Who We Partnered With

The end user is a fully integrated textile producer situated in the greater Dhaka area. Founded in the latter half of the 2000s, the facility spans roughly 45,000 m² and employs close to 2,400 staff. Its core business is ring-spun yarn supplied to garment factories that, in turn, serve well-known international fast-fashion labels.

Within the spinning hall, 80 ring-frame machines — each carrying 1,680 spindles — turn out Ne 30/1 carded cotton yarn intended for knitting. Before the overhaul, every frame was powered by a single 37 kW fixed-speed motor tied to a 4-speed mechanical gearbox. Machine tenders changed gears by hand to align spindle speed with the yarn count and draft ratio dictated by each work order.

Collectively, the hall was pushing out about 3,200 tonnes of yarn per year, operating 22.5 hours a day, six days a week, in one of the world’s most cost-sensitive RMG supply chains.

What Was Holding Them Back

In 2023 the mill’s industrial engineering group ran a full production audit. Five chronic issues surfaced, all rooted in the same mechanical gearbox architecture:

• Tension spikes and excessive end-breaks. The 4-speed box offered only coarse steps — 1,200, 1,500, 1,800, and 2,100 RPM. Between those fixed ratios, tenders had no way to dial in the exact twist-per-inch each cotton lot needed. Micronaire and strength variations from bale to bale translated into balloon-tension surges, and those surges snapped yarn ends during doffing and high-speed winding. The mill averaged 8.2 breaks per 1,000 spindle-hours. Each break meant a piecer stopping the frame, hunting the broken end, and re-threading — 45 to 90 seconds lost. Across all 80 machines, that added up to roughly 3.8 hours of lost production per machine every single day.
• Shift-to-shift quality drift. Gear selection was a matter of operator judgment. One tender might choose 1,500 RPM for Ne 30/1; the next shift might run the same count at 1,800 RPM. The resulting lot-to-lot scatter in elongation and U% blew past the ±3% window demanded by premium European buyers, triggering quarterly penalty invoices.
• Power waste baked into the design. The 37 kW motor ran flat-out regardless of how much draft the frame actually needed. During gentle winding cycles and doffing, the gearbox simply burned off surplus energy as heat and friction. Load monitoring showed the motor averaging only 58% of its rated capacity, yet the meter kept spinning at full speed. Annual electricity for the spinning hall alone hit $186,000 at $0.09/kWh — an intensity of 1,850 kWh per tonne of yarn.
• Maintenance eating into margins. Clutch packs, dog gears, and sliding splines needed grease every 200 hours and replacement every 18–24 months. The shock loads from each gear engagement also rattled the spindle rails, forcing a re-leveling exercise every six months. Gearbox upkeep alone cost $24,000 a year, and unplanned failures stole another 340 machine-hours annually.
• Noise and compliance pressure. Gear-mesh noise at the housing registered over 82 dB(A) at the tender’s standing position, adding fatigue and complicating adherence to Bangladesh’s factory noise rules under the Labour Act, 2006.

The AnyHz Approach

After a competitive tender that drew proposals from three inverter vendors, the mill’s technical committee chose the AnyHz FST-650L flux vector series for the full 80-machine rollout. The deciding factors were a proven track record in Indian and Vietnamese spinning plants, precise low-speed torque holding, and the availability of Bengali-speaking field engineers through AnyHz’s Dhaka service channel.

Closed-loop flux vector control. Running in full vector mode with encoder feedback, the FST-650L holds ±0.02% speed accuracy and reacts to torque demand in under 5 ms. That means the drive can lock spindle RPM precisely even as the yarn balloon’s tension oscillates while the cop grows from empty tube to full bobbin.

Recipe-driven speed management. Every yarn count from Ne 20/1 through Ne 40/1 is stored as a named recipe on the HMI. Selecting a recipe automatically sets base spindle speed, front-to-back draft ratio, target twist-per-inch, and S-curve acceleration ramps (8 seconds to avoid yarn shock). Doffing speed drops to 30% for safe operator access. The days of manual gear shifting — and the human error that came with them — are gone.

Active tension compensation. A dancer-arm position sensor feeds the FST-650L’s tension control loop. As the cop diameter swells from 25 mm to 280 mm, the drive trims spindle RPM to hold constant surface speed and yarn tension — a trick no mechanical gearbox can perform.

Soft-start and shock absorption. Electronic ramping replaces the abrupt mechanical clunk of gearbox engagement. Inrush current falls from 6× rated to 1.2×, and peak torque transients at start-up drop by 70%, directly extending bearing life.

Intelligent load management. During doffing, cleaning, or sliver-feed interruptions, the drive slips into energy-saving V/F mode, cutting magnetizing current when full torque is not needed. If the feed stops for more than 90 seconds, sleep/wake logic pauses the inverter entirely.

How We Rolled It Out

AnyHz’s authorized Bangladesh partner staged the work in three waves to protect committed garment-industry delivery schedules.

Pilot — Weeks 1–4. Eight machines in Line A were converted first. Vector parameters were commissioned, dancer-arm PID was tuned, and recipe storage was validated. Six maintenance technicians and twelve machine tenders received hands-on training. For two weeks, four VFD machines ran side-by-side with four legacy gearbox machines, giving the mill a live A/B benchmark.

Production rollout — Weeks 5–14. The remaining 72 frames were converted at a pace of eight per week. All work was confined to Friday afternoon changeovers and Saturday maintenance windows. Each retrofit followed the same sequence: motor decoupling, gearbox removal, encoder mounting, inverter panel installation, parameter download, and a four-hour production trial before sign-off.

Fine-tuning — Weeks 15–18. Tension PID was optimized across the full cotton mix, from local short-staple to imported US upland. The Modbus data stream was integrated into the mill DCS for real-time OEE dashboards. Standard operating procedures and emergency fault-response protocols were documented and posted.

The Numbers After 12 Months

Data was gathered from January through December 2024 and stacked against the 2023 pre-retrofit baseline.

Production & Quality

The 15.2% output jump was achieved with no increase in operating hours. The drop in end-breaks alone clawed back roughly 2.9 productive hours per machine per day that had previously evaporated into piecing downtime.

Energy & Operating Cost

Financial Summary

Environmental Impact

At Bangladesh’s grid emission factor of 0.65 kg CO₂/kWh, the project avoids roughly 312 tonnes of CO₂ per year — the equivalent of taking 68 passenger cars off the road for 12 months.

In the Client’s Words

Why the Committee Chose AnyHz

Four points tipped the decision:

1. 1. Textile-proven firmware. AnyHz had already placed more than 600 FST-650L units in Indian and Vietnamese spinning operations, with published field data for both ring-frame and open-end rotor applications.
2. 3. Standalone recipe storage. The FST-650L stores 16 recipes internally, expandable through the HMI, letting the mill standardize every yarn count without buying an external PLC or hiring a programmer.
3. 4. Lower lifetime cost. A European-branded drive with comparable vector performance was priced 2.3× higher, and its regional spare-parts pipeline stretched past eight weeks. AnyHz’s Singapore hub guarantees 72-hour component delivery.