The fastener industry should be made aware of an important recent development in the realm of. ASTM fastener standard specifications. ASTM F/. “ASME Hex Nut, 3/8 UNC-2B, SAE J Grade 5, ASTM F Zinc Coating ZN/FE Type 5B” we simply specify: “grade 5, zinc plated. ASTM F/FM: Standard Specification for Electrodeposited Coatings on Mechanical Fasteners, Inch and Metric.
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The coating must not cause the basic thread size to be transgressed by either the internal or external threads. The testing frequency should initially establish and subsequently verify over time, the ability of a process to produce parts that do not have the potential for hydrogen embrittlement. The cascading action randomly exposes the surface of each individual piece to the process electrodes while also maintaining electrical continuity between all of the parts.
Therefore, the application of a metallic coating by electrodeposition is not recommended for such fasteners. Work Item s – proposed revisions of this standard. Current edition approved Jan. The average current density is usually low enough such that the extremity-to-center coating thickness ratio is much lower than with barrel-plating. On an externally threaded fastener this occurs at the threaded tip. See Section 10 and Appendix X1. Refer to Annex A1 for neutral salt spray performance requirements for zinc, zinc alloy and cadmium coatings.
ASTM / ASME spec F for Zinc Plating Which finish to choose?
It also highlights the differences between barrel and rack plating and makes recommendations as to the applicability of each process. Thick or thin local thickness in a location other than a signi? Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Which finish to choose? We do not specify specific plating specs; we simply use the general name. Last previous edition F — The electrodeposited coating shall cover all surfaces and shall meet the following requirements: The chromate finish letter E designates a black color.
However, if not designated, signi? ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard.
Although this risk can be managed by selecting raw materials suitable for the application of electrodeposited coatings and by using modern methods of surface treatment and post heat-treatment bakingthe risk of hydrogen embrittlement cannot be completely eliminated. From beautiful Pine Beach New Sstm High current densities increase hydrogen charging.
The properties of the coatings shall conform to the ASTM standards for the individual? If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below.
F — 00 Standard Speci? It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. In contrast, the center or recesses such as the bottom of the threads, which are the low current density areas, receive the lowest coating thickness.
In this process, quantities of an item are placed within a containment vessel, called a barrel. I am getting really confused in the finishing section. Special processing is normally required for bolts with a ratio greater than 10 in order to minimize the extremity-to-center thickness ratio. Ordering Information for Electroplating 5.
Threaded Tip, 3 0. A superscript epsilon e indicates an editorial change since the last revision or reapproval.
ASTM / ASME spec F1941 for Zinc Plating … Which finish to choose?
As the barrel is moved through the process steps, it is also rotated such that the individual items are constantly cascading over one another. The external thread damage is also minimized in comparison to barrel-plating due to c1941 absence of tumbling. Refer to Appendix X3 as a guideline for the tolerances of the various thread sizes and classes and the coating thickness they will accommodate.
Screw threads that are speci?
ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date. Slight discoloration that results from baking, drying, or electrode contact during rack-plating, or all of these, as well as slight staining that results from rinsing shall not be cause for rejection.
However the following restrictions apply: Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
If the size of the fastener is large enough to economically use the rack-plating process, then the latter shall be used to obtain this thickness requirement. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. This abstract is a brief summary of the referenced standard. In this process, quantities of an item are placed on a support, called a rack.
The values given in parentheses are for information only. It is the responsibility of the user of this standard to establish appropriate safety and health practices and c1941 the applicability of regulatory limitations prior to use.
It assumes that the external thread pitch diameter is at the maximum and that the internal thread pitch diameter is at the minimum of the tolerance see Fig. For example, rather than specifying: To secure uniformity of results, samples shall be aged at room temperature for 24 h before being subjected to the salt spray test. In some of the process steps, notably the electrocleaning and electroplating steps, an electric current is applied to the group of items.