## 4 Innovation of the TPM Methodology Regarding the Division of Preventive Maintenance
### Am--Autonomous Maintenance  
This concerns time-driven preventive maintenance when maintenance is performed in the same repeating cycles aiming at performing simple, standardised work procedures while looking for abnormalities that might affect future operation of the equipment and lead to a failure. The TPM methodology counts on various frequencies for equipment downtimes and preventive maintenance. The most used are weekly or monthly frequencies based on the priority of the equipment with regards to production or its load. Smaller equipment load receives an annual frequency. This results in a more effective process as it does not require the same number of people to execute preventive maintenance. Therefore, the workforce can be effectively assigned to preventive maintenance based on priority. The factors mentioned above results in the equipment classification according to the priority, which will receive the frequency of preventive maintenance. Proposed innovative solution of equipment division according to priority, see Figure 7:  
* A--extra high priority--AM prevention on a weekly basis (W-weekly);
* A--high priority--AM prevention every-two-weeks basis even/odd week;
* B--medium-high priority--AM prevention on a monthly basis (M-monthly);
* C--low priority--AM prevention on a half-year basis (A-annually). These parameters were determined on the basis of the production hall plan. The individual priorities were designed based on production planning. Figure 7 also shows a map of equipment division based on priority from the point of view of:  
1. Production--importance of the equipment according to production planning;
2. Maintenance--importance of the equipment according to its complexity or components;
3. KPI--equipment division according to failures or abnormalities incidence. Planning of the AM block is automatic. Equipment downtimes are planned periodically in a fixed time. If preventive maintenance is not executed, a new event is planned automatically. Figure 8 shows an example of a four-shift operation, where the model is divided according to the priorities mentioned above with an effective division of the work of two electromechanics and two mechanics. It concerns a real implementation. Individual equipment downtime takes place in the given cycle for 24 h, i.e., two standard 12 h shifts. The downtime is used for preventive maintenance as well as the AM block. Whena planned repair is scheduled, the PM block is also executed; in the case of expiration, the PP block as well. We will focus on this block, which results from autonomous prevention since the standardised procedure includes activities known from autonomous prevention, i.e., so-called TLC activities. Figure 8: Innovative division of production equipment according to priorities. Figure 7: Division of production equipment according to priority. Proposed TLC activities (proposed part of the innovated methodology):  
1. Tightening--loosening is statistically the second most frequent cause of equipment failure;
2. Lubrication--critically worn places must be regularly lubricated;
3. Cleaning--failure occurrence can be caused by dirt in 50%. It is important to mention that the working procedure of the AM block is standardised, unchangeable, and registered into the working instruction. Each change to this standard must be approved and registered. This leads to a more effective and faster process of preventive maintenance when all the downtime is used with no delays. Process of AM execution:  
* TLC activities, inspection, component replacement;
* Finding and their registering--non-standard conditions of equipment components. The AM block of preventive maintenance is thus divided into two parts. The first part incorporates standardised processes according to TLC, then the second one incorporates a check for findings. Those are registered and stored in a findings database, see Figure 9. Each finding has its own ID number, date, category, description, and person who registered it. Findings are solved within the process of PM, i.e., findings removal.