By Charles D. Smith
Originally printed in the November 2002 Issue of Snow Business Magazine
What are the differences between poly plow edges and steel edges?
When should you use one or the other?
Sooner or later you will need to replace the bottom edge of your plow, also known as the "cutting edge". For years, steel has been the standard, with an occasional rubber one here and there. Steel is available in various thicknesses, and with various carbon content levels. Typically, "mild" steel has low carbon content, and is very "malleable", or bendable. Also, mild steel is much softer than steel with a high carbon content, and will wear out faster than "carbon" steel. The higher the carbon content, the harder the steel is. Rubber is also used as a cutting edge, but it's characteristics make it a poor choice for many applications. It's most prominent characteristic is that it has a "memory". After much use, or after the weight of the plow has sat on the edge during storage, the rubber begins to lean back, in the opposite direction that most of your pushing has been done in. After considerable use, the rubber tends to lean as well. Letting the plow sit on the rubber edge when not in use adds to this problem. Once the rubber is leaning back to begin with, it doesn't scrape as well, and the face of it begins to wear, instead of the edge of it. As the face wears, the rubber gets thinner, and bends easier. This escalates the problem. Shoes are a must with rubber edges, and most road plows that use rubber edges, use wheels to support the plow instead of shoes. Rubber edges ride right over hard packed snow, and the rubber wears out much faster than steel. Rubber edges are great on paver stone driveways, and even concrete driveways. Any place you don't want to leave scrape marks on the surface being cleared. Parking decks are often sealed with a special coating, and steel edges would damage it if they were used.
Enter the Urethane cutting edge. Urethane has been around a long time. It has not been used as a plow edge until recently. There are many different types of urethane, which includes polyurethane. There are urethane paints used to paint automobiles, and clear urethane used on hardwood floors and on bowling alley lanes. There are many plow moldboards made out of polyurethane, and some made out of "poly". There is a reason I use the term "poly". The definition of the word poly is "many: several". The definition of polymerization is "a chemical reaction in which two or more small molecules combine to form polymers." So keep that in mind when you think of poly. All polymers are different. Just because something is made of poly, doesn't mean it can stand up to what you intend to use it for. If a company designed it to be used for what you intend to use it for, then you should have no worries.
Urethane edges made by one particular company I have dealt with, have been researched, developed, and have evolved into the types of urethane plow edges they sell today. They sell three different grades of edges. Each grade is made from different materials, with different uses in mind. The easiest way to tell apart the edges they sell, is by color. Yellow is the most popular one. It is designed for most applications. There is also red, and blue. Yellow is for light duty applications, (light duty blade) on pickups, tractors, and small dump trucks. It is not for high speed plowing. It is for parking lots, driveways, and private roads. Blue is (special duty blade) for municipal plows. It was designed for cobblestone roads, going over manholes, and roads with raised reflectors, and at higher speeds. Red is (heavy duty blade) for heavy industrial equipment, that clears at high speed. It is superior in it's resistance to cuts and abrasion, resistance to wear, and is more resilient. It is ideal for interstates and highways. It is also obviously the most expensive.
You can see the 6" edge overlap on the ends of the plow. This allows you to put the plow end directly against curbs, and run curb lines without damage to the curb or the plow.
Users of urethane edges are very happy with them. They all report little wear after many hours of plowing. They seem to not be able to agree on all the benefits of urethane, but wear ability is one they all agree on. Another is shock absorption. When hitting obstacles, such as manhole covers, and tank fill covers in gas station parking lots, the users plow does not trip. Some even hit low curbs, and the plow rides right up over the curb without tripping. Another factor they agree on is how quiet the urethane makes the plow when plowing. No loud scraping sound. The sound of the plow dropping is much quieter too, a definite benefit when plowing residential driveways at 3 AM. These edges also plow crushed stone without tripping the blade, and without moving the stone too. Pea gravel seems to get scraped up much like it would with a steel edge, but the plow does not trip, or "bite into" the surface. I know with a steel edge as soon as the plow hits the gravel it wants to trip, or stop the truck dead in its tracks. Some users report that they can plow over frozen grass areas without tearing up the turf. I would imagine as more and more contractors begin using these urethane edges, the facts will be clearer. Just the benefits I described so far make urethane a much better choice than steel. They seem to cost as much as four times that of a steel edge, but they also seem to last at least four times as long, plus, if an edge "wide" enough is used, it can be flipped, making it last up to eight times longer than one steel edge would, with all the added benefits that urethane gives. Urethane comes in various widths too; from 6” wide to 10” wide is the most common range. The wider the edge, the more times it can be flipped, and re-drilled. For example, a 10” wide edge, will typically give you four wear surfaces. It can be worn once (wear surface #1), then flipped (wear surface #2), then re-drilled (wear surface#3), then flipped again (wear surface#4). Proper mounting of urethane edges is very important, and you should contact the dealer you purchase your edge from for proper mounting procedures. Thickness plays a part in all of this too. Typically, on a 6.5’ – 9’ plow, a 1.5” thick yellow edge is used. The thickness needed is determined by the weight of the vehicle and the plow itself. One of the complaints new owners of urethane edges have is that the edges “chatter”. This is because the “angle of attack” has not been worn in yet. The edge is riding on the front corner until it gets worn in. This process can be done two different ways. One is to cut a beveled edge on the edge with a table saw. This is difficult, because you need to know what angle to set the blade at. The second and more common way is to wear it in naturally. This process can be accelerated by driving down a paved road in the rain, at about 30 MPH for about 5 miles with the plow down and angled to one side. After 2 miles or so, fully angle it to the opposite side.
I imagine in the next ten years, most plows will have urethane edges on them, and rightfully so.
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