Mixed Assembly Line Balancing
Assembly lines are meant to be a cost-efficient way to manufacture an item through standardization. Balancing the assembly line allows for low-volume, made-to-order production up to high-volume, mass-produced items. Essentially, balancing the assembly consists of allocating or reallocating tasks to a workstation to minimize downtime or constraints.
Read this article. The article proposes balancing production lines to attenuate capacity restrictions and increase balancing efficiency. Pay particular attention to section 2.2 on assembly line balancing.
Introduction
Recent trends in customer demand for customized
products encouraged the implementation of mixed assembly lines in many
industrial environments. Mixed lines can produce
more than one kind of product in the same assembly line (AL), and different sales cycles may be combined to avoid
low asset utilization when low sale of a specific product occurs. However, in order to mixed arrangements to become
viable in high competitive markets, assembly lines designers seek to
increase the efficiency by maximizing the income rate and minimizing
operating costs. Therefore, the assembly lines project an issue of great
industrial interest.
Aspects of
balancing, layout and requested product mix affect the performance of a
joint assembly line. The product mix is the quantity of each product
being manufactured by AL. However, the lack of parts, machinery and
equipment unavailability and non-conformities parts, among others,
restrict the production of certain models in certain periods. In such
way, changes in mix production are required to ensure that available
resources are used. Such utilization, however, typically proves
difficult to be carried out as the capacity constraints, imposed by
balancing, limit the production rate. Thus, whether AL have conditions
to adapt themselves to different product mix without affecting the
productive capacity, the use of available resources can be maintained.
This
paper suggests a method for mixed AL balancing scenarios subject to
change in the product mix, making the AL able to meet the total
production demand for the period independent of the produced model. That
balancing is operated by an AL mixed moving target balancing heuristic,
where tasks are allocated to workstations respecting three constraints:
(i) meet the equivalent precedence relation from precedence diagram;
(ii) allocate tasks to a workstation until the total station weighted
average time does not exceed the moving target, and (iii) allocate tasks
to a workstation in a way the total time does not exceed the station
cycle time. The proposed method was applied in a company presenting a
mixed AL that produces 7 different models. The method increased the
production capacity by 35% (meeting the required demand for the AL),
reduced the products crossing time in AL and improved line efficiency
and balancing due to a better distribution of tasks.
This paper
is divided into five sections. Section 2 presents the literature review,
detailing the assembly line types, its balancing and applicable
solutions. Section 3 presents the method stages, and its application in
the production environment is in Section 4. Section 5 brings the
conclusions.