Bolts that are classified and measured according to the metric system are known as metric bolts. Since the metric system (which can also be referred to as the SI, derived from the French term Systeme International d'Unites) is used almost universally as a set of measurement standards, metric bolts are an essential part if a particular piece must be compatible with parts that are made in other areas of the world such as Asia or Europe.
Quick links to Metric Bolts Information
Sizing Metric Bolts
Even though the imperial system is the standard system of measurement in the United States, the use of metric measurements for certain components such as bolts have become increasingly common in recent years. Metric bolts, as well as other types of metric fasteners, are indicated by a letter "M" followed by a number that indicates the bolt’s inner diameter in millimeters (mm). For example, a bolt may be labeled M5—a metric bolt whose inner diameter is 5 mm. Bolts are available in both metric and non-metric measurements, and non-metric bolts are also labeled according to their diameter, but are labeled in inches and fractions of an inch instead of millimeters. There are some varieties of English bolts available that use an entirely separate numbering system to indicate their size.
Applications of Metric Bolts
Metric bolts are frequently used for structural and non-structural applications. Examples of these applications include equipment securing and joining, general construction, and automotive engines on motorcycles, cars, and large machinery. Metric bolts, as well as metric screws and other metric fasteners, can be manufactured with full or partial threading. Fully threaded bolts feature threads that are grooved from the bottom of the shank to the bottom of the head. The threads of partially threaded fasteners, on the other hand, can extend from the bottom of the shank to any predetermined section below the head.
Types of Bolts
Manufacturers of bolts will have their products in a wide variety of styles and materials on hand in order to accommodate any specifications your application may have. For example, the standard head design for metric bolts is hex bolts. Also known as machine bolts, hex bolts are cylindrical in shape and are used as a clamp to fasten two pieces of metal together. They get their name from their distinguishable hexagonal heads. Aside from hex bolts, metric bolts are available in other designs. A second example is the eye bolt, which features a thread at one end and a loop, or eye, at the other. These bolts are used in lifting applications, and are used to guide the cables, chains, or ropes involved in lifting various objects. A third example are flange head bolts. Flange bolts can be identified by the ridge that features below the head of the bolt, which essentially acts as a built-in washer, and assists in distributing the load over a larger area. Flange bolts are commonly used in the automotive industry, and can be just as effective as a typical washer. Regardless of the type, most of these bolts are available in both imperial and metric measurements.
Things to Consider When Purchasing Metric Bolts
In selecting the right bolt for your desired application, there are a few factors to consider, such as the style of the bolt and the material it is made of. If your desired application involves supporting heavy loads or securing things such as bridges or foundations, it is recommended that you use anchor bolts. Anchor bolts play a large role in supporting a foundation, and keeps them secure in the wake of events such as earthquakes that can threaten a foundation’s stability. With the correct measurement and placement, metric anchor bolts can hold a substantial amount of tension.
For applications that require heavy-duty bolts made from resilient materials, the most recommended material choice is stainless steel. Stainless steel is known throughout the realm of manufacturing for its advantageous properties. Since it is an alloy that features a higher amount of chromium than regular steel, it is much more resistant to rust, stains, and corrosion. In addition to its ability to resist the elements, it is highly durable and resistant to tension and impact.
Since there is such a wide range of metric bolts that can be purchased individually or in sets sorted by design or size, it can be a daunting task to find the bolt that best fits your desired application. Luckily, experienced manufacturers will be there for you to make sure all of your concerns are addressed.