| By following this simple procedure, you can make the right move and transform your factory into a smooth-running, well-oiled machine. Do you feel a little overwhelmed with the sight before you when you walk onto the factory floor? Are you sick of all the clutter? Do you feel that the equipment could be better laid out so that product isn’t travelling from one end of the factory to the other and back again? Well it probably can.
The nature of a growing business is such that with all the time pressures new equipment tends to get put in a spare corner rather than finding where the most logical place for it would be. And there it remains until years later when people get sick of the mess and inefficiency. The trouble is when it comes time to make the big move nobody is sure where the best spot is for all the machinery and equipment. Well here it is, just follow the steps outlined in this article and you can rearrange your factory with confidence that it will operate smoothly now and into the future.
1. Identify ObjectivesWhy have you decided to change the layout of your factory? What benefits do you expect to derive from making such changes? Where possible you should quantify the benefits you are seeking (eg. we want to increase the capacity of the factory by 20%.) 2. Identify Product FamiliesDevelop a list of the various products that you are manufacturing. By product family we mean a group of products that are basically the same and are manufactured via the same processes. A family of products will have variations from product to product such as different model configurations but they generally have the same base model. 3. Mapping the ProcessPlant layout should be driven by the requirements of current and expected future operations. To comprehensively compile all the intricacies of operations it is necessary to map each of the relevant processes. The quickest and easiest method of doing this is by flow-charting. Process Flow ChartsProcess flow charts are a diagrammatic representation of individual processes that show:
- each work-centre (eg. a piece of machinery, storage area or inspection area)
- sequencing of operations
- material and information flow
Process flow charts do not show physical layout or size, it is a listing of the tasks and actions required for a particular process. 4. Process ImprovementsOnce you have an understanding of the current status of your processes from having developed the Process Flow Charts you should look to improve the processes before optimising the layout. The reason being that you don’t want to invest in an optimised layout of a sub-optimal process. That is akin to automating a process that is altogether unnecessary. There is a wide range of tools available for process improvement activities such as:
- 5S Housekeeping
- Theory of Constraints
- Set-Up Time Reduction
- Process Simulation
We will not go into any of these in detail in this document, as there is plenty of information available on each of these as well as the many other process improvement tools in existence. Tip: Once you have completed your process flow chart you should identify which steps in the process comprise the bottleneck. You know then, that if your objective is to increase throughput (for example) you must increase the throughput of the bottleneck.
At the completion of this stage you should revisit your Process Flow Charts and make sure they are still a true representation of the new processes.
Note: Remembering that world-class manufacturers practice continuous improvement, this stage has the potential to go on indefinitely. You should address easily exploitable weaknesses in the process and then move on, rather than getting sidetracked and spending a large amount of time at this stage.
5. Create a Relationship ChartThe systematic process of optimising your layout requires that you understand the relationships between the various work-centres within your factory. And a relationship chart allows you to capture that information in an organised fashion. A sample relationship chart is shown below:  The first step is to take the various work-centres from your Process Flow Charts and list them in the left-hand column of the Relationship Chart. The matrix to the right of that list provides a cell for the relationship (or proximity rating) between every pairing of work-centres. Within those squares you write a rating for each of those relationships. Assigning Proximity RatingsA proximity rating is a simple weighting that reflects the desirability of physical proximity between any two work-centres. Production entities that have complicated or high volume material flow between them acquire a high proximity rating. Conversely, those entities which have undesirable interaction, (eg. one process introduces contaminants into the other), have a negative proximity rating applied. Whether such work-centres are separated by distance or a physical barrier can be determined later. Standard proximity ratings are listed below: Standard proximity ratingsA - Absolutely necessary: High rate of material transfer or materials that are cumbersome to handle E - Extremely important: Moderate rate of material transfer or materials that are somewhat cumbersome to handle
I - Important: Would be nice to have them close together, but proximity is not vital
O - Ordinary: Would be handy on occasions or for minor jobs to have them close together
U - Unimportant: Doesn’t matter if they are near or not; the entities are unrelated
X - Undesirable: Would be better if they could be kept separated
Z - Extremely undesirable: Dangerous if near or likely to be highly disruptive to one or both of the operations
Criteria that can be used to determine proximity ratings are requirements for shared supervision, shared personnel or equipment, ease of service, personnel travel and communication requirements and presence of contaminants (eg. Noise, dirt, oil and vibration). Once a proximity rating has been assigned between all of the entities you can begin redesigning the plant layout to satisfy these requirements.
6. Developing a Block LayoutThe next step in the design process is to assign areas and in some cases (eg very tall equipment) volumes to each of the given entities based on current and expected needs. These are then positioned on a diagram of the building to produce a “block layout”. The block layout is really a concept level layout that assigns sufficient space for each workcentre so the operator can then work to locate them to optimise the flow of materials and address other constraints that are captured in the relationship chart. The goal is to move the various entities around until the relationship chart is best satisfied. The best way to do this is modifying a CAD drawing of the layout. This allows simple modification, accurate measurement of distances and areas, and the ability to create several different proposed layouts. The way to satisfy the constraints of the relationship chart is to address all the ‘A’ relationships first and try to locate workcentres such that all the workcentres with an ‘A’ relationship have a minimal distance to their related workcentre. ie. If Packing and Dispatch had an ‘A’ relationship as they often would, you want to minimise the distance between those two workcentres. You then work on each of the other relationship weights in order of importance; ‘E’, ‘I’, etc. As you work through each iteration you may have to relocate some entities that you previously moved based on the new information.
It is important to note that the relationship chart is subjective, and every moved piece of equipment is added cost (and increased likelihood downtime due to damage or misalignment). Therefore the best plant layout is not necessarily the design that best meets the relationship chart. If after weighing up the costs or considering the relative worth of certain relationships, you feel that you would be better relaxing some of the criteria, then do so. The purpose of this process is simply to provide a method or tool for you to follow to simplify what is often an extremely complex problem. Keep things in perspective and make sure the process is the slave and not the master.
Once the best block layout has been selected, you may choose to develop a more detailed plan. |
