What Is Outside Processing and Why It's So Hard to Track?

If you run a job shop or manage production at a contract manufacturer, you've lost jobs to outside processing. Not because the vendor was bad. Not because the part was complicated. But because once that job left your facility, it entered a black hole — and nobody knew exactly where it was until it was overdue.

Outside processing is one of manufacturing's oldest unsolved problems. It's not a technology problem. It's a visibility problem. And it costs more than most shops realize.

What Is Outside Processing?

Outside processing (OSP) — sometimes called outside service or subcontracting — refers to any manufacturing step your shop sends to a third-party vendor rather than performing in-house. Common examples include:

• Heat treating — annealing, case hardening, stress relieving, nitriding
• Surface finishing — plating (chrome, nickel, zinc, hard chrome), anodizing, black oxide, powder coat, painting
• Non-destructive testing (NDT) — dye penetrant, magnetic particle, ultrasonic, X-ray
• Specialty machining — EDM, grinding, honing, lapping, waterjet
• Welding and fabrication — TIG, MIG, electron beam, laser welding by certified shops
• Coatings — Teflon, Parylene, ceramic, thermal spray

For most job shops, outside processing isn't a minor part of the workflow. It sits in the critical path of nearly every job with tight tolerances or military/aerospace specs. Heat treat before finish machining. Hard chrome before final grind. Anodize before assembly. The job doesn't move forward until the vendor sends it back.

How the Typical OSP Workflow Works

The standard process looks something like this: You cut a purchase order, pack the parts, call a pickup, and log the job as "at vendor" in your ERP or spreadsheet. The vendor picks up the parts. You enter a "promised date" based on what they told you over the phone.

Then you wait.

If everything goes right, the parts come back on time, you receive them, and the job moves on. If anything goes wrong — vendor backed up, parts missed a furnace run, wrong spec processed, remakes needed — you find out when the parts don't show up. Usually on or after the promised date. Usually when your production schedule is already counting on that job.

Why OSP Is Harder to Track Than In-House Work

In-house work is visible. You can walk the floor. You can pull up the machine queue. You can see if something is sitting at a workstation. With outside processing, none of that applies.

Vendors don't push status updates. OSP vendors are running high-volume, high-throughput operations. They're processing thousands of parts from dozens of customers simultaneously. They don't have systems that auto-notify you when your job goes in the furnace or comes out of the plating tank. You have to call and ask.

You're one of many customers. To your heat treat vendor, you're one job among hundreds that week. Your urgency doesn't affect their queue unless you communicate it — and even then, you're competing for priority with every other shop calling them on the same Friday afternoon.

Processing times are variable. Heat treat furnace runs depend on load, spec, and temperature cycle. Plating turn times vary by part geometry, rack density, and bath availability. NDT schedules depend on inspector availability and equipment queues. The "promised date" you got at the time of pickup reflects the vendor's best estimate under normal conditions — not a contractual guarantee.

Reruns and rejects cascade. If a lot fails inspection — wrong hardness, plating too thin, porosity found on NDT — it doesn't just delay that job. It delays every job downstream waiting for that part. And you often don't find out about the failure until the vendor calls you, which might be the day the parts were supposed to ship.

The "Friday Call" Problem

Ask any production manager how they track outside processing jobs and you'll hear a version of the same answer: "I call them every Friday." Sometimes it's Tuesday and Thursday. Sometimes it's a daily morning call during crunch weeks. But it's always manual, always reactive, and always dependent on the same person remembering to do it.

This creates a hard ceiling on how many OSP jobs you can actively manage. One person calling around can track maybe 15 to 20 active jobs with any real attention. Beyond that, things slip. The jobs that get called on are the ones that someone remembers to call on — usually the ones that are already overdue, or the ones for the customer who calls the most.

Meanwhile, the job that's 2 days from its due date with no check-in? Nobody knows it's about to miss until it does.

What It Actually Costs

The visible cost of late OSP jobs is the late delivery. But the invisible costs are bigger:

• Machine downtime — Finish machining can't start until heat treat returns. That CNC sits idle.
• Schedule compression — Every subsequent operation gets compressed as the job tries to make up lost time, increasing error rates and overtime.
• Expedite fees — Rush processing at the OSP vendor costs more. Rush freight to make a delivery costs more. These hit margin directly.
• Customer relationship damage — One late delivery is a conversation. Two late deliveries on the same account is a problem. Late deliveries that happen "because heat treat was late" don't land differently with the customer than any other miss.
• PM time — Every hour a PM spends on the phone tracking OSP jobs is an hour not spent on quoting, scheduling, or managing the next problem before it becomes a crisis.

What Good OSP Tracking Looks Like

The shops that manage outside processing well share a few common traits:

They communicate proactively, not reactively. Instead of calling on Friday when due dates are close, they send automated follow-ups at set intervals — typically at pickup confirmation, midpoint check-in, and 48 hours before the promised date. The vendor knows to expect the contact and responds more reliably because of it.

They escalate automatically. When a vendor doesn't respond to a check-in within a set window, the system flags it and escalates to a different contact or a higher-urgency message. This happens without a PM having to remember to follow up on the follow-up.

They log everything in one place. Instead of job status living in email threads, voicemails, and spreadsheet rows updated from memory, every vendor communication and status update is logged against the job. Anyone on the team can see where any job stands without asking the PM.

They connect it to their ERP. When a vendor confirms a return date, that date flows back into the production schedule automatically. No manual update, no data latency, no schedule based on information the system doesn't have. This is exactly the integration challenge we covered in The Missing Link: Closing the Loop Between ERP and Operational Reality.

None of this requires a massive system overhaul. The shops making this transition typically start by automating vendor follow-up — getting the communication layer right first — and build toward tighter ERP integration from there. The path off spreadsheets starts with one workflow at a time.