A Little Washer Can Make a Big Difference
You might think of a washer as nothing more than a dime-size slug with a hole in the center, something that you place between a bolt and a nut when you’re assembling a piece of furniture. But to manufacturers, a washer is an important piece of engineering that can make a big difference, including allowing automobiles to operate more safely and efficiently.
The most common incarnation is the thin, flat, and circular general-purpose washers that are sprinkled across the bottom of your junk drawer. They often serve the most typical purpose of a washer: distributing the loads under bolt heads and nuts by providing a larger area under stress.
But that’s only the starting point of the washer’s value and variety. Boker’s 2016 Washer Catalog boasts 30,000 sizes of washers, 2,000 materials washers can be made from, and assures there are “endless possibilities” for using them.
Nick Todora, marketing manager for Boker’s, explains the immense utility of these tiny gadgets: “A washer can go into any component you imagine. When companies engineer their washers, they’re integral to the fastening process. But they have a lot of purposes people don’t know about, like providing a space that’s needed to improve a mechanical function or protecting the mating surfaces.”
But exactly how does the washer perform a higher function? How, for example, does manufacturing washers with lighter, yet stronger materials improve a mechanical function? And how have scientists and engineers taken this information to the next level to have a big impact on all of us?
Less Friction On the Road
JATCO, a subsidiary of Nissan, wanted its new 7-speed automobile transmissions to pack more punch with a smaller footprint, and it zeroed in on improving its metal washers.
As a solution, the carmaker turned to the DuPont™ Vespel® SP-21 thrust washer, which is a graphite-filled polyimide high-performing engineering plastic. Because Vespel® SP-21 is thinner and lighter than traditional metal needle bearings, the transmission’s overall size and weight were reduced.
“With Vespel® parts, our objective is to address the complex equation involving several factors — Tribology, Mass, Space and Packaging — that can offer a higher efficiency with less friction and lower cost of ownership with longer service use,” says Loic Chereau, Global Marketing Manager at DuPont.
High-performance Vespel® SP-21 offers temperature resistance (no melting point), good wear-resistance, low friction, chemical resistance, mechanical toughness and very high pressure in lubricated conditions.
As a result of these characteristics, this seemingly simple piece of plastic helps engines function more smoothly, reduces friction and causes transmissions to function better for longer. Unlike many washers, the plastic washer can rotate directly against the aluminum housing, allowing a reduction in the number of parts and machining steps needed for the transmission and an easier assembly process. This mechanical advantage has also made the transmissions in John Deere agricultural equipment less susceptible to wear and has reduced necessary maintenance.
The possibilities of the washer are endless, and every year, clever manufacturers come up with new applications. For example, in addition to protecting devices, washers can warn when something bad is about to happen to them. At the 2013 Intel International Science and Engineering Fair in Phoenix, three teenage scientists unveiled their Smart Alert specialty washer. If the nut starts to lose its grip (known as self-loosening), the washer literally springs into action. A color-coded spring pops up to let people know that a little wrench work is in order.
Loose as a Goose
While washers might seem simple, the science behind them could fill a library. Installing a generic flat washer is not the simple act that many people assume. There are, in fact, dos and don’ts when it comes to washer installation. According to Christopher Bunai, chief engineer of engineering firm Stress Indicators, Inc.: “A common mistake is to use low-strength steel washers with high-strength nuts and bolts.” Another no-no is installing a flat washer with the coarse side facing the head of the bolt rather than the smooth side. Flipping the washer the wrong way might cause the bolt to fail under stress. Even NASA scientists have joined in on debates about the value and use of different washers.
So, the next time you install a washer, take a moment to appreciate that wonders often come in the most seemingly simple things.