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T100 failure due to load on plastic injection moulding


(Ben King) #1

Hi Guys

We’ve been using your T100 thrusters for a while now and have found that more than half of them fail where the bushing is blued to the injection moulding that passes through the stator. It seems that this part is too thin for the loads exerted by the rotor on the bushing. Going forward I believe this is going to be a reoccurring issue and requires a more robust design.


(Rusty) #2

Ben,

Thanks for the comment. I agree. That’s definitely on the list to be fixed in the next revision of the thrusters. They work pretty well already but we’d like to make them bulletproof.

-Rusty


(Ben King) #3

Agreed Rusty. The other weakness is that the inside of the stator is not protected from the water by the coating material. Perhaps a new version would solve this as well. I’ve also noticed quite a bit of galvanic corrosion between the collars and the shaft. It would be great if similar materials could be chosen where possible or some other way of electrically isolating these parts.


(Rusty) #4

Ben,

I’m not sure how old your thruster are, but we switched to all SS316 parts a while ago. That includes the shaft collar so there is very little corrosion between shaft and collar.

-Rusty


(Ben King) #5

ok, that’s great. I have the very first batch. Looks like the potting may have been improved as well?


(Rusty) #6

Ben,

Yep. We’ve been rolling in improvements as we go. The coatings on the stator are much better now and potting near the cable entrance is improved, especially on the T200. When we changed all parts to SS316 we also upgraded the rotor/magnet coating to a new process with excellent corrosion performance.

Thanks for believing in us early on!

-Rusty


(Ben King) #7

That’s great. But you have not yet improved the strength of the bush mount on the thrusters? Or perhaps this is better on the T200 anyway? If so, perhaps time to invest in a new set?


(Rusty) #8

Ben,

Not yet on the T100. We’d like to change it to a metal tube eventually. The polycarbonate is strong but the fatigue life is relatively poor. The T200 is significantly stronger in this section and much less likely to be damaged.

-Rusty