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Using Shift Work Solutions to Improve Your Lean Manufacturing Operations
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| Guest post by: Bruce Oliver |
Article Overview: When companies begin implementing lean manufacturing principles, they often overlook the possibility of using customized shift work solutions to support or enhance their efforts.
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Using Shift Work Solutions to Improve Your Lean Manufacturing Operations
Want to become really lean? Not you personally. There’s always Weight Watchers, Jenny Craig and
24-Hour Fitness for that. We’re talking about making your company lean, as in lean manufacturing, continuous improvement, process reengineering, and so on.
More and more companies are embarking on the lean journey. And why shouldn’t they? The potential benefits are huge, including major leaps in quality, productivity, and delivery performance and to improvements in employee health, safety, and morale as well. Best of all, these benefits go right to the bottom line.
If you haven’t already committed to becoming lean, you might want to think about the potential benefits. Or imagine if your competitors were able to cut their lead times, reduce defects, increase productivity every year without capital investments, and reduce their total product cost. They would have a significant advantage over your firm. It would be risky to ignore this possibility.
When companies begin implementing lean manufacturing principles, they often overlook the possibility of using customized shift work solutions to support or enhance their efforts. Shift work solutions can improve lean manufacturing systems in the following ways:
* Match flows on the shop floor with customized shift schedules that efficiently balance labor resources between production stations.
* Respond to changing customer demands with shift schedules that have the ability to flex up and down efficiently and effectively.
* Create training opportunities for teaching lean manufacturing principles and cross-training employees.
* Make preventative maintenance part of the schedule, and match maintenance resources to the maintenance workload.
Implementing the right shift schedule can prove to be a leap forward in the continuous improvement process. In particular, a 5-day operation can significantly improve just about every aspect of lean by simply converting to a 7-day schedule.
Some managers avoid schedules that include weekend work. This is mostly due to an anticipated adverse reaction from the workforce. The idea that a 7-day schedule is unacceptable to a workforce is outdated. Today’s shift schedules can offer more flexibility, pay and time off while still covering all of the hours in a week.
The intent of this article is to point out how a 7-day schedule will benefit a lean operation.
Relieve Bottlenecks
A bottleneck, or chokepoint, is the limiting factor in the speed of a process. Continuous improvement process usually deals with this phenomenon using 3 steps:
• Identify the bottleneck
• Eliminate the bottleneck
• Identify the next bottleneck
It’s the second step in this process that represents the biggest challenge. Eliminating a bottleneck may call for capital investment. A less expensive alternative is to run the bottleneck area for more hours than the rest of the facility.
For example, a company has seven lines that it runs for five days every week. Each of the lines is fed to a downstream process that is limited, by the bottleneck, to six lines of processing capacity per day. This means that every day the bottleneck falls behind the equivalent of one line of output for one day. By Friday night, the lines are done producing for the week. Meanwhile, the bottleneck has a backlog of five line-days worth of production. The result is:
• A stockpile of product that is not having value being added = Waste.
• Quality problems due to higher W.I.P. and slower recognition of flaws.
• Higher costs associated with higher inventory.
• Slower responsiveness to changes in orders. You cannot change what you have already produced and accumulated upstream of the bottleneck.
Now consider a similar plant with the same production requirements. However, this plant does not run all seven lines for five days. Instead, it runs five lines for seven days. In the end, both methods produce 35 line-days of work per week.
By running fewer lines for more days, the bottleneck has disappeared. What was a limiting factor now represents excess capacity. The downstream process can handle up to six lines of input a day and, in this example, it only has to process five. The upstream backlog has been eliminated. W.I.P. has been reduced. Customer responsiveness has improved. Quality improves. Carrying costs are reduced.
Reduce Cycle Times
One goal of continuous improvement is to reduce cycle time, the amount of time between starting work on a unit and completing the work on that same unit. Some companies will take great efforts to reduce cycle times. Then on Friday night, they shut down the plant and turn out the lights. All of the work in progress at that time will sit idle until the plant starts up again on Monday morning (56 hours later). Meanwhile, the cycle time clock continues to tick.
There is a tremendous amount of “wait time” generated by simply shutting down for the weekend. There are large production “ramps” that proceed and follow each shut down. A process that is well underway will typically have W.I.P. throughout.
A shutdown at the end of the week may mean running all of the lines empty. This has the following impact:
• Typically, everyone goes home at the same time. This implies that workers at the start of the process become idle as their process is emptied out.
• Break-downs or other, unanticipated problems can throw off a schedule designed to empty the line at a precise point in time (usually targeted for the end of a shift.)
• On Friday, raw material is prestaged for Monday, starting the cycle time clock just before the plant goes idle for 2 days.
• Monday start-up will be slow. No final product is produced until the line has completely filled back up.
Reduce W.I.P.
Most companies will avoid a 7-day schedule if they think they can reach all of the production targets with a 5-day production week. It simply does not sound right to reduce production on a daily basis so it will take seven days to meet customer demands. In reality, there are several reasons for doing this: fewer bottlenecks, improved customer responsiveness, lower inventories and reduced W.I.P. The amount of W.I.P. is a good measure of how lean you are actually running. Less W.I.P. means less inventory, less waiting between processes and faster responses to quality problems.
Not all operations are capable of making this change in production rate. For those that can, the result is a more than 28% reduction in W.I.P.
Reduce Warehouse Inventories
One of the signals in a pull production system comes from the final goods inventory. Once inventories drop below a certain level, more product is manufactured. In a 5-day production process, the inventory level expected for Monday morning must be achieved by the end of the workday on Friday. The result is a warehouse filled with product that is having no value added to it. This product is being held for two days out of every seven in this condition. This is the same as saying that 28% of the time, you will be carrying a full inventory of finished product with no return on the investment.
With a 7-day production system, you will be producing over the weekend. The result is that inventories going into the weekend can be lowered.
Let’s assume that a 5-day operation was producing 21 units per day so that the total weekly production was 105 units (5 * 21 = 105). Let’s also assume that the required inventory at the start of each week was 100 units. To achieve that, there would have to be 100 units in the warehouse at the end of every Friday...ready and waiting for the start of week. The average end of day inventory would be 100 units.
With a 7-day operation, the same volume could be produced at only 15 units per day (7 * 15 = 105). Since production would continue through the weekend, the end of day inventories could drop below 100 units. In this case, the average end of day inventory would be 85 units.
This represents a 15% reduction in the average volume of finished goods in stock. It is worth noting that companies that produce on the weekend frequently begin to ship on the weekend as well. This will have an even greater impact on lowering inventories.
Improve Customer Responsiveness
An order comes in and is immediately scheduled for completion during the next production shift. This seems pretty responsive unless the order came in on Friday afternoon. For a 5-day operation, this translates into a 2-day wait before anyone starts to fill the order. No one is around on the weekend to do any work.
With a 7-day operation, orders are received and processed without regard to the day of the week. Every day is just like the next. There is no need to schedule around a weekend. That Friday night order will be ready for shipment on Saturday.
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About the Author: Bruce Oliver RSS for Bruce's articles - Visit Bruce's website Shiftwork Solutions is a hands-on consulting firm that manages your shift work project with you. Over the last 20 years we have helped more than 300 companies worldwide. We specialize in all aspects of shiftwork operations including: * Transitioning from 5-day to 7-day operations Click here to visit Bruce's website Using Shift Work Solutions to Improve Your Lean Manufacturing Operations Employee Shift Work Schedules Characteristics of Effective Shift Work Schedules Attacking Fatigue in the Workplace Shift Work Schedules What Employees Want |
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