How Long a Custom RTV Silicone Mold Actually Takes

If you're buying a custom RTV silicone mold, production time starts when the master is freeze-ready, not when the first email lands. A shop can quote days to a couple of weeks for a poured platinum cavity around a finished master, box, keys, and jacket. A steel LSR tool with a cold-runner, or an HCR compression plate, sits on a different calendar for a molded silicone *part*. Those numbers aren't interchangeable, and neither one includes an open-ended sampling loop if you keep changing the lip.

This article is how to read an RTV timeline. It doesn't publish a fake industry average. Anyone who stamps "all custom silicone molds in 7 days" is describing a subset they won't write down.

The clock starts when the file is freeze-ready

Before freeze, elapsed time is design: DFM, shrink policy, parting, platinum versus tin, and who keeps the master. That work is real. It isn't mold production. If you count it as mold production, every supplier looks late.

Freeze-ready means:

• Process named: platinum or tin RTV (not "silicone," not a silent LSR substitution).
• STEP plus 2D with the dimensions that matter, or a physical sample that will be the master.
• Shrink: shop compensates, or CAD already compensated. One owner. Platinum RTV after a full cure is a small band; don't paste an LSR heat-cure factor onto the master.
• Texture, logo, and dump material as notes, not as later surprises.
• Quantity band for first witness and monthly dumps or pours.

A WeChat pack of photos isn't freeze-ready. A render isn't freeze-ready. A "final except the logo" file isn't frozen.

China-origin calendars include Chinese public holidays and the week the pattern shop actually has a spindle for the master. Ask for a date tied to freeze plus a witness-dump gate, not a date tied to deposit. Deposit before freeze just starts an argument.

Poured tools and metal-cut tools don't share a calendar

RTV mold-making (this site). Once the master is finished and the jacket is built, pour and cure follow the grade: mix A/B, vacuum degas, pour a thin stream, cure, pull, fit the jacket, witness dump. Master finishing is the sleeper. Print lines, inhibition on some SLA resins, and a master that doesn't match the CAD will eat more days than the silicone drum. Multi-piece molds add jacket and key days. This path can be the shortest path to a cavity you pour into. It isn't the path to an LSR production tool.

HCR compression tools. CAM, plate, mill, flash land, polish or blast. That's a molded *part* calendar. Aluminum two-plate is usually the shorter metal path. First article still needs a mill room. Different RFQ — a WYD-style parts quote, not this pour.

LSR LIM tools. Cavity steel or aluminum, heaters, shut-offs, vents, often a cold-runner. This is the long custom-mold calendar in most *part* programs because the hardware is more than a pocket. Prototype aluminum LSR tools exist and can be faster. They're still injection tools. They still need a machine slot for sampling. Different RFQ.

Don't average these three and call it "mold production lead time." Put the process on the Gantt or you're lying to yourself.

Sampling isn't a few extra days

First article on an RTV job is a witness dump: measure pocket fill-weight or a named dimension, look at peel and registration, decide recast, master refinish, or release. That gate has its own queue: dump compound, cure of the *casting*, measure, and shipping of samples if the buyer is overseas.

A single clean gate can be short. A loop that changes CAD after the master is finished is a new pattern job. A loop that only changes dump temperature or jacket clamp is process, and should be faster than a recast. Buyers who treat every cosmetic dislike as a recast turn a two-week pour into a quarter.

Air freight of samples isn't mold production, but it sits on the same calendar the VP watches. Plan it. So does destination-market testing (FDA 21 CFR 177.2600, LFGB) if you attached it to "tool done." Lab queues aren't pour queues.

What actually stretches a promised date

Open CAD. Missing shrink ownership. Compound not ordered because "any 20A is fine." Masters that inhibit platinum. Logo artwork in a bitmap that can't be cut into the master. Payment or material holds. Holiday shutdowns. A witness dump you keep rewriting because the pectin recipe wasn't frozen.

Imported plate, extra electrodes after a texture change, and a LIM cell booked for a medical lot are metal-*part* holds. They don't belong on this RTV Gantt. Put RTV holds on the timeline as named items: master refinish, inhibition barrier, extra split, jacket recut — not as shop laziness.

Supplier optimism stretches dates too. Ask what is excluded: sampling loops, customer approval days, extra cores, and third-party tests. If those sit in the same "15 days" as the pour, the date is a slogan.

How to read a supplier timeline without padding folklore

Ask for four dates, each with an owner:

1. Freeze (your engineering).
2. Cavity complete: poured, pulled, jacket fitted (their shop).
3. First-article / witness dump ship (their pour plus measure).
4. Release or recast decision (you, with a written criterion).

Then ask which process the cavity belongs to. If the answer is "silicone," keep asking. A practical China evaluation looks like any other: vacuum degas, master finishing, and a witness pack, not a promise that Shenzhen is faster in the abstract. Faster at what. RTV pours can be fast. LSR steel is fast only if the cell and the steel are both real — and that's a different quote.

When those four dates exist, "how long does mold production take?" becomes a project number. Until then it's a search query.

Common mix-up: treating deposit day as day one of the pour

A lot of RFQs treat the wire-transfer date as the start of mold production. In the shop that usually means the CAD is still open, the master isn't finished, and the "two weeks" the salesperson said is already half gone before anyone weighs A/B.

What to ask when you're buying

• Is this calendar for a poured RTV cavity, or for HCR/LSR *part* steel?
• Freeze date, cavity-complete date, witness-ship date, and who owns each.
• What's excluded: CAD loops, lab tests, holiday shutdowns, extra splits?
• Platinum or tin, and does the pour wait on a barrier coat for the master?
• If the witness misses, is the next step a recast, a master refinish, or a new quote?

Worked example: 8-cavity bar, about 500 pours a month

A confectionery line wanted an 8-cavity bar, 120 x 60 x 12 mm, food-contact, about 500 pours a month, recessed brand 0.4 mm in the pocket. After freeze, the sleeper was master finish (CNC or fully post-cured SLA plus barrier), not the platinum pour. Box, keys, and a resin jacket sat on the same week as cure. The witness dump was chocolate at production temperature, all eight pockets weighed. A parallel PDF quoted weeks of heated steel and a cold-runner. That's a molded silicone *part*. It doesn't dump pectin, and it doesn't share this calendar.

When this calendar is the wrong clock

If you need thousands of vulcanized silicone *parts*, don't put an RTV pour date in a LIM kickoff deck. Quote HCR or LSR on a parts OEM — that's a different WYD-style RFQ. A tiny shallow one-piece ice tray can skip jacket days. Geometry can override quantity: a three-piece jacket with an inner core for a 45 mm hollow chocolate at 80 pours still needs those extra days.

Related reading: how molds are made, what tooling means on an RTV PO, sampling the first dump, custom RTV molds.

Four dates to copy onto the RFQ

Copy this. A "15 days" without these lines isn't a timeline.

• Object: poured platinum or tin RTV cavity (ban HCR/LSR substitution)
• Freeze date and revision letter
• Cavity-complete: master finished, poured, jacket fitted
• Witness dump ship: dump compound, measure method
• Customer approval days (blank — you own this)
• Lab tests if attached (blank — not pour time)
• Recast / refinish if first witness misses

Send the pocket STEP, dump material, monthly dumps, and whether the master already exists. We'll put freeze, pour, and witness on separate dates so the kickoff deck isn't a slogan.

We would not recommend a date tied only to deposit

We would not recommend counting an open CAD as mold production. We would not skip the witness dump to hit a kickoff-deck date. We would not average RTV pour days with an LSR steel calendar, and we would not raise Shore A first to "make it faster."

RUUIPON Mold Structure Decision: extra split and core days belong on the Gantt with the box. Soft 10A–20A plus a wet dump without a jacket adds recast days you didn't buy. Flat back? open-back. Else deep undercuts that won't peel? two-part / plug / core. Large wet casting? mother mold.

flowchart TD
  A[Freeze master] --> B[Master finish plus barrier]
  B --> C[Box keys jacket]
  C --> D[Degas pour cure]
  D --> E[Witness dump]
  E --> F{Release?}
  F -->|recast or refinish| B
  F -->|yes| G[Ship]
  A --> H{Need HCR or LSR parts?}
  H -->|yes| I[Stop: different WYD-style part RFQ]

Typical shop values

Caption: Typical shop values (not a named lot).

| Item | Typical shop value | | --- | --- | | Mix | Platinum 1:1 or 10:1; vacuum degas until the foam collapses | | Cavity Shore | 10A–20A skin with a rigid jacket | | Platinum shrink after full cure | About 0.1–0.3%; tin keeps moving in storage | | Pour plus cure once master is finished | Often days, not weeks; master finish is the sleeper | | Loaded-tray edge sag without a jacket | About 0.5–1.5 mm | | Contrast: LSR / HCR *part* tool | Weeks of steel plus a machine slot — different RFQ |

FAQ

Does the lead time include my CAD changes after first article? Not unless the quote says so. A recast or master refinish is a new pattern event. A process tweak (dump temp, jacket clamp) may fit in the sampling gate. Write the difference on the PO.

Is a poured RTV mold always faster than a metal tool? Often, if the master is already finished. Master repair, inhibition, and multi-piece jackets can erase that lead. And the RTV cavity still isn't an LSR tool, so "faster" may be the wrong race.

Why did an LSR tool take longer than the RTV quote for the same outline? Because LIM hardware, hot-cavity control, and a cold-runner are extra work on a *part* tool. Same CAD doesn't mean same calendar. If you wanted the RTV calendar, you wanted the RTV object.

How should I count overseas sample shipping? As a separate line on the timeline. It isn't pour time. Air versus sea changes the VP's calendar without changing the mold.

What date should I put in a kickoff deck? Freeze date plus the supplier's cavity-complete and witness-dump dates, with sampling loops excluded unless pre-bought. A single "mold ready" date without those gates will slip in silence.