|
3. Is there a lower grade than ABEC 1 ? There is no GRADE lower than Abec 1, but that doesn't mean that a manufacturer has to meet ABEC standards. There are a lot of minor bearing manufacturers that are not publishing any data on their manufacturing standards, so beware. Stick to brands that are well known and you won't go wrong. 4. Are there any other standards for measuring Bearing precision ? Yes. The other commonly used standard is the ISO (International Standards Organisation) standard. There are slight differences in the standards applied, but basically ISO Grade P0 is approximately equal to ABEC 1, ISO P6 approximates ABEC 3, ISO P5 approximates ABEC 5, ISO P4 approximates ABEC 7 and ISO P2 approximates ABEC 9. Please see our Precision Grades table for the exact values of these precision grades. 5. What is the purpose of the higher precision bearings ? Higher precision bearings are designed to allow high precision machinery to operate smoother and sometimes at higher speeds than a standard bearing would be capable of. Keeping this in mind, a standard ABEC 1 608ZZ is rated with a limiting speed of 32,000 RPM with grease lubrication and 38,000 RPM with oil lubrication. The actual speed that the bearing will attain without failure also depends on the loads applied and other running conditions but there is really no need to go into that too heavily here. We feel that we must stress here that the purpose of higher precision bearings IS NOT TO GO FASTER, but (amongst other things) to ALLOW HIGH SPEED MACHINERY TO OPERATE AT FASTER SPEEDS THAN STANDARD BEARINGS WIILL ALLOW. PLEASE ALSO READ POINT 6 BELOW. 6. What will be the result of using these higher grade bearings in Skating Applications ? The most noticeable result is that you will end up with less money in your wallet and the people that sold you the bearings will be eating out at restaurants at your expense for a few days. Under the following conditions, you may notice an improved performance. (a) You spend a lot of money (i.e. thousands of dollars) to have your equipment (wheels and board) redesigned and manufactured to suit these high precision bearings. You will need to use some type of shock absorber that allows for absolutely no vibration. (b) You will have to be prepared to skate on a perfectly smooth surface and make no attempts to use your feet to propel yourself. (Doing so would cause shock loads to the bearings and any extra precision would be lost very quickly). (c) After you work out how you are going to achieve the above two criteria, you may (and that is only "may") experience a better result than using ABEC 1 bearings after you attain a speed of about 390 KPH (240 MPH) with 65mm wheels and grease lubrication. Similar calculations for different wheel sizes and lubrication methods 52mm Wheels Grease Lubed Bearings 310 kph (195 mph) 52mm Wheels Oil Lubed Bearings 370 kph (230 mph) 65mm Wheels Grease Lubed Bearings 390 kph (240 mph) 65mm Wheels Oil Lubed Bearings 460 kph (290 mph) 70mm Wheels Grease Lubed Bearings 420 kph (260 mph) 70mm Wheels Oil Lubed Bearings 500 kph (310 mph) So, what it all comes down to is "do you really think that you need to buy these bearing?", "Will Windows 95 do anything for your old XT 1mb RAM computer?", "Will you get rich investing in shares if you only have $2.00 to invest?" - We don't think so. 7. What are the grades of bearings available in order. How different are the grades ? OK, but don't forget that you really do not need to waste money on anything higher than ABEC 1 or ABEC 3 for skating applications. From Lowest to Highest ABEC 1 Approximately equal to ISO P0 ABEC 3 Approximately equal to ISO P6 ABEC 5 Approximately equal to ISO P5 ABEC 7 Approximately equal to ISO P4 ABEC 9 Approximately equal to ISO P2 There are a number of factors covered by the ABEC grades, but to give you an idea we will just examine one of these factors - the eccentricity (out of roundness) of the track in the inner ring. For an ABEC 1 (lowest grade) bearing, the maximum eccentricity allowable is 0.0075 mm (0.000295"). This is quite precise - more than precise enough for skates and skateboards. The figure for the other ABEC grades are 0.005 mm (0.000197") for ABEC 3, 0.0035 mm (0.000138") for ABEC 5, 0.0025 mm (0.000098") for ABEC 7, and 0.0012 mm (0.000047") for ABEC 9. If used in high precision, high speed machinery (see above), these minute variations can make a difference. The fact is that no matter which of these bearings you use in skates or skate boards, after 5 - 10 minutes of use the tracks won't just be eccentric, they will become irregular (albeit minutely) enough to be practically indistinguishable from one another. Your high priced ABEC 9 bearing might as well be a 50 cent Taiwanese cheapie. 8. Are the "Supermarket" ABEC precision bearings really manufactured to the correct tolerances? We have to believe that they are until it is proven otherwise. If the bearings are labelled as ABEC 7 then in most countries the manufacturers of the bearings are compelled by law to provide ABEC 7 bearings. Some of the low prices offered for high precision bearings in Supermarkets does look a little strange though. Manufacture of high precision bearings is not cheap. Our Swiss quality supplier RMB is currently conducting tests on a bearing that was purchased at the Supermarket, and labelled as "ABEC 7". We will be very interested to see the results of these tests. 9. What is the meaning of "Z" and "ZZ" in the bearing code ? "Z" is a designation which means a steel shield covering the side of the bearing (for most brands). "ZZ" simply means that the bearing has a shield on both sides. Normally, the shield itself will be branded as "608 Z" even though there is a shield on both sides of the bearing. This is for practicality in manufacturing. It is much more economical to produce all of the shields stamped as "608 Z" than it would be to manufacture the exact same component with two different stampings on them. Some manufacturers supply bearings with removable shields, whilst others have shields that are crimped in place. Neither is usually better than the other unless you intend replacing the lubricant or cleaning the bearing from time to time. 10. Is there any better sealing arrangements ? Do the seals/shields change the bearing quality ? The seals have nothing to do with the quality of the bearing, only how well the bearing keeps out the dirt and moisture. You could try using a non-contact rubber seal. These will keep out the dirt very well and shouldn't lose you any speed. You may notice a slight drag if you rotate these bearings by hand, but once they are assembled and your weight is on the skates this should not create any problem (i.e.; you won't lose any speed). Non-contact sealed bearings are not overly expensive, so it won't cost you a fortune to trial them. 11. What is the best way to get more speed out of your bearings ? The most significant increase in speed will be obtained by using a quality oil lubricant. We are currently trialing a bearing with non contact seals and a Teflon Oil Lubricant. These bearings are currently being used in Inline Hockey (Roller Hockey) with some very good initial results. We will not be actively promoting them until we are sure that they are successful and they definitely won't be sold for astronomical prices. 12. Why is there so much hype at the moment about ABEC precision ? I have been in the bearing industry since 1984, and the biggest problem with the industry is that too many bearing sales people don't know enough about the product that they are selling. I have come across people with over 20 years experience in the industry who still get scared when a customer starts to ask about load ratings, limiting speed, internal clearance and yes, you guessed it, ABEC precision. What has happened here is that someone has been told a basic fact that higher precision allows for higher speed (and this is true under certain conditions). Not fully understanding this, the information has spread (mainly by use of the Internet) and gained momentum. There are many more inexperienced people in the bearing industry than there are experienced people and this has allowed for rapid growth of this falsehood. 13. Some friends have bought ABEC 9 bearings and tell me that it definitely increases speed. Why do they believe this ? We are not psychologists but we can think of 2 reasons immediately. Firstly, if you had just paid several hundred dollars for a set of bearings, you too would "believe" that they were better than what you had bought previously for around $30.00 to $40.00. Secondly, and somewhat similarly, if you really believe that something will make you faster, it probably will (it's all in the mind). 14. Somebody recommended that I use Stainless Steel bearings. Is this a good idea ? Stainless Steel bearings are usually marginally softer than Chrome Steel bearings, but this should not matter unless you are an aggressive skater. Stainless Steel bearings are advantageous if you are skating in wet conditions or close to the sea. They will rust (they are a high carbon content stainless steel), but they won't rust as quickly as Chrome Steel bearings. 15. What are the best bearings for Aggressive Skating ? Again, you will not get any more life out of either high precision or low precision bearings. Aggressive skaters will find that they go through bearings more quickly, so the best advice is "Get the cheapest, as long as they are a decent bearing". |