# PDCA 4.0: A New Conceptual Approach for Continuous Improvement in the Industry 4.0 Paradigm
## 2 Lean Manufacturing and Continuous Improvement
### Challenges and Limitations  
An analysis about the challenges and limitations of the conventional CI practices is important in order to identify gaps that can be mitigated by the proposed PDCA 4.0 approach. A comprehensive survey was carried out through the use of the Google Scholar search engine, using the keywords \"Limitations of Continuous Improvement\", \"Limitations of Problem Solving\", \"Limitations of Kaizen\", and \"Limitations of Lean Manufacturing\". In total, 16 related publications were found. Three major aspects were identified among the selected publications regarding the challenges and limitations of CI practices (Figure 1). The typical pen-and-paper format of documentation [7; 10; 22] implies several constraints in CI projects and is not ideal to achieve an effective documentation management, as is further described. Despite their team building usefulness, the existence of Obeya rooms made the access to CI information by all the elements involved in the CI projects difficult [25]. Some authors describe the limitations of the traditional pen-and-paper value stream mapping (VSM) [7; 17], indicating that this aspect is also relevant in the mapping activity. According to [PERSON] et al. [10], due to the physical format of CI documentation, the lack of aggregated and simplified information about the status of problem-solving projects may constrain the implementation and follow-up activities. In addition, pen-and-paper formats do not allow for the storage of CI information in a computer system [22], resulting in the inexistence of a database with previous problem-solving projects, which is a need addressed by some authors [10; 26]. Therefore, the in \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Phase** & **General** & **Problem Identification** & & & & **Problem Solving** & & Follow-up and Standardization \\ \hline \multirow{3}{*}{Activity} & Information & KPI & \multirow{2}{*}{Mapping} & \multirow{2}{*}{Diagnosis} & Root & \multirow{2}{*}{Countermeasures} & \multirow{2}{*}{Implementation} & \multirow{2}{*}{
\begin{tabular}{c} Follow-up and Standardization \\ \end{tabular} } \\  & Management & & & & & & & & & \\ \hline \multirow{2}{*}{PDCA} & P & D & \multirow{2}{*}{P} & \multirow{2}{*}{P} & \multirow{2}{*}{P} & \multirow{2}{*}{P} & \multirow{2}{*}{D} & \multirow{2}{*}{C} & \multirow{2}{*}{A} \\  & C & A & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Typical process for managing and executing CI projects. Figure 1: Typical origins of the challenges and limitations of conventional CI practices. information system (IS) and its regular documentation management leads to not using knowledge acquired in previous CI initiatives, which might result in reworks in finding root causes and countermeasures. The inexistence of an IS, or its lack of application for CI purposes, leads to more challenges and limitations. In addition, the absence of an automatic data collection and result analysis platform also contributes to limit and constrain the CI project's impact and assertiveness. Regarding the KPI analysis activity, production planning using ERP combined with manual Excel sheets is a conventional practice in organizations that do not support reliable and real-time data collection to the dashboards [27]. This difficulty is also felt for the VSM because it offers only a \"photograph\" of the system, and a small change in the real situation would change its validity [7]. Concerning the diagnosis, various authors point out that data are typically collected and analyzed manually, which is very time-consuming [11; 28]. Other authors even mention the lack of access to process the data, which makes them impossible to measure, control, and improve [11; 26; 29]. This indicates the lack of connection between physical production objects and virtual IS [11; 28]. This limitation also spans the follow-up and standardization activities [11].