## 4 Conclusions  
The reliability analysis results of excavator and front loader buckets, obtained in this study, have allowed for the accurate determination of their behavior in the specific conditions of the basalt quarry. Efficient use of quarry equipment requires a reliability of approximately 80%. In practice, this was achieved through the faultless operation of the Liebherr 944 L excavator's bucket teeth for an extremely short interval of 29.71 h. For the Volvo L220 E front loader's bucket teeth, 80% reliability was achieved after about 21 h of operation, which is equivalent to three working shifts (the loader operates in two 7 h shifts per day).  
During the three-year monitoring period of the equipment, significant differences were observed in the operating times of the worn parts, specifically the bucket teeth of the Liebherr 944 L excavator and the Volvo L220 E front loader, as well as the times required for their replacement. This led to the idea of studying the evolution of the wear phenomenon under the conditions of the rocks exploited in the Bata quarry through laboratory tests. In this way, it was possible to simulate the wear phenomenon at the metal-rock contact on a tribometer, leading to the knowledge of the wear evolution of a metal sample in a friction regime with the rock with known parameters.  
The roughness value (R\({}_{\text{a}}\)), obtained and measured with a profilometer, can confirm or refute the actual wear value observed on bucket teeth in the quarry. In the case of the Volvo L220 E front loader's bucket tooth, the increase in wear of 31.03% was confirmed, corresponding to a roughness R\({}_{\text{a}}\) of 0.76 microns, as found on the tested metal samples (in contact with the same type of rock).  
The roughness value (R\({}_{\text{a}}\)) established through tribometric testing can be used to determine the maximum allowable wear limit for the teeth, as agreed upon in the maintenance and reconditioning plan. The roughness of the worn surfaces of the bucket teeth depends on the properties of the rocks and the material of the teeth; therefore, tribological tests should be repeated whenever the structure of the rocks in the massif changes, as the operating times until the teeth need to be replaced change with the changing properties of the rocks.  
The replacement times for the teeth depend on the skill of the maintenance workers, as well as the deformations of the worn teeth, which in some cases are blocked in the fastening devices. The operators' ability to coordinate the proper operation of the equipment and the constant verification of the wear of parts that are in direct contact with the rock can help avoid unjustified interruptions in operation. In this context, and considering the uncertainties regarding sales volume, equipment availability, or other causes that may intervene in the production process, it is necessary to draw up a weekly maintenance schedule for each month, which specifies the scheduled interventions on the quarry equipment.  
There is a clear need to increase the service life of replacement parts such as bucket teeth, especially through reconditioning, which is sometimes repeated. The economic efficiency resulting from the application of the optimized welding technology for bucket teeth is approximately 1700 euros for a consumption of 20 teeth per quarry, for 1.5 production cycles. The proposed and experimentally tested method of manual welding directly in the quarry for attaching bucket teeth has allowed the simultaneous achievement of two objectives: increasing the service life of bucket teeth and reducing downtime required for replacing worn ones.  
Literature review and analysis, V.A.F. and M.T.; methodology, V.A.F. and M.T.; writing M.T.; experiments, V.A.F.; results analysis, V.A.F. and M.T. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.