One of the issues with lean manufacturing is that implementation often relies upon complex six sigma calculations, analytics and concepts, some of which are redundant, time-consuming and admittedly, quite laborious. It’s a reason why some of my customers are reluctant to use these applications when measuring work cell output. However, lean manufacturing need not be complicated. In fact, lean principles should follow a common sense approach to increasing production throughput; allow work to move without interference or obstruction from one work station to another and from one work cell to another.
Simplifying the Lean Work Cell
In one of my recent posts, I outlined three essential work cell layouts; the “U” shaped layout, the “T” shaped layout and the “S” or “Z” shaped layout. All three are explained in the accompanying video, and all three follow a straightforward doctrine of simplifying how work moves between individual work stations within work cells. Some layouts, such as the "T" and "S" shaped layouts, allow you to structure your cells in and around obstructions – such as pillars, CNC machines, furnaces etc. Others, like the "U" shaped layout, are meant to minimize transit times by designating incoming and outgoing workflow.
Proper work cell layout has a simple purpose; make it easy to work and easy to move raw materials, semi-finished and finished goods to the next chain in the process. Without the proper layout, your company can't improve its manufacturing productivity rate within the cell. The following video explains the simplicity of these three aforementioned layouts and provides a summary of the five steps to identifying a given work cell's productivity rate. The video also outlines how to summarize production volumes emerging from individual cells.
The above video and five step process for productivity rate analysis is taken from the post: Manufacturing Work Cell Optimization: Design, Layout and Analysis
The Key to Lean Principles & Work Cell Output: Your Production Floor Layout
The biggest mistake companies make is how they decide to move forward with improving work cell output. Instead of redesigning their cells, they immediately move forward with trying to lower their cycle times within their current production floor layout - flaws and all. If their layout is poorly put together, then they'll immediately become frustrated by a lack of results and will likely abandon their efforts.
This points to the first area of improving work cell output: Start by assessing whether your production floor needs to be redesigned, or simply tweaked. If your production floor is fairly well put together, then you should be able to improve cycle times and increase production throughput, albeit gradually. However, if your current layout is a complete disaster, then you should start by redesigning your shop floor. In those instances where a redesign of your shop floor is a necessity, it’s best to concentrate on the following three steps.
1. Immediately Redesign Work Cells: If you want to know if your current production layout is well designed, then map out your shop floor using workflow diagrams and spaghetti outlines. This should help you determine whether your production floor is fractured and poorly structured, or whether it is one that can easily be improved upon. If that layout is poorly put together, then don’t bother tracking cycle time variances; immediately move to redesigning your work cells by using the three aforementioned layouts explained in the video; the "U" shaped layout, the "T" shaped layout and the "S" or "Z" shaped layout.
The above spaghetti diagram is taken from: Can Workflow Diagrams Help Improve Manufacturing Capacity?
2. Track Cycle Time Variances: After the shop floor is redesigned, you can then move forward with cycle time variance analysis. The process involves identifying the causes of high and low cycle times. Ultimately, you want to understand the variances in cycle times emerging from individual stations within each work cell. These variances point to how you can further reduce cycle times and improve work cell output. However, this requires you set up the perfect manufacturing work station, one where you continually eliminate the causes of work stoppages and downtime.
All of the above is taken from: Cycle Time Tracking & Variance Analysis in Excel for Small Manufacturers. The excel sheet allows you to input your own cycle times. You'll then be able to track your mean, mode and median cycle times.
3. Institute Continuous Feedback Loop: Lean manufacturing and continuous improvement simply implies that a company is constantly raising the bar on performance by continually analyzing their production throughput. In this case, it’s important to consider this entire process as a constant feedback loop, one where the improvements made in redesigning work cells and eliminating downtime are used to further lower production cycle times. As such, you’re likely to find multiple causes of downtime. Some issues may pertain to poor work instructions, improper work orders, incomplete bill of materials, lack of proper tools, and or material and part shortages. One tool that can help streamline your bill of materials, and ensure your enterprise uses more standard raw materials and spare parts, is to use a bill of material (BOM) substructure analysis. An example of a substructure analysis is outlined below, along with a link to an article that explains how to use the analysis.
The following is taken from: Bill of Materials Essentials: Substructure & Subassembly Analysis
Focus on Simplicity and Then Focus on Results
The ultimate goal is to reduce the time it takes to move raw materials, semi-finished and finished goods through a company’s production. In fact, it’s this last point that is often ignored when companies look to adopt lean manufacturing principles. They believe the best course of action is to occupy as much space as possible on their shop floor, often to the detriment of their production employees. Instead of allowing work to flow freely, they handcuff their employees by minimizing their work space – not maximizing it.
Now, by no means is this all there is to measuring production throughput and tracking cycle time variances in individual work cells. Rather, this post is meant to simplify the entire process of lean manufacturing by showing you that the end goal must be to make it easy for work to move through your production floor. Again, a lot of lean principles are based on common sense; understand the root causes of work stoppages and downtime, eliminate them as going concerns, and then systematically reduce cycle times by constantly revisiting your progress.
Sometimes the applications and analyses involved are serious endeavors and the intention isn’t to imply that all you need to do is follow those aforementioned three steps. What it does mean is that you shouldn’t be so easily dismayed by the prospect of adopting lean principles to increase work cell output. Again, it's ultimately about adopting some common sense strategies and best practices on your shop floor. If all you focus on is reducing waste, eliminating lost time, and allowing work to flow freely, then you've nailed the three most important aspects of adopting lean approaches in manufacturing.
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