to the milling machine for additional machining or repair if it does not meet specified specifications.
6.The entire iCIM3000 system is controlled using computer software that enables programming and monitoring all processes.This software also allows collecting and analyzing production data, which can help optimize production processes and improve product quality.The iCIM3000 system from Festo is an excellent tool for teaching and research automation and production control [2].
In figure 1 configuration of this FMS system is shown.

Lathe machine and manufacturing process.
It is a small-footprint CNC lathe with a stable table built to industry standards, with a grey cast iron inclined bed.It features safety technologies up to the most recent lathe standard, profile rail guides (linear guides), superior industrial components, and clockwise and counterclockwise spindle spinning.
It has high-resolution axis motors, an automatic 8-position turret, an automatic reference, and a constantly adjustable main drive.The machine has an inclined bed and a durable design.The chip protection door can be programmed to open, close, or manually operate through a pneumatic cylinder.Limit switches are used to check the position of the door.
Air compressor and air chuck Pneumatic chuck, which consists of a pneumatic full clamping cylinder with a 3-jaw power chuck and blow-out device, and automated door are prepared by the pneumatic unit.
The robotics interface can connect the machine to other machines or devices, such as loading and unloading robots, and control peripheral equipment (such as automatic doors, vices, etc.).Programs can be transported to and launched from the master computer via the DNC interface.

Group technology
The concept of group technology was first proposed by Frederick W. Taylor in the early 1900s.Taylor believed that the most efficient way to organize a manufacturing process was to group similar parts together and use specialized machines to produce them.This concept was further developed by Frank and Lillian Gilbreth in the 1920s and 1930s.The Gilbreths developed a system of coding and classification for parts that allowed them to be grouped together and produced in a more efficient manner.Group technology has since been used in many industries, including automotive, aerospace, and electronics.Group technology is a process that allows a manufacturer to create products with a high level of precision and quality.The group production process is based on having the products in related groups.The batch production process allows the manufacturer to create products with high precision and quality.GT is an approach to manufacturing in which similar parts are identified and grouped to take advantage of their similarities in solution and production.Similarities between components allow them to be classified into a component group.It is common for a company that manufactures 10,000 different parts to be grouped into 20 to 30 groups.The steps are similar in each group.If these similarities are used in production, production capabilities are improved.Improvement is usually achieved by organizing production capabilities into production cells.Each cell is designed to produce one group of parts (or a limited number of parts), so the production of a group of parts can be optimized.Each cell becomes a business within the business itself.
Currently, approaches to group technology are based on all technical or organizational evolutions within a specific production unit containing activities or data with a certain degree of similarity.Thus, they can be combined into groups for which general solutions and methods are used.Group technology in project, planning and management activities is practical because it creates basic prerequisites for using computer technology.One of the standard features of production activity is processing information based on numerous data sets.
Every production needs creation, transformation, storage, analysis and modification information.Automating data collection and processing is the first step in integrating the most critical production activities, from receiving orders through the compilation of technological procedures, making NC machine programs, operational planning and other functions up to the management of production processes [3].
Data sets need to be rationalized and their meaning discerned.Their structuring according to appropriate logic is fundamental.They apply classification procedures developed by group technology.Classification is understood as the grouping of objects based on common characteristics.The classification features are chosen objectively concerning the database.It is essential to define them in such a way as to maintain a clear logic [4].
Hierarchical structuring is mainly used in group technology.The classification process can be visualized with a progress graph.In some cases, proceeding only from top to bottom is possible.In other cases, a selection procedure can be applied.The principles of recurrence and iterative methods can also be applied.Classification systems based on the principles of group technology have a wide area of application in the production process, especially for: • data search in design, • increasing serial production and transition to higher forms of production, • standardization of group procedures and creation of group technologies, • creation of automated design and project systems, • simplification of material and information flows, • standardization of information, building a rational base, etc.
An ordered relational structure is achieved by building and using the architecture of a group information system.The group system (GT-Group Technology) is developed from the modeling of the geometry of production objects.There are a number of approaches to modeling object geometry.They are associated with the identification, classification and modeling of macrogeometry, dimensional and other properties of objects [5].
The GT code is geometric modeling based on the use of the GSC method -structural type geometry.Modeling the geometry of objects according to GSC requires: • partially defining the geometry, • multivariate geometry modeling, • non-explicit expression of connecting surfaces.The GT code of the component then defines the relationship: GT = { UG, MG, SG} where UG is a unique geometric code which guarantees a clear definition, MG -macrogeometric code (macrogeometric features) SG -semantic-geometric code

Sorting of parts and coding
A characteristic feature of the GT is a group of similar parts.It is a group of parts that have common features in geometric shape and size, or in the production steps used to produce them.There are always differences between the parts in a group, but the commonalities are close because the parts can be grouped into the same group.There are several ways that component groups are identified in the industry.One method involves visual inspection of all parts produced in the plant and uses the best judgment to group them into appropriate groups.Another approach, "production flow analysis," uses the information in "road sheets" to sort parts.Components with similar manufacturing steps are grouped into the same group.The most used method, and also the most expensive, is part sorting and coding.Component sorting and coding involves identifying similarities and differences between components and the relationship of these components using a common coded scheme [6].Most classifications and coding systems are as follows: • systems based on the properties of the shape of the parts, • systems based on the characteristics of component production, • systems based on both shape and production attributes.
In the case of group technology, we can group component families based on different criteria.Some of them are: 1. Shape and size of parts: Parts of similar shape and size may be grouped because they will likely require similar machines and tools to produce them.2. Material of parts: Parts of the same or similar material can also be grouped.It is because different materials may require different types of manufacturing processes and techniques.3. Type of manufacturing process: Parts that require the same or similar manufacturing process can also be grouped.It may include parts that need the same type of machining, welding, assembly, etc. 4. Function of parts: Parts that perform the same or similar function in the final product can also be grouped.5. Temporal and spatial proximity of manufacturing operations: Parts manufactured simultaneously or in the exact location can also be grouped to improve production efficiency.6. Number of operations: Parts requiring the same number of procedures or similar manufacturing time can also be grouped.These criteria can be used alone or in combination, depending on the specific needs and goals of the manufacturing process.

Actual production.
"Desk Set" is one of the products that can be produced on the iCIM3000 system.This product is a set of office supplies containing various components, such as a base plate, penholder, pen, thermometer and hygrometer.The minimum product is a "base plate" and "penholder" assembly.Other products of the "desk set" family are different variants of this basic set, which can be supplemented with other "purchased" parts (pen, thermometer, hygrometer).
The "Desk Set" production process is managed using computer software, which enables programming and monitoring of all operations.This software also allows collecting and analyzing production data, which can help optimize production processes and improve product quality.The "Desk Set" production on the iCIM3000 system is an example of modern production technologies and provides users with practical experience with automated production.
The base plate and penholder are parts that are produced in the system.These components can also be changed in the system.It means that these parts' shapes and dimensions can be changed.Subsequently, generating a new NC program for these changed parts is necessary.These two components are also suitable for applying group technology methods for their production.Also, the production process of the entire product is suitable for using these methods.
In the first case, we chose the penholders product family, produced on a lathe.

Complex parts
Based on the geometric and technological similarity of the individual elements of this family of parts, a fictitious complex part was created, which contains all shapes from this family of parts [6].
A complex part results from grouping a family of parts that have similar characteristics or are manufactured using similar manufacturing processes.This component contains all surfaces of components belonging to the given component family.In the case of group technology, the complex component is used as a reference model for the production of other components in the family.This model includes all the necessary information about the shapes, dimensions, materials and manufacturing processes needed to produce each part in the family.
The complex component is designed to simplify and streamline the production process.Instead of designing and manufacturing each part individually, a complex part allows the manufacturer to create a series of similar parts with minimal effort and time [7].
This process begins by identifying all components that have similar characteristics or are manufactured using similar processes.These components are then analyzed, and their main features are recorded.This information is then used to create a complex part that incorporates all these characteristics.The complex part is then used as a reference model for producing other parts in the family.This model includes all the necessary information about the shapes, dimensions, materials and manufacturing processes needed to produce each part in the family.
The advantage of this approach is that the manufacturer can produce a series of similar parts with minimal effort and time.This process also reduces the chance of errors because all parts in the family are manufactured to the same model [1].
Although creating a complex part can be time-consuming and require a significant amount of planning and analysis, the benefits it brings in streamlining the manufacturing process and reducing errors often outweigh these costs.

Figure 3 .
Figure 3.The final product -desk set

Table 2 .
Classification of parts