The ranked list of shop floor time elements is shown in Table 4-XVII. Unlike other methods in vogue, such as six sigma, TQM, TPM, etc., the ranking process includes the consideration of risk. The reduction of a particular waste time type may provide a high benefit, but this may be counterweighed by the risk of difficulty in actually
68
measuring and subsequently monitoring any waste reduction gains achieved. This may have negative consequences for the sustainability of waste reduction achievements. It is important then that benefit and risk are properly balanced when evaluating which waste time type is the most important and relevant for waste reduction action at a given point in time. The waste time types with the greatest ratio of benefit to risk are considered the optimum candidates for waste reduction process improvements. They provide the optimum benefit in achieving the specified objective when balanced against the risk of inadequate and/or unsustainable waste reduction. Inability to sustain improvement can only be possible if ongoing measurement of acceptable quality is highly likely. The risk reduction framework in Figure 4-11 includes risk elements that can hinder the sustainment of waste reduction and improvement one achieved. This inability to sustain constitutes a waste of resources that may negatively affect the attainment of continuous improvement.
Time element S11 ‘Material quality delay issues’ and S17 ‘Arrange parts (setup)’ have similar levels of benefit. If benefit alone was the basis for ranking then S11 and S17 would obtain identical ranking. The evaluated risk for S17 is considerably higher than the evaluated risk for S11. Based on the consideration of benefit against risk S11 attains a rank of 1 and S17 a rank of 14. The improvement from process improvement to reduce waste in S11 is therefore evaluated more likely to succeed and evaluated as more likely for the achieved improvement to be sustainable.
The ranking results Table 4-XVII are summarised for the individual evaluations and a group evaluation involving the individuals working together to obtain common responses. Note the significant differences in individual rankings as shown in the ‘rank difference’ column. The maximum ranking difference obtained, for example, was 14 units for time element S17. This shows some evidence that consensus in the individual
69
solution ranking has not been obtained. To increase the probability of success of the data collection project it is important that agreement is reached on the solution ranking by key stakeholders. A group meeting was called and the respondents completed one common questionnaire. Differences in scoring were discussed and common agreement and/or compromise was reached. The results of the common solution ranking by benefit/risk ratio are shown in the ‘common evaluation’ column.
Table 4-XVII: Ranking results
Ideally, to obtain maximize accuracy and consistency in measurements of time used on the shop floor; it would be beneficial to collect data categorized in all 23 categories, with a priority according to level of benefit. In practice this is not possible due to human elements, impracticality of capturing small time durations, and other risks. Work centre operators will require time to be trained and become accustomed to the new data collection system. A staggered implementation of data collection time elements is considered necessary by the respondents.
70
Assume as an example decision management has agreed the first nine time element types in Figure 4-14, at the high benefit/low risk end of the B/R ratio scale, are to be implemented in the first phase. The low risk values obtained can be interpreted as these solutions, if implemented, having a low risk of not contributing to the goal of ‘company improvement’. The improvement focus is then primarily on time elements that can be measured and the effect of waste reduction effects gauged; a closed loop system. The nine time elements may be categorized as follows:
5) Production (S1),
6) Initial setup (S2, S3, S4, S5),
7) Quality/Non-conformance related issues (S8, S11), 8) Material supply delay issues (S10, S12)
Over time the perceived risk level for the remaining time element solutions can be expected to reduce, and they can then be considered for implementation by rerunning this method or other means.
From the common agreed responses given, measurement of ‘direct cost per product’ gives the most benefit to company improvement, with a weighting obtained of 0.436. Measurement of ‘utilization per work centre’ has the least value to company improvement, with a weighting obtained of 0.137. Note the difference between the highest and lowest benefit ratings has reduced, most likely due to the need for the individual respondents to compromise on their individual positions to obtain common agreement.
71
Figure 4-14: Time element types sorted by benefit/risk ratio
The most beneficial individual work centres in providing company improvement are evaluated as the brake press and welding work centres with weightings equal to 0.460. From the responses given, the risks to company improvement as a consequence of shop floor data collection focus are not technically related, but are management related. The management related risks R3 and R4 combined account for 0.80 or 80% of the evaluated risk, with technical factor risks R1 and R2 accounting for 20% of the evaluated risk. Management miscommunication (lack of consistent message, or no message) is considered to be a higher risk to company improvement than shop floor data collection related risks, or management loss of interest.
Consider a specific example: interestingly risk R32 ‘loss of champion’ received a risk evaluation of 0.013 or 1.3% by the engineer/estimator individual evaluation. This could be interpreted as the respondent believes either:
72
If the current champion was removed for any reason other persons would take over the ‘champion’ role for the project and push it through to obtain the company improvement benefit
The project champion role has little influence on the success or failure of the project.
After discussion in the group risk evaluation of R32 increased to 0.122 or 12.2% of the total evaluated risk.