Assembly process Design variables

Starting at the top, the assembly data object has one-to-many type of relationship with the part data object, whilst part object has one-to-one type of relationship with the assembly object. This determines the schema for the assembly objeet and bill of materials (BOM) is an example of it. The part object has one-to-one type of relationship with the task sequence object and it is the same viee versa. In practical terms this means that there is always a unique sequenee of tasks to manufacture the part dictated by the material and volume involved. The task sequence object has one-to-many type of relationship with the task object and the task object has a one-to-one type of relationship with the task sequence. This means that a task sequence often contains many different types of tasks. Finally, the task object has one-to-many type of relationship with the material object and equipment object, whilst the material and the equipment objects have a one-to-one type of relationship with the task object In practical terms this means that a task often utihses many different types of materials and equipment to make the parts. The determination of these relationships together with the object attributes lead us to the schema design that can hold all the information required for the manufacturing process design. The data relationships model of Fig. 3.2 integrates the key variables involved and their interactions... 

Tolerance stack analysis - Tolerances on components that are assembled together to achieve an overall design tolerance across an assembly can be individually analysed, their potential variability predicted and their combined effect on the overall conformance determined. The analysis can be used to optimize the design through the explorations of alternative tolerances, processes and materials with the goal of minimizing the costs of non-conformance. This topic is discussed in depth in Chapter 3. 

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