Production yield

Production yield is the amount of finished product a plant obtains from the raw materials it uses.

Yield shows what proportion of the raw materials fed into production turns into saleable product. It is usually expressed as a percentage. If a plant used raw materials for 10,000 kg of product and 9,500 kg was sold, the yield is 95%. The remaining 5% is losses.

Losses occur at many points in the process, including:

• residue in pipes and tanks, flushed into the wastewater at the end of a batch,
• start-up losses, meaning the first portion of product at the start of a run, mixed with water or not yet within specification,
• end-of-run losses, meaning product left in the installation at the end of a run,
• transition zones, where one product mixes with the next during a changeover,
• product rejected by quality control, for example because it is too runny, incorrectly filled or in damaged packaging.

The higher the yield, the fewer raw materials are needed for the same amount of saleable product, and therefore the lower the cost of each kilogram or litre. That is why plants try to reduce losses at every stage of production.

Example: A fruit and vegetable processing plant produces several types of tomato sauce on a single line and changes the recipe several times a day. With every changeover, it loses the sauce left in the pipes, a portion at the start of the new run and a portion in which two sauces have mixed. After introducing pigging, the pig pushes the sauce out of the pipes into the filling machine and separates successive products from one another. From the same amount of tomatoes, spices and other raw materials, more sauce ends up in jars, so production yield increases.