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|Objective of this Session||To learn how to use usage maps to characterise business processes|
|The following topics will be covered in this session|
|Process Characterisation - Usage Maps - Introduction|
|Process Characterisation - Usage Maps - Qualitative|
A usage map is a graphic, drawn for each input that shows where the total quantity of an input finally goes. Conversely, a usage map can show, for a waste type, the various sources of that waste.
Having completed the input/output diagrams, the next stage is to start tracing input and waste quantities to gain a complete picture of (a) where the total quantity of each input ends up at the end of the business process, and (b) where in the process each type of waste is generated.
This data will be used, in the preliminary assessment, to choose targets for detailed study - targets that may yield the best opportunities for business improvement.
Usage maps involve taking a different perspective on business processes (compared with input/output diagrams) and will often lead to discovery of new data. In constructing a usage map, the input (material or energy) is traced through the business processes and unit processes to establish where it is consumed. This will often lead to the realisation that, for example, electricity is used for lighting, and lighting had not been included as an input to any of the process diagrams. Likewise, new waste sources will probably be identified.
A usage map should be constructed (in this project) for water and for each of the major raw material and energy types used in the business (up to about 5 maps total). Usage maps should also be constructed for each of the main wastes (up to about 3 maps).
When constructing usage maps, don't forget to include all scrapped raw material, partly processed materials, and product. Also include any additional material or energy costs associated with rework. (Rework is reprocessing of product to eliminate defects - it is a major hidden cost in many businesses).
A usage map is constructed in two stages. The first stage is construction of a qualitative map which shows all the unit processes that use an input (or, for a waste output, all unit processes that contribute to that waste).
The second stage is construction of a quantitative map and involves assigning costs to each item in the usage map.
A usage map is constructed for each input and waste type. To keep this task manageable, construct maps for only the main 3-5 inputs and the main 2-3 wastes.
To construct an input usage map, trace the input through the business and identify all unit processes in which the input is used. Record these in the map as shown in Figure 13.1 below.
To construct a usage map for a waste type, identify all unit processes that produce that waste and record these in the map as shown in Figure 13.2 below.
In the preliminary assessment, only qualitative maps are required (ie. no quantities shown). In the detailed study, some of these maps will be further developed into quantitative usage maps (showing the quantity of each component stream).
The input/output diagrams constructed earlier are an excellent source of information for the usage maps. Also, update input/output diagrams with additional information generated from the construction of usage maps.
The team should also brainstorm the processes, and trace the destination of every portion of each input, and identify every source of each waste output, to make sure the usage maps are complete.
Make sure any scrap raw materials and finished or partly-finished products are included in the usage map.
When constructing usage maps, the more detail included in the map, the more useful the map will be during the detailed study.
However, the time available for the preliminary assessment is very limited, so don't include more than the main half dozen or so items per map (especially for electricity).
The following example shows, for the process of making and distributing bread in a wholesale bakery, a qualitative usage map for electricity (Figure 13.1) and for waste dough and bread (Figure 13.2).
Figure 13.1: Usage Map (qualitative) for Electricity
|Spoilage from storage||à||Waste dough/bread|
|Damaged bread not packaged||à|
|Returns from retailers||à|
Figure 13.2: Usage Map (qualitative) for Waste Dough and Waste Bread
Sometimes, it is convenient to expand usage maps into multiple levels as shown in the example below. This is especially useful where a waste product is split into more than one stream in a process.
In the example shown below, wastage is denoted by "(W)", and productive usage by "(P)".
|Insecticide||à||lost to atmosphere (W)|
|à||reaches earth||à||absorbed by soil (W)|
|à||absorbed onto plants (P)|
|à||washed into river (W)|
|à||residue in aeroplane tank (W)|
|à||residue in storage drums (W)|
Figure 13.3: Two-level Usage Map for Insecticide applied on a farm (aerial spraying)