Supply
On-demand and low volume injection molding
On-demand molding decouples tooling from production. The tool exists and is maintained; parts are produced in small batches when you order them rather than in one large committed run.
On-demand molding at a glance
On-demand injection molding means the mold is built once and kept ready, and parts are produced in batches against your call-offs instead of in one committed run. At Trumould there is no contractual MOQ. A new tool takes 4 to 8 weeks to first article, and a repeat order on existing tooling leaves within 3 working days of the purchase order. The minimum economic run is typically 500 pieces to justify setup; below that we usually recommend CNC or 3D printing and quote those instead.
Which route fits your quantity
| Quantity | Usual route | Why |
|---|---|---|
| Under roughly 100 parts | 3D printing or CNC machining | No tool has to be paid for, so it is almost always cheaper. |
| Roughly 100 to 1,000 parts | Prototype aluminum tool | Costs a fraction of production steel; aluminum tools are designed for hundreds to a few thousand cycles. |
| Recurring batches on a tool you own | P20 or H13 steel tool, run against call-off | Steel selection takes the designed tool life up to 2,000,000 cycles, and each batch is ordered to actual demand. |
| Parts needed in under 4 to 6 weeks, new part | Print or machine the first batch | A new tool cannot be built in that time, from us or anyone else. |
Glass-filled resins wear aluminum tools quickly, so the resin choice can move a low volume job onto steel. The part cost guide shows where tooling stops dominating the price, and the lead time guide breaks the 4 to 8 weeks down by stage.
What it changes
Traditional molding asks you to commit to a production quantity so the molder can plan a single long run. That produces the lowest possible unit cost and the highest possible inventory risk, because you are paying to store, insure, and possibly obsolete parts you have not sold. On-demand production inverts that: the tool is held ready and parts are made against a call-off schedule.
Where it fits
- Product launches where real demand is unknown and forecasting is guesswork.
- Seasonal or campaign products with uneven demand across the year.
- Spare and service parts that must remain available for years at low annual volume.
- Designs still maturing, where a large committed run risks obsoleting stock at the next revision.
- Cash-constrained programs where inventory tied up in finished goods is the binding constraint.
What it costs
Being honest about the trade: per-part price on a small call-off is higher than on one large run, because setup, material changeover, and quality checks are amortised over fewer parts. The comparison that matters is not unit price against unit price. It is unit price plus the carrying cost of inventory you do not need yet, plus the risk of obsoleting it.
Cutting steel is the long pole. Quotation, design review and sampling are measured in days; the tool build is measured in weeks and is largely fixed by the number of cavities and the amount of hand finishing. On-demand supply attacks the queue around the tool, not the tool itself.
What has to be true for it to work
- Tool ownership and storage are documented. You should know who owns the tool, where it is stored, who insures it, and what notice is required to move it.
- Tool maintenance is scheduled. A tool sitting idle between runs still needs cleaning, protection from corrosion, and periodic inspection.
- Lead time for a call-off is stated. On-demand only helps if the response time is shorter than your planning horizon.
- Quality is consistent between runs. Same tool, same resin grade, same process parameters, with any change notified rather than made silently.
Questions worth asking any supplier
- Who owns the tool once it is paid for, and what document proves it?
- Where is it stored, and who insures it?
- What is the lead time from call-off to dispatch?
- Is there a minimum order quantity, and is there a minimum annual volume to keep the tool active?
- What happens to the tool if we stop ordering?
- Is a material or process change notified before parts ship?
How we handle it
Trumould runs production against call-off with no contractual minimum order quantity, so you can order the quantity you actually need, and the tool sits ready between orders. Call-offs on existing tooling leave within 3 working days of the purchase order. Tool ownership should be in writing before a purchase order; the questions that settle it are on the injection molds and tooling page.
Let’s get started on your part
Send your CAD files and target volumes. We come back with a price, a lead time, and any design notes that would reduce either.