Accessing low volume injection molding and precision injection molding services from China brings huge advantages for producing small batches or complex parts at competitive prices. However, the injection molding supply chain overseas does present quality, communication, and logistical hurdles. This guide covers best practices in sourcing Chinese injection molding partners capable of delivering exceptional low volume and precision molded components.
Evaluating Low Volume Injection Molding Suppliers
China’s vast manufacturing capacity includes thousands of injection molding facilities, though few specialize in truly low volume molding with short lead times or precision molding to fine tolerances. Careful vetting of potential partners on key aspects is critical:
Molding Machine Inventory
The optimal equipment mix for low volumes includes a higher proportion of small tonnage presses. Ask specifically about <100 ton machines and automation capabilities to enable fast changeovers between jobs.
Secondary Process Integration
Many precision components require value-add processes like pad printing, ultrasonic welding, CNC machining, or assembly. Seek suppliers with in-house secondary ops or trusted subs.
Tooling Capabilities
While you may supply some tooling, abilities to manufacture precision tooling onsite with design engineering input is ideal for tweaking molds to maximize capabilities.
Quality Systems
ISO certifications evidence robust quality management infrastructure – verification of approved materials, SPC process monitoring, dimensional inspection, functional testing documented for each job.
| Process | Typical Volumes | Surface Finishes | Tolerances |
|---|---|---|---|
| Low Volume | 10 – 5,000 pcs | > 63 Ra μin | ± 0.005 in |
| Precision | 100 – 5,000 pcs | < 32 Ra μin | ± 0.002 in |
Defining Optimal Specifications for Precision Molded Parts
Provide comprehensive specifications to injection molding suppliers including:
CAD Models
3D files allow assessing producibility, proposing design refinements to improve moldability/tolerances, and preparing preliminary quotes.
Approved Material
Specify grades required with expected mechanical performance parameters. Check availability/experience with each.
Dimensional Tolerances
Detail positional and form tolerances on prints, highlighting critical locations requiring precision molding capabilities.
Special Geometries
Call out challenging aspects like thin walls, fine ribs, tall cores, tight radii, threads, living hinges needing precision tool construction to fill properly.
Cosmetic Standards
Quantify surface finish requirements – grains, gloss units, or injection molding roughness (Ra) values in microns or microinches.
Secondary Processing
List any value-add operations required – decorating, machining, assembly, functional testing, protective packaging for shipping.
Clearly defined specifications allow prospective suppliers to match requirements with equipment and specialist capabilities to determine feasibility and provide reliable quotations. Reputable injection molding partners will highlight potential producibility risks and suggest refinements to ensure manufacturability.
Quality Management and Inspection
Consistently produce precision injection molded components in China through:
Stringent Tool Try-Out
Extensive sampling with dimensional measurement data, photographic evidence of fills from multiple positions, and functional testing results supplied to qualify tools prior to approval for production. Request 5~10 free samples for your own verification too.
SPC Tracking
Suppliers should monitor key process parameters shot-to-shot and track dimensional quality with documented control charts – verifying stability and reacting to out-of-control signals.
Full Traceability
Each raw material lot, tool used, and production batch should have unique identities for full traceability. This aids root cause analysis if issues arise later.
Final Part Inspection
100% inspection against an approved quality plan – detail dimensional, visual and functional checks confirming compliance. Share data or do periodic audits.
Robust quality infrastructure ensures low volume and precision molded parts consistently progress through qualified production cells, tools, processing parameters to meet specifications – despite frequent changeovers between short run jobs.
Logistics and Customs
With production remote, define terms suiting your supply chain model:
Order Quantities
Given setup costs, minimum economic quantities for production apply – though may run as low as 500-1000 pcs for automation-enabled low volume molding
Inventory and Fulfillment
Some precision parts suppliers hold finished goods inventory to enable just-in-time ordering. Or direct ship piecemeal orders as they release.
Labeling and Packaging
Protect critical dimensions and surface finishes by specifying interior packaging and shipping cases to prevent damage in transit.
Getting connected with specialty Chinese manufacturers ushers access to advanced capabilities and technologies for producing high mix, low volume or precision injection molded components. Just take diligence selecting and collaborating with the right partners.