Chapter 1 illustrated how to develop the product and process information essential to rationalizing a plant. Your next tasks are the preparation of scale layout drawings of the current plant and descriptions of its existing and future processes.
Clean up your plant
First, you should improve your overall housekeeping by conducting a plant-wide 5S project. It’s not necessary to initiate a full-blown lean conversion to benefit from this key component of the lean philosophy. An orderly plant floor is a certain sign of a well-managed facility. So clear out all unneeded equipment and materials. Create a place for everything that remains and ensures that everything is located in its assigned place.
Neatness always takes less space than the chaos found in many operations. Make this housekeeping effort part of everyone’s routine and strive to maintain the order you initially achieve. Call it lean manufacturing or just common sense. The goal is to construct a starting point for your layout project that includes only the process elements required for the current product line. A 5S effort can reveal under-utilized space that can be profitably re-deployed, reduce unnecessary materials handling, and engage your employees in the rationalization process.
Draw your current plant layout
A must for any process evaluation project is a detailed scale drawing of your existing operation in AutoCAD or similar CAD software. The file must include all process machinery; fixed conveyors; raw and in-process materials storage; support equipment such as air compressors, dust collectors, and utilities; functions like offices and restrooms; and aisles. In addition, the file should accurately locate walls, doors, floor pits, changes in floor elevation, and all other building features that may impact a new layout.
To use the full power of your CAD software, you should assign each component type to a separate drawing layer. In addition, creating a layer that defines the boundaries of departments and functions will facilitate calculating space allocation and generating high-level block layouts. Using such layouts you can visualize and appraise alternative process arrangements using the tools presented in Chapter 3.
Describe your process & support elements
Creating a plant layout consists of three general steps:
- Defining the process elements that must be included in the final design.
- Allocating and configuring space for the required elements into a high-level block layout.
- Detailing the arrangement and positioning of all elements.
For our purposes, an element is a group of assets that combine to complete or support a production step. A process element can be a single machine/work center or a multi-machine department. A support element consists of the infrastructure that enables production.
Documenting your elements requires seven steps:
- List all the Elements in your plant - Be as granular as possible. Account for all the space in your building(s). Include any activity or function that requires space no matter how insignificant.
- Document the critical information for each Element by completing a Process & Support Element Summary shown in Figure 1:
Process & Support Element Summary
- Name of the Department/Activity/Work Center/Support Function
- List of Machines/Work Centers located in the Element
- Utilization Factors for Machines/Work Centers indicating % capacity at current volume
- Number of Shifts per Day
- Square Footage not including main aisles connecting to other Elements
- Geometry of Space, such as square, rectangle, L-shaped including dimensions
- Configuration of Flow, such as straight line, L, T, or U
- Materials/Products/Waste In/Out of Element – Types and volumes per shift
- Origin of Materials/Products processed in the Element
- Destination of Materials/Products processed in the Element
- Types of Material Handling used in the Element
- Storage Requirements in the Element
- Building Requirements, such as overhead clearance, utilities, dock-level access, etc.
- Headcount of Workers per shift
- Workers’ Special Needs, such as lockers, time clock, office, information system
- Assess the fitness of the current space allocated to each Element – In many existing plants, few, if any, Elements are efficiently equipped and laid out. By walking through each element and discussing its strengths and weaknesses with relevant personnel, you can determine if the current space is tight, adequate, or excessive. Based on that discussion establish an adjustment factor for each Element increasing or decreasing the current space accordingly. For instance, an existing machine may not have sufficient one-shift capacity and should be replaced by a larger machine. Or you may want to shift material storage from an Element to a central storeroom. Remember to document the reason(s) behind any adjustment.
- Calculate adjusted current space requirements for each Element – Once the current space used by each Element is fine-tuned in step 3, you can begin building a ground-up total space projection. Using the boundaries established earlier in your layout file calculate the square footages of each Element. Then develop a Space Planning spreadsheet for use in compiling current actual and adjusted footages by Element.
Space consumed by main aisles should not be included in the Elements. Rather you should determine the total space used for main aisles from your layout drawing and enter it in the spreadsheet in a row entitled ‘Space for Main Aisles’. Typically in plants that manufacture products like furniture and cabinetry aisles account for 10 to 20 percent of total space.
- Include information describing the needs for future periods in each Element Summary and create new Elements as required for new products and capacities – Always drill down as deeply as possible given your knowledge at the time. Remember to update the Summaries as new information becomes available. Beyond space estimation, the information provided in the Summaries is also invaluable in defining the relationship between the Elements and their arrangement in the overall layout.
- Estimate space for future processes and capacity – Now the tough part. The task of projecting space requirements for industrial operations is highly subjective, a mix of science and educated guess. On each current and future Summary add information that describes the modifications required to create the future state of that Element. Will new machinery or work centers be added? Will more storage space be required for in-process materials? If so, roughly how much new space will be required? Insert the estimated addition/deletion in a column on the Space Planning spreadsheet for each future period.
The most accurate method for determining space needs is to develop a rough layout of the modified Element. Account for everything – machinery, benches, storage, tooling, conveyors, and infrastructure such as compressors, etc.
As you project new space demands, remember to consider the current utilization factors for machines and work centers. Growth that doubles capacity often does not require twice the current number of machines. If a machine’s current utilization rate is 40 percent, doubling plant capacity can be achieved on the existing machine. Planning for a 100 percent utilization factor is not recommended especially in plants manufacturing custom, semi-custom, and seasonal products.
- Review the final Summaries and Space Planning estimates with the project team – Test your assumptions and space estimates for each element with the entire project team. Adjust as required.
Milestone: Start developing alternative block layouts. In Chapter 3 you will learn about three tools that compare the efficiency of your alternatives.
Credit: Every student, teacher, and engineer who has read the late Richard Muther’s Systematic Layout Planning will recognize his fingerprints on this three-part series. Find Chapter 1 here.
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