Bonnell Spring Coil
- Hongjiabin
- Henan
- Determined by the order quantity
- 100000 pcs/month
1. Bigger diameter at the two ends and the smallest one in the middle, this shape offers a powerful vertical support upon being compressed. The material did not deform even after 100,000 durability tests.
2. The diameter of the main spring wire ranges from 2.0 to 2.4 mm, and it is subjected to 260°C high-temperature tempering to eliminate the internal stress, resulting in a long-lasting, stable elasticity.
3. Each spring unit is linked with serpentine steel wire, forming an entire support network with precise force distribution.
Product Introduction:
Many buyers grapple with ±0.1mm wire tolerance and > 3 mm height variation in basic Bonnell springs. Such inconsistencies in firmness (ILD variation >12%) cause a lot of guest complaints, and the return rate is 15-20% higher. Besides that, bad stress relief results in spring fatigue within 5 years, thus raising your warranty costs.
Our Bonnell springs feature a wire gauge tolerance of ≤ ±0.05 mm and a height variation of < 1.5 mm (which is 30% more stringent than industry standards).
You want foam coils that work stable, batch after batch.
We stress-relieve every coil at 260°C. Then we test it with automated load-deflection machine.
Here is the data.
ILD difference is below 6% between batches. Load loss is only <6% after 80,000 cycles. That beats ASTM standard. Anti-friction coating cuts squeaking by 40%.
So for hotel or bulk bedding with high turnover, you get consistent stack height. Fewer sagging complaints. And reduced logistics cost.
ISO 9001 certified.
Core Advantages:
| Comparison Item | Standard Bonnell Springs (Generic) | Our Bonnell Springs | Your Benefit |
|---|---|---|---|
| Wire Gauge Tolerance | ±0.1mm (common industry) | ≤ ±0.05mm | Consistent firmness across all batches |
| Height Variation | ±3mm – ±5mm | < 1.5mm | No uneven mattress surface; less foam needed |
| Heat Treatment | Basic tempering | 260°C stress-relief + slow cooling | Longer spring life, lower sagging risk |
| Load Loss (Durability) | 10–15% after 50k cycles | < 6% after 80k cycles | Fewer warranty claims; better for hospitality |
| Noise / Squeaking | No coating (metal-on-metal) | Anti-friction coating (40% quieter) | Silent compression, premium mattress feel |
| Quality Testing | Random sampling | 100% automated load-deflection test | Every spring is verified, not just a sample |
| Customization | Limited (fixed height/gauge) | Height 50–200mm, wire 2.0–2.4mm | Perfect fit for your mattress design |
| Certification | None or generic ISO | ISO 9001 + cycle test report available | Traceability and audit-ready documentation |
Technical Specification
| Category | Parameter | Standard Value / Range | Our Typical Tolerance / Performance |
|---|---|---|---|
| Dimensions | Wire Diameter (Gauge) | 2.0 mm – 2.4 mm (BWG 13–8) | ≤ ±0.05 mm |
| Outer Diameter (OD) | 65 mm – 85 mm (custom up to 100 mm) | ≤ ±0.8 mm | |
| Inner Diameter (ID) | 45 mm – 65 mm (matched to OD) | ≤ ±0.8 mm | |
| Free Height | 80 mm – 220 mm (custom available) | ≤ ±1.5 mm | |
| Number of Coils | 4 – 7 turns | ±0.25 turn | |
| Pitch (between coils) | Consistent or tapered as design | ≤ ±0.5 mm | |
| Performance | Spring Constant (k-value) | 0.8 – 2.5 N/mm (depending on wire/height) | ≤ ±6% batch-to-batch |
| Load at 50% compression* | 80 N – 250 N (configurable) | ≤ ±7% | |
| Solid Height | Calculated per design | ≤ ±1.0 mm | |
| Maximum Deflection | 60% – 70% of free height | N/A | |
| Durability | Load Loss after 80k cycles | — | < 6% |
| Height Loss after 80k cycles | — | < 2% | |
| Fatigue Test Standard | ASTM or EN 1957 (optional) | Pass | |
| Material | Steel Type | High-carbon spring steel (72A/82B) / Oil-tempered | Optional: Zinc-plated / Epoxy-coated |
| Surface Treatment | Clean, minimal scale | Anti-friction coating available | |
| Quality | Testing Method | 100% automated load-deflection | Report available per batch |
| Certification | — | ISO 9001:2021 |
Custom Services:
The above values are standard ranges. We also support:
Tapered Bonnell springs (smaller top OD, larger base OD)
Pre-set load requirements (specify target load at XX mm compression)
Anti-squeak coating thickness (adjustable by request)
We customize the thickness of wire, the height of the spring and the type of edging. These changes can be done with the consideration of the specification of the load and mattress core sizes. For large orders, customers can negotiate the packing style, whether it is a bundle or the whole pallet. Our expert R&D team is always ready to support and assist you from the first stage of spring selection to the final stage of structural improvement.
ABOUT US
Hongjia Bin was established in 2002 and since then they focus on mattress spring innovation and production for 20+ years. They employ 168 staff and have a 58,000 m2 plant with >20 varieties of professional machines, running an automation level above 95%. We possess an independent spring R&D unit and fully automated spring coiling machines, so we produce the whole product chain from raw material conversion to end mattress spring units. We are exporting our goods to more than 20 countries, among them US, Canada, South Africa, Turkey, Southeast Asia & Middle East, and supplying more than 200 international clients.
Our Quality Testing Certification
Hongjiabin springs have received SGS certification and they have been tested according to the standards of material composition, tensile strength, and durability.
Our Quality Certification
Environmental Management System Certification No. :17723 EU0066-10ROM
China Environmental Labeling Product Certification No. :CEC2024ELP4225104
China Green Product Certification No. :COM236GPP004397
Manufacturing Process:
We specialize in mattress spring R&D and production. To this end, we have a complete set of fully automated spring winding machines and integrated spring production lines, enabling us to be highly efficient and productive. The spring manufacturing process starts with a very precise winding operation by which each coil is interconnected with serpentine helical wires ensuring the least possible stress of the metal compared to the old designs of springs. Then the springs are subjected to a high-temperature tempering treatment that enhances their elasticity and resistance. The quality of the supply is secured by proper control of the spring dimensions and the uniform rebound throughout all processes.
Thus, each individual piece is tested for uniformity. On a monthly basis, we manufacture 30,000 mattress cores and 100,000 springs. The number of order deliveries that remain stable exceeds 300,000 every year. In support of this, we have carried out SGS inspections on all our products to ensure quality that can be traced and controlled.
Logistics and Shipping:
Delivery Time: Normally 25-35 days after finalizing the order details, excluding any changes due to order volume.
Shipping Methods: Customer voice determines the mode of shipping, i.e., sea, rail, or land.
Packaging: Bundle or pallet packaging, tailored according to the quantity of order.
Sales Reach: Our products find a way into more than 20 countries, including the US, Canada, South Africa, Turkey, Southeast Asia, and the Middle East.
Payment Terms: Payment by wire transfer, 30% advance deposit, and the balance 70% payment against the delivery.
After-Sales Service:
15-year warranty for manufacturing and material faults (assuming normal usage)
Full traceability of each batch – every spring lot is accompanied by the complete production and test documentation
Handling of defects: Replacement or monetary compensation following inspection by an independent third party
Round-the-clock remote technical assistance for installation and troubleshooting
Customized upkeep schedules offered for long-term relationships
Sample Policy
If you want to check the quality of our product, you can request a free sample and we will send it to you, but please note that you,
as the buyer, will have to cover the shipping cost.
Samples made to order (according to your specifications) – time for lead 7–10 days, price can be discussed
Production sample before mass order – available upon request
Exhibitions:
In 2024, we attend two big building material fairs: the Seoul International Building Materials Expo in South Korea and Almaty Construction Expo in Kazakhstan. At the Seoul event, our main goal will be to present our bonnell spring and mattress spring technology, and have in-depth discussion with local mattress manufacturers. For the Almaty Expo, we will mainly show our bulk customization abilities and the technology behind it, and meet with engineering clients from Central Asia. Through these fairs, we will get more familiar with the East Asian and Central Asian markets and increase our exposure there.
