Plastic Injection Molding in China: 22 Frequently Asked Questions

Sourcing plastic injection molding in China has never been easier, offering significant cost advantages and access to mature manufacturing capability. In practice, most issues are not caused by a lack of factory capability, but by unclear RFQs, assumptions around tooling ownership, or missing verification steps during mold-making and production.

At the same time, companies looking to find plastic injection molding services in the country often have legitimate questions about quality, lead times, intellectual property, hidden costs, and how sourcing risks typically arise. Understanding where these problems commonly occur makes it easier to evaluate suppliers and avoid preventable mistakes.

The following are some of the most common buyer concerns we encounter at Haizol from companies evaluating injection molding suppliers in China, including both standard process questions and “insider” risks frequently raised during sourcing discussions.

What Plastics Can Chinese Injection Molders Work With?

Chinese injection molding factories can mold most standard thermoplastics and many engineering resins, depending on local material availability and factory capability.

Commonly supported injection molding materials in Chinese factories include:

• ABS
• Polypropylene (PP)
• Polycarbonate (PC)
• Nylon (PA)
• PVC
• TPU
• TPE
• Higher-performance resins such as PEEK or Ultem are available through specialized suppliers.

You should state the exact resin or performance requirements upfront, because not every injection molding factory can source or process engineering-grade plastics. When a specific brand-name resin is required, such as a DuPont Zytel grade, Chinese factories may suggest a “local equivalent” that is 30–50% cheaper. This may be acceptable, but you should request the datasheet and sample parts to confirm that mechanical, thermal, and chemical properties meet your requirements before approval.

Will the Factory Use “Regrind” (Recycled Scrap) in My Parts?

Yes, injection molding factories may use regrind in your injection molded products unless you explicitly request otherwise.

Chinese factories often grind up waste runners and failed parts to mix back into the melt ("regrind"). While 10–20% regrind helps to keep the production costs down and is standard practice for non-critical parts, it can degrade mechanical properties and colour consistency. 

For critical parts requiring maximum strength and a flawless appearancee, you should explicitly specify “100% virgin material only” in the RFQ when sourcing injection molded parts from China.

Do Chinese Molders Offer Assembly and Packaging?

Yes. Many Chinese injection molding factories offer basic assembly and packaging services. These assembly lines can often perform time-consuming processes like installing screws, applying labels, painting, or packaging products in retail boxes (kitting). Completing these tasks at manufacturing origin is usually more cost-effective than shipping bulk parts to be assembled domestically.

• Large, more sophisticated factories (often serving automotive, medical, or export OEMs) are more likely to have established assembly lines, standardized work instructions, and in‑house packaging, sometimes including logistics and warehousing.​
• Small molders and workshops may focus mostly on molding and simple manual operations; they might offer only basic assembly or subcontract more complex kitting/packaging.

However, the key strength of most Chinese injection molding shops is in manufacturing the molds rather than assembly. For assembly or packaging work, you must provide detailed work instructions and clear quality standards, because execution quality often depends heavily on how precisely the process is defined.

What If I Need a Specific Texture (E.G., VDI or Mold-Tech)?

If you need a specific texture, it’s important to specify what you need early in the negotiation process with Chinese injection molders. Otherwise, the standard "local equivalent" texture plaques (e.g., YS or MT-equivalent) may be used to save money. 

The local equivalents often match visually but may differ slightly in depth or feel. Therefore, if the texture is mission-critical for your part, you can request the factory to buy an official Mold-Tech plaque or provide a physical "texture sample", so that they can precisely match what you need.

How Long Does Mold Making and Production Take?

For Chinese injection molding suppliers, mold making and first-article production typically take 2–8 weeks, depending on part complexity, tolerance requirements, and tooling configuration. You can expect simple aluminium molds to be completed in around 10–18 days, while steel molds take longer—around 20–30 days to first sample.

Based on analysis of the Haizol network of verified injection molding factories, typical timelines are:

• Production tooling: 30–45 days, depending on complexity.
• Mass production: 6–10 days after mold approval.

Who Owns the “Mold Base” If “Cavity Inserts” Are Used?

One issue that can come up with injection molding orders is whether the buyer owns the mold base used in production or simply the cavity inserts that run in a “MUD base” (Master Unit Die) owned by the factory.

If you have fully paid for the mold/tooling and your contract clearly states that you own the complete mold (including the mold base and any cavity inserts), the factory cannot legitimately keep it or refuse to transfer it to another Chinese injection molding factory, and you can enforce your rights through the Chinese legal system if necessary. Based on observed tooling contracts and transfer cases across the Haizol network of verified Chinese injection molding factories, mold ownership disputes are very rare when tooling scope and ownership terms are defined before production.

A golden rule is that if the quotation seems much cheaper than others, a red flag should be raised: you may be only buying inserts that rely on a MUD base owned by the supplier. To avoid confusion, always confirm exactly what the quote includes and clearly state from the start if you require a fully self-contained mold that you will own and can move freely.

Can I Save Money by Using a “Family Mold”?

Some companies save tooling costs by creating a “family mold”, which can manufacture several different parts (e.g., top and bottom housing) in the same cycle.

Despite the cost savings, our advice is to avoid this practice unless the required parts are of approximately similar volume. If you decide to take this route, request a "flow balance analysis" during DFM.

If parts are of significantly different volumes, it’s best to make individual molds, as different filling pressures may be required. Family molds risk leading to quality issues with defective parts.

How Do I Verify That the Specified Mold Steel Was Actually Used?

An issue that crops up occasionally with Chinese injection molders is the use of sub-standard steel in orders.  While not commonplace, so-called “steel fraud” does receive a lot of concern. For instance, a factory charges for high-grade H13 steel but use cheaper soft steel, which wears out faster. 

This is simply resolved for companies by requesting a Steel Certification and a Hardness Report from the supplier with mold deliveries. For an extra layer of verification for high-value jobs, consider hiring a third-party inspector to perform handheld XRF metal testing on-site.

What Are Typical MOQs (Minimum Orders) for Injection Molded Parts in China?

From experience with injection molding RFQs handled on Haizol, Chinese molders usually quote a minimum order quantity of 200–1,000 pieces per batch. Below this volume, the setup costs of machine purging, heating, etc. cause the price per part to spike dramatically, making it unfeasible for some companies.

If your volumes are below typical MOQs but you still need molded parts, low-volume injection molding for short-run production can be a better fit than full production tooling.

What Dimensional Tolerances Are Realistic With Injection Molding?

Standard consumer-grade tolerances from Chinese injection molding factories are ±0.1 mm for most features. Tighter tolerances (±0.05 mm) are possible but such requirements increase the tooling and production costs. 

To ensure capability with your required tolerances for precision molds, specify requirements early with suppliers. Especially if you require tighter tolerances than the standard 0.1 mm for critical dimensions.

Do Chinese Injection Molding Companies Help With DFM and Design Review?

Many injection molding suppliers in China perform a DFM (Design for Manufacturability) analysis before the mold-making process.

Look for reputable suppliers who can analyse and provide feedback on potential issues with your design. Common design issues include thin walls, sink marks, etc., but problems can be prevented with design modification suggestions from experienced mold manufacturers.

However, don’t forget to review and approve the DFM feedback with your engineering team before manufacturing starts.

What Are T1/T2 Samples and the Revision Process in China?

The T1/T2 and revision process are checks before large-scale production begins. Skipping these checks and rushing into injection molding production can be costly for companies and should be avoided.

Once a mold is finished, the supplier will produce a T1 sample, which is a first shot. It is normal for T1 parts to have minor defects. It’s better to identify these after this first stage than much later down the track.

Based on your feedback, the factory will modify the mold to produce T2, T3 samples, etc., until the final "golden sample" is approved. Only then should you sign off for mass production.

Can I Visit the Injection Molding Factory to Supervise Critical Runs?

Many issues can be avoided by having a representative of your company on the factory floor to supervise first runs. It is highly recommended. If you cannot go in person, hire a third-party engineer to attend the first run. But at times you may not be able to physically visit the factories in China, in these situations we recommend this.

Three ways to verify an injection molding factory without visiting

• Check the Haizol factory profile: Review machine tonnage, in-house mold-making equipment, supported materials, and certifications (e.g. ISO 9001, IATF 16949, ISO 13485) on the Haizol factory profile to confirm both technical capability and quality system maturity.
• Request live production proof: Ask for recent shop-floor photos or a live video call (for example via WeChat) during active production to verify that the equipment and processes in use match the factory profile claims.
• De-risk tooling before scale: Use DFM review, sample approval, or phased tooling milestones to confirm communication, execution quality, and process control before committing to full production.

You can use online injection molding manufacturing platforms like Haizol that verify suppliers and provide free access to detailed factory profiles when sourcing injection molding suppliers in China. Beware of suppliers on some open marketplaces that are not factories at all—simply sales offices or trading companies without much technical know-how acting as “middlemen”.

For buyers who want a curated starting point, see our list of the best injection molding companies in China, based on verified factory capabilities, certifications, and production scope.

Should I Deal With a Injection Molding Manufacturer or a Trading Company?

Working directly with the factory improves control and removes the markup from middlemen, which can be as high as 10–25%. Bear in mind that trading companies may offer little technical input or value. If you end up working with a trading company, make sure they have access to real tooling shops and aren't just resellers, or you may run into problems.

To identify legitimate Chinese injection molding manufacturers and eliminate intermediaries, use the Haizol injection molding directory, which independently verifies factories based on business registration, in-house injection molding machines, in-house mold-making capability, supported materials, and valid quality certifications.

If I Move the Mold to the US or Europe Later, Will It Work on Local Machines?

If you plan to move production later, you should bear in mind some potential issues that have affected other Western companies with the same plan.

For instance, Chinese molds typically use metric components and cooling fittings, while US molders often use Imperial standards. This can cause incompatibility issues and result in expensive fixes.

So, if you plan to export the mold (a "Class 101" export mold), ask for HASCO or DME standard components so the mold is compatible with Western machines without expensive retrofitting—and verify that this request has been addressed by the supplier.

What Happens If a Batch of Parts Arrives Defective?

Receiving defective parts from Chinese injection molders can be minimized by doing due diligence. For example, verifying suppliers on platforms like Haizol, specifying precise requirements and tolerances in RFQs, DFM reviews, and using pre‑shipment inspections (PSI).

If defects are discovered, cash refunds from Chinese suppliers are rare. Many injection molding suppliers will offer rework, especially if you can document the defect with clear photos, measurements, and inspection reports, and if your contract includes defined quality standards. ​

To protect yourself at the time of order, define a clear "defect rate" (e.g., <1%) in your contract. For further protection before your order leaves the port, perform a pre-shipment inspection (PSI). Once parts are shipped, fixing defective molds becomes far more challenging.

How Will Injection Molded Parts Be Shipped from China?

Small urgent batches can be shipped by air freight in as little as 5–9 days. Most orders ship by ocean freight, typically taking 18–28 days. Buyers should clarify shipping terms (FOB, EXW, CIF) at the time of order and account for duties and certifications.

How Can I Protect My Design and IP When Dealing with Chinese Injection Molding Companies?

To protect your design and IP in China, you can use China-specific legal agreements, register IP locally, and limit full design exposure during production.

Before sharing detailed drawings you can sign a NNN agreement (Non-Disclosure, Non-Use, Non-Circumvention) which isenforceable under Chinese law. Agreements governed by foreign law are difficult to enforce in China. Then, register your patents and trademarks in China immediately (China operates a "first-to-file" system). 

For extra-sensitive products, some companies add another layer of precaution by splitting production across multiple factories, so that no single site has the complete design.

How Are Mold and Part Prices Quoted in China?

Chinese injection molding suppliers typically present pricing in two distinct components: a one-time tooling (mold) cost and a recurring per-piece (unit) price. 

The standard quotation format often follows this formula: Total Project Cost = Mold Cost + (Unit Price × Quantity)

Mold quotes are based on factors like size, steel grade, number of cavities, complexity, and expected lifetime (number of shots). You’ll usually see a single lump‑sum price for the tool  often paid in milestones such as 50% deposit and 50% after sample approval.

Injection molded part prices in China are calculated from:

• Material type and part weight.
• Cycle time and machine size.
• Labor, finishing, packaging, and overhead.​

Across tooling price comparisons reviewed within the Haizol supplier network, injection mold costs in China commonly benchmark 30–50% below equivalent tooling quoted in Europe or North America. Chinese suppliers often quote the part price with an Incoterm, such as EXW (pickup at factory), FOB (including export and loading), or occasionally CIF/DDP if they handle freight and duties. Quotes should be checked to confirm tooling scope, materials, tolerances, finishes, and whether terms are FOB or EXW.

What Payment Terms Will a Chinese Molder Require?

The payment terms with Chinese molders will depend partly on whether you’re a first-time purchaser or long-term repeat customer. Better terms are often negotiable for long-term customers. Tooling typically requires a 50% deposit upfront and 50% after final sample approval. Production orders usually require 30–50% down payment with balance paid before shipment.

What Hidden Costs or Red Flags Should I Watch For When Injection Molding Parts in China?

You should check supplier quotes carefully to understand exactly what is included. In many cases, quotes from verified Chinese injection molding factories are comprehensive and cover tooling, materials, and basic production requirements.

Occasional issues that can arise with unverified and unscrupulous suppliers are excluding trial runs, samples or revisions from the costs, pricing for cavity inserts for a Master Unit Die owned by the factory rather than a mold you own, sub-standard materials or finishes, hidden packaging or shipping costs.

If you have any doubts, request further details before ordering. Always get a detailed written quote that spells out exactly what’s included and anything that’s not.

What About VAT and “Fapiao”?

Be aware of the “fapiao” in China. This is a government-regulated, official invoice or receipt that serves as both a sales receipt and a tax document for VAT purposes for Chinese suppliers. The most common practice is to use FOB (Free on Board) terms. This means the factory handles the export formalities, and later keeps any eligible Chinese export VAT rebate as part of its margin.

However, in most cases, you’ll be responsible for paying som domestic import duties, tariffs, and VAT/GST. It’s best to check rates with your customs broker.

Conclusion: When Is Injection Molding in China a Reliable Sourcing Option?

Injection molding in China is reliable when companies define materials, tooling ownership, tolerances, and verification steps upfront, rather than relying on assumptions or the lowest quote. Most sourcing problems stem from unclear RFQs and insufficient factory validation, not from factory capability.

To identify legitimate injection molding manufacturers and avoid intermediaries, you can use the Haizol injection molding company directory, which provides free access to verified factory profiles covering in-house equipment, mold-making capability, supported materials, and certifications.