Flywheel Grinding - engineprofessional.com · 34 OCT 2017 FLYWHEEL GRINDING BY CHUCK LYNCH push CBN...
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32 OCT-DEC 2017 engine professional There was a time that all vehicles were fitted with a flywheel and a clutch as the coupling to transmit power from engine to the rest of the driveline. Much like carburetors, flywheel and clutches are taking a side seat to more modern automatic transmissions and at some level, even in heavy trucks and industrial equipment. That is understandable from points such as comfort and ease of use but also like carburetors, the equipment that is fitted with a clutch and flywheel still must be serviced periodically. Like the carburetor, we are losing the technical know-how in shops to accurately diagnose issues and do quality repairs. Moreover, there are fewer shops that have the equipment that is capable of accurately machining flywheels to ensure that they perform as well as they did when new. I can tell you from experience on the tech line that the information like minimum flywheel thickness, step and cup dimension and where to even measure from can be difficult to acquire. Without specifications and basic flywheel knowledge, it makes reconditioning flywheels a challenge. And then you add challenges like which dual mass flywheels can be reconditioned and how to grind them, if they can be reconditioned. We here at AERA are always looking for different means of getting flywheel specifications, from talking to flywheel manufacturers to talking with clutch rebuilders and so on. The OE’s offer little help and often just suggest to buy a new one. Although the general population of consumers have made the switch to automatic transmissions, there is still opportunity no matter how difficult the OE’s are seemingly making it. In automotive, it is mostly high-performance but the heavy duty Flywheel Grinding BY CHUCK LYNCH Keeping up with the past The flywheels have gotten harder and more wear resistant, which in turn makes them harder to grind. One very effective option to overcome the harder flywheel is to switch to CBN (Cubic Boron Nitride) wheels, shown above. and industrial sector still have a high percentage of flywheel and clutch applications. We as an industry are a tenacious bunch and we find a way to do what we are told we can’t do. We sleeve it, we weld it, we coat it…we find a way. I have had several shops share how they use set screws to lock dual mass flywheels solid so that it can be ground. This doesn’t work for every application but it does for many. These ideas and some modern tooling options that can be adapted to older grinders can make this a viable income addition to many shops. Over the years, the type of alloys that flywheels are made of have changed to increase the amount of time between service repairs. The flywheels have gotten harder and more wear resistant, which in turn makes them harder to grind. One very effective option to overcome the harder flywheel is to switch to CBN (Cubic Boron Nitride) wheels. CBN is applied at a plating to a carrier hub and the actual abrasive material is minimal but the carrier fills the area that will still accept vitrified abrasives. The nice thing about CBN is that it is also effective on the softer grey cast iron flywheels as well. CBN grinding wheels can improve a lot of things. It will allow longer grinding periods between dressing the wheel (which is not dressing the wheel with a diamond like vitrified abrasives, it is using a dressing stick that helps remove embedded grinding material from the grinding wheel plated abrasive). You can
Transcript of Flywheel Grinding - engineprofessional.com · 34 OCT 2017 FLYWHEEL GRINDING BY CHUCK LYNCH push CBN...
32 OCT-DEC 2017 engine professional
There was a time that all vehicles were fitted with a flywheel and a clutch as the coupling to transmit power from engine to the rest of the driveline. Much like carburetors, flywheel and clutches are taking a side seat to more modern automatic transmissions and at some level, even in heavy trucks and industrial equipment. That is understandable from points such as comfort and ease of use but also like carburetors, the equipment that is fitted with a clutch and flywheel still must be serviced periodically.
Like the carburetor, we are losing the technical know-how in shops to accurately diagnose issues and do quality repairs. Moreover, there are fewer shops that have the equipment that is capable of accurately machining flywheels to ensure that they perform as well as they did when new.
I can tell you from experience on the tech line that the information like minimum flywheel thickness, step and cup dimension and where to even measure from can be difficult to acquire. Without specifications and basic flywheel knowledge, it makes reconditioning flywheels a challenge. And then you add challenges like which dual mass flywheels can be reconditioned and how to grind them, if they can be reconditioned. We here at AERA are always looking for different means of getting flywheel specifications, from talking to flywheel manufacturers to talking with clutch rebuilders and so on. The OE’s offer little help and often just suggest to buy a new one.
Although the general population of consumers have made the switch to automatic transmissions, there is still opportunity no matter how difficult the OE’s are seemingly making it. In automotive, it is mostly high-performance but the heavy duty
Flywheel Grinding
BY CHUCK LYNCH
Keeping up with the past
The flywheels have gotten harder and more wear resistant, which in turn makes them harder to grind. One very effective option to overcome the harder flywheel is to switch to CBN (Cubic Boron Nitride) wheels, shown above.
and industrial sector still have a high percentage of flywheel and clutch applications.
We as an industry are a tenacious bunch and we find a way to do what we are told we can’t do. We sleeve it, we weld it, we coat it…we find a way. I have had several shops share how they use set screws to lock dual mass flywheels solid so that it can be ground. This doesn’t work for every application but it does for many. These ideas and some modern tooling options that can be adapted to older grinders can make this a viable income addition to many shops.
Over the years, the type of alloys that flywheels are made of have changed to increase the amount of time between service repairs. The flywheels have gotten harder and more wear resistant, which in turn makes them harder to grind. One very effective option to overcome the harder flywheel is to switch to CBN (Cubic Boron Nitride) wheels. CBN is applied at a plating to a carrier hub and the actual abrasive material is minimal but the carrier fills the area that will still accept vitrified abrasives. The nice thing about CBN is that it is also effective on the softer grey cast iron flywheels as well.
CBN grinding wheels can improve a lot of things. It will allow longer grinding periods between dressing the wheel (which is not dressing the wheel with a diamond like vitrified abrasives, it is using a dressing stick that helps remove embedded grinding material from the grinding wheel plated abrasive). You can
34 OCT-DEC 2017 engine professional
FLYWHEEL GRINDINGBY CHUCK LYNCH
push CBN harder as it does not break down rapidly like vitrified but you must flow a high volume of clean coolant to keep the heat level down and flush away the abrasive grinding swarf for optimal surface finishes. You can run the CBN wheel with less tilt which will produce a flatter clutch surface.
What CBN can’t do. You cannot fix a worn-out grinder by simply throwing a CBN wheel on it. So… before you buy a CBN wheel, make sure that the machine is mechanically sound, meaning good spindle bearings, can maintain vertical position and has enough horsepower to run CBN effectively. Basically, you will be tempted to grind more aggressively because the CBN can handle it but if you have a very old low horsepower grinder with less than 3hp, you may still have to be cautious about the amount of material that you grind each pass so that you don’t stall or burn up the motor.
In addition to flywheels, flywheel grinders can do an outstanding job on brake rotors as the ground surface has lesser break in time than that of a turned surface which has deeper tooling marks that must be worn down before the brake pads can have total contact and full braking capacity.
So, if you have that old flywheel grinder that you don’t use any longer for some reason, think about updating and capitalizing on something that is still needed. With all of the black smoke-rolling, hot rod diesels on the roads these days, we know there are burned flywheels and brake torqued rotors just begging for some attention.n
AERA Technical Specialist Chuck Lynch spent 20 years of his career at Jasper Engines in many roles, including process engineer. He has also worked as a quality auditor, analyzed tooling needs, coordinated procurement and training for equipment and tooling, incorporated the use of super abrasives, coordinated failure analysis of components, and more. For more information, email: [email protected].
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