Raw engineering data often contain missing values, sensor faults, mislabeled records, unit inconsistencies and duplicates. Preparation includes documentation of sources, handling of missing data, outlier analysis based on physical reasoning, resampling and alignment of time series, and feature construction. Each step is recorded so that it can be reproduced, and the data processing is fitted using training data only to avoid leakage.
Where privacy or confidentiality applies, we recommend anonymisation or on-premises processing and agree on arrangements at scoping.