Modularity is a degree to which a system’s component maybe separated and recombined. However, it can be used in different contexts and its definition changes accordingly. For example. In Biology, it is the concept that organisms or metabolic pathways are composed of modules. In Nature, modularity refers to the construction of a cellular organism by joining together standardized units to form larger compositions. In cognitive science, the idea of modularity of mind holds that the mind is composed of independent, closed, domain-specific processing modules, etc. But here we will be concentrating on Modularity in operations management, which refers to an engineering technique that builds larger systems by combining smaller subsystems.
The growing concern for the environment has spurred a great interest in environmentally aware design and manufacturing amongst designers worldwide. Introducing Modularity in consumer products can help bring multiple manufactures come together creating differentiated assembly lines that can decrease the production time while keeping the cost of production at minimum and providing multifaceted products to the consumers.
To infuse Modularity in the manufacturing of a product, it is necessary to understand the various manufacturing processes that each attribute of each component has to go through. The design elements of the product are then split up and assigned to modules following a formal plan or setting. This leads to the formation of two types of modules, one that are ‘hidden’, meaning the changes implemented on to them do not affect the other modules and the other being “visible” meaning that they comprise of certain “design rules” that the designers of the hidden- module must follow for them to function together. Through such Modular products a range of alternatives are offered that enable designers to replace earlier inferior solutions with the later superior solutions without affecting any change in the assembly lines that the product has to go through, further reducing costs of redesigning.
Definition of Modularity
To begin with the definition of modularity, the design description of IBM’s mainframe computer offers few interesting hints. “The design of IBM’s 360 mainframe computer was truly modular—it was designed to have various parts, called modules. The modules were designed and produced independently of one another, but, when combined, they worked together seamlessly. As a result, all systems built out of System/360 modules could run the same software. Further, new modules could be added to the system, and the old ones upgraded, without rewriting code or disrupting the operations”.
In the above mentioned example some of the parts are underlined to identify the importance of the critical features related to modularity.
Firstly, modules are “designed and produced independently”. One of the main advantages in the modular organization of design activities is the independence in each modules design. A complex system being separated into individual modules means that these can be placed into separate, specialized teams and then designed and produced independently. Here these teams can work autonomously, both inside or outside the company, due to the structure of modularity that allows “information hiding”. Now coming towards the sentence “they worked together seamlessly”, meaning irrespective of these modules being designed separately, they are able to work coordinately. Truly, if it were compensated by a greater difficulty in coordinating due to the independence in the organization of design, modularity would not be considered of such a great importance. And so the modules ability to work together with the other modules in the system becomes really important and hence it drives the usage of standard interfaces.
Lastly, the three underlined sentences can be discussed all together: “all systems, could run the same software. Further, new modules could be added, and old ones upgraded”.
Here, thequestion arises again of modules independency, both in terms of an organizational and technical perspective. Nonetheless, they still work together, sharing common resources as in this case being a common software. Due to such independency of the modules, new modules can further be added and that old ones can be updated. As these modules are independent to each other, the entire system can be improved and updated overtime through the simply substituting single or a group of modules. The only condition here is that the new or upgraded module contains the same set of standard interfaces so that the system can work as they worked seamlessly with the older version, even if it is with a higher performance.
There are a variety of products around us that can be considered as modular at a certain degree. Currently the use of pre-assembled modules has become customary in the automotive manufacturing practice of elements such as the cockpit (which incorporates a dashboard with a sound system, ventilation pipes and multiple controls and gadgets that are placed in front of the car’s interior), gadgets related with the vehicles doors (that includes power windows, latches and loud speakers) and for bumpers (including Park distance control and headlights). Such parts are produced independently by different suppliers and then assemble together to offer multiple application usage to the Customers. The above mentioned example reflects the increase in variety of uses that is associated with the modular architecture. Splitting a product into a set of modules helps in increasing the number of possible variations, allowing each of these modules to be combined in many different ways. This provides an advantage not only to the end-user but to the producers as well.
Nevertheless, the example of the car is implicitly based on the existence of a variety limit in the parts size and design: not the all parts can fit any given car and could demand a change in the external structures in order to be used. This means that the variations obtained through a modular configuration in a product is limited by the overall architecture of its system. So give a certain set of standard interfaces, the modular variety can be the highest variety but not the maximum possible variety. The main modularity characters arose here can be completed by two more definitions.
Modularity is about how parts are grouped together and about how groups of parts interact and communicate with one another. Here the focus is on: interaction, communication and grouping of parts. This shifts the attention from physical products to a system where processes like interaction, communication and part grouping can take place. Modularity becomes a matter of language. Finally, modularity is a matter of degree of complexity. A complex system can be modular at various degrees.
Then, the significant step is to measure the degree to which the system is modular, determining its evolutionary trajectories towards configurations of higher or lower modularity and also identifying the dimensions that drive its temporal evolution.
Advantages of Modularity
The advantages of modular design for manufacturing centred on extending the elements of flexibility and economies of scale that modular products have used to greatly increase the end user experience. Integrating flexibility, modularity, and adaptability into design to provide additional freedom to adjust and adapt to change. The advantages of manufacturing modularity include: streamlined suppliers, reduced inventory, fewer works in process and faster process time, as well as component economies of scale, ease of product upgrade, increased product variety from a smaller set of components, and decreased order lead-time.
The advantages of modularity concept are listed below;
- Reduction in Product Development Time – Modularity depends on splitting a product into multiple components with a clear definition of the standard interfaces. These interfaces allow the design task to be separated and later combined. This separation reduces the complexity of the overall design and enables design tasks to be performed coincidently, which directly influences the product development time and hence the product can be developed faster.
- Customization and Upgrades – Modular products fulfill the requirements of the end-users by accommodating several functional components that interact in a specific manner. This interaction of components allows the products to be improved and updated over time with the use of more efficient components performing the given functions effectively. Further, these components can be replaced or customized to fulfill different functions.
- Cost Efficiencies Due to Amortization – Modular components can be used in numerous product lines, meaning that their production volumes are greater. Allowing the amortization of the expenses involved with the development over a large number of products.
- Quality – Modularity enables production tasks to be able to perform simultaneously. Thus, components that are independent can be produced and tested separately before they are integrated into a modular product design. This helps is improving the overall quality of the product.
- Design Standardization – Modular design facilitates design standardization by identifying the relative component functions which can be group together reducing the incidental interactions between these component and the other parts of the product.
- Reduction in Order Lead Time – Modular products can be developed by incorporating standardized and customized components. This enables the designer to inventory the standard components, and then focus on the customization of the differentiated components. Furthermore, modular products can work as a combination of standard components, as in, the same standard components (inventoried) can be integrated in multiple ways to interact and perform variety of functions that can respond to end-users requirements.
Modularity in Products
Modular products through the combination of discrete building blocks or modules can attain various overall functions, and this overall function performed by the product can be further divided into sub-functions that can be incorporated by different modules or components. One of the important facet of modular products is the development of a basic core unit to which different modules or elements can be fitted, hence enabling the production of variety of versions of the same module. This core unit needs to have sufficient capacity to cope with all the variations created with the independent modules and their performance and usage.
Many Product systems are modular, they can be decomposed into a number of components that can be mixed and matched in a variety of configurations. These components are able to join, interact, or exchange resources (like energy or data) in some way, by clinging to a standardized interface. Unlike a tightly integrated product, where each of the component is designed to be working specifically (and often exclusively) with other specific components in a tightly integrated system, Modular products are systems of components that are “loosely coupled”.
Another good example of a modular product is the personal computer (PC). A PC consists of multiple varieties of components (parts) or building blocks such as hard drive, CPU, RAM, CD-ROM, graphics card and many other modules. Many of these can be upgraded or changed with little or no modification to the other modules when needed. For example, a mother board of a CPU can be sold with different combinations of processor, hard drives, RAM, and etc. with the use of such modular parts, a company can choose from a huge variety of elements and form a product that can meet the end-user’s requirements.
The modules containing a high number of elements which have minimal dependencies upon and correspondence to other components in the product, not in the module but which have a higher degree of dependency upon and correspondence to other components in the module. These dependencies and correspondence include those which emerge from the relationships between the component’s attributes and those which emerge from the relationships between the components during the various phenomena the components undergo during their life-cycle.
Thus, in a module, each of the components is independent of all the other components that are contained within the same module (Independence). Furthermore, each component present in a module must go through a similar during each phase of its life-cycle (similarity) to reduce the interdependencies between the modules.
While complete modularity could be seen to be unrealistic except in the most trivial cases, a product that displays a higher degree of modularity is more likely to sustain a lower total life-cycle cost especially when examining the entire product family.
Manufacturing modularity, a particular characteristic modularity. Manufacturing Modularity can be defined as the development of the product modules with minimal dependencies consequent to other components in the product with regard to their manufacturing processes. Furthermore, the components present within the module have minimal similarities to external components and maximal similarities to each other with regard to their manufacturing processes. Such modularity can emerge from, e.g. A module that comprises of all the components present in a product that are injection molded.
When defining the manufacturing modularity of a product an important consideration to undertake is the chosen level of abstraction of the manufacturing process itself. The manufacturing of a product comprises of multiple tasks and these task are further made up of sub-tasks. A product could be modular (similar and independent) when examined from the viewpoint of the overall manufacturing processes (For example, injection molding vs forging) but at a certain task level, the structure may not be modular at all with respect to the manufacturing process (For example: similarity of fixturing components within a module). And so, when relative manufacturing modularity of a product is being defined, one must do so with respect to the tasks and sub-tasks comprised in the manufacturing process. It’s parallel to considering the level of abstraction of the product.
Finally, it is important that the effect of manufacturing on each product attribute is taken into account by each manufacturing modularity. Similarly, it is important to consider each attribute of the product, components and modules, when looking for interactions and dependencies between components and modules. For example the housing of an electric coffee maker which is a modular assembly comprising multiple components. And all of the components of the housing are made of the same type of plastic and are manufactured to have similar tolerance specifications, possess the same surface condition, and undergo the same set of manufacturing process. Product attributes include: geometry, features, tolerances, surface condition, materials, and facilities.
Three Facets of Modularity
It is important to look at manufacturing modularity from the viewpoint of creating more modular products. Which is quite different from designing products that have reconfigurable or interchangeable parts. It’s also seen to be quite different from maintaining form/function independence. One of the goals of modular design is to combine all attributes with similar process into a single module and separate them from all other attributes and processes. When creating modular products it is important to ensure that at each level of abstraction the products attributes remain as independent from each other as possible for each level of abstraction of the manufacturing tasks. And if the dependency does occur, it should occur within a given module. Further, for every attribute within a module the manufacturing process should be similar.
The goal of modular design for manufacturing includes a one-to-one form/process relationship (independence). This involves maintaining both form to form, process to process independence and the relationship between the two. Another important aspect of modular products is the similarity of how the module and its components are manufactured. In addition, one more perspective on the independence between the form and the process is similarity. The entire module needs ti undergo the same manufacturing processes for each part of the form (module). The final aspect of modular design is having minimal varieties of interfaces (interchangeability). This is used commonly in the industry today.
A product must be designed while undertaking the facets of modularity in practice to increase independence and similarity. These facets of modularity are commonly known as attribute independence, attribute similarity, process independence, and process similarity.
The more unique and independent the components and their manufacturing processes, the more modular the product. (Attribute similarity is not necessary for modular products as long as attribute independence is preserved and so it is excluded) e.g. In a given product many distinct modules can have blue components and still remain modular, although, if the components must all be similar in color then there is a dependency which reduces modularity.
Following are the three facets of modular product design with examples:
- Attribute Independence – The component attributes having fewer dependencies on the attributes of the components outside the module, such components are called external attributes. If the dependencies do exist, there should be fewer of them and should be dependent on to a lesser degree. Attribute independence produces yields for independence which enables modularity. It allows for the redesigning of a module with minimized effects on the rest of the product system, which further helps in making a product that is more agile in meeting the changing requirements of the end-users. E.g. A large cast aluminium component which rests on a plastic box. Now if there’s change in material being heavy iron for the cast component, a rib component will be needed inside to do so. Therefore, both the module will need to be redesigned for the change that should’ve only affected on one of them.
- Process Independence – The manufacturing processes of each module are independent or have fewer dependencies on the processes of external components. It requires the manufacturing processes that the module undergoes be independent of the processes that the external components and modules have undergone by. Once more, and dependencies that still exist are minimized in criticality and number. For example, in a given process where two cast parts that have to be pressed together still in a hot state to strengthen the bond. If one of the process changes related to either of the parts so that there is a difference in cooling time, the processes that the other part has to undergo should also be changed so they can be pressed together at the same time.
- Process Similarity – To reduce the number of external components that undergo the same process and create a strong differentiation amongst modules, it is necessary to group the components and sub-assemblies that undergo the same manufacturing processes into the same module. For example, Reinforced plastic components that are used in motorcycles like rear swing, rear forks, arm, wheel and disks can be woven fibres, chopped fabric, a slightly twisted fibre or a continuous lengths of fibre. Good bonding between the polymer matrix and the reinforcing fibre can only be achieved by coating the reinforcement with polymer. All of the components will undergo this specialized process. Therefore if they were grouped in a single module, each of these components that went through this process could be made at a single location and have a similar reaction to any changes proposed in the manufacturing process.
The process uniqueness also ensures that the changes to individual life-cycle only affect a single module of the product, hence conserving redesign energy. It can prevent the cascade of design changes caused by small changes in manufacturing process of a product when coupled with the other three facets of modularity.
Ignoring the rest of the life-cycle of the product while designing only for manufacturing modularity is not optimal, manufacturing modularity is important. Manufacturing is one of the most influential parts of the products life-cycle as it has the largest body of knowledge.
These factors facilitate in developing a sound methodology to understand manufacturing modularity. Hence the having products that are modular in terms of manufacturing have decreased change time and set-up costs, better utilization of production resources and decreased scheduling complexity.