Process tree

From WikID

What is a process tree?

Figure 1: Examples of a Process Tree (Roozenburg and Eekels)

A Process Tree is a schematic diagram of the processes that a product goes through during its life. Between its origination and disposal, a product goes through processes such as manufacturing, assembly, distribution, installation, operation, maintenance, use, reuse and disposal. Each of these processes comes with certain requirements and wishes for the new product. Making a process tree forces you to think ahead: in which situations, places, activities will the new product turn up? Who is doing what with the product then? What problems are to be expected? What requirements do these situations necessitate? A process tree forces the designer to systematically think through all the subprocesses that a product goes through: production (including development), distribution, use and disposal. Starting with these four main processes, a tree of (sub) processes comes into being (see figure 1).

When can you use a process tree?

A process tree is preferably made in the beginning of the problem analysis.

How to make a process tree?


Starting points

The starting point of a process tree is a product, or a product group.

Expected outcome

The outcome of a process tree is a structured overview of the important processes that a product goes through. This overview helps in setting up requirements and defining functions.

Possible procedure

  1. Define the product, or product group.
  2. Identify the relevant stages in the lifecycle of the product. Use the following stages as a start: production, distribution, use, maintenance and disposal.
  3. Describe all the processes that a product goes through in the determined stages.
  4. Visualise the process tree (for example, see figure 1).

Tips and concerns

  • By taking on the role of the product, you can ask yourself in respect of each stage in which processes am I involved during this stage...?.
  • When identifying requirements from the process tree, ask yourself the following question: which criteria must the product satisfy during the process of...?.
  • You will sometimes identify processes that are preceded by a more important process. It is important to break down this hierar­chy in processes till you have reached a level where further breakdown is not possible.
  • When describing the processes, use verb-noun combinations, for example: transport product to store - place product in the store.
  • Use is typically the stage in which the product fulfils its function. In the stage of use, you can distinguish between processes performed by the user and processes performed by the product. Ideally, processes performed by the user are user tasks and processes performed by the product are functions of the product. However, they can also be forms of misuse (or unintended use) and malfunction, respectively. It is a good idea to distinguish these different types of processes, for instance by using different colours or fonts.
  • Create a table in Micrsoft Word (or any other word processor or spreadsheet) for the process tree: the column on the left shows the general stages in the product life cycle (production, distribution, use and disposal), the column on the right presents the processes.

References and Further Reading

  • Roozenburg, N.F.M. and Eekels, J. (1995) Product Design: Fundamentals and Methods, Utrecht: Lemma.
  • Roozenburg, N. and Eekels, J. (1998, 2nd ed.) Product Ontwerpen: Structuur en Methoden, Utrecht: Lemma.

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