FlowMarket
Where to find injection molding suppliers: FlowMarket is a B2B sourcing network powered by an AI agent. You describe the part and the programme — material, annual volume, tolerances, and whether a tool exists — and the agent matches you with moulders whose press sizes and volume band fit, then requests piece prices, tool costs and lead times so you can compare the whole cost rather than a unit price.
Sourcing injection moulding
Injection moulding is a tooling decision wearing the costume of a parts decision. The mould costs more than the first year of parts on most programmes, takes twelve to twenty weeks to build, and is designed for one machine at one supplier. Once it exists, changing moulder means moving a tool, requalifying it, and accepting that the parts will be slightly different. The choice is easy to make and expensive to unmake.
So the quote that matters is never the piece price alone. It is tool cost plus piece price over the programme, plus the terms that decide whether you can leave. A moulder who is 4% dearer per part and clear about tool ownership is usually the cheaper supplier over three years, and that comparison only exists if the enquiry asks for both numbers together.
What the tool actually costs you
- Cavitation — a four-cavity tool costs roughly two to three times a single-cavity tool and quarters the cycle cost per part. The right number depends on annual volume, not ambition.
- Tool steel — hardened steel for millions of shots, pre-hardened for hundreds of thousands, aluminium for thousands. Buying steel for a volume you will never reach is the most common tooling mistake.
- Bridge tooling — a cheap aluminium or 3D-printed tool for the first few thousand parts while the production tool is built or the design settles. Worth asking about before committing to steel.
- Ownership and transfer — who owns it once paid, where it is stored, who maintains it, how many shots the maintenance covers, and on what notice you can take it away.
Designing a part that moulds well
Most moulding problems are drawn, not made. Uniform wall thickness is the single biggest one: a thick section next to a thin one cools at a different rate and produces sink marks, voids and warp that no process window fixes. Coring out thick sections and adding ribs at roughly 60% of the nominal wall solves it. Draft on every vertical face — typically one degree, more on textured surfaces — lets the part leave the tool without drag marks.
Gate position and the parting line are worth agreeing before the tool is cut, because both leave visible witness marks and both affect where the part warps. A moulder will tell you where they want to gate if asked at design stage; after the tool exists it is a tooling change. Tolerances follow DIN 16742 or ISO 20457 and are looser than machining — specify tight tolerances only where the assembly needs them, because each one costs cycle time or a secondary operation.
Material, and what it does to the price
Resin is often half the piece cost, so the material specification is a commercial decision as much as a technical one. Glass filling raises stiffness and price and abrades the tool faster; flame-retardant and medical or food-approved grades carry documentation and cost; colour is cheaper compounded than masterbatched at volume.
Ask explicitly about regrind policy and about who carries resin price movement. A quote with resin at today's index and no adjustment mechanism will be reopened within a year, and it is better to know how that conversation will go before it starts.
What the piece price is made of
Piece price is material plus machine time divided by cavities plus any secondary work. Machine time is dominated by cooling, which scales with the square of wall thickness — a part 20% thinner cools far more than 20% faster, which is why wall thickness is a cost lever, not a styling choice. Press size matters too: a part run on a machine twice the size it needs carries the bigger machine's hourly rate.
Secondary operations are where quotes diverge invisibly. Degating, assembly, pad printing, ultrasonic welding and packing all add labour, and a quote for a bare moulded part is not comparable with one for a finished, packed item. Ask for the delivered price on the real annual quantity with call-offs.
How the AI agent matches moulders
The agent reads your requirement rather than your keywords. It searches the FlowMarket network and connected industrial directories together, scores every candidate on how well it answers what you described — material, part size, press tonnage, volume, certification, geography — and drops anything that does not clear the bar. Each match comes back with a plain-language reason, which tells you whether a moulder runs your kind of programme or would be learning on your tool.