Abstract:
This industrial research aims to reduce the number of claimed products from customer, emphasizing
on reducing imperfect product classified as internal defect category of a rolled and heated metal
plate process. The cause of this problem is the acceptance sampling plan of incoming raw material
inspection. An inspection plan for raw material loading section was designed as raw material was
considered to be a dominant cause of product's imperfection. Subsequently, a capability of process
was studied thoroughly. It was found that process was in control. However, a value of process
capability index was significant low. Therefore, inspection using a sampling plan was applied with
a purpose of attribute acceptance. Due to the massive size of inspected material and the time
consumption in the inspection process, a double-sampling plan was used as a tool to reduce a
number of total average inspections. Moreover, the quality profile and the process capability were
assessed in order to determine a quality level. The assessment revealed that the designed sampling
plan had the acceptance quality limit of 2 percent, the lot acceptance probability of 95 percent, the
outgoing quality limit of 6.7 percent of the total product. After following up the result of new
sampling plan, the internal defect is reduced about 56.2 percent.