MaxWIP

The MaxWIP1, short for maximum work in process, is a production control logic (PCL) that restricts the maximum WIP over parts of or the complete production flow. The user specified maximum WIP level is kept from being exceeded by keeping track of the WIP level in the desired part of the production flow and restricting the entry of more product to that part when the maximum WIP level is reached. The objects marking the entries and exits of the controlled part of the production flow is referred to as the entry and exit objects of the PCL. The special case when the PCL exit is the bottleneck operation of the production flow is referred to as Drum Buffer Rope (DBR)2.

The MaxWIP object is used by simply connecting it with flow objects in the model. A connection from the MaxWIP object to a flow object marks an entry point of the MaxWIP and vice versa a connection from a flow object to a MaxWIP object marks an exit point of the MaxWIP. There can be several entry and exit objects of a MaxWIP, see example below (Operation1/Operation2 - entries and Operation3 - exit).

Note: The entries and exits of the MaxWIP logic as well as the MaxWIP object itself must be on the same level in the model, e.g. connections can't be made into a Component.

Note: Assembled parts are only counted as one unit.

Settings

The settings of the MaxWIP are listed below along with a short description and possibly a link to a more detailed description about the setting.

Setting

Description

Name

Sets the name of the object.

Location

Displays the location of the object.

Max WIP

The user specified maximum allowed WIP level. Range [0,∞).

Limit table

Used to devide the Max WIP between variants. The variant capacities are calculated by dividing the Max WIP among the different variants using a proportion figure, see image to the right.

Given a MaxWIP of 100 and the proportions in the example to the right the variant capacities would be:

  • Black: 100 * 3 / (3 + 3 + 2 + 2) = 30

  • Gray: 100 * 3 / (3 + 3 + 2 + 2) = 30

  • Red: 100 * 2 / (3 + 3 + 2 + 2) = 20

  • Blue: 100 * 2 / (3 + 3 + 2 + 2) = 20

Note: Limits for assembled parts should be specified using the assembly identity of the assembled parts, see assembly identity for more details.

Note: If left blank (i.e. unset) any variants will be allowed.

User attributes

Lists all attributes that the user has added to the object. See User attributes for more details.