How to Buy a Used Injection Molding Machine from China: A Step-by-Step Buyer’s Guide

Buying a used injection molding machine from China can save you a large share of the cost of a new machine — if you buy on evidence instead of promises. The difference between a good purchase and an expensive mistake is almost never the brand on the cover. It is whether you checked the right things, in the right order, before the balance left your account.

Step 1: Define What You Actually Need

Start from your product, not from a machine listing.

Clamping force (tonnage). Thin-wall packaging needs more force per gram than thick-wall houseware. As a rough starting point, small caps and closures run on 90–160T, buckets and crates on 180–320T, and large bins, pallets and industrial parts on 380T and above. When in doubt, size up one step.

Tie-bar distance. Your mold must fit between the tie bars, with room for ejection. Check the mold’s length × width against the tie-bar spacing, plus minimum/maximum mold height. Right tonnage, wrong tie-bar distance = wrong machine.

Shot weight. The injection unit must deliver enough plastic per cycle for your part plus runner, with margin. Check shot weight in grams (usually quoted for PS) against your part weight — run in the middle of the machine’s range, not at its limit.

Write these three numbers down before contacting any seller. They filter out most unsuitable listings at once, and let a serious seller answer with matching stock instead of a generic catalogue.

Step 2: Know Where Used Machines Come From

Most used machines on the Chinese market come from three sources:

• Factory upgrades and closures — running machines sold when a factory renews its fleet or shuts a line. Condition varies widely; some are worked hard, some are nearly idle.
• Dealer and trader stock — machines bought in bulk and resold, often cleaned but not mechanically refurbished.
• Refurbishers — sellers who inspect, repair and test machines before sale, and can show you exactly what was done.

None of these sources is automatically good or bad. What matters is what the seller can prove about this specific machine — its photos, its nameplate, its test video, and its repair record.

Step 3: Judge the Listing Like an Inspector

A trustworthy listing gives you evidence. A weak one gives you adjectives.

Real photos of the actual unit. Look for photos from all sides: clamping end, injection end, electrical cabinet, platens and tie bars, toggle or clamp mechanism, and the controller powered on. Stock photos or a single front shot are a warning sign — the seller may not even have the machine.

Read the nameplate. The metal nameplate is the machine’s identity card. It shows the manufacturer, model, year of production, serial number, clamping force (often in kN — divide by 10 for tonnes) and shot weight. Ask for a clear photo and cross-check it: a “200T, 2020” machine should have a plate that says exactly that, like our PowerJet BJ200-S6 (200T, 2020). If the plate is missing, unreadable, or different from the description, stop.

Check the controller. The controller brand and model tell you a lot about age, spare-part availability and whether your technicians will be able to run it. A clear photo of the controller, switched on, should be standard in every listing.

Step 4: Insist on a Real Test — and Know What Each Test Proves

Photos show condition; only running the machine shows health. There are three levels of testing, and a good seller will tell you exactly which level a price includes:

1. Dry cycle test — the machine runs clamp close, carriage movement, mold open and ejector strokes with no mold and no material. It proves the hydraulics, clamp unit, ejector and basic electrics work, and reveals leaks, slow movements and abnormal noise.
2. Purge test — the barrel is heated and material is purged through the nozzle. This proves the screw and barrel can plasticise properly — a worn screw or damaged barrel shows up here as poor, uneven melt.
3. Production trial — an actual mold is mounted and parts are produced. This is the only test that proves the machine makes your product to your standard.

A practical standard used by serious sellers is: dry cycle & purge tested — production trial before shipment. At MoldMach, every listing is backed by a dry-cycle and purge test video. A production trial with your mold takes time and ties up the machine, so it normally happens after a deposit is paid and always before the machine ships — you approve real parts on video before paying the balance. Be cautious with a seller who refuses all testing, and with one who promises a free trial on every enquiry: that “trial” video is usually not of your machine.

You can see how we document and grade this work on our refurbishment page.

Step 5: Understand Refurbishment and Grading

“Refurbished” is the most abused word in this trade. It can mean anything from a wash and a repaint to a genuine mechanical rebuild. Protect yourself by asking two things: what exactly was replaced or repaired, and how is the machine graded?

A transparent grading system looks like this:

Grade	What it means
A	Fully refurbished: worn parts replaced (itemised list), hydraulics and electrics serviced, safety devices tested, repainted, test-run
B	Checked and serviced: tested under power, faults found are fixed, wear items inspected, sold in honest working condition
C	As-is / project machine: basic power-on check only, priced for buyers who will rebuild it themselves

The grade is only meaningful if the refurbishment list is published per machine. At MoldMach every unit carries an A/B/C grade with its list on its own page — browse the current stock on our machines page, for example a Nanhua YH178 (178T) or a LOG 160-S8 (160T). The paper trail is what you are paying for: the list is the proof that a refurbished machine’s higher price is real.

Step 6: Ask the Seller These 10 Questions

1. Can you send a clear photo of the nameplate (model, year, serial number)?
2. Is the price for this exact stock number, or a range for several machines?
3. What is included in the test — dry cycle, purge, production trial?
4. Can I see the unedited test video of this unit, with the stock number visible?
5. What was refurbished? Can I have the itemised list?
6. What grade is this machine, and what does that grade include?
7. What warranty do you offer, and which parts does it cover?
8. What voltage and frequency is the machine wired for? (380V/50Hz is standard in China; many export markets need 60Hz or different voltage.)
9. What is included in the price — packing, loading, spare parts, manuals?
10. What are the payment stages, and when exactly is the production trial done?

A seller who answers these directly is a seller you can work with. Evasive answers are also an answer.

Step 7: Packing, Loading and Shipping Basics

A machine that tests perfectly can still arrive damaged if packing is an afterthought. For sea shipment, expect: rust-prevention treatment on platens, tie bars and the screw; the machine secured and wrapped for container transport; loose parts boxed and labelled. That is what “sea-worthy packing” means — ask what is actually done, and ask for photos or video of loading, with the container number visible. Loading supervision matters: most transit damage happens inside the container, in the first hour.

Also confirm the machine’s weight and dimensions for your freight quote, and that your factory can unload and install it. Sourcing tooling too? Our used molds section can sometimes pair a machine with a suitable mold.

Step 8: Pay in Stages, Never All Upfront

The safe structure in this trade is staged payment: a deposit to reserve the machine and trigger the production trial, then the balance after you have approved the trial and before shipment. It protects both sides: the seller is not running trials for free, and you never pay in full for a machine you have not seen run your product.

Basic hygiene: pay the company account that matches the contract and invoice, keep paperwork consistent (proforma invoice, stock number, serial number), and refuse last-minute requests to redirect payment to a different name or personal account. If an offer requires 100% payment before any test evidence exists, walk away — there are always other machines.

Red Flags: Walk Away When You See These

• Prices far below every other seller for the same model — in this market, a price 50% under the cluster is usually a lead-generation bait price, not a real machine
• Stock photos, or photos that change when you ask for more angles
• No nameplate photo, or a nameplate that doesn’t match the description
• No test video available “until you pay”
• Pressure to decide today because “another buyer is coming”
• A seller who cannot tell you the machine’s stock number, year or serial

The Short Version

Define your tonnage, tie-bar distance and shot weight. Buy the specific machine in the photos, verified by its nameplate. Require a dry-cycle and purge test video, a published refurbishment list with an honest grade, and a production trial with your mold after deposit and before shipment. Pay in stages. Do that, and buying used from China is a rational, low-risk way to expand capacity.

Browse our current machines — every unit has real photos, a grade and a test standard behind it — or message us on WhatsApp at +86 156 0798 6886 or sales@moldmach.com with your target tonnage and product. We reply within 24 hours in English, Vietnamese or Spanish, and ship to Vietnam, Malaysia, Indonesia, the UAE, Mexico and beyond.

Frequently Asked Questions