A used circular knitting machine is not a bargain simply because its purchase price is below a new machine quotation. The commercial decision depends on what is included in the refurbishment, which measurements are documented, how the machine is commissioned, and who carries the risk when the first production trial fails.
For a buyer, the right question is not “What is the machine price?” It is “What condition is being transferred, what evidence supports that condition, and what acceptance tests protect the production plan?” This guide turns that question into a practical inspection and commissioning checklist.
The cost figures below are planning categories, not quotations. Final cost depends on machine make, diameter, gauge, age, control system, shipment condition, local labor, replacement-part availability and the supplier’s warranty scope.
Define the machine before discussing refurbishment cost
Ask the supplier to identify the machine with more than a model name. A usable identity record should include:
- Manufacturer, model, serial number and manufacturing year.
- Cylinder diameter, gauge, number of feeders and fabric system.
- Controller, inverter, motor, encoder and electrical cabinet versions.
- Needle, sinker, cam, yarn-feeder and lubrication-system part numbers.
- Last production date, storage conditions and previous overhaul records.
- Current photos of the cylinder, dial, cam tracks, feeder area, frame, cabinet and safety devices.
This record prevents a common procurement mistake: comparing a refurbished machine with an incomplete specification against a new-machine quotation with a complete scope. It also gives the buyer a baseline for checking replacement parts after delivery.
A buyer evaluating needle and component condition can use the circular knitting machine needles technical guide as a terminology reference, but the supplier’s drawing and machine-specific parts list must control the final decision.
Inspection scope: five evidence groups
1. Frame, cylinder and mechanical alignment
Inspect the frame for cracks, repaired welds, corrosion, loose mounting points and signs of distortion. Record the condition of the cylinder, dial, needle beds, sinker rings and cam boxes. The supplier should state which surfaces were cleaned, ground, replaced or left untouched.
Do not accept a general phrase such as “precision checked” without a measurement record. Ask for the instrument used, measurement location, date, operator and acceptance limit. Where a geometric check is relevant, the test method should be agreed before the machine is dismantled. ISO 230-1 is a useful reference for the discipline of documenting geometric accuracy tests, but it is not a circular-knitting acceptance specification.
2. Needles, sinkers and cam tracks
Request a sample inspection of needles and sinkers from several sectors rather than one visually clean area. Look for hook wear, latch movement, butt damage, corrosion, burrs and uneven replacement patterns. On cam tracks, inspect the working surface, fasteners, alignment, coating condition and evidence of local overheating.
The supplier should classify parts as:
| Classification | Meaning for the buyer | Required evidence |
|---|---|---|
| Reused | Original part retained after inspection | Inspection record and acceptance limit |
| Reconditioned | Cleaned, adjusted or repaired | Process description and final check |
| Replaced | New or approved replacement installed | Part number, batch and supplier record |
| Exception | Known defect accepted temporarily | Written deviation and expiry/action |
The table matters because “refurbished” can mean a clean exterior with unchanged wear parts or a documented mechanical overhaul. Those are different risk profiles.
3. Drive, control and electrical cabinet
Run the motor and drive through the operating range specified for the machine. Record start-up behavior, alarms, current trend if available, speed stability, emergency-stop response and controller fault history. Check cabinet fans, filters, terminals, grounding, cable insulation and spare drive availability.
If an encoder or controller has been replaced, request its compatibility record. The replacement must match the electrical interface, feedback protocol, resolution, mounting arrangement and control parameters. A machine that turns during a bench test can still fail when the control loop is loaded by production yarn and fabric tension.
4. Yarn feeding, lubrication and pneumatic functions
Inspect yarn feeders, positive-feed settings, belts, tension elements, oil lines, filters, pumps and reservoirs. Record the oil specification and cleaning method. The circular knitting machine oil specification guide can help align terminology, but the machine manufacturer’s manual and the supplier’s approved lubricant list should remain the controlling references.
Check every pneumatic or electrical actuator under the same sequence used in production. A static “on/off” demonstration is not enough if the machine uses repeated selection, tuck, plating or jacquard functions.
5. Safety and documentation
The refurbishment scope should include guards, interlocks, emergency stops, warning labels, electrical drawings, manuals, recommended spares and a maintenance schedule. Ask which safety devices were tested and whether any have been bypassed. A buyer should not accept a machine that requires operators to defeat a guard or silence an alarm to maintain production.
Commissioning and acceptance sequence
Use a staged acceptance plan instead of accepting the machine immediately after power-on.
- Document review: Confirm serial number, parts list, manuals, drawings, open deviations and shipment photos.
- Cold inspection: Check frame, fasteners, guards, lubrication levels, cable routing and visible damage before energizing.
- Dry run: Operate the machine without production yarn. Record alarms, noise, vibration, speed control and emergency-stop behavior.
- Yarned run: Use the agreed yarn and a controlled low-speed start. Check feeder stability, needle action, oil delivery and fabric take-down.
- Sample fabric: Produce a defined length or weight of fabric under agreed settings. Record gauge, yarn, speed, stitch settings, defects and operator actions.
- Reliability run: Run for an agreed continuous period or production quantity. The duration is a contract term, not a universal industry number.
- Punch list: List open defects, responsible party, due date, replacement part and acceptance impact.
- Final sign-off: Transfer passwords, drawings, spare parts, training records and warranty start date only after critical punch-list items close.
A useful acceptance form separates “machine runs” from “machine produces acceptable fabric.” The second statement requires a defined fabric specification and defect criteria.
Refurbishment cost model for a buyer’s RFQ
Instead of asking for one lump-sum refurbishment price, request separate lines for:
- Inspection and condition report.
- Mechanical overhaul and alignment.
- Needles, sinkers, cams and feeder replacements.
- Drive, controller, encoder and electrical work.
- Lubrication-system cleaning or replacement.
- Guards, interlocks and safety testing.
- Trial fabric, commissioning labor and operator training.
- Packaging, freight, installation and local service.
- Recommended critical spares and warranty extensions.
This structure makes quotations comparable. It also prevents the supplier from hiding an essential replacement item inside a vague “service package.” For total ownership planning, compare the refurbished machine with the used versus new circular knitting machine TCO comparison and add the cost of downtime, installation delay and training.
Supplier comparison checklist
| Question | Supplier A | Supplier B | Supplier C |
|---|---|---|---|
| Serial-numbered inspection report supplied? | |||
| Replacement parts listed by part number? | |||
| Electrical and control compatibility documented? | |||
| Trial fabric and acceptance criteria included? | |||
| Warranty response and exclusions stated? | |||
| Critical spares available after delivery? | |||
| Installation and training included? |
Ask each supplier to answer in the same format. A lower quotation is not comparable if it excludes commissioning, controls, safety restoration or the first set of critical spares.
Frequently Asked Questions
Is a used machine acceptable for high-volume production?
It can be, but acceptance depends on documented condition, parts availability, controls compatibility, trial-fabric results and service response. Production volume alone is not a reason to reject or accept a used machine.
Should the buyer replace all needles during refurbishment?
Not automatically. Replace based on inspection evidence, wear distribution, machine history and the agreed fabric requirement. A blanket replacement may be wasteful; retaining unknown wear without evidence creates avoidable risk.
What should happen when a supplier refuses a trial run?
Treat the refusal as a commercial risk. Request a written explanation and an alternative acceptance mechanism, such as a witnessed video test, third-party inspection or conditional payment milestone. Do not convert an untested machine into an unconditional acceptance.
How should warranty start?
Define whether warranty starts at shipment, installation, commissioning or final acceptance. For a used machine, final acceptance after the agreed production trial is usually the clearest commercial milestone, subject to contract review.
Conclusion
Used circular knitting machine refurbishment is a controlled engineering and procurement decision, not a cosmetic cleaning service. A buyer protects the project by defining machine identity, separating reused and replaced components, recording measurements, testing controls and safety devices, producing agreed sample fabric and linking payment to acceptance evidence.
The most useful RFQ asks for a condition report and acceptance plan before it asks for a discount. That approach makes refurbishment cost visible, gives maintenance teams a usable baseline and reduces the risk that an apparently cheap machine becomes an expensive production interruption.
References
This industry report is used for the service-network and spare-parts continuity context; it does not define a universal refurbishment standard.
This standard is referenced for disciplined measurement records and test documentation, not as a circular-knitting acceptance limit.
This official page provides context on product lifecycle information, repairability, reuse and recycling data.
This internal technical guide supports consistent terminology for needles and component selection.
This internal resource provides a related total-cost comparison framework for procurement planning.