1. Drawings First
A supplier who quotes from a drawing is quoting your chain. The drawing should define pitch, roller diameter, inner width, plate dimensions, pin diameter, attachment spacing, hole size, and special features. A catalog page or model number may be enough for common chain, but it is risky when sprockets, guide rails, or take-up limits are fixed. Send the current revision and ask the supplier to confirm every dimension they will manufacture to.
Require the supplier to note deviations, standard tolerances, or proposed alternates before quoting. This gives you a basis for incoming inspection and avoids later arguments about "equivalent" chain. For attachments, get a detail view: position, bend angle, hole diameter, and material thickness affect fit and fatigue life. The quote should list the drawing number and revision it is based on.
2. Material Certificates
Ask what steel grade goes into pins and plates. The answer should be specific: 40Cr, 45#, 20CrMnTi, 304, 316, or another named grade. "High-quality steel" is not a grade. Pins usually need hardenable alloy steel; plates may be carbon or alloy steel depending on load and corrosion. Bushings and rollers may use case-hardening or stainless steel. The grade must match the application, not just the drawing.
Ask whether material certificates ship with the batch. Certificates should identify heat number, grade, chemical composition, and mechanical properties. They should trace to pins, plates, bushings, and rollers. For critical conveyors, request mill or supplier certificates with the heat number recorded on the batch. A generic "steel" certificate or one from a different heat number does not verify your order. The certificate is not a substitute for testing, but it is evidence that input material is controlled.
3. Heat Treatment Control
Pins and bushings must be hardened in a controlled process. Wear life depends on hardness and case depth, not just base steel. A pin that is too soft wears quickly and may bend. A pin that is too hard or brittle may crack under shock loads. Heat treatment must be specified, monitored, and recorded.
Ask for hardness data, not adjectives. "Heat treated" or "hardened" tells you little. You need target hardness range, measured values, and test location. For pins, specify surface HRC and case depth. For bushings, inner and outer surfaces may differ. For critical applications, agree on sampling frequency and testing requirements before ordering. Furnace calibration, quench medium, tempering temperature, and holding time also matter. If heat treatment is outsourced, ask who does it and how results are recorded.
4. Test Reports
Ask whether tensile test reports are available and how often they are issued. The report should show breaking load of a representative sample or component, test standard, test date, and batch number. A tensile report verifies that the tested sample met the required minimum breaking load — it does not by itself prove fatigue life, wear life, or the allowable working load, which must be established separately with a safety factor. If no tensile documentation is available, consistency cannot be verified.
100% finished-product inspection is better for critical applications. That may include pitch, pin diameter, plate thickness, attachment position, and roller rotation. It may also include proof load testing or magnetic particle inspection of pins. Ask how samples are selected. A test on a specially prepared sample is not the same as a test on production chain. The report should include actual measured values, not just pass/fail. A catalog tensile value is a design guide, not batch evidence.
5. Sample Policy
A factory confident in its chain will cut a sample length for approval. MOQ 1 meter is reasonable for many conveyor chains, especially when material and tooling already exist. A sample lets you check pitch, articulation, pin retention, attachment fit, surface finish, and marking. It also lets you compare the sample to the drawing and test report.
The sample should be from the same production process and material as the future order. A hand-made sample or one from a different batch is not representative. Ask for the sample batch number and material certificate reference. If the supplier refuses a sample or requires a large minimum order before approval, treat it as a risk. After approval, seal or photograph the sample with dimensions recorded. Future shipments should match within agreed tolerances. If material, heat treatment, or tooling changes, require a new sample.
Red-Flag Phrases in Supplier Quotes
- "We use high-quality steel." Not a grade, heat number, or certificate. Ask for specific grade and traceability.
- "Heat treated for long life." Not a hardness range or case depth. Ask for HRC values and test locations.
- "Tensile test report available if needed." Ask how often reports are issued and whether they reference your batch. Vague availability is worth clarifying before ordering.
- "Sample not possible; MOQ is 100 meters." A 1-meter approval sample is often practical. Refusal may signal inability or unwillingness to be inspected.
How to Read a Test Report (Tensile/Hardness)
A tensile report should identify sample, batch, standard, and equipment. Look for actual breaking load in kN or N and whether failure occurred in chain, pin, plate, or attachment. Compare it to required minimum breaking load and design working load. Do not confuse breaking load with working load; the safety factor is applied separately. Check that the report matches your pitch, plate thickness, and pin diameter.
A hardness report should state scale, such as HRC, HV, or HB, and test location. For pins, check surface hardness and, if specified, case depth. For plates, check whether hardness is required and where it was measured. A single reading on one part is weak evidence. A useful report shows multiple readings, average, range, and specification limits. "Hardened" or a catalog value is not a batch-specific test report.
Sample Approval Checklist
- Sample length matches requested size and includes an attachment if applicable.
- Pitch, roller diameter, inner width, pin diameter, and plate thickness measured against drawing.
- Attachment position, hole size, bend angle, and orientation verified.
- Pin retention, cotter pin, riveting, or press-fit checked.
- Articulation free without excessive radial play.
- Surface finish, markings, and batch identification recorded.
- Hardness and tensile reports referenced to sample batch.
- Approved sample sealed, photographed, and signed by engineering and quality.
- Change notification requirement agreed with supplier.
RFQ Template Fields List
- Chain type, pitch, and standard.
- Drawing number and revision.
- Material grades for pins, plates, bushings, rollers, and attachments.
- Heat treatment requirements: hardness range, case depth, test method.
- Tensile strength requirement and test standard.
- Dimensional tolerances and critical dimensions.
- Attachment details and quantity per pitch.
- Surface treatment or coating.
- Batch traceability and certificate requirements.
- Test report requirements: per batch, per shipment, or 100% inspection.
- Sample policy and MOQ for approval sample.
- Packing, marking, and delivery requirements.
- Required approval documents before production.
- Change notification and deviation approval process.
Approving a conveyor chain supplier should be based on evidence: drawings, certificates, hardness data, test reports, and a physical sample. If any are missing, the quote is incomplete. Fix the gaps before the first order, not after the chain fails on the conveyor.