For manufacturers of custom machinery and custom equipment, the Factory Acceptance Test (FAT) is one of the most important milestones in the entire project lifecycle. It's the moment when your customer comes to your factory, tests the machine against the contract specification, and decides whether it's ready to ship.
Changes to the FAT date affect customer planning, installation arrangements and the project schedule. This guide covers what machine builders and assembly companies need to know about FAT and how to track parts delivery against the agreed dates.
What Is a Factory Acceptance Test?
A Factory Acceptance Test is a formal process conducted at the manufacturer's premises before a machine or system is shipped to the customer's site. During FAT, the equipment is tested against agreed specifications, design requirements, and functional criteria — typically in the presence of the customer's engineers and, in some industries, third-party inspectors.
FAT is used across a wide range of industries: industrial automation, food and beverage processing, pharmaceutical manufacturing, oil and gas, and any sector where custom-built equipment is supplied.
What Happens During a FAT?
A typical Factory Acceptance Test covers:
- Visual inspection — confirming the machine matches the design drawings, all components are fitted correctly, wiring is neat and labeled, and safety guards are in place
- Functional testing — running the machine through its operating sequences to confirm it performs as specified
- Safety testing — verifying emergency stops, safety interlocks, and guarding function correctly
- Performance testing — confirming the machine meets specified cycle times, throughput, accuracy, or other performance metrics
- Documentation review — checking that manuals, wiring diagrams, and certificates are complete and accurate
Any issues identified during FAT are typically classified as either "hold points" (must be resolved before shipping) or "punch list items" (minor issues that can be resolved on site). The goal is to resolve all hold points before the customer leaves.
FAT vs SAT: What's the Difference?
FAT (Factory Acceptance Test) takes place at the manufacturer's premises before shipping. SAT (Site Acceptance Test) takes place at the customer's facility after installation. Both are important, and FAT provides a controlled setting for checking the machine before shipment.
Why FAT Readiness Needs Delivery Tracking
A single late component can prevent assembly, delay commissioning, and push back the entire test date. Complex machines with many components and suppliers therefore need proactive delivery tracking.
A practical response is proactive delivery tracking: recording which parts are at risk of arriving late and assigning follow-up actions.
Identify Long Lead Time Items Early
At the start of each project, flag every component with a lead time greater than four weeks. These are critical path items that need an owner and a recorded status while the BOM is finalized.
Set Internal Required Dates, Not Just FAT Dates
If your FAT is on 1 June, you don't need all parts on 1 June — you need them 3–4 weeks earlier to allow for assembly and pre-commissioning. Set internal required dates for every component and manage to those dates, not to the FAT date itself.
Track Supplier Commit Dates vs Your Required Dates
For every open purchase order, compare the supplier's committed delivery date against your required date. Any line where the supplier commits later than your required date is a risk to record and escalate.
Chase Early, Not Late
By the time a part is overdue, your options may be limited — expedite shipping, find an alternative supplier, or delay the FAT. Contact suppliers one to two weeks before the expected delivery date, not on the day it was due, so there is time to discuss any issue.
Managing FAT Readiness Across Multiple Projects
If you're running multiple projects simultaneously — each with its own FAT date — keeping track of delivery risk across all of them is a real challenge. A project tracker that shows each project's FAT date, the number of days remaining, and the current delivery status of parts gives a workshop manager or project director a shared view of readiness.
Color-coded urgency (green for 30+ days, amber for 8–30 days, red for under 8 days) gives a visual summary of which projects need attention.
After FAT: Preparing for Dispatch
Once FAT is complete and signed off, the focus shifts to dispatch preparation: packing, transport arrangement, export documentation (if applicable), and site preparation. Any punch list items from FAT should be allocated to a named engineer with a clear resolution date.
Conclusion
FAT follows engineering, procurement, and assembly work. A documented parts-delivery process can track required dates from order placement through arrival on the shop floor.
AssembleFlow's Delivery Tracker is designed for this workflow: it tracks the customer order and FAT dates with a countdown, holds the order placed, delivery requested and supplier commitment dates for every assembly, and the project list shows managers which projects need attention. Start your free 14-day trial today.
Frequently Asked Questions
What is a factory acceptance test (FAT)?
A formal test at the manufacturer's premises, before shipping, that shows the machine meets the agreed specification. The customer usually witnesses it and signs it off.
What is the difference between FAT and SAT?
FAT takes place at the manufacturer before shipment. SAT, the site acceptance test, takes place at the customer's site after installation.
How do I prepare for a FAT?
Confirm every bought-in part has arrived, agree the test procedure and acceptance criteria in advance, and track the dates and open items with the team.
Free tools: the Excel templates (BOM, PO tracker, cost and quote worksheet), the margin calculator and a product tour need no sign-up.