A standard approach for creating a new production facility layout for either a green field or an existing facility is as follows:
- Perform PQ Analysis
- Preparing a Product Process Routing Matrix
- Develop Block Layout alternatives
- Optimize the size, shape, placement of the blocks.
PQ (Product Quantity Pareto ABC Analysis) and Product Process (find common routings in a mixed model business) are defined elsewhere. For many practitioners Block Layout seems be be either a bit of artistry or is mired in software complexities. Here are a few thoughts on how to approach this step in the facility design process.
First a few considerations:
In a green field we know the product and process and want to determine the size of the building we need and it’s layout. For a brown field we’re trying to make the best use of the use of the four walls we already have. In both scenarios there are trade offs to make. Having a decision making at the beginning of the project can save a lot of time and money. Some will take a mathematical approach, others organic consensus. Either way agree on the design process methodology up front.
Determine “best” layout type based on customer demand, product and processing characteristics, and business strategy. Common layout types include:
- process functional – group common machines or processes together
- product – line up equipment in sequence of operation
- fixed position – for large projects where you can’t move the product
- hybrid – mixed model, shared monument, group technology cells
In brown field facilities the main layout consideration is often in fact moving from one layout type to another as business conditions and strategies evolve.
Determine the activity and proximity relationships between the various blocks. A great approach for understanding relationships is the Simplified Systematic Layout Planning method by Muther and Wheeler.
The Product Process Routing Matrix noted above determines the quantity and type of equipment needed. One complication is that very expensive or large machines may need to be shared, so compromises may need to be made. I like the table top trial and error Paper Doll approach. Once we’ve gathered data on the importance of proximity and activity relationships between blocks, equipment footprints, maintenance and material handling access and clearance requirements, utilities, building codes, facility constraints, etc. and then we determine the gross footprint size. Now through trial and error we arrange the equipment in the block in a logical flow or sequence manner. We then have a beauty contest and subject each alternative to a decision selection matrix where we score and rank various design factors such as compactness, adjacency (relationship closeness), least travel distance (material handling cost and speed), etc.