Preventing Lower-Ranked Orders from Filling Schedule Gaps

MxAPS can allow a lower-ranked operation to fill idle time before a higher-ranked operation. This is controlled by the hole algorithm.

To prevent lower-ranked operations from filling these gaps, configure the full hole solution.

How Hole Scheduling Works

Hole scheduling depends on three areas:

1. The scheduling rule must define a Hole On parameter.
2. The work center or machine center must define allowed hole durations.
3. The operation must allow or disallow hole behavior using Allow Holes.

If the scheduling rule does not use Hole On, or the work/machine center hole durations are not configured, changing Allow Holes alone may not produce the expected result.

Step 1: Configure the Scheduling Rule

1. Search for MxAPS Scheduling Rules.
2. Open the scheduling rule used by the production cell.
3. Set Hole On.

Hole On defines the point of indifference for the hole algorithm.

Use a scheduling rule parameter that matches the intended ranking logic. For example, use the parameter that determines whether a lower-ranked operation is allowed to schedule before a higher-ranked operation.

Step 2: Configure Hole Values on the Work Center or Machine Center

Configure the hole durations on the capacity that is being scheduled.

For a Work Center

1. Search for Work Centers.
2. Open the relevant Work Center Card.
3. In the MxAPS FastTab, set:
   • Hole Total Duration
   • Hole Idle Duration

For a Machine Center

1. Search for Machine Centers.
2. Open the relevant Machine Center Card.
3. In the MxAPS FastTab, set:
   • Hole Total Duration
   • Hole Idle Duration

Hole Duration Fields

Use lower values to make hole filling more restrictive.

Use zero or blank values only if that matches the intended implementation behavior for the site.

Step 3: Configure the Operation

Configure Allow Holes on the operation.

From a Production Order

1. Open the production order.
2. Select the production order line.
3. Choose Line > Routing.
4. On Prod. Order Routing, find the operation.
5. Set Allow Holes.

Use:

From a Routing

1. Search for Routings.
2. Open the routing.
3. Open the routing lines or routing version lines.
4. Set Allow Holes on the relevant operation.

This controls the default value copied to production order routing lines when production order routings are created.

Step 4: Regenerate the Schedule

After changing the scheduling rule, capacity setup, routing, or production order routing line:

1. Search for MxAPS Generate a Schedule.
2. Generate the schedule again.
3. Review the Machine Schedule Summary.

Example

Machine 1:
Order 1, Operation 10, Rank 1000

Machine 2:
Order 2, Operation 10, Rank 3000
Order 1, Operation 20, Rank 2000

In this example, Order 2, Operation 10 is lower ranked than Order 1, Operation 20, but it may fill the available gap on Machine 2 if the hole setup allows it.

To prevent this:

1. Confirm the scheduling rule has the correct Hole On parameter.
2. Set restrictive Hole Total Duration and Hole Idle Duration values on the relevant work center or machine center.
3. Set Allow Holes to Disallowed on the lower-ranked operation if it should not fill gaps.
4. Regenerate the schedule.

Troubleshooting

If lower-ranked operations are still filling gaps, check:

1. The production cell uses the expected scheduling rule.
2. The scheduling rule has Hole On set.
3. The relevant work center or machine center has Hole Total Duration set.
4. The relevant work center or machine center has Hole Idle Duration set.
5. Allow Holes is set correctly on the production order routing line.
6. The schedule was regenerated after the change.
7. The operation is not being moved by another rule, manual move, order set, material constraint, or alternate machine decision.