What is meant by metric thread?

What is meant by metric thread?

The size of a metric fastener (screw, bolt, etc.) is generally specified as diameter, pitch and length, all in millimeters (mm). Metric fasteners are usually classified as either coarse or fine, referring to their thread pitch, although some sizes are available in an extra fine thread.

ISO Metric Machine Screw Thread Dimensions

Thread Size Nominal Diameter (mm) Effective Diameter (mm)
M4.5 4.5 4.013
M5 5.0 4.480
M6 6.0 5.350
M7 7.0 6.350

Metric fasteners are specified with a thread pitch instead of a thread count. The thread pitch is the distance between threads expressed in millimetres (measured along the length of the fastener). For example a thread pitch of 1.5 means that the distance between one thread and the next is 1.5mm.

Metric thread callouts are fundamentally different because the thread pitch (distance between each thread, in mm) is specified instead of threads per inch or per mm. For example, an M10x1. 5 (coarse) thread has a 1.5mm pitch, while an M10x1. 25 (fine) thread has a 1.25mm pitch.

What are standard metric thread sizes?

Metric clearance and tapping drill hole sizes.

Size Clearance Hole mm Tapping Drill (std Pitch)
M10 11 8.5 mm
M12 14 10.25 mm
M16 18 14 mm
M20 22 17.5 mm

What are the standard metric threads?

ISO metric threads consist of a symmetric V-shaped thread. In the plane of the thread axis, the flanks of the V have an angle of 60° to each other. The thread depth is 0.54125 × pitch. The outermost 1⁄8 and the innermost 1⁄4 of the height H of the V-shape are cut off from the profile.

Are metric threads different than standard?

Metric thread pitch measurements are read differently than standard ones. While for standard thread pitch measurements the lower number is coarse thread and the higher number refers to fine thread, in metric this is opposite.

Specification of Metric Threads: Metric threads are defined in the standards document ISO 965-1. Metric thread specifications always begin with thread series designation (for example M or MJ ), followed by the fastener’s nominal diameter and thread pitch (both in units of millimeters) separated by the symbol “x”.

M16 is the bolt thread with the shank diameter of 16-pitch size. Eg. An M16 x 2 bolt has the diameter of 14mm. After tapping the hole, we attain the required thread size.

Designation. A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter for external thread and the minimum diameter for internal one) and the pitch P, both expressed in millimetres and separated by the hyphen sign, – (e.g., M8-1.25). Oct 29 2019

What is the diameter of M4 thread?

Internal Thread Size: M4 x 0.7. Length: 6.0mm (1.5x diameter) Material: 18-8 (304) Stainless Steel. Type: Locking. Tap Size: M4 x 0.7 STI.

What is a metric thread used for?

Superfine pitch metric threads are occasionally used in automotive components, such as suspension struts, and are commonly used in the aviation manufacturing industry. This is because extra fine threads are more resistant to coming loose from vibrations.

What is the form of a thread?

The thread form is the configuration of the thread in an axial plane; or more simply, it is the profile of the thread, composed of the crest, root, and flanks. At the top of the threads are the crests, at the bottom the roots, and joining them are the flanks.

For Metric parallel threads, taking a caliper reading of the threads outer diameter in millimetres (mm) will give a reading of the exact thread size but not the thread pitch. For example, a caliper reading of 12.03mm indicates it is very likely a 12mm thread.

Metric thread callouts are fundamentally different because the thread pitch (distance between each thread, in mm) is specified instead of threads per inch or per mm. 5 (coarse) thread has a 1.5mm pitch, while an M10x1. 25 (fine) thread has a 1.25mm pitch.

What is the difference between metric and UNC?

A 1/4 UNF thread is about 14% stronger than its UNC counterpart. The metric coarse thread is actually between UN coarse and fine thread, and the metric fine thread is finer than the UNF threads.

What is the angle of metric thread?

60°
M – Metric Thread (ISO) The Metric Thread is one of the first internationally agreed general-purpose thread type. The V-shaped thread form has a 60° flank angle and male and female threads are both parallel (Figure 4). Metric Threads come in different pitch sizes for a given diameter: coarse pitch and fine pitches.

How do you identify a metric thread?

What is the pitch of International Metric thread?

International Metric Fine Thread: The International Metric Fine Thread form of thread is the same as the International system but the pitch for a given diameter is smaller. German Metric Thread Form: The German metric thread form is like the International Standard but the thread depth = 0.6945 P.

How are metric threads defined in ISO 68-1?

The design principles of ISO general-purpose metric screw threads (“M” series threads) are defined in international standard ISO 68-1. Each thread is characterized by its major diameter and its pitch. ISO metric threads consist of a symmetric V-shaped thread. In the plane of the thread axis, the flanks of the V have an angle of 60° to each other.

Which is an example of a metric thread?

Metric Threads – Finer Threads. It is common to designate metric fine threads with the capital M plus an indication to their nominal outer diameter and their pitch: M size x pitch. Example: M 10 x 1.5. The table below indicates the typically used finer threads up to size M 100. Note that the ISO 724 standard specifies threads up to M 300.

How does the metric thread designation system work?

This designation is not done defining the thread, though. The final point it makes is whether the thread is an internal or external thread. This is simply done through capitalization. Similar to the UTS designation, the metric thread designation system allows for additional modification of the standard specification.