Shipping a Step Out to a Plating Vendor and Back: A Transit Days Walkthrough

An operation that happens at an outside vendor is scheduled as a gap, not as a machine: you set transit days on the step whose completion starts the wait, choose calendar or working days, and the downstream operation cannot begin until the parts are back. This walkthrough runs a plated bracket through that model in EDGEBIC by User Solutions, including the mistake most shops make first (inventing a fake work center for the vendor) and what it costs them. It is one of the worked examples we publish with the numbers on the page.

Outside processing is common enough that getting it wrong distorts every promise date a shop makes. Getting it right is one field and one radio button.

The Cast: One Bracket, One Plater

Ridgeline Metalworks runs a bracket that goes out for zinc plating between machining and assembly:

Coastal Finishing quotes 5 working days for plating. The truck runs Tuesdays and Thursdays and takes a day each way. Total time parts are away from the building: 7 working days.

Every in-house work center runs one instance on a day shift, Monday to Friday, 08:00 to 16:00. The order is 80 pieces, due Friday, November 7.

Step 1: Reject the Fake Work Center

The instinct is to create a work center called PLATING with some enormous capacity, put the vendor's turnaround on it as hours, and move on. Do not.

A fake work center does three things wrong. It appears on the utilization report as a real station with real load, so plant utilization numbers stop meaning anything. It competes in the scheduling logic as if it were a machine your plant owns, which it is not. And it forces you to express a five day calendar wait as a number of hours, which requires it to have a shift, which means the wait mysteriously pauses at 16:00 every day and over weekends.

The transit days mechanism exists precisely so you do not have to do any of that.

Step 2: Set Transit Days on the Upstream Step

The gap starts when the parts are ready to leave, which is when the deburr operation finishes. So the transit goes on step 30, not on a step of its own.

1. Open the BOR tab and select the bracket's routing.
2. Select step 30, the deburr operation.
3. Set Transit Days to 7.
4. Set Is Calendar Days to off, so it counts working days only.
5. Save the routing.

That is the whole configuration. There is no step 40 row at all in this version, because the vendor operation has no hours and consumes no capacity: it is entirely a wait, and the wait is now modeled where it belongs.

If your traveler needs a visible line item for the plating operation so the shop knows the parts leave the building, you can carry a step for documentation, but the timing still lives on the transit field. The field-level recipe is how to add transit days between two steps.

Step 3: Schedule and Read the Gap

Run Drive Schedule for the job. The result:

Deburr finishes Thursday October 23 at noon. Seven working days from there, counting only days the shop is open, is Monday November 3. Assembly starts there.

Notice what the working-day mode did: seven working days spanned 11 calendar days, because two weekends fell inside the window. In calendar mode the same 7 would have landed on Thursday October 30, which would have been a lie by two full working days. On a routing with three outside operations, that class of error compounds until nobody trusts the promise dates.

The job ends Tuesday November 4, three working days ahead of the Friday November 7 due date.

Step 4: Read What the Gap Cost

Total in-house machine time on this job: 34 hours. Total elapsed time from first cut to final inspection: 12 working days.

The plating gap alone is seven of those days, more than half the job's calendar footprint, and it books zero machine hours. That is the honest picture of a shop that outsources a finishing operation, and it is the number a planner needs in front of them when a customer asks why a 34 hour job takes two and a half weeks.

It also tells you where lead time reduction actually lives for this part. Shaving an hour off the mill step changes the finish date by an hour. Getting the plater to a four day turnaround, or arranging a daily truck instead of a twice-weekly one, changes it by days.

Step 5: What Happens When the Vendor Slips

Two weeks later the plater calls: a tank is down, the batch will be three days late.

You have two honest ways to record it, and the choice depends on whether this is a one-off or the new normal.

One-off: leave the routing alone and let the job's own copy carry the change. Open the Scheduled Job BOR tab, select the job, and raise the transit days on step 30 from 7 to 10 on this job's copy only. Every job's routing is a frozen copy taken when it was scheduled, so editing it changes this order and nothing else. Reschedule the one job.

Result: assembly moves from Monday November 3 to Thursday November 6, inspection finishes Thursday afternoon, and the job now ends one day before its due date instead of three. Still on time, with the float visibly spent. That is the moment to decide whether to tell the customer, and you can decide it with a number.

The new normal: if the plater's turnaround has genuinely moved, change the master routing so every future order carries the truth. The next order planned will use 10 days from the start.

The distinction between the master routing and a job's frozen copy is the reason both options exist, and it is covered in production routing snapshots explained.

Step 6: Do Not Stack Transit and Transfer Delay by Accident

One trap worth naming. Transit days and transfer delay are additive on the same gap. Transfer delay is a sub-hour handling lag that belongs with lot streaming, where the first transfer batch of parts is walked to the next machine. Transit days is a whole-day gap for shipping.

For a multi-day vendor turnaround, use transit days alone and leave transfer delay at zero. Setting both because they sound similar produces a gap longer than either field suggests, and it is genuinely hard to spot afterward because each number looks reasonable on its own.

The order the engine composes these gaps in, and the related interaction where an active lot-streaming flow replaces a queue time rather than adding to it, is laid out in how queue, flow, and transit stack after an operation.

What This Walkthrough Proves

1. An outside operation is a gap, not a machine. Modeling it as transit days keeps the utilization report honest and stops a vendor competing for capacity you do not own.
2. The transit belongs on the upstream step. The gap starts when the parts are ready to leave.
3. Working-day mode is usually right. Seven working days spanned 11 calendar days here, and calendar mode would have promised two days that do not exist.
4. Outside time dominates the calendar. Seven of 12 elapsed days, and zero machine hours, is where the lead time conversation actually belongs.
5. A vendor slip is a one-job edit or a routing change. Which one depends on whether it is an exception or the new truth, and the frozen copy is what makes that choice available.

For transit between your own buildings rather than to a vendor, multi-plant scheduling with transit times covers the same field applied to internal shipping, and a material step is holding up my job handles the related case where the wait is for purchased material rather than for outside work.