Contract injection molding from Huangyan, China, since 2002
Contract Manufacturing for Injection Molding: Types, Costs, and How It Works
Short answer: Contract manufacturing injection molding means one supplier runs your plastic parts program from start to finish. That covers tooling, molding, inspection, assembly, and delivery. You pay a one-time tooling fee plus a per-part rate. Three contract models exist: full-service, tooling-plus-molding, and consignment. Choose based on annual volume, IP control, and material traceability.
I have run contract programs for OEMs since 2002. The same questions come up every time. What does it cost? Who owns the mold? What happens when a part fails inspection? This page answers all of them with numbers from our shop floor in Huangyan.
What is contract manufacturing for injection molding?
Contract manufacturing for injection molding is an outsourcing agreement. One manufacturer takes responsibility for your plastic parts from mold tooling through finished, inspected, packaged goods.
It differs from spot buying in three ways. You get reserved machine capacity. You get one accountable quality owner. And you get pricing locked for the contract term instead of a fresh quote on every order.
For an OEM the math is simple. No capital tied up in presses. No quality drift across three or four suppliers. Your engineers stay on product development instead of chasing production problems.
Topworks has delivered contract manufacturing injection molding programs to buyers in the USA, Germany, the UK, Italy, and 47 other countries. Most started with a single mold. Many now run twenty or more tools with us.
Contract manufacturing vs spot buying vs in-house molding
Before choosing a contract type, decide whether a contract is right at all. Here is how the three sourcing routes compare.
| Contract manufacturing | Spot buying | In-house molding | |
|---|---|---|---|
| Upfront capital | Tooling only | Tooling only | Presses, tooling, floor space, staff |
| Per-part cost | Locked for term, volume-tiered | Requoted each PO, often higher | Lowest at high volume, hidden overhead |
| Machine capacity | Reserved for you | First come, first served | Fixed, hard to scale |
| Quality ownership | One supplier, one 8D report | Varies per order | Entirely yours |
| Lead time control | Written into contract | Uncertain | Full control |
| IP exposure | NDA plus mold ownership options | Higher, more hands involved | Lowest |
| Best for | Steady annual volume, no plant | One-off runs, prototypes | Very high volume, deep pockets |
Most OEMs we work with sit in the first column. They have steady demand but no reason to run a plastics plant.
Three contract manufacturing models
We offer three contract structures. Each matches a different volume, IP requirement, and risk profile.
Full-service contract
Topworks manages everything: tooling, molding, QC, assembly, packaging, and DDP delivery. You receive finished goods and one invoice.
Best for
- Brands without in-house manufacturing
- Startups scaling to mass production
- Products with multi-step assembly
Tooling + molding only
You own the mold and the tool design. Topworks runs production on a dedicated contract basis. You can relocate the mold at any time.
Best for
- Established brands re-sourcing production
- Products with proprietary geometry
- Dual-sourcing strategies
Consignment molding
You supply the resin. Topworks molds and returns finished parts under strict material traceability. Common with FDA-grade and flame-retardant compounds.
Best for
- Medical and food-contact applications
- Regulated-industry compliance
- Proprietary engineering resins
How contract injection molding is priced
Every contract quote we issue has the same five lines. Knowing them lets you compare suppliers on equal terms.
| Cost item | Typical range (China, 2026) | What moves the number |
|---|---|---|
| Aluminum / soft tool (prototype, up to 10k shots) | $1,500 – $6,000 | Part size, cavity count |
| P20 steel production mold (300k–500k shots) | $5,000 – $25,000 | Cavities, side actions, surface finish |
| Hardened H13 / S136 mold (1M+ shots) | $15,000 – $60,000+ | Hot runner, tolerance class, texture |
| Per-part molding rate | $0.08 – $3.00 | Resin, shot weight, cycle time, press size |
| Assembly / secondary ops | $0.05 – $1.50 | Manual vs automated steps |
| DDP freight to US / EU | per shipment | Volume, sea vs air |
These ranges come from our 2025–2026 quotes. For exact figures on your part, see the injection molding cost guide or send us drawings.
Three things that cut your contract price
- Commit annual volumeOur per-part rate drops at 10k, 50k, and 100k tiers.
- Accept DFM changesA 10% wall reduction often cuts cycle time by 20%.
- Consolidate SKUsA family mold runs two or three related parts in one tool where geometry allows.
How a contract program works: 6 steps
- Day 1RFQ
Send drawings or 3D files. NDA first, then a proposal within 24 hours.
- Week 1DFM review
Free. We flag wall, draft, gate, and tolerance risks before any steel is cut.
- Weeks 2–7Tooling
4–6 weeks for a P20 production mold. Weekly photo updates.
- Week 8T1 sample
Samples ship with a CMM report. Tooling balance due on your approval.
- Weeks 9–10Production
First-article, SPC, AQL outgoing. PPAP Level 3 for automotive.
- Week 10+DDP delivery
Door-to-door. Duties and customs handled by us.
Industries we serve
Automotive
IATF 16949 with PPAP Level 3 as standard. Interior trim, connectors, under-hood PA66. See automotive injection molding.
Medical devices
FDA-grade resins, lot-level traceability, full documentation. Most medical clients use consignment. See medical injection molding.
Consumer electronics
PC/ABS housings, PMMA light guides and lenses, SPI A-2 cosmetic finishes. Tight color matching across batches.
Industrial equipment
Glass-filled nylon, PP, and large housings up to 2500T. Low-volume runs for spares and legacy products.
7 reasons OEMs choose Topworks
- ISO 9001 + IATF 16949Dual-certified quality system covering commercial and automotive work. PPAP, FMEA, and control plans available.
- Tooling and molding under one roofWe build the mold and run it. No handoff between a tool shop and a molder. No finger-pointing when something drifts.
- Dedicated machine capacityPriority scheduling on 80+ presses from 50T to 2500T. You never compete with spot orders.
- 100% in-process QCFirst-article inspection, SPC monitoring, Zeiss CMM reports, and outgoing AQL on every run.
- NDA and IP protectionNDA signed before we open any drawing. Encrypted storage, restricted access, no subcontracting without written approval. Zero IP disputes in 20+ years.
- DDP worldwide shippingDoor-to-door to the USA, EU, UK, Australia, and 47 other countries. One price, no surprises at customs.
- English-speaking project managerOne PM with an engineering background handles your account end-to-end. Weekly updates, same-day WhatsApp response.
Frequently asked questions
What is the minimum order quantity for contract injection molding?
Contract programs start at 1,000 parts per run with an annual commitment of 10,000+ pieces. For prototype or low-volume work, soft-tooling programs start at 100 pieces with no annual commitment.
How much does contract manufacturing injection molding cost?
Expect a one-time tooling fee of $5,000–$25,000 for a typical steel production mold, plus a per-part rate of $0.08–$3.00. Assembly, packaging, and DDP freight are quoted separately. Annual volume commitments lower the per-part rate.
How long from RFQ to first shipment?
Typically 7–9 weeks. That is 4–6 weeks for tooling, one week for T1 sampling and approval, and one to two weeks for the first production run. Air freight adds 5–7 days; sea freight adds 30–40 days.
Who owns the mold in a contract program?
You do, once the tooling invoice is paid in full. Under Type 02 you can relocate the mold at any time. Under Type 01 we store and maintain it at no charge for the contract term.
How do you handle quality control in contract manufacturing?
Every program includes a first-article inspection report, SPC process monitoring, Zeiss CMM dimensional reports at the agreed frequency, AQL outgoing inspection, and full material traceability. Automotive programs include PPAP Level 3 as standard.
Can we visit your factory before signing a contract?
Yes, and we encourage it. We are in Huangyan, Taizhou, China’s mold city. We arrange airport pickup from Wenzhou (WNZ) or Ningbo (NGB). Live video factory tours are available if you cannot travel.
What happens if parts are out of spec?
Topworks bears full responsibility for non-conforming parts caused by our process. We replace or rework at no charge and issue an 8D corrective action report within 5 business days. Our defect rate on contract programs is below 0.3% based on 2024 audit data.
What are typical contract terms and payment structure?
Standard contract length is 1–3 years with annual renewal. Tooling: 50% deposit, 50% on T1 approval. Production: 30% deposit, 70% before shipment. Clients with 12+ months of payment history qualify for net-30 or net-60. L/C accepted over $50,000.
Ready to start a contract program?
Send your part drawings or a product description. You get a tailored contract proposal and a free DFM analysis within 24 hours. No obligation.
Get a free contract proposal
NDA signed before we review any drawings. Response within 24 business hours.
Contract manufacturing injection molding works when three things line up: steady annual volume, a supplier who owns tooling and molding together, and pricing you can see line by line. Pick the contract type that matches your IP and material needs. Then hold your supplier to a written process with inspection at every gate. That is how our longest-running programs started, and it is how most of them are still running today.
