Understanding Metric Fasteners . Length is measured the same as inch fasteners, except in millimeters. For button, cheese, hex, pan, socket and low socket heads, measure length from under the head. For flat heads, length includes head height. Measure oval heads from the largest diameter point—where the dome top meets the conical bearing surface— Whether you buy, use or specify metric fasteners , this easy to follow, eight-page guide belongs on your bookshelf. Simple drawings guide you through important metric and inch fastener differences, starting with how pitch is determined. Thread Count/Pitch. US fasteners specify threads per inch (TPI), commonly called thread count, so 20 would represent 20 threads per inch. Metric fasteners instead specify a thread pitch which is the distance between the threads. Therefore, a 1.5 pitch would have 1.5 millimeters between each thread.
Metric bolts list measurements in millimeters. Besides using metric measurements, a metric bolt uses the distance between the threads rather than the thread pitch, used in American measurements, which is the number of threads per inch. Determine the diameter of the bolt by looking at the first number. Dec 30, 2006 For metric threads, the thread pitch is given in millimeters per thread. Thus, an M2 x 0.4 screw has threads every 0.4mm. Although most metric fasteners have two or more standard pitches (fine coarse threads), the pitch is often omitted from a thread callout; it is always helpful to carry a sample with you to the hardware store. • Metric Property Classes for Steel and Stainless Steel Fasteners • Dimensional standards for bolts , nuts, socket products, screws and washers • Metric product dimensional tolerances • Plating specifications • Inspection and Testing • ISO Metric Threads This is a technical webinar, but it is appropriate for all levels of experience.
• Understanding the metric tolerancing system • What is required by ISO Metric Fastener Specifications – and what is not • A summary of the most important ISO fastener standards • hereparison of Inch and Metric fastener specification • How tight is right – for metric Understanding Fastener Grades and Classes. Property class (often just class) specifies metric fasteners. Special markings on screw heads and nuts identify the fastener's grade. Replace a graded fastener with same or higher grade (don't replace a Grade 8 fastener with a Grade 5 or 2). If in doubt, ask a professional for assistance.