That preventing blade wear is essential to quality concrete was demonstrated by a National Institute of Standards and Technology report indicating how
That preventing blade wear is essential to quality concrete was demonstrated by a National Institute of Standards and Technology report indicating how wear and buildup change a mixer’s geometry and material flow pattern. Consequently, when purchasing a mixer, NIST emphasizes, one should evaluate its sensitivity to blade wear and ease of cleaning, plus the cost of component and wear part replacement.
Installing blade liners, typically an option in the purchase of a mixer, should be mandatory, Durex Products contends. While any blade liner is better than none, the company asserts, choosing the appropriate blade liner for an application is clearly the best solution. Today, steel liners Û long the traditional choice Û are increasingly bypassed in favor of longer-wearing urethane products.
A new, yet field-proven option, Durex Products affirms, is the Dur-X-Line Urethane Wrap-Around Blade Liner, which literally wraps around the edge of a blade to prevent wear. In contrast to conventional urethane treatments, the company contends, the wrap-around design prevents peeling and premature penetration of concrete material under the liner. Lightweight and easy to install, the Durex blade liner reportedly wears up to eight times longer than steel liners and is highly resistant to material buildup.
According to Durex Sales Engineer Robert Frey, These liners are lasting from three to four years without any concrete penetration. The wrap-around blade liner does not allow lifting or peeling, even when mixers sit idle between pours. Moreover, he adds, they are available for most mixer brands.
PROVEN FIELD PERFORMANCE
Among ready mixed producers providing feedback on the Durex blade liner is Meyer Material Co., a leading supplier in the Chicago and Milwaukee metro areas. Three of the 12-yd. Rex mixers in its Wisconsin division have been equipped with wrap-around blade liners. We’ll probably be installing them on our Illinois plants, as they have saved us a lot of time and expense, says Meyer Material Maintenance Foreman Tom Madala. Noting that steel liners previously failed to eliminate blade wear and the need for parts replacement, he explains, The steel liners are just facial liners. They’re good for about 50,000 yards. These wrap-around liners are now in their fourth year with over 100,000 yards per year, and we don’t have any downtime in installing new blades.
Cleveland area-based Osborne Companies, Inc. installed wrap-around blade liners on two Ross mixers. It’s usually between the one- and two-year points that you start to see separation around the edges of the old-style urethane liners, says Osborne Maintenance Supervisor Bob Trench. We’ve been using urethane liners for many years, and these wrap-around liners are the first to stay on, with no wear or separation, even after two years.
Since the old-style liner is constructed as one piece, when it inevitably starts to lift at the edge, you lose the entire liner. On the wrap-around liner, the edge piece is separate from the center portion. The edge tip takes the brunt of the damaging action, so if it should become worn, you can replace just the tip and not the whole blade cover, he affirms.
As to eliminating blade liners altogether, Trench says, I’ve worked with plants where we have not used liners, simply allowing the blades to wear out. In my mind, if you’re installing a mixer liner, it doesn’t take much more to install blade liners. It’s a highly cost-effective thing to do. Plus, our wrap-arounds are welded on, so it’s really not labor intensive.
Mark Laskowski, head of maintenance for Metro Ready Mix in Salt Lake City, agrees that it’s easier to install wrap-around liners than replace worn blades. It’s a major project to replace blades, and it’s expensive, he observes. You have to shut down production and open the drum. Then, you need a crane to complete the job. Accordingly, Metro Ready Mix installed wrap-around blade liners on its 12-yd. Erie Strayer mixer more than a year ago. We expect several more years of wear, says the maintenance chief. I do a periodic check on them to look for any peeling or unusual wear. Other than that, I just let them run.
Emphasizing that steel and concrete don’t go together, Laskowski adds, When we first started up this plant, the drum itself was lined Û the blades were not. After about 18 months, I was missing half the blades, but I was able to weld them and install liners. Now, I don’t have to worry about cutting out worn steel, as these
Troy Merriam, superintendent for Phoenix-based McNeil Brothers, also attests to wrap-around blade liner performance. We have them on two of our four Erie Strayer mixers, and they have been in our portable plant through more than 40,000 yards. They still look brand new, he says, adding that the portable plant was used recently on an Interstate-15 widening project near Las Vegas.
Lack of success with other liner options prompted Merriam to consult Paul Nielsen, owner of Black Canyon Process Equipment, which supplies and installs Durex liners for producers in the Arizona region. We’ve used steel liners, but they wear out so fast, the superintendent recalls. Then the blades start wearing out and getting smaller, and we can’t do the job we need to do. We’ve tried the conventional urethane liners, but they couldn’t withstand the Arizona heat. If you’re not running all the time, the typical urethane liner will get water and slurry underneath it, and will rot out. Merriam reports that wrap-around liners were installed in just a few hours. Even in this heat, the liners are not wearing or peeling. They are thicker and will stay on a lot longer, he affirms. Û Prepared by Carol Wasson for Durex Products, www.durexproducts.com