Frame of reference
The following chapter presents the theories that has been set as the foundation for the study. As an introduction, an overview of the theoretical frame of reference will be presented along with its connection to the research questions. Further on, the theories will be presented
Components of the frame of reference
The theory that is fundamental in order to support the research questions of the study is being described in the following chapter. Figure 4 illustrates the relation between the research questions and theory.
The fundamental theory for the first research question comprises characteristics and criterions for when it is adequate to have an assembly line. Further on, the characteristics of modular house manufacturing is being covered. This will provide a base for identification of benefits respectively drawbacks of implementation of an assembly line for the modular house manufacturing industry.
The fundamental theory for the second research question comprises modular house manufacturing characteristics that needs to be considered as critical factors in relation to design of an assembly line. This will provide a base for the actual design of an assembly line for modular house manufacturing.
At last, the fundamental theory for the third research questions comprises the main aspects that needs to be decided in order for the assembly line to be adequate for the products being produced along with the demands that need to be met
Benefits and drawbacks
When manufacturing large volumes with few product variants, which has a high and even demand; a product-oriented assembly line is appropriate, where stations have an operating system that is specialized for homogeneous products (Kucukkoc and Zhang, 2017). The stations are often close and interconnected to one another where the product moves in a flow direction, thus value is being added to the product by the use of the resources at each station (Limère et al. 2012; Ikuma et al. 2010). Each station is performed in a predetermined working pace, also known as cycle time (Atasagun and Kara, 2013).
In an assembly line; the operators have relatively simple working tasks, due to specialized equipment and standardized work procedures that facilitates the work process (Xu and Xiao, 2009). An assembly line requires extensive balancing between all stations (Sancı and Azizoğlu, 2017). Therefore, even the slightest disturbance in the manufacturing process can cause the entire production to be decelerated (Xu and Xiao, 2009; Gurevsky et al., 2013).
(Figure 5). The two most common types are the traditional straight assembly line and the U-shaped assembly line (Kara et al. 2010) whereas the second mentioned provides higher flexibility and quality compared to the traditional straight assembly line according to Atasagun and Kara (2013).
Modular house manufacturing
Modular houses are manufactured in factories, under controlled conditions and by qualified specialists (Mullens and Kelley, 2004). Modular house manufacturing companies are following the same laws and legislations as other construction companies; however, the production is characterized by manufacturing and assembling the units in a central location using standardized methods of practice before the final formation (Molavi and Barral, 2016; Nasereddin et al. 2007).
The construction of the modular houses can be for example schools, offices and residents (Lee et al., 2016). The modular houses can be built up to 95% degree of completion in the factory (Ikuma et al., 2011).
The finished modular houses are transported from the factory to the construction site and assembled into a unitary modular unit (Nasereddin et al. 2007). The high level of completion derived from technology and a standardized manufacturing process saves time and costs as well as improving the efficiency and quality (Steinhardt and Manley, 2016) along with avoiding the problems that may arise due to weather conditions thus create a safer working environment (Ikuma et al. 2011; Molavi and Barral, 2016).
According to Molavi and Barral (2016); the cost can be an advantage for modular house manufacturing. Modular house manufacturing imply a lower production cost due to the need of less and cheaper labor without obstacles such as bad weather compared to a traditional construction site. On the other hand, design engineering, contract administration, and procurement are departments that increases in costs for the modular house manufacturing industry (Molavi and Barral, 2016).
A disadvantage for modular house manufacturing is the need for materials. Units can require more extensive solutions in order to accomplish the necessary structural performance compared to traditional techniques. Due to the extensive amount of fabrication as well as transportation; the complexity of planning and scheduling will enhance (Molavi and Barral, 2016)
A classical problem in manufacturing industries is the balancing of the assembly line (Pereira, 2015; Xu and Xiao, 2009; Gurevsky et al. 2013). Line balancing is a challenging task due to complexity and constraints in the process of the modular house manufacturing industry; such as dry time and bulky materials (Corominas et al. 2011; Ikuma et al. 2010). To continue, the complexity also adheres to the level of standardization whereas it is common to address mixed-model assembly lines for industries that offers variety in their products. Product variation implies deviation in processing time at each assembly line workstation (Boysen et al. 2011).
When the tasks of the manufacturing process are evenly distributed; i.e. the cycle time at each workstation is equal; the production efficiency will increase (Roy and Khan, 2010; Sancı and Azizoğlu, 2017). The challenge behind this issue are precedence constraints that adheres the need for completing some tasks to be able to undertake another task (Blum, 2010; Roy and Khan, 2011).
In relation to line balancing, the dry time included in the manufacturing process of the modular house manufacturing industry is an issue (Yaghubian et al. 1999). Gluing of roof and floor carpets needs to reach a desired dry state before further production can be carried on (Sterley et al. 2012). The same goes for the dry time of paint and spackle (Steinhardt and Marley, 2016).
The material supply has a large impact on the production efficiency of the assembly line thus the layout needs to be designed in a way that the material can feed the line with the right amount at the right time (Lee et al. 2016). One critical factor within the issue of having a good material supply for the modular house manufacturing industry is the bulky materials (Steinhardt and Manley, 2016). Bulky materials result in inflexibility for placement of materials; i.e. having the materials close to the working stations. Further on, loading of materials can be challenging due to space occupation. In relation to the assembly operation; bulky materials require aid such as traveling cranes to facilitate the material handling (Nasereddin et al. 2007)
1.2 PROBLEM FORMULATION
1.3 PURPOSE AND RESEARCH QUESTIONS
1.4 SCOPE AND DELIMITATIONS
2 Frame of reference
2.1 COMPONENTS OF THE FRAME OF REFERENCE
2.2 BENEFITS AND DRAWBACKS
2.3 CRITICAL FACTORS
2.4 DESIGN OF ASSEMBLY LINE
3 Method and implementation
3.1 RESEARCH APPROACH.
3.2 RESEARCH STRATEGY
3.4 DATA ANALYSIS
4 Findings and analysis
4.1 CASE COMPANY DESCRIPTION
4.2 EXISTING MANUFACTURING PROCESS
4.3 BENEFITS AND DRAWBACKS FOR HAVING AN ASSEMBLY LINE FOR MODULAR HOUSE MANUFACTURING
4.4 CRITICAL FACTORS TO CONSIDER WHEN DESIGNING AN ASSEMBLY LINE FOR MODULAR HOUSE MANUFACTURING
4.5 POSSIBLE FUTURE MANUFACTURING PROCESS
5 Concluding discussion
5.2 THEORETICAL AND PRACTICAL IMPLICATIONS
5.3 LIMITATIONS AND FURTHER RESEARCH
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