Лако-красочные материалы — производство

Testing standards and performance specifications for anaerobic adhesives and sealants have been established by government agencies and industrial organizations in several countries. In the United States there are military specifications for thread lockers, sealants, and retaining compounds. Mil-S-22473E, 12 April 1983, ‘‘Sealing, Locking and Retaining Compounds: (Single Component)’’ covers 15 of the earliest ‘‘letter grade’’ products. Specifications are set for color, viscosity, locking torque on |-24 steel nuts and bolts, and fluid tightness. The effects of immersion in a number of fluids, heat aging at 149°C, and hot strength at 149° C (or 93° C for some grades) are also measured. This specification calls for measurement of an ‘‘average locking torque’’ after 90, 180, 270, and 360 degrees of turn.

Mil-S-46163A, 12 July 1983, ‘‘Sealing, Lubricating and Wicking Compounds: Thread-Locking, Anaerobic, Single-Component’’ covers nine grades of product for sealing (type I), lubricating (type II), and wicking (type III). Specifications are set for color, viscosity, locking torque (break and prevailing torque) on |-16 steel, zinc — and cad­mium-plated nuts and bolts, fluid tightness, lubricity, and ‘‘wicking’’ into preassembled fasteners. The immersion, heat aging, and hot strength tests are similar to those done in Mil-S-22473E.

Mil-R-46082B, 10 June 1983, ‘‘Retaining Compounds Single Component, Anaerobic’’ (Amendment 6, 9 January 1990) covers three types of retaining compounds, which are tested with a pin-and-collar compressive shear specimen. The three types vary primarily in viscosity, although there are also differences in heat resistance and strength. These products are subjected to immersion, heat aging, and hot strength tests similar to those described above.

In the United Kingdom the Ministry of Defence (MOD) has issued specifications DTD 5628-5633, which cover test procedures and performance requirements for a range of products. Five strength bands and four viscosities, from penetrating to thixotropic, are defined. The torque strengths are tested on M8 nuts and bolts and the shear strength in 12-mm pins and collars. The development of these specifications and the test procedures have been described by C. L. Brett at the MOD. The ‘‘breakloose’’ torque on nuts and bolts requires particular attention to a transient measurement where the first torsional motion is detected. Other products show somewhat different behavior, with no distinct ‘‘breakloose,’’ and the torque at which the sealant begins to yield is not easily detected [77]. British Standard BS 5292 relates to the use of anaerobic sealants on gas appliances.

In Germany, standards have been published describing the “Compression Shear Test’’ (DIN 54452), ‘‘Dynamic Viscosity Determination of Anaerobic Adhesives by Rotational Viscometer” (DIN 54453), ‘‘Initial Breakaway Test at Bonded Threads’’ (DIN 54454), and ‘‘Torsion Shear Test’’ (DIN 54455). DIN 54455 is particularly interest­ing since it is one of a very few tests in which a nut and bolt (M10) are seated to a measured torque before the anaerobic sealant is allowed to cure.

In the United States the Industrial Fastener Institute has published standards entitled ‘‘Test Procedure for Locking Ability Performance of Non-metallic Locking Element Type Prevailing Torque Lock Screws’’ and ‘‘Test Procedure for the Locking Ability Performance of Chemical Coated Lock Screws.’’ The American Society for Testing and Materials (ASTM) has published a ‘‘Standard Test Method for Shear Strength of Adhesives Using Pin-and-Collar Specimen’’ (ASTM D4562-90, October 1990). A subcommittee of ASTM Committee D-14 on Adhesives has studied torque strength tests and performance standards for anaerobic adhesives.

The International Organization for Standardization (ISO) has finalized an International Standard (ISO/DIS 10964: 1993) ‘‘Adhesives—Anaerobic Adhesives— Determination of Torque Strength of Anaerobic Adhesives on Threaded Fasteners.’’ This standard describes testing procedures for liquid and preapplied sealants using manual and graphical procedures.