When searching for screws, nuts, washers, retaining rings, or dowel pins, you may encounter a long list of standards: DIN, ISO, JIS, ANSI, ASTM, CNS, GB, BS, AS…Why are there so many? What’s the difference? How do you choose the correct one? This article breaks down the origins, differences, and real-world uses of global fastener standards in a clear and easy-to-understand way. --- 1. Why Do We Need Fastener Standards? Fasteners are mating parts —screws match nuts, washers ma

Screw You use screws every single day — you just don’t notice them. They’re inside your phone, furniture, motorcycles, cars, computers, door locks, home appliances, factory machines, medical instruments…Small as they are, without screws, the world simply cannot be assembled, cannot operate, and cannot be repaired. This article will help you understand screws quickly — their functions, materials, and where they are used. --- 1. What is a screw and why is it important? A screw

In hardware parts, machining, and equipment maintenance, it’s common to encounter a confusing situation: you only want to find a screw or a pin, yet the specifications appear in two completely different formats — one written as M4, M6, M8 (metric), and another as 1/4"-20 or #8-32 (imperial). Many people wonder:“Why aren’t these specifications unified?”“Since they look similar, can they substitute for each other?” The answer is: No.Metric and imperial systems differ in units,

In metal, plastic, or aluminum parts, threaded holes can wear out and strip over time. That’s when a helical insert becomes the hero. A helical insert is a thread-reinforcement liner used to repair stripped threads or strengthen threads in softer base materials. Put simply, it’s like cutting a fresh, durable thread inside the hole, so screws hold tighter and last longer. --- 1) Functions & Benefits of Helical Inserts In assembly and maintenance, a stripped thread is one of th

On engineering drawings, we often see numbers like “±0.1” or “±0.05” written beside dimensions.These represent tolerance — the allowable deviation in size.But when a drawing contains hundreds or even thousands of dimensions, specifying every single tolerance individually becomes time-consuming and prone to error or omission. To help designers, manufacturers, and inspectors interpret allowable deviations consistently, the ISO 2768 international tolerance standard was created.

1. What’s the Difference Between a Dowel Pin and an Internally Threaded Dowel Pin? Internally Threaded Dowel Pin A common question first: what makes an Internally Threaded Dowel Pin different from a regular dowel pin? A standard dowel pin is mainly used for positioning and alignment, commonly found in molds, mechanical components, and assembly jigs.The internally threaded dowel pin, however, adds one key feature — a threaded hole inside the center. This thread isn’t for decor

1. Why Do Plastic Parts Often Contain Metal Nuts? Brass Insert Nut Ever had this happen?You’ve tightened a screw into a plastic housing many times — eventually, the screw hole gets loose, won’t grip, and can’t hold anymore. That’s exactly when the Brass Insert Nut comes to the rescue. The concept is simple:Embed a brass nut inside the plastic hole so the plastic part can have a metal-strength threaded anchor. These nuts are installed using heat, ultrasonic vibration, or press

1. What Is a Retaining Ring? A retaining ring (circlip) is a small fastening component used to prevent parts from sliding axially along a shaft.It ’s commonly seen in motors, gears, and bearings — essential for keeping machines running smoothly. However, depending on the region or industry, retaining rings follow different design and dimension standards.Globally, the three most recognized systems are JIS (Japan), DIN (Germany), and ANSI (United States). Let’s explore the key

Although it may look insignificant, the flat key plays a crucial role in preventing slippage and ensuring stable torque transmission...

Self-Locking Retaining Ring When people hear Self-Locking Nut (SPN / Press-Fit Nut, Self-Locking Retaining Ring), they often assume it...

In machines and structures, washers are the most common yet most overlooked small parts. Placed between the screw/nut and the mating...

Clevis Pin In various machines and structures, the Clevis Pin is a simple yet versatile fastener. It typically consists of a pin with a...

When installing C-type retaining rings (circlips / retaining rings), relying on bare hands or non-specialized tools can lead to slipping,...

In many machines and structures, a spring pin is a fastener that relies on its own elasticity to fasten and locate parts.It is typically...

In many machines and structures, the cotter pin is a simple-looking part that provides crucial safety. Commonly used with nuts,...

In mechanical transmission and assembly, the parallel key  is a small yet crucial component that determines whether parts operate...