creep or distortion

[maspogi]

Guys I am new on this forum, I wonder if someone can help me.

I am trying to solve a design problem of our Plastic propeller fan, the fan tends to creep/distorted when subjected to higher temp (60 C) that leads to broken blades. It originally uses an ABS20GF, I tried to use
PP30GF but result show worse. A friend of my suggest to
use PA6+30GF but the part cost will surely goes high. Iam
thinking of using AS30GF first, my question is will this
can solve creep problem?

My next question is: I am seaching candidate material at
Azom.com, on the property table, what does "Max Operating Temperature means?

Thank you in advance.

 

[patprimmer]

Nylon will solve your problem. It might not need glass at 60 deg C, but it probably will, but not 30%. You might get by with 10% glass.

The nylon will mould faster that might offset the cost a little.

The property you are looking for is heat deflection at high load.

If you are looking to long term durability at higher temps, the continuous use temp is the one. You probably should consider both.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[maspogi]

Thanks Pat, appreciate your reply.

I think you are refering to Heat defelection or HDT (i.e. HDT@ 1.80MPa (pls correct me). There is another temp which say Max Operating temp which confuses me. For example on
PA6-30GF HDT @1.80MPa temp is 205C then the data on Max Operating temp is only 80C. Is this the application temperature limits?

Regards,

 

[patprimmer]

HDT@1.80MPa is the short term resistance to temperature under load, and is relevant to distortion or yield, whereas the 80 deg C rating is a continuous use temperature and is a measure of chemical degradation and consequent change in properties over a longer time frame. It is not relevant to distortion, yield nor creep.

You will get a result with cheaper materials if you can increase the shaft dia as that will apply the load to a larger area, and reduce mechanical advantage that the fan load has on the fan mounting interface.


Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[maspogi]

Pat,

Thanks a lot.