The guys at AirSplat were kind enough to send me a set of the Kanzen 7mm ceramic ball bearings. Being that I had yet to upgrade my Dboys SCAR-L, this seemed like a good starting point. Kanzen bearings are well known for their quality of craftsmanship and durability.
Ceramic bearings offer greater load handling than traditional nylon bushings, and lower rotational resistance than either nylon or steel bushings. This in turn, should lead us to a greater ROF and lower trigger response times. I expect these should be a dramatic improvement over the stock nylon bushings, but how much?
The packaging is quite nice for something as simple as bearings. Honestly it is probably one of the cleanest and most most attractive packages I’ve seen for an airsoft part. Once in the package a look at the bearings doesn’t really reveal much more than just a set of bearings.
Materials and Construction
Technically, these are hybrid ceramic bearings. Hybrid ceramic bearings feature silicone nitride ball bearings inside a steel inner and outer ring. Overall they look to be manufactured well, without any notable blemishes or imperfections that would hinder installation or performance.
First I just want to fill you in as to why ceramic is better. Ceramic bearings can be made of various forms of ceramic (silicone nitride, silicone carbide, zirconium dioxide, etc.), but in the end they share a common characteristic. Friction is the enemy of efficiency, and ceramic is the weapon to fight it. Ceramic bearings have a lower coefficient of friction than steel or even nylon bushings and as such create less heat. That in turn means faster rotation with less energy applied… or greater efficiency. According to QuantumPrecisionGroup.com:
Silicon Nitride ceramic balls do not have as high a toughness or ductility as steel. But, due to their high strength, stiffness, and microstructural make-up, they are actually much more durable than steel balls.
Compare The Material Properties of Silicon Nitride Balls to Steel Balls.
Ceramic balls are >60% lighter, >50% stiffer, >70% smoother, and much, much harder than steel balls. Ceramic balls have >100X better rolling contact fatigue life in comparison to Vacuum Melt 52100 Steel.
Enough of the science lesson and on to the performance…
I installed these in my Dboys SCAR – L, replacing the stock nylon bushings. The bearings all seated easily into place with the exception of one, but that ended up being due to loose tolerances on the Dboys gearbox not the bearing. With the bearings installed and the gearbox shimmed properly it was out to the range for testing.
Before installing the bearings I had installed a G&P M120 motor and clocked the gun at 17.5 rps on a 7.4v ThunderPower 30C 2250mAh lipoly battery. After installing the Kanzen bearings the performance jumped to a very nice 20 RPS. Seeing an increase of 2 RPS just by putting in bearings is pretty remarkable. Usually an upgrade like that yields maybe one round per second.
I do attribute some of the increase in ROF to the better than stock shimming the gearbox received after installing the bearings. Due to the very loose shim job the factory had done, I expect that the gain from the shimming alone was marginal. I expect that most of the gain was from the bearings themselves.
Kanzen makes a beautiful package with an excellent set of bearings inside them. The gains archived from switching from stock nylon bushings to hybrid ceramic ball bearings was incredible. I had expected to see maybe a 1 RPS increase, but it looks as if was underestimated the performance of the ceramic bearings. I will definitely consider Kanzen ceramic bearings in my future upgrades, and I highly recommend them based on the findings of this test.
Durability: 10/10 This number will be updated if there is a failure at some point in the future. As of now this rating has been determined by the materials used in construction.
Performance: 10/10 These bearings increased the ROF by a much greater margin than I had expected.
Price at time of publication: $39.95