Briefing Engineering Before RFQs

RFQs fail more often from missing engineering context than from price. When procurement asks for quotes without a shared understanding of what “good” looks like, suppliers either (1) pad risk and cost, or (2) assume the wrong requirements and deliver parts that miss intent. In regulated programs (ITAR, DFARS, AS9100) the cost of rework is not just dollars—it's schedule, compliance exposure, and credibility with your customer.

This internal-playbook article is a request for quote checklist for briefing your engineering team before the RFQ goes out—especially when the process chain includes additive manufacturing (AM) such as powder bed fusion (PBF) / DMLS / SLM, densification via Hot Isostatic Pressing (HIP) or PM-HIP, and precision post-processing like 5-axis CNC machining, NDE, and CT scanning. The goal is simple: align engineering, quality, and sourcing so suppliers can quote the right scope with the right risk posture.

Define CTQs

Start by forcing clarity on CTQs (Critical-to-Quality characteristics). CTQs are the features that drive performance, fit, safety, certification, or downstream assembly yield. If you can’t clearly name them, suppliers will guess, and guessing is expensive.

Step 1: Identify functional CTQs. For each interface, load path, sealing surface, or thermal contact, document what the feature does and what failure looks like. Examples: bearing bores that control runout, turbine-like airfoils where chord thickness affects efficiency, or valve seats where surface finish drives leakage.

Step 2: Separate “must-have” CTQs from “nice-to-have.” Engineers often carry legacy tolerances forward. For AM parts that will be HIPed and machined, you can frequently relax as-printed requirements and shift CTQs to machined datums. The RFQ should distinguish “CTQ: must meet” from “engineering preference.”

Step 3: Establish ownership and measurement method. Each CTQ should include who verifies it (supplier, your receiving inspection, or a third-party lab) and how (CMM, optical, profilometry, CT scanning, functional gage). A CTQ without a verification method is a dispute waiting to happen.

Step 4: Tie CTQs to the process chain. AM + HIP + machining workflows move CTQ control around. For example, internal features may be best verified via CT scanning prior to HIP (to catch gross build defects) and then again after HIP (to confirm densification and geometry stability), while external interfaces are controlled by post-HIP CNC machining.

Deliverable for the RFQ package: a one-page CTQ table listing feature, intent, nominal, tolerance, datum scheme, inspection method, and acceptance criteria. This single page often reduces supplier Q&A by 50% or more.

Set tolerance and finish goals

Before requesting quotes, align engineering on what tolerances and surface finishes are required and where. Over-tolerancing is a top driver of cost and lead time, especially when mixing as-printed AM geometry with machined interfaces.

Step 1: Decide which surfaces are “as-built” vs. “finish machined.” For PBF (DMLS/SLM), as-built surfaces typically have higher roughness and may include support artifacts. If a surface matters for fatigue, sealing, electrical contact, or flow, assume it will need machining, abrasive flow finishing, polishing, or other controlled post-processing. Call this out explicitly in the RFQ scope.

Step 2: Define realistic tolerance zones for each manufacturing stage. Treat the part like a routed traveler:

1) As-printed geometry: define allowable stock, distortion allowances, and “do not machine” regions.

2) After stress relief / HIP: expect dimensional shift. Engineering should specify machining stock and where datums will be established post-HIP.

3) After CNC machining: apply tight tolerances only where function requires. If you need true position, flatness, or cylindricity, ensure the datum scheme is stable and machinable.

Step 3: Communicate finish requirements in measurable terms. Surface finish should be specified with a target (e.g., Ra) and where it applies. If your design is fatigue-sensitive, align on whether the fatigue driver is roughness, subsurface porosity (addressed by HIP), or tensile residual stress (addressed by heat treat/stress relief and machining strategy). Don’t ask suppliers to “make it smooth”—ask for a measurable finish on defined faces.

Step 4: Call out edge conditions and burr requirements. In defense and aerospace assemblies, uncontrolled burrs drive FOD risk and assembly damage. If you need break edges to a specified radius/chamfer, include it. If sharp edges are acceptable, say so. This is low-effort clarity that prevents expensive “interpretation.”

Deliverable for the RFQ package: a marked-up drawing or model notes identifying as-built zones, machining zones, required Ra values, and any special geometric tolerances tied to datums.

Material and cert requirements

Material definition is where RFQs most commonly get derailed. “Ti-64” or “Inconel” is not enough—especially for AM and PM-HIP. Engineering needs to brief procurement on the exact material standard, allowable suppliers, and the certification pack required at delivery.

Step 1: Specify the material as a procurement requirement, not a nickname. Include the alloy, form, and standard that matches your application. For AM, that often means specifying powder chemistry limits, particle size distribution expectations, and whether virgin/reused powder is allowed. If you have internal powder reuse rules (e.g., max blend ratio or max reuse cycles), align on those before the RFQ.

Step 2: Decide whether HIP or PM-HIP is required and why. For PBF parts, HIP is commonly used to reduce internal porosity and improve fatigue performance. PM-HIP routes (powder consolidated directly via HIP into near-net shapes) may be relevant for larger billets or where AM isn’t the right fit. Engineering should define:

• Is HIP mandatory or optional with a cost adder?

• Target density/acceptance criteria (e.g., “fully dense” is not an inspection criterion by itself; tie to NDE/CT or metallography expectations).

• Heat treatment requirements before/after HIP, including any solution/age cycles.

Step 3: Define material traceability and documentation. If the program has DFARS specialty metals requirements, flow that down. If the work is ITAR-controlled, specify handling and data controls. At a minimum, align on:

• Heat/lot traceability for powder, HIP can, and any bar/plate used for machining fixtures or weldments.

• Certificates of Conformance (CoC) and material test reports (MTRs) required in the cert pack.

• Whether the supplier must be AS9100 certified (common for aerospace) and whether NADCAP special process approvals are required for heat treat, NDE, chemical processing, or coatings.

Step 4: Clarify allowed substitutions and equivalency rules. Procurement will inevitably ask if “equivalent alloy” is acceptable. Engineering should pre-decide what equivalency means: same spec revision, alternate spec, or no substitutions. If alternates are allowed, require supplier to propose them at quote time, not after PO award.

Deliverable for the RFQ package: a material/cert requirement sheet listing alloy/spec, powder controls, HIP/heat treat requirements, traceability needs, and the exact contents of the certification package at ship.

Inspection approach

Inspection is not a checkbox; it is a process plan. If you don’t brief engineering and quality on inspection strategy, you will get quotes that omit key steps (and then you’ll pay later), or quotes that assume worst-case inspection on every feature (and you’ll pay now).

Step 1: Define the inspection stages across the route. For an AM + HIP + machining flow, a practical inspection plan often looks like:

1) Incoming material verification: powder CoA review, lot traceability capture, and any incoming verification you require.

2) In-process AM inspection: build record review, machine logs as applicable, visual checks, and support removal verification. If you require build parameter control or a frozen parameter set, state it.

3) Pre-HIP NDE (optional, but common): CT scanning or other NDE to detect gross lack-of-fusion, trapped powder in internal passages, or geometric nonconformities that would become unfixable later.

4) Post-HIP inspection: density-related verification via CT scanning (where feasible), coupon testing, or metallography per your program plan.

5) Post-machining dimensional inspection: CMM for GD&T features, plus gaging for production-critical bores or patterns.

6) Final inspection and documentation: FAI per AS9102 if required, plus cert pack and final CoC.

Step 2: Decide where CT scanning is required versus “nice to have.” CT scanning is powerful for internal geometries and porosity mapping, but it is not universally required. Engineering should decide whether CT is needed for:

• Internal channels (cooling passages, manifolds)

• Thin-wall regions

• Porosity acceptance (qualitative vs quantitative)

• First article only vs every lot

Step 3: Define acceptance criteria for NDE and dimensional results. If you require penetrant inspection (PT), radiography, ultrasonic, or CT, specify the standard and acceptance class/level appropriate to the part. If you require CMM reports, specify whether you need full data output or “pass/fail” summaries. Align internal stakeholders on what happens when a single feature is out-of-tolerance: rework allowed, repair allowed, or scrap.

Step 4: Flow down regulated workflow requirements. For defense/aerospace programs, spell out any requirements for controlled calibration systems, inspection record retention, serialization, and configuration control. If your supplier must be AS9100, say so in the RFQ. If you need NADCAP-accredited NDE or heat treat, specify which processes. This prevents late-stage “we assumed commercial inspection” surprises.

Deliverable for the RFQ package: an inspection expectations page listing required methods (CMM, CT scanning, NDE), required standards, FAI expectations (AS9102), and report deliverables.

Lead time constraints

Lead time is a technical requirement. If your schedule demands are aggressive, engineering needs to help procurement identify what can be parallelized and what cannot—especially when HIP, heat treat, and 5-axis machining capacity are bottlenecks.

Step 1: Separate “need date” from “quote assumptions.” Provide suppliers a target ship date and ask them to state assumptions: material availability, powder lead time, HIP queue time, machining fixtures, inspection capacity, and certification pack turnaround.

Step 2: Identify long-lead process steps early. Common long-lead items for AM programs include:

• Powder procurement for specialized alloys or DFARS-compliant sources

• HIP cycle scheduling (internal vs outsourced)

• NADCAP special processes (heat treat, NDE, chemical processing)

• CT scanning capacity (especially high-resolution scans)

• FAI creation and review (AS9102 packages can take time)

Step 3: Decide what is acceptable to expedite. Engineering should pre-approve expediting options such as:

• Build priority and weekend shifts

• Parallel machining fixture development during printing/HIP

• Partial shipment (ship machined critical components first)

• First-article-only CT scanning, followed by reduced inspection for repeats (if allowed)

Step 4: Clarify revision stability and change-control expectations. A volatile model/drawing destroys lead time. If design changes are likely, say so and request alternate pricing: “Quote Rev A, plus delta pricing for Rev B changes.” This turns schedule chaos into managed scope.

Deliverable for the RFQ package: a schedule note identifying required ship date, acceptable expediting levers, and assumptions suppliers must disclose in their quote.

Supplier questions

Finally, agree internally on the questions you want suppliers to answer in the quote. These questions are your early-warning system for risk, compliance gaps, and unrealistic pricing.

1) Process chain and responsibility. Ask the supplier to list every step they will perform and who performs it (in-house vs subcontract): AM (PBF/DMLS/SLM), stress relief, HIP, heat treat, CNC machining (including 5-axis), surface finishing, coatings, and NDE. Require them to identify subcontractors and provide their certifications as applicable.

2) Machine, build strategy, and support approach. Without asking for proprietary build files, you can ask what machine class they’ll use, how they will orient the part, how supports will be placed/removed, and what “do not touch” surfaces require protection. This catches geometry that is technically printable but impractical at your tolerance/finish requirements.

3) HIP and heat treat details. Ask for the HIP cycle standard they follow (time/temperature/pressure ranges) and whether HIP is in-house or outsourced. If properties are critical, ask how they validate (test coupons, witness samples, tensile/fatigue data where required by your spec).

4) Dimensional control plan. Ask which datums they will establish post-HIP, how they will hold the part during machining, and how they will verify CTQs (CMM strategy, gage plan). If the part requires tight true position, ask how they will control stack-up across operations.

5) NDE/CT scanning plan and acceptance. If you require CT scanning, ask what resolution/voxel size they will use, what regions will be evaluated, and what the output report includes. If you require PT/UT/radiography, ask whether it is NADCAP-accredited and what acceptance criteria standard they will apply.

6) Quality system and compliance. Require the supplier to confirm AS9100 status (or equivalent), calibration controls, record retention, and flowdown handling. For ITAR-controlled work, ask how they segregate and control technical data access. For DFARS, ask how they ensure specialty metals compliance and traceability.

7) Quote structure and risk items. Ask for separate line items for: printing/build, HIP, machining, inspection/FAI, CT scanning/NDE, and certification pack. This makes it easier to compare suppliers and to negotiate scope without losing compliance.

8) What they need from you. A mature supplier will ask for missing details. Invite that: “List any ambiguities, missing requirements, or design risks that impact cost, yield, or lead time.” Their answers are often as valuable as the quote itself.

Deliverable for the RFQ package: a standardized supplier questionnaire embedded in the RFQ (or attached) so every bidder answers the same technical and compliance questions.

Bottom line: The best RFQs read like a mini build plan: CTQs, tolerance/finish intent, material and cert flowdown, inspection method, schedule constraints, and supplier disclosures. Brief engineering first, and procurement will get quotes that are comparable, defensible, and aligned to how defense and aerospace parts are actually built.