The external environment in aluminium sand casting

Published - 27th Jun 2018

In this blog, we explore the environmental factors that can affect sand casting – which we must manage carefully to maintain quality and safety in the foundry.

Damp conditions

Moisture in the air can present certain risks. Even the smallest water droplets can cause a reaction in the furnace or melting crucible through the combustion of hydrogen and oxygen at high temperatures. To prevent this issue, our sand is stored in a dry silo and the metal bars are gently warmed by the furnace before use. This helps to reduce any risks as much as possible.

Moisture in the air can also affect the amount of degassing required. As we’ve explained in a previous blog, degassing involves purging the molten metal with nitrogen to remove any hydrogen before the metal pour. Hydrogen can be introduced from the air – leading to gas porosity in the final castings. So, degassing is vitally important.

The levels of hydrogen naturally increase in damp conditions. In this scenario, we increase the amount of nitrogen used in degassing.

The air temperature

The external air temperature does not have a particularly significant impact on the sand casting process. However, it does impact on the setting of the sand moulds. The moulds set or ‘cure’ at a much faster rate in hot conditions. For this reason, we adjust the quantities of the chemical catalysts used at different times of the year.

Dust and other contaminants

Foundries have changed a great deal in the past 50 years – with the advent of new technologies, working practices and strict regulations governing the use of machinery and materials.

These days, most foundries are very clean environments. At Haworth Castings, this is due to the stringent health and safety measures we have in place and the hard work of our team in terms of maintaining a safe working environment.

Some tasks such as fettling and shot blasting do create dust emissions but we have very effective ways to address this. For example, our ‘wet scrubber’ filtration unit transforms dust emissions from fettling into a wet sludge – thus removing these particles from the atmosphere.

All areas in the foundry have excellent ventilation, filtration and extraction in place to ensure the safety of our team and the wider environment.

If you would like to find out more about our casting work, please call us today on +44 (0)1794 512685 or email us.