The Truth About “Black Plastic Rollers”: And Other Garage Door Hardware Legends
© 2007 Door & Access Systems
Publish Date: Spring 2007
Author: Tom Wadsworth
The Truth About “Black Plastic Rollers”
And Other Garage Door Hardware Legends
We need to set the record straight.
In our interview with Precision Door Service (cover story, fall 2006), we reported several comments about “black plastic rollers,” center bearing brackets, and struts. I’m not a mechanical engineer, but several of those remarks bothered me.
In the interest of publishing accurate information, we talked to several respected experts to get the facts.
Here are our experts:
· Tony East, formerly Director of Applications Engineering, now Director of Manufacturing - Carolina plant at Amarr. With 12 years in garage door engineering, he holds a B.S. degree in engineering and an M.B.A. East also developed an Amarr bench test for performance testing of rollers.
· Ismaël Lafrenière, Roller Product Manager at Canimex. With 15 years in the garage door industry, he holds a B.S. degree in mechanical engineering. Lafrenière designs and tests rollers and establishes their performance ratings.
· Al Mitchell, Director of Research at Wayne-Dalton. With 20 years in the garage door industry (primarily in product research, development, and design), he holds B.S. degrees in chemistry and mechanical engineering (BSME). Mitchell is the past chairman of the DASMA Commercial & Residential Garage Door Technical Committee.
· Patrick Morin, Engineering Manager at Canimex. With nine years at Canimex, he also holds an M.B.A.
· Jerry Schutt, Director of Engineering at Arrow Tru-Line. With 15 years in engineering and metal stamping, he holds a B.S. degree in mechanical engineering technology and an M.S. degree in occupational health and safety.
· Mark Westerfield, Director of Product Development and Engineering at Clopay. With 20 years of experience in testing and engineering garage door systems, he holds a B.S. degree in engineering and an M.B.A., and is licensed as a Professional Engineer (P.E.) in four states.
Note: The word “precision” in “precision roller” and a “precision ball bearing” has no connection to Precision Door Service.
Black plastic (bearingless) rollers are inferior and should be replaced.
Morin: Bearingless nylon rollers are good rollers. If manufactured with good quality raw materials and assembled rigorously with the right equipment, these rollers can fulfill with pride their functions on residential doors. An 8' x 7' light pan door that cycles twice a day doesn’t need precision bearing rollers, while … a heavy carriage door should be sold with bearing rollers.
East: The weight capacity for all rollers is not a secret; it’s available data from all major suppliers in the industry. As an example, the non-bearing nylon rollers in some of our doors are rated for 50 lbs. per roller for no less than 10,000 cycles. We also perform our own internal testing to no less than 22,000 cycles at 50 lbs. per roller.
Lafrenière: People underestimate the performance of the bearingless nylon roller. It’s rated for 50 lbs. per roller at 10,000 cycles for an 8' door. Many people have the mentality that a roller with a bearing is always better, but it’s not completely true.
Mitchell: These (plastic) rollers are nylon rollers, and they are a lot quieter than steel rollers. However, a metal ball-bearing roller can adjust itself to a slightly misaligned hinge. A non-bearing nylon roller doesn’t adapt as well to misalignment.
Westerfield: We have performed extensive door and roller cycle tests over the years and found that no two rollers perform equally. Some nylon rollers without bearings are superior to many rollers with bearings. We perform testing to determine which rollers and other garage door components work best for the particular application.
The 13-ball nylon rollers last forever.
Schutt: Even though we rate this (13-ball) roller at the high end of what would be expected in a residential application (75-lb. load at 15,000 12' door cycles), the roller rating could be much higher. On our roller test machine, we have never had a failure of these rollers in terms of the bearings or nylon tire. While the testing has shown that this is a superior product, ATL has chosen to be conservative in terms of the rating we have given it.
Westerfield: Back when I started in the garage door industry some 20 years ago, there was a claim that a certain plastic roller with 13 ball bearings was by far the best roller in the industry. However, testing revealed that this roller was inferior to any we tested. That roller is hardly used anymore.
Morin: Some products on the market, even if sold as exceptional rollers, are in fact not as good as they appear, due to poor construction/design.
The “nylon 6” on 13-ball nylon rollers is a better nylon than that used in other nylon rollers.
Schutt: The composition of our nylon tire is proprietary information. (Schutt says the nylon in the 13-ball roller is indeed different.) From testing we have conducted, the tires on our precision rollers outlast many of the lower-end rollers on the market.
Mitchell: Nylon 6 rollers are nothing new. Companies that use “black plastic rollers” are actually using nylon 6. To my knowledge, nylon 6 or nylon 6/6 is what everybody uses. Nylon 6 is a little softer and quieter than nylon 6/6.
Lafrenière: We use nylon 6 tires on all of the 2" nylon rollers that we presently offer. The bearingless nylon roller is also nylon 6.
Center bearing brackets with “black plastic bearings” should be replaced.
East: The black nylon bearing used in most residential applications primarily perform the function of maintaining shaft alignment. The nylon bearings used in the industry have been tested, and data on their load capabilities is available from all major suppliers. We have tested these nylon bearings ourselves up to hundreds of thousands of cycles and have never had one fail, in testing or in the field.
Mitchell: It’s probably more accurate to call it a nylon bushing. Before we make a decision about any component, we do extensive testing first. In our testing, we have not found the nylon bushing to be a problem for lighter doors, which constitute a large portion of our residential doors. If a door weighs more than 250 pounds, it may be necessary to upgrade the bushings and the rollers.
Many doors are not installed with the right number of struts.
Mitchell: I don’t know if a service tech would automatically know how many struts are required. The right number of struts depends on many factors, such as the weight of door, whether it has a trolley operator, wind-load requirements, and others. If you add struts, you need to change springs. And you may need to change rollers, the track, and the jamb brackets.
East: The correct number of struts for a given door is determined through performance testing of complete doors. Doors of various sizes are tested with monitoring and measuring devices that capture deflection measurements and cycle counts. This is done on no less than three specimens. At the conclusion of the testing, a final strut configuration is determined.
You can justify a $200 service call (replacing hardware) on a door that was installed yesterday.
Westerfield: I take strong exception to the implied claim that garage door manufacturers make doors that need immediate service work. Reputable garage door manufacturers go to great lengths designing and testing systems that, with minimal maintenance (i.e., oiling hinges annually), operate virtually trouble-free.
Mitchell: I would urge caution about that (replacing hardware on a new door), especially if the door is under warranty. If you change the components, you may void the warranty. I can support our hardware with a lot of data. We need it from a liability standpoint.