Downloaded from https://www.everyspec.com SECTION INSPECTION ASPECTS OF ARTILLERY AMMUNITION DESIGN QUALITY ASSURANCE AS.PECTS3 OF AMMUNITION DESIGN 5-1. Quaitv Assurance It is necessary not Four factors militate against the performance only to state the dimensions 'o which an item of 100 percent acceptance Inspection of Ord- must be produced, and the nature and properties nance materiel. of the materials of which the item must be a.
The cost of 100 percent inspection (or made, but also to state methods fordetermining "screening") of all materiel would be prohibi- whether these rcquIrrments have 'zen met to tive, unless suitable automatic machines of an extent which will be satisfactory to the Gov- proven reliability are available. ernment. b. because of the extent of human fatigue I associated with the inspection of large lots, 100 The term "quality assurance" embraces the percent inspection by other than automatic ma- techniques used in the determination of the ac- chines in seldom 100 percent effective. ceptability of products. Thise techniques in- c. The contractor would tend to rely on the clude:
Ordnance inspection to screen out defectives, and would fail to inspect his product adequately; I.- -- stablishment of homogeneity criteria (lot definition) yet, inspection, is properly his own responsi- j 2. Establishment of acceptance criteria (in- biity. I spection plans, sampling plan) d. When inspection testing is destructive, I Determination of amethsof inspec 100 percent inspection obviously is impossible. •,;3. Determination of methods of inspection (gaging, testing, visual inspection) In most cases, adequate quality control may be 4. Classification of defects.
obtained by a lot-by-lot sampling inspection; The specification provisions for quality assur- that is, a predetermined number of units of the ance must be formulated with care in order that product are selected from a lot in such a man- maximum assurance of satisfactory quality may aer that the quality of the sample will repreoent be obtained at the minimum cost that is consis- as accurately as possible the quality of the lot. tent with the requirements of safety and effi- Normally, every effort should be made to select ciency of the end item. Incorrect classification a sample consisting of units of product selected of defects, unrealistic or ambiguous acceptance at random from the lot.
criteria, incomplete analysis of quality desired, 5-S. Definition of Lots. A lot is an aggregton and wrong methods of inspection may result In of objects that are essentially of the same kind, unreliable, costly, or hazardous ammunition, kindt and render difficult the satisfactory fulfillment size, form, and composition. of A contract. homogeneous lot is one in which the units of product are so thoroughly mixed that all por- 5-2. Amount of Inspection. The designengineer, tions of the lot are essentially alike. A lot may "unfamiliar with the practical aspects of inspec- be homogeneous, but the units of which it is tion, may reach the conclusion that in order to composed may not be identical.
For example, obtain materiel of satisfactory quality, accept- a lot produced on an automatic machine may ance must be based on 100 percent inspection be homogeneous, but not all the units will be for every defect which is likely to occur. Ac- identical. On the other hand, the ingots poured tually, this is not the case, unless it is essen- from one heat of steel may be considered iden- tial that there be no defective pieces accepted. tical in their chemical composition. 5-1 .... ....... L-