Many Americans are uncertain when it comes to purchasing metric screws. Most measurement products come in two types, metric and standard. Tools, fittings and accessories are no different. Americans are accustomed to using the standard system for measurement. However, most of the world uses a metric system for measurement.

If your company exports products or communicates with other countries, you may find that you need to use metric tools, including metric screws. Metric screws are compatible only with metric tools such as wrenches and hex keys. When examining the metric screws basics, think about the following:

1. Metric screws are important for products exported to other countries.

2. Metric screws are compatible to use with metric wrenches and metric hex keys.

3. Metric screws serve the same purpose as standard screws.

Action Steps
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Discover the difference in metric screws and standard screws

From a distance, metric screws and standard screws look the same. They serve the same purpose. The two screws are from the same materials and are of the same quality. The difference in metric screws and standard screws is the way the manufacturer measured and labeled them. They measure standard screws in inches. On a standard screw, one will see measurements such as ½ inch, 1 inch, and ¾ inch. Manufacturers measure metric screws in millimeters.

I recommend: Read an article about metal metric fasteners from Ezine. View metric screw data from I Crank.

Learn why many companies use metric screws

Most of the world and the field of science use the metric system as a way of communicating measurement. When companies work in the science field or with other countries, it is helpful that they use a common form of measurement in products and supplies. Therefore, it may be necessary to use metric parts such as metric machine screws.

I recommend: See the strength of metric bolts from Tripod. Read an article about metric screws from BNet.

Understand how to read a metric screw size

To replace a screw, one must match the old one exactly with the new one. It is important to know exactly what size screw you need when purchasing a new one. To read the size of a screw, you will see three numbers. The first number tells you the diameter of the screw. Metric screws have an m and then a number. The number is the diameter. The second number listed tells the measurement between each thread on the screw. The number may be in the form of a decimal. The last number after the x is the length of the screw. One measures the length from the bottom of the screw to the bottom of the head. For metric screws all measurement are in millimeters.

I recommend: View information from American Fastener about ordering specialty metric fasteners. View metric screw information from Sizes.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Standard screws and metric screws look very much alike. If you are uncertain which type of screw you have, consider the source from which it came. If the screw is from a product that was not created in America or Canada, it is likely that you have a metric screw.

Metric fasteners (screws) come with the same names as US fasteners. For example, a machine screw remains a machine screw. With a global economy, many businesses deal with the metric system of measurements in their own applications or for the consumer. Conversion charts help alleviate the complexity of understanding the difference in sizes.

Common metric fasteners include wood, sheet metal, bolts and machine screws. Basic material composition consists of steel, stainless steel, brass, titanium and plastic. When looking for metric screws consider the following:

1. Look for metric bolts with full or partial threads.

2. Select metric machine screws in either metal or plastic compositions.

3. Find companies with wide selections of metric screw products.

4. Go to informational sources for conversion charts and other metric screw details.

Action Steps
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Find metric bolts

Locate the right size, head and composition based on threads. Typical use for these fasteners includes industrial and construction businesses.

I recommend: For a nice range of metric sizes of fully or partially threaded hex bolts in bulk go to Mutual Screw & Supply. This supplier also carries larger diameters; just click “Metric Hex Bolts & Sockets Large Diameters” from the “Metric Fasteners” list on the same page. Choose metric size and material for fully threaded hex bolts (DIN 933) at Coburn-Myers Fastening Systems, Inc. This company also carries DIN 931. Get wholesale pricing by entering the part number or by contacting Bolt Products, Inc.

Get metric machine screws

Machine screws find many applications based on composition. For example, stainless steel resists corrosion. Joining two parts through a tapped hole ranks high on use.

I recommend: Go to Barnhill Bolt and scroll down the page to select stainless steel, steel or nylon slotted with Phillips flat or pan head machine screws. Find a metric machine screw in sizes 2mm x .4 to 8mm x 1.25 stainless steel Phillips pan or flat head at Bolt Depot. Select by screw style and drive for nylon and other plastic materials at Craftech Industries, Inc.

Buy a variety of metric screws

These companies offer a complete line of metric screws.

I recommend: Click by type to see the product number, size and price that includes socket, cheese, wafer and button, Phillips and flat head screws at Micro Fasteners. Go to Victory Bolt & Specialty, Inc., and choose the type of metric fastener needed. See AaronsMetricScrews.com for cap, machine, rolling and socket set screws.

Locate well supplied metric screw manufacturers and distributors

These companies carry a full range of metric fasteners. Order or contact for business specific solutions.

I recommend: Use the “scroll up or down” on the page after choosing from the specs categories that includes types, styles, drivers and request info or quotes at Rumco, Inc. Find the kind of screw you need in the online catalog by clicking a letter for screw name, index by DIN or other indices at Metric Screw & Tool Co. See the large selection of metric fasteners by clicking the type needed at Fasteners Plus, Inc.

Obtain metric screw information

These websites provide a wealth of technical information in non-technical language.

I recommend: Click a category at Bolt Depot that includes fastener type chart, measuring fasteners, materials and grades and other useful information. Go to Mission Fasteners for information and charts. Find a list of Fastener Associations at K-J Fasteners, Inc.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Metric fasteners sometimes carry a DIN number to note a set of standards for the screw. Several sites allow searches for known DIN numbers.
• •  Usually, the letter 'M' precedes the size of the fastener indicating metric. Class tells the grade of metal, for a specific fastener with the metric size. For example, a class 8.8 hex bolt M10 x 1.5 x 20 means the diameter equals 10mm with a thread pitch of 1.5 and measures 20mm long.

If using metric fasteners has your employees running for the door, find a convenient way to help them gain confidence and understanding of the common nuts, bolts, screws and other fasteners they use that come in metric sizes. A simple metric training session can save the company thousands of dollars when it comes to finding the correct fasteners.

Before you buy metric screws, making sure you understand the conversion calculations and differences in structure and uses is very important. Metric education can come as easily as referring to a manufacturer conversion chart or finding a more detailed training session that gives an advanced overview of metric screws and fasteners. To learn more about metric screws, you should:

1. Get help from knowledgeable suppliers or metric fastener manufacturers.

2. Find information about metric bolts and screws through networking with other industrial organizations.

3. Sign up your employees and associates for a metric fastener refresher course.

Action Steps
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Ask suppliers of metric screws for advice and training resources

Suppliers or manufacturers of metric machine screws and fasteners know the business better than anyone else. Ask for any information they can provide to help educate your company about the details of the metric fasteners.

I recommend: Use Mission Fastener's metric fastener chart to compare your options. They also have a glossary of fasteners and other metric screw information. The metric fastener information at Bolt Depot can also be used in metric screw education and training for employees.

Gain access to metric fasteners resources when you join a technical association or group

Networking with your peers is an ideal way to gain access to valuable metric screws training and education materials. Find a group of industrial fastener users or manufacturers that can provide you with links to many different kinds of training materials from online courses to upcoming training seminar information.

I recommend: Use the free technical information at Industrial Fastener's Institute, or join their group to gain access to many more educational materials. Join the National Fastener Distributors Association to find links for many fastener resources.

Find metric screws education and training online educational resources

For a more in-depth line of education, consider outsourcing your educational needs to a professional organization. Many technical schools, colleges and online engineering organizations offer on-site training, web-based courses or even seminars on metric fasteners.

I recommend: Purchase IPT's Industrial Fasteners Training Manual online for a full manual of metric fasteners and screws. Find a guide to metric structural fasteners at the University of Iowa's College of Engineering. Take a fastener course at ToolingU that includes an overview of metric fasteners.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Join a state or local fastener association for more information about the metric screw as it pertains to your business and area, or look for metric conversion information in the current industrial, engineering or manufacturing associations to which you belong.

Companies that operate solely within the United States often use standard measurements when it comes to tools and screws. However, if you intend to sell tools or screws overseas, or if you are manufacturing products that may be shipped overseas, you may need to consider using metric tools and screws that are measured in millimeters rather than inches. Understanding the difference between standard and metric measurements is essential to your business, and knowing a few basic metric screws key terms will help get you started.

Action Steps
The best contacts and resources to help you get it done

Machine screws

Metric machine screws come in pan head and flat head versions. Machine screws have a flat tip and are designed to be screwed into pre-made holes.

I recommend: You can see pictures of pan head and flat head metric machine screws and see the different sizes available at Aaron's General Store.

Flat head socket screws

Flat head socket screws come in many varieties and range in size from miniature screws to standard metric sizes. Flat head socket screws are designed to sit flush with the material they are screwed into and usually have a hex or square socket.

I recommend: Micro Fasteners has an assortment of metric screws, including flat head socket screws in stainless steel and alloy finishes. It also provides illustrations.

Hex head screws

A hex head screw gets its name from the shape of the hexagonal head of the screw. They are designed to be used with a wrench and, like almost all screws, come in metric sizes.

I recommend: Mutual Screw & Supply shows an example of a metric hex head screw.

Cap head screws

Cap head screws are similar to hex bolts, but can be used for tighter tolerances. They have a head similar to the six-sided head of a hex head screw.

I recommend: Hobby People offers cap head screws for sale and gives a description of the features of the screws.

Metric washers

Metric washers are washers that are sized to be used with metric screws. Washers are thin disks with a specific size hole in the middle for the screw to pass through.

I recommend: Northeast Fasteners offers metric flat washers and metric lock washers.

Metric nuts

Like metric washers, metric nuts are simply nuts that are designed and sized to work with metric screws. Like standard-sized nuts, they are threaded on the inside to match the thread of the screw and usually have a hexagonal head.

I recommend: Allen's Fasteners has different types and sizes of metric nuts for sale.