Cast Iron Motor Brackets 1

[ButchCWIPSCI]

I have some motor brackets for overhead doors that are made out of cast Iron... One of these motor brackets broke into two pieces, this is where I found Large 1/8"-1/4" air bubbles in the casting.. my question is where can I find a specification for the Minimum size of the air bubble sizes in casting of these parts
I have looked at the ASTM Ferrous Specifications and can not find anything that refers to the casting other than Piping and Flanges
maybe there is no Spec. for these parts not sure
when this part broke it cost a lost time accident so I want to get a path forward for the remaining ones but need a base to inspect to any information will help Thanks in advance

 

[metengr]

Are you sure these motor brackets are even cast iron (CI)? ASTM has specifications for castings (CI and cast steel) to be used in general applications and other more specific applications (high pressure, etc.,). Nondestructive testing (NDT)is used to find casting defects provided it is specified in the purchase order and the purchaser (you) has stated the severity level (casting defect size) and type.

If the castings are not produced to any specification or there are no specific requirements regarding severity of flaws, you are stuck.

 

[arunmrao]

I am surprised that you could get a blow hole in CI casting. Normally a blow hole is formed due to air entrapment or low pouring temperature. CI has a good fluidity and with a good casting practice this can be avoided in the casting.

ASTM standards for CI should guide you regarding acceptance criteria for these defects. Can you radiograph a few castings to know the presence of blow holes in the casting? Normally for a batch 5% of the castings need to be radiographed,before accepting them.

" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke

 

[Tmoose]

was any surface porosity present?

 

[dbooker630]

You should get a copy of ASTM E446, E186 (CS >2" thick), and their associated reference radiographs. ASTM E1025 is also helpful for setting quality levels. Typical internal soundness levels for gas are level 2 or 3, more relief for larger size castings (>50 lbs); gate or riser areas may allow one size larger; critical areas one size smaller.

The best way to minimize grief in the future is to develop a soundness drawing showing exactly where and to what extent discontinuities can be allowed.

 

[arunmrao]

Concerns regarding structural integrity are generally low for gray iron compared to steel. This is because CIis a brittle material but they are east to cast due to their high CE. Also it is one of the cheapest material available for many low stressed applications.

A simple destructive hammering of the casting in the suspected region might suggest the existence of any major flaw. This can help decide if there is a need to proceed with expensive radiography test or simply scrap the castings. Please remember no salvaging is possible or permitted.

" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke