I am new to the x winder. After a few hickups, I completed some good 2 axis winds in 3 axis mode. My question is on the subject of winding torque... How do i know if i need more torque or less torque on a particular motor? Do i increase torque for larger the diameter of mandrel? How about the delivery head torque? I noticed both delivery head motors getting warm ( I turned down the torque)...? I'm also have trouble with loose ends on 35* wind angles on small diameter mandrels...? I'm wondering if reducing the torque on the carriage motor would help this? I'm going to attempt a large diameter 6" tube and could use any advice before i give it a go. Thank you in andvance for any suggestion!!
tuffbuiltoffroad@gmail.com
Gary Michalak
Indycar mechanic
Replies
Hi Gary,
I will try to answer all of your questions.
More or less torque on the mandrel motor is not really going to help you. The stock standard nema23 motor has plenty enough torque to wind a good tube. All the other motors require very little torque in comparison as they essentially "guide" you filament to where it is needed.
The mandrel motor combined with the combined tension in the filament (from the spool tensioner to the friction in the rollers and squeegee system) is what creates the "pressure" or "pull" on the mandrel. When there is no tension on the filament you get a very sloppy and very badly consolidated tube. When there is too much tension the resin will want to push out of your wound tube and the filament can start to pull and move across the tube with low angle winds (again creating imperfections and failure points). The trick with it all is to have variable pressure througout the wind to accommodate different angles. The stock standard x winder is hard to calibrate to this extent. I have made plenty of modifications to overcome this issue.
The delivery head motors will get warm (warmer than they probably should in my opinion) this is probably due to the fact that the same motor driver can run the bigger motors as well and the small motors are probably running with some extra current. Don't worry about them for now.
Reducing the motor torque is an option on small mandrels... but you should focus more on the filament and what it is doing. Place the filament through the rollers and bath and the tie it to a set of hanging scales (or luggage/travel scales) Give the filament a pull and you should see how many Kg's it takes to move it. The trick is to make your sqeegee system almost frictionless (ie.no load) then you add a tensioning system to provide your desired filament tension. The tension will need to change on the angle of wind, not so much on the diameter of the mandrel.
Yes the torque is larger required to move a larger diameter mandrel but that is MOTOR Torque. The amount of force required to pull your filament stays the same whether the mandrel is big or small.
The trick I found with small diameter mandrels is to put a taper on each end where the wind finishes. This makes it a lot hader for the wind to slip at low winding angles. The tapered section is cut off and thrown away after.
I find larger tubes a lot easier as it can be a lot more forgiving for fiber placment (I won't get into the math). Smaller tubes means smaller filament width which means it can take longer to wind.
Essentially...After this long winded speech...You just have to trial and error it. If your motors are making funny noises you probably are pushing them to hard so either dial back your speed (less speed = more torque with stepper motors) or rethink your mandrel size.
Anyway I hope this helped
Aaron
Thank you Aaron! This information is very helpful. Im certain i need some more work on my roller/filiment delivery drag. im thinking of using a fish scale to test the tension on the filiment. Do you have any suggestions on the amount of tension in lbs/kg that you find works best? I have been pleased with the results of my test pieces, and agree that trial and error will be the best teacher. Thank you again Aaaron. cheers!
No problem Gary,
The tension setting will change on the winding angle. Even as the diameter increases the tension can change on the same winding angle because you essentially have more friction to hold your windings in place.
You want to aim for a tube that is 70% fibre and 30% resin (final weights). So your squeegee system is crucial to achieve this. Once your squeegee is getting the resin ratio approximately correct then you can adjust the tension to not be loose (you will get air voids) and not be to tight ( you can force to much resin out of the fibres).
Long story short...happy testing haha
I am working on a automated digital tensioner system to work with the angle of the wind. Less tension for low angle winds to stop drag, and high tension for high angles or hoop winds to get better consolodation.
You can do this process manualy but you need to watch the machine for the entire wind
Aaron,
Did you have any luck with designing an automated tensionor system yet? I need one! I had a few ideas myself, but after reading how winding angle changes tension, my ideas may be a moot point.. Any insight would be greatly appreciated!
Thanks,
Josh