1、I L MIL-STW293 18 October 1956 SUPERSEDING NRV8hipS-250-344-8 1 April 1956 - Licensed by Information Handling ServicesMIL-STD-273 73 77777311 Q0159q7 3 MIL-STD-293 18 October 1956 OFFICE OF THE ASSISTANT SECRETARY OF DEFENSE WASHINGTON 25, B. C. Supply a.nd Logistics VISUAL INSPECTION GUIDE FOR CELL
2、ULAR RUBBER ITELMS MIL-STD-293 18 October 1956 1. This sbandard has been approved by the Department of Defense and is mandatory for use by the Departments of the Army, the Navy, and the Air Force, effective immediately. 2. In accordance with established procedure, the Standardization Division has de
3、signated the Ordnance Corps, tshe Bureau of Ships, and the Air Force, respectively, as the Army-Navy- nonsealing 24. Missing material, sealing surface-major; 2. Calendar check-not a defect 25. Porosity-not a defect 26. Shrivel, sealing surface-minor ; nonsealing 3. Cold check, s,ealing surface-major
4、; non- surface-not a defect sealing surface-minor ; nonsealing and 27. Bad splice-major nonvisible surface-not a defect 28. Trapped air-major 4. Heavy stock check, sealing surface-major; 29. Trapped air-minor 30. Blowhole-major nonsealing surface-not a defect. 5. Light stock check, sealing surface-m
5、inor; 31. L core area-major nonsealing surface-not a defect 32. urface dirt, slight amount-minor 6. Concavity-not a defect 33- Discoloration-will show through cover- 7. Cover stock missing, sealing surface- major; will not show through cover- 8. Cover stock missing, under K6 inch-minor 9. Crac.k-maj
6、or 1 O. Crack, sealing surface-major ; nonsealing 11. Bad fill, below dimensional toierance- 12. Poor fill, nonsealing surface-minor 13. Poor fill, sealing surface-major 14. Poor fill, nonsealing surface-minor 15. Poor fill, nonsealing surface-minor 16. Poor fill, nonsealing surface-minor 17. Poor f
7、ill-major i 8. Poor fill-minor 19. Missing material-major 20. Missing material-major 21. Missing material-major 22. Missing material, sealing surface-major ; 23. Missing material, sealing surface-major ; surface-minor nonsealing surface-minor major; nonsealing surface-minor not. a defect. 34, Distor
8、tion, large-major 35. Hard spot-major 36. Separa tion-maj or 37. Shrinkage mark-major 38. Loose skin-major 39. Tough skin-minor 41. Sunburst: A-major; B-minor 42. Edge tear-major 43. Surface tear-major 44. Corner void-major 45. Curface void-major 46. Buff repair-acceptable 47. Plugged core holes-acc
9、epta ble 48. Punc.hed core holes-acceptable 49. Froth repair-acceptable 50. Insert repair-acceptable 5 1, Resurfaced repair-accepfable nonsealing surface-minor 52. Section repair-acceptable 53. Section repair-acceptable nonsealing surface-minor 54. Tear repair-acceptable surf ace-minor major 40. Wri
10、nkled skin-minor - - IV Licensed by Information Handling Services- M%b-STD-Z73 93 71999LL ROai595i- 3 I MILSTD-293 18 October 1956 FOREWORD Government material procurement specifications have been primarily concerned witah detailing composition, const,ruction and necessary physical requirements. How
11、ever, little attention has been paid to defining the limits of acceptable quality regarding manufacturing defects other than such generali- zations as “the workmanship shall be first class.” In such a diverse industry as that of rubber manufacturing, individual plants vary considerably in their prod
12、uction and quality control techniques. Defects are likelg to occur from many causes such as variation in the quality of the basic materials and varia- tions in manufacturing processes and finishing operations. Therefore, the qualiey generalizations used in this document must of necessity cover a con
13、- siderable range which represen8 the best available judgment. This documen t- is issued as a practical yardstick which inspectors will use to appraise visua.lly the quality of cellular rubber items. 6 a 1 o Licensed by Information Handling ServicesMIL-STD-273 93 777771L 0035753 5 MIL-$TD-293 18 Oct
14、ober 1956 i. SCOPE AND PURPOSE 1.1 Scope. This document covers only visual defects for %porige“ rubber items. These include chemically blown or expanded rubber items having either open and interconnecting cells or closed and . noninterconnecting cells. Also included are cellular products made from c
15、hemically or mechanically foamed latices or liquid elastomers. 1.2 Purpose. The primary objective of this document is to present word descriptions and photographs of possible defects in cellular rubber items that may be presented for in- spection. In addition it provides a training aid for inspector
16、s. 1.2.1. In general this document is not in- tended to take the place of a particular inspec- tion procedure aid which may be provided for inspectors. to verify conformance with a par- ticular specfication. The quality require- ments specified in the basic specification are governing. 2. REFERENCED
17、 DOCUMENTS 2.1 Standards MILITARY MIMTD-i05 Sampling procedures and Tables for Inspection by At- tribu tes MIMTD-i77 Rubber Prod uc. ts, Terms for Visible Defects of (Copies of specifications, standards, drawings, and publications required by contractors in connection with specific procurement funct
18、ions should be obtained from the procuring agency or as directed by the con- tracting officer.) 3. DEFINITIONS 3.1 Categories, major and minor defects, are as defined in Standard MILSTD-105. 3.2 Word descriptions of visible defects used in this standard are in accordance with Standard MIGSTD-177. 4.
19、 GENERAL 4.1 The classification of visual defects for cellular rubber items is more complex t.han for a single-shape, single-application item such as V-be1t.s. Cellular rubber goods are produced e 2 -. - - i in a nearly infinite variety of sizes and shapes so that there is no common or typical shape
20、 for this class of item. Also, these items have several principal end uses or service require- ments which are dissimilar in the amount of perfection or quality required. These include the following: a. Flezing. A critical use where the item undergoes constant or intermittent bending, twisting or de
21、flectiug during service such as a vibra tion isobtion ma terial. b. Sealing. A critical use where the item serves as an airtight or watertight closure such tm a gasket. An intermediate use where theitem serves as a covering material and physi- cal stress is not existent or occurs infrequently, such
22、as rug underlay. A noncritical use where the item serves merely as an internal space filler and physical stress is not existent or occurs infrequently, as an insulation material. A cellular rubber item may, and frequently does, have two or mort3 of these service require- ments in combination. 4.2 It
23、 is recognized that the rejkction of an inspection lot of cellular rubber items for flaws which are not commensurate with the dimen- sional tolerances or degree of quality required by the user can result in an appreciable increase in the cost of production. in some instances the enforcement. of very
24、 high standards could result in an appreciable decrease in the volume of production. Accordingly, some of the visual defects in this guide are classified under three categories (major, minor, or acceptable) de- pending on the type of service requirement. 4.3 Since the classification of certain visua
25、l defects depends on the service requirements of the item, it is imperative that the end use be known before inspection is started. In the majority of cases, the end uses will be apparent or can be readily determined from the procure- ment document, However, in case of doubt, the cognizant technical
26、 bureau or agency (on primes) or the endorsing inspection service (on subs) should be. requested to supplj- this information. The following flaws may be allowed, provided they are corrected as indicated and c. Protecting. d. Faling. 4.4 Licensed by Information Handling ServicesMIL-STD-273 73 9779911
27、 ._ the resulting product conforms to the require- ments of the procurement document: a. Tears occurring during removal from mold, carefully cemented together. b. Small voids corrected by addition of material of identical composition and quality as that of the base item and finishing to a level, nea
28、t appearing surface. c. Increasing the compression resistance by the addition of material of identical com- position and quality as that of the base item to the core holes in a symmetrical pattern through- out the product to produce the required uniform compression resistance, (ee fig. 49.) d. Decre
29、asing the compression resistance by the removal of material in a symmetrical pclttern throughout the product to produce the x au15759 7 MG$%)-293 18 October 1956 required uniform compression resistance. (See fig. 48.) e. Assembled products where the finished item required is larger than it is feasib
30、le to mold in one section. f. Hand built shapes where the order is small and/or the nature of the shape is such as to make molding uneconomical. ome acceptable examples of the above de- scribed conditions are illustrated in figures 46 through 54. 4.5 For the convenience of presentation in table i, t
31、he defects are grouped into two t-ypes by method of manufacture, namely (A) chemi- cally blown and (B) latex foam. While a number of the defects are peculiar to the individual type, some of them a,re common to both types. TABLE I-Defects chsifiation Defect I Major I Minor I Figurenumber A-Chemically
32、 Blown Blister, on sealing surface, proportionally larger than shown or more than two Blister, on nonsealing surface, no larger proportionally than shown, or no more Blowhole (internal void). Check, Check, cold, sealing surface- _-_- _ _ _ _- _-_ - - _- -_- -_ _ of size shown per foot of cord. than
33、two of size shown per foot of cord. See blowhole under latex foam. Nonsealingsurface_T_-_-_-_-_-_-_-_-_-_-_. Nonsealing and nonvisible surface- - _ - - _ _ - - _ - - _ - - - _ - _ - - - - _ _ _ -. Check, heavy stock, sealing surface- _ _ _ _ _ _ _-_ Nonsealing surface, greater than amount shown- - _
34、 _ Nonsealing surface, no more than amount shonm Nonsealing surface, no more than amount shown- - _ Check, light stock, sealing surface, no more than amount shown-_-_-. _ _. Concavity (die cut), no greater than shown _ _ _ _= _. Cover stock missing, sealing surface_- _ - - _ - _ - - - _ _-_ _ - - -
35、_ - - - - _ _ _ - _ . Nonsealing surface-_ _ - - _ - _ - - - _ - - _ - - - - _ - _ - _ - _ - _ _ - _ - _ - - - - - - _ - -. Cover stock missing (open mold), if under 56 inch, that is, if it. will seal closed in service. Crack, sealing surface- - _ _ _-_ -_-_ _ - _ - - -_ _ - _ - - _ Distortion (defo
36、rmation). Fill, bad, molded item, below dimensional tolerance- _ _ _ -_ - _ _ _ _ - - _ Fill, poor, molded item, sealing surface 13- - - _ _ Fill, Fill, poor, strip, no greater han yS inch wide and /e inch deep Foreign material (wood, metal, etc.) , over y8 inch (any dimension) _ - _ _ _ - - - -. Ha
37、rd spot, lump of unblown material over inch (any dimensioii)_-_-. Nonsealing surface_- - - _ _ - - - - - _ - - _ - - _ _ _ - - - _ - - _ - - _ - _ - - - See distortion under latex foam. Nonsealing surface 12, 14, 15, 16_- 3 I 1. 1. 2. 3. 3. 3. 4. 4. 4. 5. 5. 6. 7. 7. 8. 9. 10. 10. 11. 13. 12, 14, 15
38、,. 16. 17. 18. Not showii. Kot showii. U Licensed by Information Handling ServicesMIL-STD-273 73 7977733 0035955 9 MIE-STD-293 18 October 1956 TABLE I-Defects chfiathn-Continued Defect I Major I Minor I Figurenumber _. A-Chemically Blown-Continued I Hard spot, lump of unblown material, yS inch to in
39、ch (any dimension)-_- Missing material _-_-_- Missing material, (dirty mold) sealing surface, more than 10 percent of area Nonsealing surface no more than 20 percent-of area or no more than se Nonsealing surface, more than 20 percent of area or more than e inch Porosity, no applied skin and no great
40、er than sbown _-_ Shrivel, no more than shown, sealing surface _ Nonsealing surface- - - - _ - _ _ - _ _ - - - - _ - _ _ -_ - - _ - - _ _ _ - _ _ - - - - - - _ - Splice, Bad _-_-_-_-_-_- Trapped air, sealing surface, more than 10 percent of area or more than %2 “onsealing surface, no more than 20 pe
41、rcent of area or no more than e honsealing surface more than 20 percent of area or more than inch or more than fi2 inch deep, inch deep. deep. inch deep. inch deep. deep. Trapped air, surface marking only _ _ B-Latex Foam Blowhole (internal void other than core hole) , large or showing surface reces
42、- Small, no surface recession and compression resistance not appreciably Core area, low, over 54 inch deep _-_-_-_-_- _ Under /B inch deep and dimensional tolerances met _ Dirt, surface (entrapped foreign material), large particle which will be felt or Slight amount which will no be felt or seen thr
43、ough cover to be used- _ Discoloration (surface stain), where will show through cover to be used_-_ Where will not show through cover to be used _ Distortion (deformation), exceeding dimensional tolerance- - _ _ _ - - - _ - _ - _ - Over )/s inch but within dimensional tolerance- _ Hard spot (a lump
44、of the basic material), large lump which will be felt through Small lump which will not be felt through cover to be used_-_-_-_- Separation (an internal splitting or delamination) _ _ _ _ _ - _ - - _-_ _ - Xote: This is almost exclusively a large area defect so the minor defect Shrinkage mark (pulla
45、way or a definite recessed area on the top or side surface) Under (e inch deep and tapering gradually _._-_ See also core area, low. Skin, loose, greater than 2 inches in diameter or more than 2 percent of he 1 to 2 inches long or $6 to 2 percent of the surface area _ Skin, tmgh (dense hide or great
46、er densit.y surface layer) _._ Skin, wrinkled, dimensional distortion _ - _ _ - - - - - - - - - _ _ -_ - _-_ - - - L _ _ Shallow or fine surface wrinkles _ sion. changed. seen through cover to be used. cover to be used. does not occur. over 5/16 inch deep. surface area. 4 -_- 1 x I x Not shown. 19,
47、20 and 21. 22, 23 and 24. 22, 23 and 24. 22, 23 and 24. 25. 26. 26. 27. 28. 28. 28. 29. 30. Not shown. 3 1. Not shown. Not. shown. 32. 33. 33. 34. Not showii. 35. Not showii. 36. 37. Not shown. 38. Kot shown. 39. Not showii. 40. Licensed by Information Handling ServicesMIL-STD-273 73 7797712 001595b B Bunburst (shallow surface voids) individual void over % inch in width and depth. Individual voids under % inch in width and depth _ Tear, edge, over 3 inches long or projecting more than inch into a plane- 1 to 3 inches long
