## 4 The Results  
As can be seen in Figure 2, the ribs have been modified according to actual problems of the process of sleeper production (Measurement, Materials, Methods, Environment, Manpower, Machine). The whole diagram was not used to construct the Pareto diagram; rather, only the most numerous, and especially measurable, causes were taken into account. _Problem Statement: Faulty Concrete Sleeper_  
Regarding the \"Measurement\" rib, three possible causes of non-conformity in the final product were identified, namely the absence of temperature and humidity gauges, an uncalibrated pneumatic bolt tightener and an uncalibrated steel reinforcement tension line. Inaccurate torque settings of the tightening bolts can reduce their service life or cause  
Figure 2: Ishikawa diagram. them to crack. The same applies to the tension line, where the prescribed arrangement of the steel wires may not be ensured at a low tension, while the wires may crack at high tension. The root cause for this rib is the absence of a measurement management system in the organization. Three possible causes have been identified in the \"Materials\" rib: incorrect bolt material composition, non-compliant bolt heat treatment process or improper bolt cutting process. These causes are virtually unaffected by the organization. They concern only the supplier. The organization does not carry out an entry checks of bolts, rather it has been relying on the supplier's certificate. One possible cause was identified in the \"Methods\" rib: the method of fixing the steel reinforcement (improperly fitted wires, flanges, jaws, cross bolt). The manual is confusing, voluminous, and difficult to understand. The \"Manpower\" rib is extremely important because the factors involved influence other ribs as well. The operator that forms its core is involved in what is happening in the other ribs and thus in the causes they contain. Three causes were identified in this rib: non-compliance with technological process (incorrect mold preparation, imperfect mold cleaning, imperfectly applied separation emulsion), incorrect mold furnishing (incorrect steel reinforcement preparation, improperly selected steel reinforcement preload, non-observed prescribed moment in bolt tightening process), the premature start of mold vibration could be a problem due to the segregation of concrete mix components and loosening or snapping of wires, improperly selected concrete mixture. Cracking and subsequent ejection of parts of bolts causes security threats where the operator may be injured or disturbed. An anxious operator is more prone to making a mistake. Two causes have been identified in the \"Machine\" rib, namely excessive vibration and power outage or failure. The \"Environment\" rib has two possible causes: non-compliance with the hydration temperature, non-compliance with the humidity in the warehouse (bolts, fronts, reinforcement elements) are exposed to corrosion. During 1 8-h shift, 300-350 pieces of sleepers are produced, depending on their length, 4 or 5 sleepers are produced in 1 mold. The service life of the bolts is half a year in two-shift operation, during which the bolt is used about 240 times. Data obtained for the month of April 2021 were used for statistical analysis, after the production of 14,081 sleepers, of which 301 were defective, or an error occurred in the production process that prevented its finalization. Based on the Ishikawa diagram and statistical analysis of nonconforming products listed in Table 1, a Pareto diagram, Figure 3, was constructed. \begin{table}
\begin{tabular}{c c} \hline
**Causes of Faulty Concrete Sleeper** & **Total (\%)** \\ \hline Fractured bolt & 41 \\ \hline Fragments on the sleeper & 24 \\ \hline The steel reinforcement defect & 15 \\ \hline Loosening of the dowel & 8 \\ \hline Front face concrete overflow & 7 \\ \hline Unsuitable concrete mixture & 3 \\ \hline Power outage/failure & 2 \\ \hline \end{tabular}
\end{table} 
Table 1: Causes of faulty concrete sleeper.