This section introduces the use cases for the OPC UA for Machine Tools specification. For the use cases described in sections 5.2 to 5.9, a maximum sampling rate of 1 Hz is considered to be sufficient.
The machines of different manufacturers shall be identifiable in a standardised manner. To realize this, a number of basic and static information like manufacturer name and serial number are offered on the Machine Tools interface. This information can be found on the interface in an instance of the MachineToolIdentificationType.
Using information provided by the Machine Tools interface, an overview if the machine tool is in production or not should be possible. Additionally, if the machine tool is in an erroneous state, it needs to be evident over the interface.
If the machine tool is not in production, the reason for this state should also be identifiable.
The information of the machine tool and controller state can be found in the information model in the Monitoring Component (defined by the MonitoringType) of the MachineToolType. Other nodes that provide important information for an overview if the production is running are the override values of NC channels and working units in the ChannelMonitoringType and the WorkingUnitMonitoringType.
Another indication of the machine tool status is the machine stacklight. Its representation in the Machine Tools information model can be found in the StacklightType.
The errors and warnings on the machine tool shall be available on the Machine Tools interface with the OPC UA mechanism described in OPC UA Part 9 – Alarms and Conditions.
Using the Machine Tools interface, an overview of the target and actual manufactured parts is possible. Additionally, it is possible to see which parts belong to which internal or customer order. If there is an irregularity in the process which might affect the part quality, the part’s representation on the interface is marked accordingly.
The relevant information can be found in the information model in the part counters of the ProductionPartSetType, the CustomerOrderIdentifier of the ProductionPartType and ProductionJobType and the quality information of the ProductionPartType.
In order to calculate cycle times and prognoses for production, the Machine Tools interface provides the time data of start, end, interruption and aborting of machining processes and programs on the machine tool.
The events can be found in the information model as InterruptionConditionType with its ConditionClassId and ConditionClassName (that specify the reason for the interruption further), ProductionJobTransitionEventType, ProductionProgramTransitionEventType and ProductionPartTransitionEventType.
To receive the events for a specific program, job or controller, the OPC UA client can subscribe to the associated StateMachine.
With the interface, information on the machine tool state is available, e.g. in the MachineOperationMonitoringType. The MachineOperationMonitoring type also contains the MachineryItemState and MachineryOperation mode from OPC 40001-1.The states of NC channels and controllers in the machine tool are available as well.
In the information model, the status of the production is shown in state machines of each available production job (ProductionJobType), program (ProductionProgramType) and part (ProductionPartType). The reason for an interruption in a production job can be qualified with the ConditionClassTypes defined in 10.
For a machine operator who works on multiple machine tools in his shift, an indication which of the machine tools has the soonest need of a manual intervention is helpful (e.g. tool change, part change, preparation for the next job…).
To achieve this, the Machine Tools interface offers the possibility to give prognoses for different events. These prognoses can of course only be provided if the machine tool can estimate the time of the respective future event.
The available types of prognoses are: MaintenancePrognosisType, ManualActivityPrognosisType, PartUnloadPrognosisType, ProcessChangeoverPrognosisType, ProductionJobEndPrognosisType, PartLoadPrognosisType, ToolLoadPrognosisType, ToolUnloadPrognosisType, ToolChangePrognosisType and UtilityChangePrognosisType.
On the Machine Tools interface, there is a list of available prognoses, which is of PrognosisListType. It contains all known prognoses with their times to happen.
The machine tool is expected to offer all current errors and warnings over the Machine Tools interface.
These errors and warnings shall be mapped to OPC UA event types accordingly. For errors, the Machine Tools information model offers the AlertType. For messages with lower urgency, there is the NotificationEventType.
To facilitate the calculation of different KPIs like for example OEE, the Machine Tools interface offers different machine times. These times allow to calculate the durations of different machine modes. To calculate the KPI, additional data not provided by the interface may be necessary.
Some of these relevant times are transferred via the event mechanism in OPC UA.
For detailed information about KPI calculation and possible values of the information model to use, please refer to Annex B.
On the Machine Tools interface, data concerning the tools in the machine tool is available.
In the Machine Tools information model, the tool data are constrained to very basic information. Especially all geometric information about the tool is omitted on the interface. This is mainly due to the multitude of different norms for different tools.
On the interface, there are the identifiers of the tools in the machine tool. With these, it can be verified if a machine tool is prepared to execute a certain machining task.
There is also some information about the tool life condition of the tool. The interface will show at which tool life value a warning to change the tool is issued and the tool life limit value at which the tool is intended to be changed.
If there are multiple tools of the same type equipped in the machine tool, the one that will primarily be used in the machining process is marked as planned for operating. Using this information, the tool distribution among different machines can be planned remotely and changed without disturbing the current machine operation.
The Machine Tools interface makes use of OPC 40001-1. As such, it is providing the use cases “Machine Identification and Nameplate”, “Finding all Machines in a Server”, “Finding all Components of a Machine” and “Machine Monitoring”. It also provides the MachineryBuildingBlocks folder, directly referencing all Machinery Building blocks used by the Machine Tools interface instance.