The short answer
On SLM structural RFQs, **lattice / infill notes** are not cosmetic preferences. They change powder removal, support strategy, stiffness, and whether CNC skim faces remain machinable. Silence on **cell type, relative density, and keep-outs** is what widens many [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** / powder estimate bands—not the outer envelope alone.
This guide is for buyers packaging Ti-6Al-4V SLM parts where CAD shows a lattice but the PDF only says “lightweight OK.” Illustrations use an **Example part** only—not a flight bracket. Related notes: [SLM vs CNC hybrid part strategies](https://3dwk.com/resources/slm-vs-cnc-hybrid-part-strategies), [powder reuse notes for SLM buyers](https://3dwk.com/resources/powder-reuse-notes-slm-buyers); here we focus on **lattice/infill labeling** so estimators do not guess.
What lattice notes mean for quoting
Open lattices need powder evacuation paths; closed or trapped cells force manual review. Relative density and unit-cell size drive build time and risk. Process pages for aerospace titanium ([SLM Ti-6Al-4V aerospace](https://3dwk.com/en/slm/ti-6al-4v/aerospace.html), [SLM Ti-6Al-4V](https://3dwk.com/en/slm/ti-6al-4v.html), [CNC 3-axis Ti-6Al-4V aerospace](https://3dwk.com/en/cnc-3axis/ti-6al-4v/aerospace.html)) assume hybrid skim faces when lattices meet datum pads.
Do not bury “gyroid / lattice OK” in a notes cloud. Put **LATTICE: [type] / TARGET REL DENSITY ~X% / NO LATTICE WITHIN Z mm OF DATUM PADS** on the PDF and RFQ text. Background: [DFM checklist before an online CNC quote](https://3dwk.com/resources/dfm-checklist-before-online-cnc-quote), [what files to send for a CNC quote](https://3dwk.com/resources/what-files-to-send-for-cnc-quote).
Build orientation and distortion risk
Orientation that favors lattice growth can fight datum-pad flatness after release from the plate. Say which face sits on the build plate and whether critical pads are solid enough to skim flat. Distortion allowances belong in the RFQ as stock-to-leave numbers, not as silent hope. Hybrid CNC pages for titanium aerospace remain relevant when pads must meet GD&T after print—link the skim faces explicitly rather than assuming the lattice core “will be fine.”
If heat treat or HIP follows, note whether lattice exits stay open through that step so powder and media do not trap. Estimators reading a silent orientation note often widen the **rates.v1.1** / powder band or flag **needs_manual**.
Powder removal, supports and skim stock
Name powder-exit holes and whether they remain open after HIP/heat treat. Support keep-outs on lattice skins matter as much as on solid walls. If CNC skim follows, leave solid stock on pads and bores—see hybrid guidance in [SLM vs CNC hybrid part strategies](https://3dwk.com/resources/slm-vs-cnc-hybrid-part-strategies). Silent “print light then machine” without skim map often routes to **needs_manual**.
Powder and machine-time planning under **rates.v1.1** / powder tables moves with solid volume fraction; a vague “max lightweight” note is not a density.
Documentation pack for lattice RFQs
Attach: (1) solid+lattice STEP or clear B-rep notes, (2) PDF with density/type/exits, (3) skim-face list, (4) powder-handling notes if reuse constraints exist. Buyers who send only a mesh screenshot leave estimators guessing cell size and trapped volumes. Cross-check hybrid skim language against [SLM vs CNC hybrid part strategies](https://3dwk.com/resources/slm-vs-cnc-hybrid-part-strategies) so pads and bores are not lost inside the lattice body.
Structural intent vs cosmetic shells
If the lattice carries load, say load direction and whether skin thickness is structural. Cosmetic weight-reduction lattices still need evacuation and inspection access. Do not invent allowables—state the design intent only.
Tolerance and inspection traps
GD&T on lattice nodes is rarely meaningful; put positional and profile controls on solid datum pads and machined bores. Default as-built skins to agreed visual criteria; put Ra only on skimmed faces—see [surface roughness Ra callouts that raise quotes](https://3dwk.com/resources/surface-roughness-ra-callouts-that-raise-quotes) and [GD&T callouts that raise CNC quote bands](https://3dwk.com/resources/gdandt-callouts-that-raise-cnc-quote-bands).
Illustration 1 shows an **Example part** with labeled lattice core, solid skim pads, and powder-exit keep-outs.
Example part walkthrough
**Example part:** Ti-6Al-4V near-net bracket envelope ~120×80×40 mm, internal lattice core, four solid datum pads, one bore with skim stock. With STEP + **LATTICE OPEN GYROID TARGET ~25% REL DENSITY; SOLID SKIN ≥1.5 mm; NO LATTICE WITHIN 5 mm OF PADS; POWDER EXIT Ø3 MIN; CNC SKIM PADS+BORE**, expect a clearer hybrid planning path on [quote-new.php](https://3dwk.com/quote-new.php). Same geometry with “add lattice for weight” and no exits often lands **needs_manual**—without inventing any flight cert or customer PO.
Illustration 2 contrasts a vague lightweight RFQ versus a labeled lattice/skim/powder pack and the clearer estimate path.
What widens bands fastest
Trapped cells, missing powder exits, lattice through datum pads, and “as-built all over” when seals need skim. Quantity breaks help unit minutes but do not erase powder-risk packaging—see [what needs_manual means](https://3dwk.com/resources/what-needs-manual-means-preliminary-quote) and [powder reuse notes for SLM buyers](https://3dwk.com/resources/powder-reuse-notes-slm-buyers).
What to do next
Name lattice type/density, powder exits, and CNC skim keep-outs, then upload on [quote-new.php](https://3dwk.com/quote-new.php). Service pages: [CNC machining](https://3dwk.com/cnc-machining-service.php), [materials](https://3dwk.com/materials.php). Treat **rates.v1.1** / powder figures as estimates, not invoices or allowables.
Common questions
Is a finer lattice always better?
No. Finer cells can trap powder and raise risk under estimate packaging. Open, evacuable cells with named density are clearer.
Can I leave lattice selection to the vendor?
Only if you state functional limits (stiffness intent, keep-outs, exits). Blind “vendor optimize” widens bands.
Do HIP notes replace lattice callouts?
No. HIP and heat-treat sequence are separate—still name lattice geometry and exits.
Should every face be skimmed?
Usually no. Skim functional pads/bores; leave as-built skins where agreed—see hybrid guide linked above.