About lots

A lot can be a difficult thing to define, due to the fact that there is no standard terminology used across industries to represent this concept.

In regards to AVEVA™ Production Management, a lot is an allotment of material, and it has a unique lot identifier. How the allotment is defined is based upon the industry and location within the supply chain. Generally, a lot has attributes that describe it. For example, the physical location of the lot, who supplied the lot, and the physical characteristics of the lot; that is, quality attributes.

A lot is a uniquely identifiable amount of material for which a single set of measurements defines the composition, quantity, and process characteristics. For accounting and production control purposes, the plant treats a lot as a unit in processing. With AVEVA™ Production Management, you can generate unique identifiers for lots, and you can configure AVEVA™ Production Management to track them at key measurement points known in AVEVA™ Production Management as items of equipment.

In a continuous process, the creation of a lot is generally not based upon a discrete event; such as a truck unloading or train loading, but on a time-based event; for example, creating a lot every 2 hours. This is because every 2 hours, a sample of the material is taken and sent to the lab for analysis. The lot represents the 2 hours of production and the material that moved within that time frame is considered to have the same quality attributes. In fact, the sample could represent the material for 1 hour before the sample was taken to 1 hour after the sample was taken. In this case, the lot identifier is the same as the unique tag that was applied to the physical sample taken. This enables the quality results from a LIMS to be correctly imported and linked.

Is a movement the same as a lot?

The answer is; it depends. In some parts of the process, it is, in others, it is not. A lot is created when an automatic movement occurs that specifies a destination lot identifier that does not exist in the destination work center. If configured, this automatically creates a record in the relevant Lot reporting point and Material Quality reporting point.

Remnant lots

A lot can be a remnant lot. If the source work equipment is of type WeightedAverage, then material is taken from each lot in weighted amounts. After repeated weighted average movements, these lots have very small balances and are known as remnant lots. For weighted average movements, AVEVA™ Production Management moves remnant lots first, and then the remaining lots are moved in weighted amounts. When remnant lots are calculated, AVEVA™ Production Management considers only lots where material exists, so debt lots are not considered.

Negative balances and debt lots

A lot can have a negative balance or be a debt lot. This occurs when the balance in a source work equipment is not enough to fulfill a material movement request. AVEVA™ Production Management creates a negative balance on a lot, or a debt lot to hold the negative balance at the source work equipment. Whether a negative balance or a debt lot is added, depends on the LotBehaviour for the work center. When remnant lots are calculated, debt lots are not considered.For more information, see Understand lot behavior for negative balances.

Lots and survey results

You can use a survey result to change the balance of a lot to reflect the result of a survey. AVEVA™ Production Management uses the survey result to automatically calculate the adjustment so that the balance of the lot is equal to the balance of the survey result.

For example, LOT1 has a balance of 100. An aerial survey is performed on the lot and determines that the surveyed balance of LOT1 is 120. AVEVA™ Production Management calculates the adjustment so that the balance is equal to the survey result.

Lots and SampleIdentifier

Movements have a SampleIdentifier field that AVEVA™ Production Management matches with a unique RecordIdentifier field on a Quality record when configured. When material is moved from a source to a destination, the SampleIdentifier can be inherited by the destination.

For more information, see About Sample Identifier.

Related topics

• Add and configure a Lot reporting point

• Add a Lot custom field

• Understand lot behavior for negative balances.