{"id":429,"date":"2026-01-30T03:16:04","date_gmt":"2026-01-30T03:16:04","guid":{"rendered":"https:\/\/www.jccncmachining.com\/?post_type=process&p=429"},"modified":"2026-11-05T13:34:00","modified_gmt":"2026-11-05T05:34:00","slug":"imperial-threads","status":"publish","type":"process","link":"https:\/\/www.jccncmachining.com\/fr\/capacites\/imperial-threads\/","title":{"rendered":"Filetages imp\u00e9riaux"},"content":{"rendered":"

<\/p>\n

\n

Sp\u00e9cifications cl\u00e9s<\/h3>\n\n\n\n\n\n\n\n\n\n\n
Sp\u00e9cification<\/th>\nPlage technique<\/th>\nRemarque<\/th>\n<\/tr>\n<\/thead>\n
Thread Range<\/strong><\/td>\n#0-80 to 6.0 inches<\/td>\nSmall instrument screws to large pipes<\/td>\n<\/tr>\n
Standard Profile<\/strong><\/td>\nASME B1.1 (60\u00b0 V-Thread)<\/td>\nMeasured in TPI (Threads Per Inch)<\/td>\n<\/tr>\n
Tolerance Classes<\/strong><\/td>\n1A\/1B, 2A\/2B, 3A\/3B<\/td>\n3A\/3B is tightest (Aerospace)<\/td>\n<\/tr>\n
Series<\/strong><\/td>\nUNC (Coarse), UNF (Fine), UNEF (Extra Fine)<\/td>\nUNJ (Controlled Root Radius)<\/td>\n<\/tr>\n
Methods<\/strong><\/td>\nSingle Point, Tapping, Thread Milling<\/td>\nDepends on thread size<\/td>\n<\/tr>\n
Validation<\/strong><\/td>\nGo\/No-Go Ring & Plug Gauges<\/td>\nSystem 21 or 22 gauging<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

\n

Imperial Thread Series<\/h3>\n\n\n\n\n\n\n\n
Series<\/th>\nDescription<\/th>\nPrincipaux avantages et applications<\/th>\n<\/tr>\n<\/thead>\n
UNC (Unified Coarse)<\/strong><\/td>\nThe most common general-purpose thread. Has fewer threads per inch (e.g., 1\/4″-20).<\/td>\nAvantage :<\/strong> Fast assembly, less cross-threading, tolerant of minor damage.
\nApplication :<\/strong> General construction, machinery housings, brackets.<\/td>\n<\/tr>\n
UNF (Unified Fine)<\/strong><\/td>\nMore threads per inch (e.g., 1\/4″-28). Larger tensile stress area.<\/td>\nAvantage :<\/strong> Stronger than UNC, better for fine adjustment, resists vibration loosening.
\nApplication :<\/strong> Automotive drivetrain, precision instruments.<\/td>\n<\/tr>\n
UNJ (Aerospace)<\/strong><\/td>\nA variation of UN threads with a larger, controlled root radius to reduce stress concentration.<\/td>\nAvantage :<\/strong> Maximizes fatigue strength for critical flight parts.
\nApplication :<\/strong> Aerospace bolts, engine components (AS8879 standard).<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

\n

Design Guidelines for Imperial Threads<\/h3>\n

Class of Fit (Tolerance):<\/strong>
\nClass 2A\/2B:<\/strong> The industrial standard. Allows for plating buildup and easy assembly.
\nClass 3A\/3B:<\/strong> Zero clearance fit. Used for high-precision applications. Conseil :<\/strong> Do not specify Class 3 if you plan to plate the part heavily, or the screw won’t fit.<\/p>\n

Plating Allowance<\/a>:<\/strong>
\nImperial threads are often plated (Zinc\/Cadmium). Plating adds thickness (4x the plating thickness on the pitch diameter). Conseil :<\/strong> We machine “pre-plate” threads slightly undersized (external) or oversized (internal) to accommodate the coating.<\/p>\n

TPI vs. Pitch:<\/strong>
\nRemember that Imperial threads are defined by “Threads Per Inch” (TPI), not the distance between threads. A higher number means a finer thread (opposite of metric<\/a>).<\/p>\n

UNJ Root Radius:<\/strong>
\nIf designing for Aerospace, ensure you specify UNJ<\/strong> (e.g., UNJF). This requires us to use specialized inserts with a larger nose radius. A standard UN tool will create a stress riser that can fail certification.<\/p>\n<\/div>\n

<\/p>\n

\n

Applications industrielles<\/h3>\n

A\u00e9rospatial et d\u00e9fense<\/strong>
\nAlmost exclusively uses Imperial threads (UNF\/UNJ) due to legacy standards (Mil-Spec\/NAS) and strict fatigue requirements.<\/p>\n

P\u00e9trole et gaz<\/strong>
\nDrilling equipment and valves often utilize large diameter Coarse (UNC) or special 8-Thread Series (8-UN) for heavy-duty connections.<\/p>\n

North American Automotive<\/strong>
\nWhile modern cars are metric, the custom car, racing, and restoration markets rely heavily on Imperial fasteners.<\/p>\n

\u00c9quipements pour semi-conducteurs<\/strong>
\nMany US-designed vacuum chambers and wafer handling robots utilize Unified threads for component mounting.<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

The Unified Thread Standard (UTS) remains the backbone of the North American engineering landscape, particularly dominating the Aerospace and Oil & Gas sectors. Jucheng Precision bridges the gap for global clients by maintaining a comprehensive inventory of imperial tooling and gauges, covering the full spectrum from Coarse (UNC) to Extra-Fine (UNEF) series. Unlike standard fasteners, precision CNC machined threads require strict adherence to ASME B1.1 specifications regarding pitch diameter and flank angles. We specialize in achieving specific thread classes, ensuring that whether you require a standard Class 2B fit for general assembly or a tight-tolerance Class 3B fit for safety-critical flight hardware, your components will assemble perfectly every time.<\/p>","protected":false},"featured_media":430,"template":"","process_category":[41],"class_list":["post-429","process","type-process","status-publish","has-post-thumbnail","hentry","process_category-threading-capabilities"],"_links":{"self":[{"href":"https:\/\/www.jccncmachining.com\/fr\/wp-json\/wp\/v2\/process\/429","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jccncmachining.com\/fr\/wp-json\/wp\/v2\/process"}],"about":[{"href":"https:\/\/www.jccncmachining.com\/fr\/wp-json\/wp\/v2\/types\/process"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jccncmachining.com\/fr\/wp-json\/wp\/v2\/media\/430"}],"wp:attachment":[{"href":"https:\/\/www.jccncmachining.com\/fr\/wp-json\/wp\/v2\/media?parent=429"}],"wp:term":[{"taxonomy":"process_category","embeddable":true,"href":"https:\/\/www.jccncmachining.com\/fr\/wp-json\/wp\/v2\/process_category?post=429"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}