Analyse

Here, analysis of the various collected data is done to provide information on where the biggest areas of improvement lie, to brainstorm potential solutions and plan to implement these solutions during the Improve phase.

WIP

WIP needs to be reduced, as too much inventory is tied up at all stages to cover for various issues. Inventory is one of the seven original wastes.

Line Metrics

The line metrics board will be updated, so that the information is easy to read and understand, easy to update, can track output per shift.

Cycle Time

From analysis of the time and motion studies, improving the manual work aspects by standardising the work of various stages can reduce the cycle time, allowing got more pieces to be produced each shift.

Process Yield

Eliminating defects due to the supplier, which are caught in stage 1, will provide the biggest improvement in process yield, while training operators in better manual handling procedures will reduces the in-process defects caught in stage 8.

Layout

Changing the layout will improve the flow of the product through the cell. It will also, in conjunction with takt time calculations, allow for the reassignment of one operator, and the work to be divided more evenly between the remaining two operators. Kanbans will also be used to move product through the line.

OEE

OEE (Overall Equipment Effectiveness) charts were introduced in week 11, as a means to add value to all the primary data collected. Visit www.oee.com for further information.

Figure 7

Figure 7 shows how OEE scores are arrived at, where the losses occur and are assigned.

Plant Operating time is the amount of time the facility is open and available for work.

From here, Planned Shutdown ( schedule maintenance, no products to produce, lunch, breaks) is subtracted to give Planned Production Time.

OEE calculations begin with planned production time, and look at the various losses that occur, with the goal of eliminating these losses. Down time losses are times which stop the machine from working, IE failure, material shortage, changeover time. The remaining time is Operating Time. Operating time as a percentage of planned production time is known as Availability.

This time is reduced by machines not running at maximum capacity, by machine wear and tear, operator inefficiency etc.The leaves us with Net Operating Time. Net Operating Time as a percentage of Operating time is known as Performance.

This is reduced by the time spent making defective products, including parts that require rework.

This leaves us with Full Production Time. Full Production Time as a percentage of Net Operating time is known as our Quality output. This is also our first time yield of the process.

These three numbers (Availability, Performance, Quality) are then multiplied to give the OEE score for the process.

Above information taken from http://www.vorne.com/pdf/fast-guide-to-oee.pdf

                        

Fig. 8

Figure 8 show how the percentages for each stage are rated, and how multiplying them quickly reduces the OEE figure. Quality is the most important of these figures.

Fig. 9

Fig. 10

Figures 9 & 10 show OEE scores for weeks 11 and 12. It shows how the process can change on a weekly basis.

     

Stage 6 is not included in the OEE chart as it is done in another area by a different person.

For week 11, machine reliability/unavailability was a big factor on many of the stages, resulting in the poor scores for availability. Stage 3 was used for some R&D during the week, resulting in no products being processed for a time. This created a domino effect, with parts being unavailable at the next stages for a time also, as no buffer WIP was available to keep machines working.

Performance scores suffered as a result, with operators giving time to fix/ adjust machines, thus targets were missed.

Quality scores are good overall, with stage 1 catching all raw material defects, and stage 8 catching the majority of in process defects.

In addition, these scores highlight the areas with greatest potential for improvement for the Kaizen week.

Following on from figure 5 in the measure stage, and taking OEE scores into account also, stages 3 and 6 are the areas that require greatest improvement, as they are the bottlenecks, with stage 7 running at only 75% during hours worked, and stage 3 running at 79%. In addition, the number of hours worked per day also needs to improve, by reducing setup times, length of handover meetings, staggering break times etc.

Overall, the improvements required are:

• Increase the amount of available working time per day, thus eliminating the need for overtime.
• Improve machine reliability by better maintenance.
• Improving the throughput through the bottleneck processes by 15%.
• Reduce cycle time by 5 seconds.
• Reduce in process defects from 3% to 2%, by better handling of the product.
• Reduce the variation in output between operators by 5% by further training and upskilling.
• Reduce WIP in the line by improving the flow through the line.
• This should all lead to an increase in output by 10%

OEE charts are a very valuable tool to identify areas of improvement in a process. It turns the raw data into easy to understand information, it allows for problem areas to be identified easily, RCA to begin on these areas, solutions to be implemented, and the results identifiable on updated OEE scores.