Any manager would no doubt agree that optimized use of the available production and logistics areas is a key goal of factory planning. After all, floor space is a limited resource. Where optimization is on the agenda, value adding and waste are shifted into the focus of attention. But how can these factors be determined and evaluated in the context of floor space planning?
When is floor space use optimal?
“Optimal” is a frequently used adjective when formulating objectives, and that is naturally also the case in floor space planning. The optimum here is normally the minimum area required to realize the given production task. In other words, as much value adding potential as possible must be accommodated per unit of floor space. Various parameters offer orientation: In the retail trade, for example, we speak about surface area productivity, which means the turnover generated per square meter.
In manufacturing and assembly, categories of lean production are customary. Examples which can be mentioned are value-adding, value-supporting and waste. In the case of a machining group, the workspaces of the machines can be declared value-adding areas. Handling or staging areas, on the other hand, are value-supporting. Areas for the storage of tools and fixtures belong to the same category. The remainder is waste.
If these classifications are extrapolated for a whole factory, the result is a very small area devoted to actual value adding. Floor space planning must also observe a diversity of standards, guidelines and laws. Aspects covered by such rules include escape route widths, safety clearances and the circulation or functional areas. None of this fits into any of the value categories and must thus be considered waste.
Another point to be taken into account is that individual areas may overlap. In an assembly center, for example, materials may be supplied directly into the extended reaching space above the workplace. In the top view, the value-adding and value-supporting areas then overlap. This effect is always to be observed where equipment is used at several levels. A transport system suspended from the hall ceiling is especially space-saving. On the other hand, it is technically more complex and less flexible than floor conveyors.
These examples illustrate the multitude of factors to be considered when describing an optimum in floor space use. And that is probably the main reason why there are so few benchmarks for floor space planning in production. Consequently, planners tend to follow the simple rule of planning to use as little floor space as possible.
Approach to floor space planning
Generally speaking, the best solution to a floor space planning problem will thus lie in a comparison of different variants. An area balance supplies the necessary data. It lists area categories and their corresponding proportions of the total floor space.
It must be noted that analyses of shopfloor areas generally pursue different knowledge goals to area balances for an entire site. It is thus useful to specify separate observation levels, each with their own area categories. Hierarchy levels within the factory can here serve as orientation, for example workplaces, departments, halls or premises. This enables areas to be categorized according to aspects of value adding at the level of a workplace, while maintaining functional classifications at site level.
The elaboration of area balances can be quite a complex calculation for layout planners. After all, production and assembly areas are often not simple rectangles. All manner of polygons are encountered, for example L-shapes. Possible overlaps of different area categories also play an important role. In other words, calculations can quickly evolve into an exercise for spreadsheet freaks.
It is thus quite logical to expect factory planning software to calculate area balances. In this context, the answers to the following questions can provide necessary orientation:
- Is there an explicit software function for area balance calculations?
- How complex is the elaboration of an area balance, and could it even be done automatically?
- Does the software itself offer relevant templates?
- Can area categories be defined or added by the user?
- Are transparent rules defined with regard to the overlapping of areas?
- Is it possible to influence the range of the evaluation (balance domains)?
- Is there a function to export the area balance?
- Does the software offer a function to import tabular floor space planning data (e.g. from Excel)?
You can assess how useful such features are in floor space planning by testing the visTABLE® demo version: