MFI what range of deviation is acceptable
MFI what range of deviation is acceptable
(OP)
thread709-252160: MFI value and decomposition of PC/ABS
Hi all
Recently, we got a serious hinge and base broken issues and we sent defect samples to SGS lab. for MFI analysis, data shows MFI change from 22(raw material) to 28 g/10min under ASTM D-1238 260degree/2.16kg, We doublt that large ratio of re-cycle material has been added during the process.
Any idea ? or suggestion.
Tks
Hi all
Recently, we got a serious hinge and base broken issues and we sent defect samples to SGS lab. for MFI analysis, data shows MFI change from 22(raw material) to 28 g/10min under ASTM D-1238 260degree/2.16kg, We doublt that large ratio of re-cycle material has been added during the process.
Any idea ? or suggestion.
Tks






RE: MFI what range of deviation is acceptable
Moulded in stress or to much shear in moulding can seriously degrade the impact properties of PC/ABS
MFI is increased by inadequate drying, overheating, being hot to long or to much shear.
Regards
Pat
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RE: MFI what range of deviation is acceptable
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: MFI what range of deviation is acceptable
Or:
Incorrect drying
Too low tool temperature (causing frozen-in stress)
The above are the most comment cause of PC problems (IMO)
Cheers
www.tynevalleyplastics.co.uk
RE: MFI what range of deviation is acceptable
Thanks for the inputs.
Is there any relationship or evidence could show
the MFI deviation between these factors ?
Tks
RE: MFI what range of deviation is acceptable
You should check whether someone lubricated your hinge with oil as that could destroy it and cause your failure and check whether the material was dried properly and molded correctly.
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: MFI what range of deviation is acceptable
Thanks again !
Our dry process is 80 degree C 4hrs and no any oil will polute the hinge during the process, but we do have a female
screw hot bury within the hinge after injection. is this the root cause ?
Since MFI is the index for the material(PC/ABS) quality
what is it stand for ? purity or something else ?
Tks
RE: MFI what range of deviation is acceptable
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: MFI what range of deviation is acceptable
Thanks for the input
Our appalictions are mobile entertainment system, and for fire proof purpose we used PC/ABS with MFI around 22, is it sufficient for tensile strength and impact resistance ?
or what range of MFI should we use ?
any idea or suggestion ?
Tks
RE: MFI what range of deviation is acceptable
MFI is Melt Flow Index. All it tells you is the approximate viscosity of the polymer and it's not even very good at that.
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: MFI what range of deviation is acceptable
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: MFI what range of deviation is acceptable
Thanks for input again !
In the other word, what will be the main issues caused by large percent of re-cycled material, and which index can show it as a evidence ?
Tks