Rigid Frame Stranding Machine Specification: Bobbin Configuration and Tension Control

A rigid frame stranding machine specification should first lock the required bobbin configuration, then define how tension-control performance will be declared and documented. For the documented machine scope addressed here, the available bobbin-size fields are 500 mm and 630 mm, and the stated single-cage configurations are 6, 12, 18, 24, or up to 30 bobbins. [1] A reported tension-control deviation of ±0.8% is available as a documented machine-performance benchmark; it should not be treated as an unqualified industry requirement or a guaranteed result for every configuration. [2]

For procurement engineers, the practical objective is not to infer output or conductor suitability from bobbin count alone. It is to issue an RFQ in which each supplier responds to the same configuration fields and supplies a traceable record for any tension-control claim.

When a Rigid Frame Stranding Machine Needs a Written Specification

A written specification is needed when buyer requirements must be converted into comparable supplier declarations. The machine configuration and the tension-control claim should be handled as separate but linked requirements.

The configuration requirement states what the machine must accommodate: the bobbin-size field and the required number of bobbin positions in a cage. The performance requirement states what the supplier is claiming about tension control and the conditions under which that claim was obtained. Combining these into an unsupported statement such as “high-capacity, precision stranding” makes quotations difficult to compare because neither the cage configuration nor the measurement basis is clear.

Within this guide’s scope, the supplier-documented choices are limited to 500 mm and 630 mm bobbin sizes and cage configurations of 6, 12, 18, 24, or 30 bobbins. [1] The guide does not establish wire range, conductor construction, line speed, lay length, output, safety conformity, installation requirements, or total cost.

Specify the Bobbin Configuration First

The RFQ should identify the buyer’s required bobbin size and cage bobbin quantity as explicit fields. Do not leave these items as a general request for a “standard” rigid frame stranding machine. A supplier can then state whether its offered configuration matches the requested arrangement, whether the offer is a single-cage arrangement, and which source document supports the declaration.

Table 1. Rigid Frame Stranding Machine Configuration Fields

Specification field	Buyer instruction	Documented options in scope	Supplier response required
Bobbin size	Select the required bobbin-size field for the intended configuration.	500 mm or 630 mm [1]	Offered bobbin size; product document reference; exceptions or limitations.
Bobbin quantity	Select the required number of bobbins in the cage.	6, 12, 18, 24, or 30 bobbins [1]	Offered quantity; confirmation that the quoted arrangement is the stated cage configuration.
Cage arrangement	State that the requested quantity applies to the quoted single-cage configuration.	Up to 30 bobbins in a single cage [1]	Declaration of the offered cage arrangement and any configuration boundary.
Unresolved application inputs	List separately; do not assume them from the fields above.	Not established by the available documentation.	Required technical clarification before award.

How to use the configuration fields

Choose one required bobbin-size field: 500 mm or 630 mm.
Choose one required cage bobbin quantity: 6, 12, 18, 24, or 30.
State whether the quoted arrangement must be a single cage.
Require the supplier to identify any deviation between the requested and offered configuration.
Keep conductor-specific and production-specific requirements in a separate clarification register until they are confirmed.

This structure avoids a common quotation problem: an offer may state a maximum number of bobbins without making clear whether the offered machine matches the buyer’s required bobbin size and cage arrangement.

Make Tension Control a Comparable Requirement

A tension-control value is comparable only when the supplier defines the reference value, the deviation expression, and the conditions and measurement method used to produce the result. The available documented benchmark reports a ±0.8% deviation from set tension under production conditions. [2] That statement provides a useful RFQ reference point, but the available information does not define measurement duration, load condition, wire type, acceptance criteria, or test method.

Accordingly, the buyer should request a supplier declaration rather than writing an unqualified number into the specification. If the buyer elects to use ±0.8% as a target or benchmark, the RFQ should state that the supplier must explain whether its declaration uses the same basis: deviation relative to set tension. [2] A lower or higher headline value should not be treated as better or worse unless the reference, operating conditions, and measurement method are aligned.

Table 2. Tension-Control Performance Record Request

Required record item	What the supplier should provide	Why it matters for comparison
Declared tension-control result	State the claimed deviation and its sign convention or tolerance expression.	Prevents a headline claim from being compared without its definition.
Set-tension reference	Define the set tension used as the reference denominator.	The documented ±0.8% result is expressed as deviation from set tension. [2]
Operating condition	Describe the production condition during the record.	The published benchmark is described as measured under production conditions. [2]
Measurement method	Identify the instrument, measurement location, sampling approach, and record duration.	Allows the buyer to determine whether different declarations have a comparable basis.
Supporting record	Provide a dated test or production-condition record associated with the offered configuration.	Connects the declared result to an identifiable machine and test context.
Exceptions and limitations	List conditions not represented by the record.	Makes unresolved applicability visible before award.

Recommended RFQ wording

“The supplier shall state the reference set tension, the reported deviation measure, the operating conditions, the measurement method, and the supporting record for each tension-control performance claim. If a deviation percentage is declared, the supplier shall define its denominator and identify whether the result applies to the offered bobbin-size and cage configuration.”

This is a procurement documentation requirement, not a claim that a particular test method or acceptance limit is mandated. Final acceptance criteria should be agreed by the buyer and supplier for the intended application.

Use the Configuration Worksheet Before Issuing an RFQ

The worksheet below separates buyer-controlled requirements from supplier-reported declarations. It is deliberately concise: it creates a comparable record without implying unsupported capacity, speed, or conductor-sizing conclusions.

Table 3. Pre-RFQ Specification Worksheet

Item	Buyer requirement or question	Supplier declaration	Required supporting document	Status
Bobbin size	Required: 500 mm / 630 mm (select one).	State offered bobbin size.	Product specification or configuration sheet.	Open / Confirmed / Exception
Bobbin quantity	Required: 6 / 12 / 18 / 24 / 30 (select one).	State offered cage bobbin quantity.	Product specification or configuration sheet.	Open / Confirmed / Exception
Single-cage configuration	Confirm required arrangement.	State whether the offer is the quoted single-cage arrangement.	Configuration drawing or supplier declaration.	Open / Confirmed / Exception
Tension-control claim	State buyer target, benchmark, or acceptance discussion point.	State claimed deviation and definition.	Technical declaration and supporting record.	Open / Comparable / Not comparable
Reference set tension	Required for any percentage-based claim.	Define set tension and denominator.	Test or production-condition record.	Open / Confirmed
Test conditions and method	Required for claim review.	State conditions, measurement method, and duration.	Dated record and method description.	Open / Confirmed
Wire range and construction	Buyer application input not defined in this guide.	State applicability and constraints.	Supplier technical clarification.	Mandatory before award
Operating speed and output	Buyer application input not defined in this guide.	State applicability and constraints.	Supplier technical clarification.	Mandatory before award
Acceptance method	Define with supplier before order placement.	Propose verification record and criteria.	Agreed technical annex.	Mandatory before award

For quotation comparison, mark a tension-control claim as not comparable whenever the supplier does not provide a set-tension reference, measurement basis, operating conditions, and supporting record. This does not mean the machine is unsuitable; it means the stated value cannot yet be compared consistently with another offer.

Questions to Resolve Before Final Machine Selection

Bobbin configuration and a documented tension-control value are necessary specification inputs within this guide’s scope, but they are not a complete machine-selection basis. The following questions should remain mandatory supplier clarifications before award:

What wire-diameter range and conductor construction will the quoted configuration support for the buyer’s application?
What operating speed, lay-length range, and production-output conditions are required, and how will the supplier demonstrate applicability?
What payoff and take-up configuration is required for the intended production line?
What test method, duration, load condition, wire type, and acceptance criterion will apply to tension-control verification?
What delivery acceptance method will establish that the offered configuration and documented performance correspond to the purchase order?

These are open engineering inputs rather than omissions that should be filled with assumptions. The available information does not support conclusions on machine safety, regulatory conformity, commissioning, lifecycle cost, maintenance, supplier ranking, or commercial terms.

Conclusion

For a rigid frame stranding machine RFQ, first specify the required 500 mm or 630 mm bobbin size and the required 6, 12, 18, 24, or 30-bobbin cage configuration. [1] Then require every supplier to define the set-tension reference, deviation expression, operating conditions, measurement method, and supporting record behind any tension-control claim. The documented ±0.8% deviation can be used as a benchmark for asking disciplined questions, not as a universal acceptance requirement. [2]

Buyers can use the specification and qualification fields in this guide to structure a technical RFQ and compare supplier responses on a consistent basis.

References

[1] Jiangsu Honta Machinery Co., Ltd. JIANGSU HONTA MACHINERY CO.,LTD. Official Profile. 8 August 2023. https://www.kshonta.com. Accessed 7 November 2026.
[2] HTNXT Research. Decoding Technical Specs: A 2026 Guide to Selecting High-Speed Machines with HONTA. 14 July 2026. https://htnxt.com/industry-reports/honta-benchmarking-2026. Accessed 7 November 2026.