Modularity in mass customization

There are many definitions for modularity in literature, and it can be defined for example as “building a complex product or process from smaller subsystems that can be designed independently yet function together as a whole” (Baldwin and Clark 1997).

Product modularity means assembling of products from pre-determined modules.

Products should be designed in order to effectively pursue mass customization. This will enable firms to pre-design the required product variants to satisfy market-driven customization while allowing the variants to be produced in a relatively high-volume production environment. (Salvador et al. 2002) Process modularity consists of standard sub-processes and customization sub-processes. The standard sub-processes are placed before the customization sub-processes to postpone manufacturing in assembling to achieve maximum flexibility (Bask et al. 2011; Tu et al. 2004). Product modularity can take various types of forms, and examples of different types are introduced in figure 8 (Ulrich & Tung, 1991; Duray et al. 2000).

Figure 8. Different types of modularity (Ulrich & Tung 1991).

The different types of product modularity can be used separately or in combination to provide customized end products. Modules can be altered during design or fabrication to match unique requirements of the customer. For example made-to-measure apparel customization would be described as cut-to-fit modularity where components are altered to the physical dimensions specified by the customer in the fabrication phase before assembly. During the assembly and use stages, modules can be arranged or combined differently according to requirements, but it is not possible to manufacture or alter modules. (Ulrich & Tung, 1991; Duray et al. 2000).

Benefits of modularity include reducing overall costs, ability to increase product variety, increased flexibility and simplification of complex systems. Modularity has been closely related to mass-customization strategies and identified as one of the most important methods in implementing mass customization. It is a strategy for organizing complex products and processes efficiently. (Bask et al. 2011; Gilmore & Pine 2000;

O’Grady 1999) Even though jeans are not complex products compared to for example electronic devices or automobiles, it is reasonable to take modularity into account when designing and developing the product and process for mass-customized jeans.

Standardizing the different parts makes manufacturing more efficient, as well as reduces lead-time and cost.

Duray (2002) infers in her article that mass customizers can be typed on basis of two key dimensions, modularity and customer involvement, so that manufacturers, which do not involve customer or do not employ modularity should not be considered as mass customizers. Instead, manufacturers that produce customized product without modularity should be considered as traditional customizers, a producer of one-off goods with out the economies of repetitive manufacturing. (Duray 2002) It is possible to produce high volumes of customized products without modularity, but in most cases this decreases the cost-effectiveness and increases lead-times and complexity.

Modularity is an efficient way to improve operations and ability to more agile production of customized products.

Duray et al. (2000) and Duray (2002) introduced separate frameworks of modularity and different mass customizer types. Based on those, Bask et al. (2010) present a framework combining modularity and customization (figure 9, next page). The framework focuses on the level of modularity and not on the type. The measure for the modularity from the customer perspective is the product variant offered with different modules and service levels, and from the production side, the use of modularity principles in production. The measure for customization level is the depth of the customization experience for the customer, and in the service production perspective, it is the depth of the customer involvement.

There are four categories in the framework: non-modular regular, modular-regular, modular customized and non-modular customized. Regular implies to more pre-determined and standardized service, and customized to more customer-specific element. In the framework, only one quadrant in the matrix represents mass-customization, and this is the modular customized, which has high degree on both customization and modularity. Most apparel customization concepts belong to the non-modular customized category, as does NOMO Jeans. In this category, the product is fully customized according to customer needs, and this type of service is called “tailor-made-solutions”. (Bask et al. 2011)

Figure 9. A Framework for combining modularity and customization in service offerings (modified from Bask et al. 2010).

Modularity can be applied also into production processes. A module is a team of workers who are assigned to produce a specific product or a part of it. Production flow is arranged so that it is synchronized and there are no bottlenecks. This requires finding out the optimal operation order, and estimating the production times for each operation.

For workers, this differs a lot from traditional in-line production, where one worker is only responsible of handling one operation from the whole production process. Working in module demands wider variation of skills, but on the other hand, the work is more versatile than in line production. A module requires efficient teamwork with high consistency of quality and willingness to improve continuously. When transferring from traditional line production to module production, the management should be convinced about advantages, so that coordination and organizing the change would not fail.

forming of operations as well as change from individual incentives to promotion of teamwork with goals to improve quality. (Sarache Castro et al. 2003)

Organizing flow, layout and quality of input in production reduces lead-times. Flexible production methods are needed in all production concepts that want to respond quickly to markets or produce made-to-order clothing. Modular production is an applicable method in fashion manufacturing as it consists of specialised cells, where a group of trained workers are able to be in charge of the whole cycle of assembly for the products associated within the cell. A single garment is made up as fast as the sum of the separate sewing operations involved without intermediate stocks or pauses. Unitary production system (UPS) is another method used, and is more suitable for the upper part of a range and for small batches. In the UPS, the pieces to be made up are put on mobile shelves suspended on rails. The shelves pause in front of every workstation, and keep up continuous flow of work (Forza, C. and Vinelli, A. 1997, according to Colgate 1989).

Modular production reduces waiting time compared to traditional line production and increases overall production. It also saves occupied space, does not require precise planning beforehand, and it is more rewarding for the workers. (Forza, C. & Vinelli, A.

1997, 2000)