In this research, we targeted the defect of rebar manufacturing at rebar manufacturing factory, and consider how to ensure quality in rebar manufacturing by analyzing the relevance of manufacturing process and manufacturing information. The result of this consideration will be the basic data for realizing the use of ICT and BIM that contribute not only to ensuring quality but also to improving productivity by building a system that can consistently manage digitized manufacturing information.
At the rebar manufacturing factory, “manufacturing instruction” is created. Manufacturing instruction was created using computer software. There are 16 items of production information described in the “manufacturing instruction” used at the manufacturing factory investigated, 9 items are used only at the manufacturing site, 6 items are common with the construction site, and 1item was used only at the construction site. QR codes are printed on the “manufacturing instruction”, and manufacturing information is automatically set by reading it into a manufacturing machine that supports QR codes.
The largest number of defects in the rebar manufacturing factory were 33.3% of "manufacturing shape", followed by 27.1% of "number of manufacturing" and "loading". These three items account for 87.5% of all defects. There was a 5.2% error in creating the “manufacturing instruction”. The place where the defect was discovered was that the construction sites shipped from the rebar manufacturing factory accounted for 61.5%.
The mistake in the “number of manufacturing” in the A line occurred during the precision cutting process. This work was all handled manually by the workers, but all defects could be dealt with before shipping the manufacturing factory. All the rebar cutting machines are compatible with QR code reading, and the worker did not need to set the cutting dimensions and number of cuts. In the bending process, which is the next process of the cutting process, workers themselves input the manufacturing shape and number of manufacturing into the machine. All of the defects of the "manufacturing shape" in the C line occurred during bending. In this line, there is a machine that can read the QR code and performs cutting and bending with one unit, but it can only handle flat bending, and the three-dimensional shape was manually bent by the worker. In the loading yard of the C line, a bundle of rebar with “manufacturing instruction” lined up side by side, and it was confirmed that the driver in charge of carrying into the construction site looked for the manufacturing instructions.
Depending on the manufacturing machine, by linking with the QR code, the procedure did not depend on confirmation by workers, but all work was not linked with digitized manufacturing information, so it was partially optimized, and defects at the manufacturing site caused by the confirmation by workers. In the future, by clarifying the relationship between the manufacturing information handled in the manufacturing process at the manufacturing site and the production information used at the construction site, and digitizing manufacturing information and studying the possibility of managing it consistently, we think that it will be possible to build a workflow for rebar manufacturing and assembly using ICT which not only to ensures quality but also to improves productivity.