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Porosity Post - machining

2004

We are also facing problem of very small (miniature) porosity problem post machining. Our alloy is LM24 and component is 86 grams thick walled. High pressure die casing process with 75 ton machine is being used. Die is with 2 cavities.

Drawing specifies 0.8 Ra surface finish. Hence we machine (boring for ID and profile milling for OD) the component. The machining allowance is 0.5 mm radially. After machining we are getting very small size porosity (one or two places dia. <0.5mm) mainly on bore surface. The customer says no visible porosity is acceptable on machined part and resin filling is also not acceptable. Despite trying various parameters, we are getting porosity with 25% jobs and loosing heavily.

Is there any international standard for reference? Is High Pressure die casting process really suitable for NO POROSITY castings? Is radiography level 1 achievable with this process? Whether using still higher tonnage / velocity machine desired? At the moment there is no cooling for pins which define bore. Whether pin cooling will help eliminating the porosity at skin level?

Regards,

Nandkumar Telang
Owner - Pune, Maharashtra, India

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Reduce machining allowance. ideal is 0.2mm max. please let me know if you see any improvment.

Regards,

Suman
IT - Bangalore
2004