THE PROBLEM THE SOLUTION
Sept 2015  By Mike Quinn VP Sales & Marketing

Our customer has hundreds of shipping locations throughout the United States which employ moveable docking ramps. Many of these facilities are located in cold weather areas where ice, snow and freezing rain are standard fare during winter months. To clear snow and ice from ramp platforms, maintenance personnel employ deicing fluids and rock salt. Further, in order to provide safe footing for employees, sand is thrown on the platform plates. All of this makes for a tough, brutal environment for linear bearings and shafts. I was called to see if LM76 could find a solution that would be a drop-in system, due to the installed base, it would be too expensive to field retrofit a redesign. I determined both the shaft and the linear ball bearing were steel - prone to rapid oxidation. Because of this, bearings and shafts - in short order - corroded and locked-up, freezing the loading platforms in position. If the loading platform cannot be adjusted, there's no way to ensure a safe meeting of the ramp and truck being loaded/unloaded creating a safety issue. To ensure the balls would not rust/adhere internally, we nickel coated the balls and used a plastic/resin retainer. To increase the surface hardness and corrosion resistance of the shaft, we applied Armoloy® (thin dense chrome coating) to a host 440C stainless. Armoloy® raised the surface hardness from Rc60 to Rc78 while making it resistant to deicing fluids, debris and oxidation. After 1 season, some areas of the ramp are showing signs of corrosion, not our linear bearings and shafting.

I would have selected our sleeve-style Minuteman Self-Lubricating bearings (immune to deicing fluids, salt and sand) on an Armoloy coated shaft but because of high moment loads and poor bearing spacing, the coefficient of friction was too high - making it difficult to reposition panel extensions by hand.

A note about the advantages of Armoloy® coatings: Armoloy® is much more than a surface anodize. This coating forms a layer of nodes, spherical balls form along the surface being treated. If the shaft deflects, the nodes realign to mirror the deflection - no chipping or cracking.  Further, the nodes are spherical, they present a point loading contact to the mating surface - not a line-to-line or sliding friction. Thus, Armoloy® lowers static friction:

"The coating's nodular finish reduces the amount of surface area exposed to surfaces in contact with it, thereby substantially reducing friction and extending wear life. This nodular finish also retains smaller amounts of industrial lubricants for longer periods, both further reducing friction and creating a cleaner work environment."

Lastly, Armoloy® is one of the few materials that can successfully run on itself. I specify this coating on many naval, FDA, bio/pharma and other applications where hardness, corrosion resistance, high temperature (up to 1400F) and FDA/Washdown compliance is required. Typically, Armoloy® adds about 20% to the cost of shafting.

The other guys have catalogs, we have solutions. For more information on this application or if you have an application that seems to defy correction, please call Mike Quinn @ 1-800-513-3163, Cell: 617-538-8756 or email me at mquinn@LM76.com

Share our PDF