Research On Acceptance Sampling For The Inspection Of Bulk Materials

Bulk sampling is amount of material within which component parts are not initially readily distinguishable on the macroscopic level. Bulk sampling may be of gaseous, liquid or solid form. Such as coal, iron ore, fertilizer, flour, sugar, oil and so on. The research on bulk sampling has great significance in our country. The bulk sampling discussed in this paper is primarily interested in estimating the mean quality of the bulk material with reasonable cost, so as to adjust the price and process duly when necessary.Much has been written on the sampling of coal or iron ores. Recently, the need for acceptance sampling of bulk materials has increased especially for industrial products, such as powder chemicals or plastic beads. The research on bulk sampling is hysteretic relatively in China, there are many problems both in theory and application.In this paper, the author firstly introduces the sampling plans and procedures. The procedures for inspection of individual lot includes: (1)increment sampling; (2)constitution of composite samples; (3)preparation of test samples; and (4)measurements. The sample sizes in bulk sampling are, the number of sampling increments in a composite sample, the number of composite samples per lot, the number of test samples prepared from a composite sample, the number of measurement per test sample. The determination of sample sizes is complex. The lot acceptability value shall be determined according to the acceptance quality limit and non-acceptance quality limit. The upper control limit of control chart should be obtained, for each of the 10 lots, regardless of lot acceptability. Re-estimation of population standard deviation shall be made for the immediately preceding G lots.The third chapter is the demonstrational analysis. An industrial chemical consisting of fine granules will be periodically delivered as bulk material. The characteristic chosen for testing lot acceptability is a physical property. The author gives sampling plans and results.At last, the author analyzes the weakness of the thesis and gives the future directions of research.