The short answer: a quote-ready aerospace mounting strap drawing defines the retained item, approved material and temper, formed-state datums, hole relationships, contact-edge condition, finish, traceability and inspection evidence. A narrow blank with two bends is not fully specified until those installation controls are released.
The design authority must establish loads, fatigue requirements, installation clearances, material allowables and airworthiness approval. The fabricator’s job is to manufacture and inspect the released part without silently changing material, grain direction, bend condition or finish.
This guide helps engineering and procurement teams prepare an aerospace mounting strap RFQ that can be quoted consistently and inspected in the formed state.
Choose the page that matches your next task:
- For load-path inputs, drawing details and RFQ preparation, continue with this design guide.
- To request build-to-print straps, links or retention hardware, use the aerospace mounting straps manufacturing and RFQ page.
- To evaluate the broader aerospace fabrication scope, visit the aerospace sheet metal capability hub.
- Related customer project: Aerospace Mounting Straps: Hole Pattern and Safe Edges.
A strap drawing must describe the installed function without transferring design responsibility to the supplier. Identify critical interfaces, contact surfaces and inspection features; keep load substantiation and final aircraft approval with the responsible design authority.
Begin with the load path and retained item
Before setting thickness, define what the strap retains and how it is loaded. Relevant inputs may include static, vibration, inertia, thermal and installation loads; preload from the fastener stack; and movement of the harness or tube inside the strap.
Ask these questions:
- Is the strap a locator, a retainer or part of a structural load path?
- Does it clamp a rigid tube, flexible harness, insulation sleeve or equipment tab?
- Can the retained item move, expand or fret during service?
- What clearance is required to adjacent structure?
- Is the strap removed repeatedly during maintenance?
- Which surface may contact the retained item?
- What failure mode and inspection interval did the design authority assume?
Those answers belong in the design process, even when the supplier receives only the released manufacturing definition. DRAmetal’s aerospace mounting straps page covers strap-style parts specifically; aerospace sheet metal fabrication covers the wider component family.
Specify material, temper and grain direction
Alloy alone is incomplete. Temper, product form, thickness, specification revision and permitted substitutions affect forming and final properties.
| Drawing input | Why it matters for a strap |
|---|---|
| Alloy and temper | Controls strength, formability, corrosion behavior and springback |
| Sheet thickness and tolerance | Affects stiffness, bend development and fastener stack |
| Grain direction | Influences cracking risk and formed consistency |
| Minimum bend radius | Must suit the specified material and temper |
| Finish and masking | Affects dimensions, electrical bonding and corrosion protection |
| Material traceability | Ties the delivered part to the accepted material lot |
Do not allow an apparently equivalent aluminum or stainless grade unless the design authority has approved the substitution. The supplier should be able to preserve heat or lot identity through cutting, forming, finishing and packout when the purchase order requires it.
Design holes and bends as one feature system
Hole-to-hole, hole-to-bend and bend-to-edge relationships often control whether a strap installs cleanly. If a hole is placed too close to a bend, it may distort during forming. If the inspection datum is defined only on the flat blank, the delivered part can pass a laser inspection and still miss the installed interface after springback.
Good released drawings normally make clear:
- Which dimensions apply in the flat and which apply after forming.
- The inside bend radius and bend direction.
- The datum surfaces used to inspect installed geometry.
- Hole size, position, countersink or spotface requirements.
- Edge break or radius on contact surfaces.
- Burr direction restrictions.
- Finish buildup at holes and bonding points.
Springback should be controlled through material consistency, tooling, bend sequence and an approved inspection method. The supplier may compensate tooling to achieve the released shape, but it should not change the nominal design geometry without approval.
Choose the cutting and forming route from the drawing
Laser cutting is efficient for many prototype and low-volume strap blanks because it handles varied profiles without dedicated blanking tooling. Higher volume, edge requirements or program rules may justify punching, hard tooling, machining or another approved route.
The laser cutting service is therefore a manufacturing option, not a blanket statement that laser edges are acceptable for every aerospace program. The drawing or process specification must define permitted methods, heat-affected-edge restrictions, recast or oxide removal, edge finish and inspection.
After cutting:
- Preserve part identity and material lot.
- Remove burrs and tabs using the approved method.
- Protect contact edges from gouges and over-grinding.
- Form with tooling appropriate to the material and radius.
- Inspect the strap in the specified restrained or free state.
- Apply finish and verify masked or bonding areas.
A small strap can be damaged by uncontrolled bulk handling. Trays, separators or lot bags may be needed to protect formed shape and surface condition.
Inspect what controls installation
Inspection should follow the released definition rather than a generic checklist.
Useful first-article or lot controls may include:
- Material and temper record linked to the manufacturing lot.
- Thickness and flat-blank profile where required.
- Formed height, angle or offset from drawing datums.
- Hole pattern after forming.
- Visual and tactile edge-condition acceptance.
- Finish coverage, masking and cosmetic condition.
- Part identity, revision and lot-separated packout.
Calling a document “FAI” does not define its content. The purchase order should identify the required report format, characteristic ballooning, sampling, retention period and approval path. Likewise, special-process approvals and certification requirements must be stated before quotation.
DRAmetal holds AS9100D certification; certification details are available on request for supplier qualification. If Nadcap-approved special processes are required, identify the process, approved source and applicable records in the RFQ. Buyers should confirm the quality-system scope and every required special-process source against current, contract-specific evidence.
Control edge condition at harness and tube interfaces
An edge can meet a broad deburr note and still be unsuitable for contact with a harness sleeve or tube. The design authority should define the required separation, cushion, grommet or contact surface. The drawing should identify edges that need a controlled radius rather than an unspecified “break sharp edges.”
Avoid removing material so aggressively that the strap width, hole edge distance or protective finish is compromised. Edge treatment needs a measurable or at least reference-based acceptance rule that production and inspection teams understand the same way.
Keep responsibility and change control explicit
The aerospace OEM or tier design authority normally owns:
- Design loads, stress and fatigue substantiation.
- Material allowables and approved substitutions.
- Interface, clearance and retained-item requirements.
- Qualification, conformity and airworthiness approval.
- Approval of deviations and process changes.
The build-to-print supplier normally owns:
- Conformance to the released drawing and purchase order.
- Material, process and revision records included in scope.
- Tooling and manufacturing controls used to make the approved geometry.
- Inspection and packout defined by the control plan.
- Notification and disposition of nonconforming conditions.
Never accept a verbal substitution to material, temper, thickness, bend radius, cutting route, finish source or marking method. Route it through the customer’s approved deviation or change process.
Aerospace mounting strap RFQ checklist
Include:
- Controlled 3D model and 2D drawing revision.
- Part function and identified critical interfaces.
- Material specification, temper, thickness and grain direction.
- Permitted cutting and edge-finishing processes.
- Bend radii, formed-state datums and inspection condition.
- Hole, countersink, fastener and finish-build requirements.
- Contact-edge and cosmetic acceptance rules.
- Material, finish and inspection record requirements.
- Part marking, serialization or lot-identification rules.
- Prototype, first-article, pilot and production quantities.
- Packaging, lot separation and shelf-life controls where applicable.
- Required supplier or special-process qualifications.
Related customer project: Aerospace Mounting Straps: Hole Pattern and Safe Edges. Related resources: aerospace industry capability page.
When comparing suppliers, evaluate the assumptions behind the quote: material certification, deburring, forming fixtures, finish source, inspection records and protected packout can be more important than blank-cutting price. For a build-to-print review, send the released strap drawings and contract requirements.
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