Manufacturers often rationalize idle time. After all, how bad is a couple of seconds here and there? Well, those seconds turn into minutes, until finally, the costs can no longer be ignored. When faced with a couple of seconds "here and there," a manufacturer will just assume that the impacts are minimal and require no further investigation. However, it’s these little periods of downtime that make all the difference. So, what can you do to improve things?
1. Make Employees Part of the Solution
Make it a point to bring production managers and employees together. Have them bring forward every cause of downtime they encounter. Interruptions can be caused by unclear work instructions, machine downtime, poor bill of materials, and or confusing work instructions. In some cases, it can be caused by production bullies, ones who insist on having the best available tools, whether needed or not, and ones who use fear and intimidation to get what they want.
Don’t be closed-minded to the issues that are brought forward. Be open and willing to discuss the information these production employees bring up. Most importantly, be ready to investigate every issue they feel is causing them problems. You might just be surprised at what they uncover.
2. Capture Lost Time by Analyzing Work Stations
Nothing compares to capturing the causes of work interruptions than to actually see them happen first-hand. A number of companies claim to know how much downtime they encounter and what their cycle times are. However, knowing what they are, and putting plans in motion to lower them, are two different things entirely. I’ve come across a number of production managers who’ve made statements such as; “...yeah, we know what the cycle times are...” – as if knowing what they are is enough. It isn't. You must do more.
Companies must capture the causes of downtime and document them at the source. Each of their work stations must be viewed as surgical stations; like a doctor operating on a patient, the employee's equipment and tools should always be in good working order, ready for use and never defective or irreplaceable.
One way to capture downtime is by witnessing production in person and writing down the root causes of work stoppages. The sheet below is taken from the article: Manufacturing Capacity Planning: The Perfect Manufacturing Work Station. The article provides some essential steps to setting up a lean work cell. Read it thoroughly.
3. Maximize Cycle Times
It means nothing to eliminate work stoppages in one work station, only to leave the next untouched. All this does it create a backlog in the process. Understand that there is a cycle time for the finished good, and there are individual times for each operation in making that finished good. Improving one work cell, and not the next, will only create more problems.
One tool to help you increase production throughput is to track the cycle time variances and volumes emerging from individuals work cells. The table and graph below are taken from the article: Cycle Time Tracking and Variance Analysis in Excel for Small Manufacturers. The article includes a sample excel sheet that allows you to determine your mean, mode and median times emerging from an individual cell. You can then graph them to determine your own variances in times, while pinpointing how often work interruptions occur.
4. Minimize Transit Times
Work should flow easily through the shop flow. It should be seamless and uninterrupted. This includes minimizing the transit time between stations. Document the amount of time it takes to move work from one location to the next. At the end of the day, you'll likely find it can take 10, 20 or even 30 minutes moving work from one work cell on the shop floor to the next. How many locations are like this? How many employees spend time sitting idly by, waiting for something to do? Again, it's the few seconds "here and there" that end up making a big difference.
5. Clean Up Bill of Materials, Assembly Drawings and Work Instructions
It’s amazing how often interruptions are caused by unclear work instructions, poor assembly outlines and drawings, and incomplete bill of materials. Perhaps most surprising is to hear companies claim that they “simply don’t have the time to fix these things”. I’ve never been in a situation where there simply wasn’t enough time to correct these kinds of issues. However, I have been in situations where management hasn’t given people the time needed to clean these issues up.
This is entirely up to management to set the priorities. As such, setting aside the time to clean up these aforementioned issues is essential. One simple tool that has always worked in my favor is to use a sub-assembly or sub-structure analysis (table below) in order to clean up bill of materials and assembly outlines. This will work for the fifth and sixth tip on this list.
What Does the Analysis Accomplish?
With the substructure analysis, you are finding the most common sub-components across multiple product offerings and eliminating redundant parts and materials. The end-goal is to reduce your inventory skews, lower costs and reduce interruptions by eliminating the confusion that comes from working with incomplete and incorrect parts lists, work orders and bill of materials. If you can call upon more standard parts in your overall finished good, then you'll increase the amount you produce in a given day.
6. Use as Many Standard Parts & Standard Sub-Assemblies as Possible
Don’t allow your manufacturing to be fractured by repetitive and redundant parts and assemblies. Use standard parts as much as possible, and build up an inventory of these sub-assembly standard parts. If your business manufactures custom-made finished goods, then you can still offer an end-to-end custom-made product, and fit in a couple of standard sub-assemblies inside the product’s envelope. In this case, it's about adopting standard parts at the design stage - so that they are not issues later on in the product's life-cycle.
These are but a few examples on how to identify and remove downtime as going concerns. In the end, it means being open to suggestions from management and employees, while also being inclusive and not exclusive. It requires setting the table for the company’s priorities, and it requires an understanding that to eliminate lost time, is to make it every employee's responsibility. Finally, it means helping employees operate like surgeons so that they are never affected by work stoppages.
This video outlines several lean work cell designs. You can learn more by going to: Manufacturing Work Cell Optimization: Design, Layout and Analysis
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