What Drives Aerospace Lead Time and How to Shorten It
On most aerospace parts, cutting time is a small share of lead time. Material availability, special process queues, first article inspection and paperwork set the delivery date, and defense rated orders under DPAS change the queue order at every tier.
Where the time actually goes
A typical machined aerospace part spends most of its lead time waiting: for material, for an outside process, for inspection or for a document. Mapping those waits is the fastest way to find days.
| Stage | What happens | What stretches it |
|---|---|---|
| Quote and order | Review of drawing, requirements and flow downs | Unclear requirements, missing model, questions sitting unanswered |
| Material | Buy certified stock to the specification | Uncommon alloy, size or temper; specialty metals restrictions; mill lead times |
| Programming and fixturing | CAM, fixture design and build | Complex 5-axis work, new fixtures |
| Machining | Setups and cycle time | Machine availability; scrap and rework |
| Special processes | Heat treat, finishing, NDT, cleaning | Supplier queues, approved source restrictions, batching |
| Inspection and FAI | CMM, AS9102 report | Large characteristic counts, nonconformances |
| Packaging and shipping | Pack, document, ship | Special packaging, export filing, hazmat |
The logistics hub covers the stages after the part leaves the shop.
Material availability
Material is often the longest single wait. Common alloys in common sizes are usually on the shelf at service centers; uncommon combinations of alloy, temper, form and size may need a mill run with a long, unpredictable lead time.
- Allow alternate sizes or forms where function permits, such as bar instead of plate, or a larger standard size.
- List acceptable equivalent specifications if your design authority allows them.
- Know whether DFARS specialty metals rules apply, because they restrict source and can rule out stock on the shelf; see material certs and traceability.
- Consider furnishing material for long lead or controlled alloys, or ordering it ahead of the part order.
Special processes and outside processing
Heat treatment, anodize, plating, passivation, NDT and precision cleaning are often done by outside suppliers, and many primes require those suppliers to be approved, sometimes Nadcap accredited. That narrows the field and creates queues.
Each outside process adds transport both ways, a queue at the processor and its own certification paperwork. A part that goes out for heat treat, comes back for finish machining, then goes out for anodize and NDT can spend more time in transit and queues than on machines. Ask suppliers to show the routing, then look for ways to batch or combine steps. Process detail is in heat treatment and surface finishing.
First article inspection
AS9102 first article inspection verifies that the production process can make a part that meets every design characteristic. A full FAI covers every characteristic on the drawing, specifications and purchase order, which on a complex part can mean hundreds of balloons.
Plan for it. FAI is generally triggered by a new part, a design change, a change in manufacturing process, location or source of material or process, and a lapse in production of more than two years; check your customer's requirements for the exact triggers. Revision C of AS9102 made the reason for full or partial FAI a mandatory field on Form 1. Submit FAIs promptly and answer customer questions fast, because a part can sit finished while its FAI waits for review.
DPAS rated orders: DO and DX
The Defense Priorities and Allocations System, 15 CFR Part 700, lets defense programs place rated orders that suppliers must prioritize over unrated work. It is the only formal mechanism that changes a supplier's queue order by law.
| Rule | DO rated | DX rated |
|---|---|---|
| Precedence (700.11) | Equal with other DO orders; ahead of unrated orders | Equal with other DX orders; ahead of DO and unrated orders |
| Accept or reject within (700.13(d)) | 15 working days after receipt | 10 working days after receipt |
| Rejection | Reasons given in writing or electronically | Same; scheduling conflicts with previously accepted lower rated or unrated orders are not sufficient reason to reject either rating |
A rated order must contain the rating with its program symbol (for example DO-A1), a specific required delivery date or dates, the signature of an authorized official, and a statement that it is a rated order certified for national defense use and that the recipient must follow the DPAS regulation (700.12). Words like "immediately" are not a delivery date. A supplier must not accept a rated order it cannot fill by the required date, and must tell the customer the earliest date it can deliver (700.13(b)).
Ratings flow down. Under 700.15, a supplier must use rated orders with its own suppliers to obtain what it needs to fill a rated order, carrying the same rating through the whole supply chain. If your order is rated, say so clearly on every purchase order, and expect your suppliers to do the same with material and process vendors.
Expedite options and their tradeoffs
| Option | Saves time by | Tradeoff |
|---|---|---|
| Expedite fee for overtime | Running extra shifts | Cost; fatigue risk on complex work |
| Split lot | Shipping a partial quantity early | More FAI and shipping overhead; second lot later |
| Furnished or pre-bought material | Removing the material wait | Buyer carries material risk and certification |
| Alternate approved processor | Avoiding a queue | Must be approved; may trigger FAI |
| Accept partial FAI or delta FAI | Reducing inspection scope where allowed | Only valid where the standard and customer allow |
| Premium freight | Shortening transit | Cost; handling risk on sensitive items |
| Engineering relief | Loosening a tolerance or allowing an alternate material | Requires design authority approval |
The cheapest expedite is a clean, complete RFQ package. Missing models, ambiguous notes and unanswered questions cost more days than most fees save.
What to expect at each stage
- Order acceptance. Supplier confirms requirements, delivery date and any exceptions. For rated orders, within the DPAS response window.
- Material in. Certs reviewed against the specification on receipt.
- First piece. First part inspected before the run continues.
- Outside processing. Parts out and back with certs for each process.
- Final inspection and FAI. Report prepared and reviewed.
- Ship. Cert pack assembled, packaging per the order, notice sent.
Ask for status at each of these milestones rather than a single promise date. Slips show up early at material and outside processing.
How to read a quoted lead time
A quoted lead time is only useful if you know what it includes and when the clock starts. Ask four questions.
- From when? Order receipt, receipt of approved model and drawing, or receipt of furnished material. A supplier waiting on answers to questions has not started.
- To where? Ship date from the supplier's dock or delivery at your dock. Transit and export filing can add days.
- Including what? Material purchase, every outside process, FAI preparation and any source inspection you require.
- What is the long pole? A good supplier will tell you which step drives the date, usually material or a special process, and that is where to apply effort.
Treat a lead time that does not distinguish these as an estimate. Compare suppliers only on the same basis.
Get a realistic lead time
When you request a quote, include material specification, special processes, FAI requirement, any DPAS rating and your required date. We match the job to qualified suppliers, flow down the requirements including ratings, track the job and check the paperwork before delivery. A person replies within 1 business day.
Questions
How fast must a supplier respond to a DPAS rated order?
Under 15 CFR 700.13(d), within 15 working days after receipt for a DO rated order and 10 working days for a DX rated order. A rejection must state reasons in writing or electronically. If the supplier cannot meet the required delivery date, it must not accept the order as written and must tell the customer the earliest date it can deliver.
Can a supplier refuse a rated order because it is busy?
Not for that reason alone. 15 CFR 700.13 says scheduling conflicts with previously accepted lower rated or unrated orders are not sufficient reason to reject. Rejection is required in some cases, such as when the date cannot be met or the order would interfere with previously accepted DX orders, and optional in others, such as when the item is not something the supplier makes.
Does a DPAS rating flow to my supplier's material vendors?
Yes. Under 15 CFR 700.15, anyone filling a rated order must use rated orders with its suppliers to obtain the items needed, carrying the same rating down the supply chain. Make the rating, program symbol, delivery date and DPAS statement explicit on every order so each tier can place properly rated orders with its own vendors.
When is a new first article inspection required?
Commonly cited triggers include a new part, a design change, a change in manufacturing process, location or material source, and a production lapse of more than two years. AS9102 Revision C requires the reason for a full or partial FAI to be stated on Form 1. Your customer's requirements may add triggers, so read their quality clauses as well as the standard.
What is the most effective way to shorten lead time?
Remove waits rather than speeding machines. Send a complete package, allow alternate stock sizes or approved equivalents, buy long lead material early, combine or batch outside processes, and answer supplier and FAI questions the same day. Paid expedites help on overtime and freight but cannot shorten a mill run or another company's heat treat queue.
Related
Sources
- 15 CFR 700.11, Priority ratings (DO and DX)
- 15 CFR 700.12, Elements of a rated order
- 15 CFR 700.13, Acceptance and rejection of rated orders
- 15 CFR 700.15, Extension of priority ratings
- Net-Inspect, AS9102 Rev B vs Rev C first article inspection changes
- Textron Systems, supplier first article inspection requirements QASP52 Rev C (PDF)
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