Time Management of Work Instructions

Work instructions are details added to an operation. By default, they do not affect the cycle time of the operations with which they are associated.

To keep work instructions from unintentionally affecting a parent operation's cycle time, the total number of work instructions for an operation equally share the time of the parent operation. Each work instruction's share is automatically recalculated when a new work instruction is added or an existing one is deleted, assuming the addition or deletion occurs within the Work Instructions Planning workbench. For example, if an operation takes 10 seconds, and you add a single work instruction to the operation, the time of work for the work instruction also equals 10.

Note: The Work Instructions Planning workbench does not provide access the Gantt chart; you can view the effects of time calculations by accessing the Gantt chart from Manufacturing Systems Definition.

If you create four work instructions in Work Instructions Planning, each work instruction's time of work equals one quarter of the parent operation's estimated time.

If you delete a work instruction in Work Instructions Planning, each work instruction's time increases to one third of the parent operation's estimated time.

If you alter attributes of work instructions from the Manufacturing Systems Definition workbench, you may adversely affect the estimated time function in Work Instructions. For example, if you copy a work instruction from one parent operation (with a duration of 10 seconds) to another 10-second operation, the copied work instruction retains its estimated time from its original location, which in turn affects the estimated time of the parent operation.

If you alter the default settings of Tools > Options > Manufacturing Planning > Work Instructions, you can alter the time mode of each operation for which you create a work instruction.

By default, each operation containing work instructions has its Time Mode set to Estimated Time. If you enable Set Time Mode on parent operation to Work Instruction Time in Tools > Options > Manufacturing Planning > Work Instructions, each work instruction's parent has its Time Mode set to Work Instruction.

The change in Time Mode is effected when you create a work instruction. If you have previously created work instructions underneath the operation, you are prompted before the operation's Time Mode is changed. If you are creating work instructions beneath the operation for the first time, the shift is automatic.

Once you have created the work instructions, you can open a Gantt chart in Manufacturing Systems Definition. You can use the Gantt chart to control each work instruction's cycle time.

Generally, work instructions can be created before resource planning. Work Instructions are for tasks performed by humans. The task specification (and, therefore, the time specified for the task) is independent of the additional resources that may be needed for the task. Examples of work instructions independent of the resources include:

• Insert one product into another
• Clean a surface before drilling a hole
• Put part into oven for curing at 425 deg for 30 minutes (in this case, the resource is an oven, which is presumably already present)

In only a few cases are work instructions be dependent on resources being added (e.g., putting a part into a fixture and clamping down the part). In this case, the time for the Instructions depends on the type of fixture being used. In such cases only should resource planning be done before the Work Instruction Planning.