The Job Left the Factory for Outside Processing. Do You Still Control It?
Outside programming, coating, machining, inspection or other subcontract steps can break visibility if material identity, quantity, revision, expected return and quality status are not connected to the original EMS work order.
The short answer
EMS subcontract WIP remains controlled when the outside process is treated as part of the original work order rather than a separate purchase with little production context. The business should preserve revision, quantity, material identity, expected process, supplier, due-back date, quality status and the next internal operation.
The work may leave the building; the manufacturing record should not.
The same question belongs to the wider High-Mix EMS Changes Every Day. How Do You Keep Production Under Control? operating picture: subcontract WIP control has to remain connected to the decisions made before and after it, rather than becoming a separate local control.
Define what is being sent
Before shipment, identify:
- work order;
- product/revision;
- quantity;
- lot or serial range where required;
- process required;
- material ownership;
- expected return.
This creates a controlled handoff. Keep subcontract purchase and WIP linked. The purchase order manages the commercial supplier transaction.
The work order manages the manufacturing context.
Connect them.
This lets purchasing see the service while production sees the work. Preserve material identity. Some outside processes affect trace-controlled units.
Do not replace the internal identity with a supplier reference that breaks genealogy.
Use labels or documents that preserve the relationship. Control revision. The subcontractor needs the correct revision of:
- drawing;
- program;
- specification;
- process instruction;
- quality requirement.
If the product changes while WIP is outside, determine whether the external work is affected.
Track quantity sent and returned. Reconcile:
- quantity sent;
- quantity processed;
- scrap;
- quantity returned;
- shortages.
Unexplained quantity difference should not disappear into inventory adjustment. Track due-back date. An outside process can become the true schedule constraint.
Show expected return in production planning.
If the supplier slips, the customer date may need to change.
Include transport time
The process lead time is not only supplier run time.
Add outbound and return transport, booking and receiving/inspection where relevant.
This makes delivery promises more realistic. Define quality acceptance. Returned WIP may require inspection before it is production-ready.
Treat the quality status explicitly.
Do not assume arrival equals usable WIP. Handle supplier rework. If the outside processor needs to redo work, preserve the history.
The manufacturing record should show the additional cycle and quantity impact.
This can matter to cost and delivery analysis. Preserve customer approvals. Some special processes may require approved suppliers or customer-defined sources.
The subcontract decision should follow those rules.
This is similar to approved component sourcing.
Manage partial returns. Suppliers may return work in batches.
The internal system should show what quantity is back and what remains outside.
This supports partial continuation where appropriate. Protect packaging and handling. Electronics WIP may require ESD, moisture, protective packaging or controlled transportation.
Include those requirements in the handoff.
A correct process can still produce damaged WIP if logistics are uncontrolled.
Connect outside processing to genealogy
Where the process changes the unit or lot history materially, include it in genealogy.
Examples can include coating, programming, machining or specialized inspection.
The exact depth depends on customer requirement. Capture actual supplier performance. Track actual turnaround, quality and loss.
This data can improve future routing and supplier choice.
It also helps purchasing distinguish low price from reliable total performance. Avoid invisible off-site inventory. Finance and production both need to know that material still exists even when it is not physically in the factory.
Use appropriate inventory/WIP status so off-site material is neither forgotten nor double-counted. Include supplier capacity in the plan. Outside processors can become constrained just like internal equipment.
For critical subcontract operations, understand supplier capacity and booking lead time.
A purchase order placed today may not guarantee immediate processing.
Define responsibility for loss or damage. If WIP is damaged or lost outside the plant, the business needs clear commercial and operational treatment.
The manufacturing record should identify the affected quantity and disposition.
This supports supplier recovery and customer communication. Use approved subcontract sources. Some customers or processes may require approved external processors.
Keep the source rule connected to the job.
The cheapest or fastest supplier may not be technically authorized.
Track off-site age
Just as internal WIP age reveals hidden queues, off-site age reveals supplier delay.
Use exception thresholds.
Escalate before the customer date becomes impossible. Include return logistics and receiving discipline. Returned WIP should be identified correctly and matched to the original job.
If required, receive it into a controlled quality status before the next operation.
This prevents externally processed material from bypassing normal verification. Feed supplier performance into sourcing decisions. Track turnaround, quality, quantity loss and communication.
Use this evidence when selecting future outside processors.
A slightly higher price can be economically better if the supplier protects schedule and yield. Use a dispatch-and-return checklist. For important outside processing, confirm before dispatch:
- correct revision;
- quantity;
- identity labels;
- required documentation;
- expected process;
- due-back date;
- packaging/ESD requirements.
On return, confirm:
- quantity;
- identification;
- process completion;
- damage;
- quality status.
A simple checklist prevents many off-site control gaps.
Manage customer-owned WIP carefully. The physical material may belong to the customer even while the subcontractor holds it.
Ownership, liability and traceability remain important.
The system should not lose that context during external movement. Use subcontract status codes that support planning. Examples can include:
- dispatched;
- received by supplier;
- in process;
- waiting supplier inspection;
- complete;
- in transit return;
- returned awaiting inspection.
Use only as much detail as the business can maintain reliably.
Control documentation exchange
Outside processors may need drawings, programs or special instructions.
Send controlled revisions.
If the specification changes, confirm whether the supplier has started.
Emailing a new file is not enough if the old process is already underway. Include subcontract WIP in customer risk review. A job outside the plant can be easy to forget in daily factory meetings.
Include late or critical external work in the same exception review as internal WIP.
This keeps the delivery risk visible. Reconcile subcontract invoice to actual service. The enterprise purchase cost should match the work actually performed.
Unexpected setup, premium or rework charges should be traceable to the job.
This improves both supplier management and job-cost accuracy.
Plan contingency for critical external processes. If one subcontractor performs a process that no internal resource can replace, the supplier becomes part of the production constraint.
For important products, consider:
- approved backup supplier;
- spare capacity;
- alternate route;
- agreed escalation;
- buffer lead time.
Not every process needs redundancy.
But the risk should be visible before a supplier problem turns into a customer-delivery emergency. Close the loop after late return. When external WIP returns late, record why.
Supplier capacity, transport, documentation, quality rejection and internal dispatch delay require different corrective actions.
This prevents every delay from being classified simply as “subcontractor late.” Review external-process economics. Outside processing can look inexpensive on the purchase order while creating transport, waiting, inspection and schedule risk.
Compare total job impact, not only supplier price.
This can support make-or-buy decisions, supplier negotiation and better lead-time assumptions for future quotations.
It also gives planning a stronger basis for deciding whether outside processing should remain the standard route or only an overflow option.
That decision should use actual turnaround, quality and total job impact rather than habit alone.
What management should measure
Useful indicators include:
- subcontract WIP overdue;
- quantity mismatch;
- supplier scrap;
- outside rework;
- turnaround variance;
- WIP outside without current status;
- jobs delayed by outside process;
- return inspection holds;
- external process cost variance.
These show whether subcontracting is a controlled extension of the factory.
A practical review
Choose every work order currently outside the plant.
For each, identify exact quantity, revision, supplier process, due-back date, traceability status and next internal operation.
Any unknown answer is an off-site WIP control gap.
Where Epicor Mars fits in subcontract WIP control
For subcontract WIP control, the key system-design question is how to keep enterprise control and electronics-specific execution on the same operating thread. Epicor provides the enterprise-grade ERP foundation for customer orders, purchasing, inventory, planning, costing, finance, approvals and governance. Epicor Mars extends that foundation with the EMS industry context needed at the point of work, including material identity and readiness.
That connection is directly relevant to The Job Left the Factory for Outside Processing. Do You Still Control It?. Outside programming, coating, machining, inspection or other subcontract steps can break visibility if material identity, quantity, revision, expected return and quality status are not connected to the original EMS work order. When the Epicor Mars execution record stays tied to the Epicor work order, material and customer context, management can compare the business commitment with what the factory actually executed without maintaining a second source of truth.
For subcontract WIP control, that complementary positioning is the point: Epicor remains the enterprise-grade foundation, while Epicor Mars adds the EMS workflows needed to make this particular control operational on the factory floor. Explore Epicor Mars for electronics manufacturing.
Frequently asked questions
Is subcontract processing just a purchasing issue?
No. Purchasing controls the supplier transaction, but production still needs WIP, revision, quality and schedule context.
Should off-site WIP remain in inventory?
The accounting treatment depends on system design, but the business should retain visibility and ownership.
What if only part of the quantity returns?
Track the returned and outstanding quantities separately and continue the work only under the defined process.
Does subcontracting break traceability?
It should not. Preserve identity through the handoff where traceability requirements apply.