Shrink, Cavity OD, and Gram Bands: What We Can Lock vs What Your Pour Owns

CNC-style tolerances on a flexible tray and a sticky fill are how gram fights start. If you're locking size, this service splits what CAD can own from what the dump owns. Platinum RTV linear shrink is typically about 0.1-0.3% - we compensate in the master when you send a solid. Piece weight still lives in fill, viscosity, depositor pitch, and tray sag (~0.5-1.5 mm unsupported; outer-row gummies often 3-6% heavy). ISO 3302-1 on a drawing is a rubber tolerance class, not the word "precision."

Custom/simple 3D is USD $50 when that scope applies. Prototype 3-7 days after CAD lock, weighed in the real dump. MOQ 20 per design. Pair with multi-cavity and prototype validation. Catalog: process catalog. HCR ~1.5-2.5% / LSR ~2-3% shrink an HTV product RFQ here. part tools - don't paste those onto this master.

What we can lock vs what you own

CTQ	Who owns it	Measurement condition
Cavity OD / map in CAD	Shop, after platinum shrink	Relaxed / jacketed - say which
Logo depth mm	Shop, on the master	Unsanded pattern
Piece grams	Your dump + tray flatness	Loaded tray, named cavities
ISO 3302-1 class	Drawing class if you put it on the 2D	Not a slogan

A tolerance without a measurement method is incomplete. Soft silicone changes under caliper force.

Common mix-up: millimetres locked, grams called "precision"

Locking CAD mm does not freeze 4.0 g pectin. Jacket and fill do.

Typical shop values

Reference values only. Confirm material-specific limits against the supplier’s technical data and agree project acceptance criteria before production.

Item	Typical shop value
Platinum shrink	About 0.1-0.3% linear
HCR / LSR (contrast only)	~1.5-2.5% / ~2-3% - wrong object here
Loaded-tray edge sag	About 0.5-1.5 mm unsupported
Outer-row vs center	Often 3-6% heavy if sagging
Prototype / MOQ	3-7 days after lock; 20 pcs/design
Custom/simple 3D	USD $50 when that scope applies

Failure: ISO 3302-1 M2 pasted on a gummy tray, cavity 11 heavy

Symptom: Buyer rejects grams; OD was in; jacket omitted on production.

Confirm: Measurement condition? Dump process vs golden sample? Shrink family on CAD (platinum, not LSR)?

Fix: Jacket. Re-weigh named cavities. Don't tighten OD to fix fill.

Worked example: 4.0 g bear, 12-up, depositor

CAD compensated ~0.1-0.3% platinum. Prototype on the depositor, center 4.0 g, edge sag ~1 mm would have pushed 3-6% - jacket stayed. ISO class on the 2D was not used as a grams slogan. MOQ 20 after the note. 3D $50 for the map.

What to ask when you're locking shrink and grams

Which shrink family is in CAD?
OD measured relaxed or in jacket?
Gram band and which cavities?
Jacket in the production price?
Don't copy LSR shrink onto this master?

When this service is the wrong metrology

Rigid plastic drawing on a 10A skin without a method. Part FAI on LSR: an HTV product or mold RFQ here, or ask us if you need a high-volume LSR cold-runner tool. Tiny stamp with no grams CTQ. Geometry can override: a cored vessel cares wall mm more than tray sag.

Related: QC sign-off, contact.

RFQ: OD vs grams

Copy this.

Target OD mm and/or grams: ISO 3302-1 class if any (class, not "precision"): Measure: relaxed / jacketed / loaded Dump + peak °C Jacket: yes/shop to mark 3D at $50 in scope? Prototype 3-7 days after lock, MOQ 20

Send grams and measurement condition. contact - [email protected] · +86 135 3006 2969. Ask us not to call grams "precision."

We would not recommend LSR shrink on an RTV master. We would not recommend skipping jacket to hold grams. We would not recommend ISO 3302-1 as a marketing word.

RUUIPON Mold Structure Decision:

Loaded tray? - yes -> Jacket + prototype loaded
Loaded tray? - no -> CAD + platinum shrink
Jacket + prototype loaded -> Weigh named cavities
CAD + platinum shrink -> Weigh named cavities
Weigh named cavities -> MOQ 20

FAQ

Which shrink do I put on CAD? Platinum RTV ~0.1-0.3% here.

Can you guarantee grams from STEP only? No. Dump owns grams.

What is ISO 3302-1? A rubber drawing class. Not "precision."

Will a tighter OD fix outer-row heavies? No. That's sag.

MOQ? 20 per design.