How Steel Castings Indian Manufacturers Classify The Defects, Causes And Their Remedies?

Casting is a method and a process that carries risk of failure occurrence during production. This is why steel castings Indian manufacturing foundries take action while production process to eliminate defects from the castings. Majority of casting defects are concerned with process parameters. And so engineers need to control the process parameter to attain zero-defect parts.

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The classification of casting defects:
• Filling defect
• Shape defect
• Appearance defect
• Thermal defect

Under filling defect, there are blowholes, sand burning, sand inclusion, cold lap, misrun, and gas porosity.

Blowholes are kind of cavities, which are further split into two kinds- pinhole and subsurface blowhole. Pinholes are relatively tiny, but subsurface holes are visible after machining. Major causes behind such defects-

Resin-bonded sand
• Excessive release of gas from core
• Inadequate core venting
• Excessive moisture absorption by the cores
• Low gas permeability

Clay bonded sand
• Excessive release of gas from lustrous carbon producer
• High Sand temperature
• Excessive moisture content
• High Bentonite content

How Do Steel Castings Manufacturers In India Fix These Defects?

Resin bonded sand
• They enhance the core venting
• They lower the amount of gas
• They apply dressing to cores
• They dry out the cores and store dry

Clay bonded sand
• Lower the moisture content and enhance sand conditioning
• Enhance gas permeability
• Lower the sand temperature
• Lower the bentonite content
• Use of low reactive lustrous carbon producers

Sand burning includes metal penetration and chemical burn-on. When impurities sinter and melt inside the mouldings, sand allows the molten metal iron to penetrate at faster rate.

Major Causes Behind This Defect:

Clay-bonded sand
• Low lustrous carbon content
• High proportion of low-melting point substances

Gating and pouring practice
• Uneven distribution of inflowing metal and over heating
• High temperature of molten metal

Moulding plant
• Uneven mould compaction

How Do The Foundries Fix The Defect?

Clay-bonded sand
• Raise the proportion of lustrous carbon producer
• Use quality and contamination free silica sands.
• Lower the dust content and if required, lower the bentonite amount.

Gating and pouring practice
• Even out incoming metal flow
• Lower the pouring rate
• Lower the molten metal temperature

Moulding plant
• Ensure use of uniform compaction
• Raise heat removal from the mould, if required

To learn other defects and their remedies, please follow our other post here.

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