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SPRING 2015

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Distributor's Link Magazine Spring Issue 2015 / Vol 38 No2

56 THE DISTRIBUTOR’S

56 THE DISTRIBUTOR’S LINK Carmen Vertullo Lead Trainer, Fastener Training Institute ® FASTENER TRAINING INSTITUTE ® 5318 East 2nd Street #325, Long Beach, CA 90803 TEL 562-473-5373 FAX 661-449-3232 EMAIL info@fastenertraining.org WEB www.fastenertraining.org WASHERS - WHAT ARE THEY GOOD FOR? The First In A Series Of Articles On Washers When we think of threaded fasteners, screws, nuts and bolts come readily to mind. Washers are somewhat of a forgotten second-class accessory. Although washers are not threaded fasteners, they are critical components of many fastened joints, and some of our most important bolted joints would simply not function without the help of a washer. In this series of articles we will look at some of the most common washer types as well as some of the more mysterious washer applications. We will discuss what they do and how they do it, and identify the specifications and standards covering washers. If you have an IFI Inch Standards Book, or a compilation of ISO or DIN metric standards, get it out and refer to it as you read these articles. This first article in our series highlights two of the most common, but important washers on the market, the inchsized steel flat washers commonly called USS and SAE flat washers. Before going there let’s take a moment to explore what washers of all kinds are good for. An Overview Of The Most Important Functions That Washers Perform They spread the load of the joint over a larger area. This is especially important in non-rigid joints and in fastened materials made of soft or thin materials. In order to do this effectively the washer must be of sufficient thickness and hardness to transfer the load across the entire area of the washer, otherwise the load simply passes through the washer as if it were not even there. They help provide a consistent torque-tension relationship. Even though torque control is the tightening strategy used for most bolted joints, a specific tension is the goal. Most of the energy applied in tightening the fastener goes into overcoming friction. About half of that friction is in the surface between the turned fastener (bolt head or nut) and the surface of the assembled component. A hardened washer will help to reduce and control this friction so that a more predicable tension will be developed for a given amount of torque. Conical washers and some TECHNICAL ARTICLE very special proprietary washer designs use controlled deflection to effect tension control. They improve the appearance of the assembly. Some washers have the specific purpose of improving appearance, and for others it is just the nice by product of using a washer. They prevent the joint from coming loose. Washers that help prevent loosening are generically called Lock Washers. There are many different types. Some work well and some do not. For the most part they perform as advertised when used properly and within their limits. They act as spacers to accommodate longer bolt lengths. This may not be the most efficient way to take up space in the bolted joint, but it is effective and common. Long bolts stay tight better than short bolts. They insulate or isolate dissimilar metals in the assembly. Dissimilar metals in contact with each other are a major source for electrolytic corrosion. Separating them with a washer that is friendly to both materials can prevent this corrosion. They protect the surface of the assembled components from damage during tightening. This is especially important with soft materials such as aluminum or plastic and materials with painted surfaces. They function as a seal or a gasket. A soft copper washer can seal an oil drain plug. A metal washer with rubber bonded to it can seal out rain in metal building assembly. They provide positive electrical conductivity or grounding in electrical and electronic assemblies. This is one of the main functions of toothed lock washers. They can give an indication that the fastener is properly tightened or that it has come loose. This function can be the sole purpose of some very special “washers”, or a side benefit of some very ordinary washers. They provide a very application specific function. Washers such as torque washers, spherical washers, tab washers and clipped washers have features that are unique to their purpose. CONTINUED ON PAGE 164

THE DISTRIBUTOR’S LINK 57 Your reliable option for FORMED SPRING STEEL FASTENERS Supplying Distributors Nationwide Since 1989 U-CLIPS U-NUTS • DIRECT COMPETITOR MATCHES • MANY IN-STOCK ITEMS J-NUTS • DISCONTINUED ITEMS! • FACTORY DIRECT PRICES • SHORT LEAD TIMES • ON TIME OR B4 DELIVERY SPECIALS e-qual-fast Your e-conomical Source for qual-ity Fasteners and fast Delivery ® brand TWIN NUTS 405 Production Drive • South Elgin, Illinois 60177 FLAT NUTS Toll Free: 888-NUTS-R-US (888-688-7787) Fax: 847-695-6336 On Line: www.e-qual-fast.com E-mail: sales@e-qual-fast.com

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