Buffers

A buffer is a (logical of physical) inventory point for an item at a certain location.

Different types of buffers exist:

  • Default:
    The default buffer uses an “producing” operation to replenish it with additional material.
  • Infinite:
    An infinite buffer is unconstrained and has an infinite supply of the material.
    Propagation through a bill of material will be stopped at an infinite buffer.

Field

Type

Description

item

item

Item being stored in the buffer.
The combination item+location+batch is the unique primary key of this table.

location

location

Location of the buffer.
The working hours and holidays for the buffer are taken from the available calendar of the location.
The combination item+location+batch is the unique primary key of this table.

batch

string

Blank, unused for make-to-stock items.
Batch identification for make-to-order items.
The combination item+location+batch is the unique primary key of this table.

description

string

Free format description.

category

string

Free format category.

subcategory

string

Free format subcategory.
If this field is set to ‘tool’, the field ‘tool’ will automatically be set to true.

onhand

double

Inventory level at the start of the time horizon.
Default is 0.

minimum

double

Desired minimum inventory, aka safety stock.
Use this field if the safety stock doesn’t change over time.
The solver treats this as a soft constraint, ie it tries to meet this inventory level but will go below the minimum level if required to meet the demand.
A problem is reported when the inventory drops below this level.The safety stock target is expressed as a quantity. If you want to define a safety stock target as a time value (aka days of inventory), you can set a post-operation timeon the producing operation of the buffer.
Default is 0, indicating no safety stock.

minimum_calendar

calendar

Refers to a calendar storing the desired minimum inventory level, aka safety stock.
Use this field when the minimum inventory level is varying over time. Otherwise use the minimum field. If both fields are specified, the minimum field is ignored.

maximum

double

Desired maximum inventory, aka order-up-to level.
When the buffer needs to be replenished, the planning algorithm tries to refill to this level.
Default is 0, indicating replenishments of any quantity are accepted. Note that operations can still define constraints on the replenishment size.

maximum_calendar

calendar

Refers to a calendar storing the maximum inventory level.
Use this field when the maximum inventory level is varying over time. Otherwise use the maximum field. If both fields are specified, the maximum field is ignored.

tool

boolean

A flag to mark buffers that are actually representing a tool.
Default is false.
The impact on the planning results is visible in the pegging and criticality calculations.
This field is only visible in the planning engine. In the user interface you use the subcategory field to set this field to true.