Bengali
Case Study: Replacing Mercury UV with CG-CT2 1000W Water Cooled LED UV Lamps
Client Background
The client is a label and flexible packaging converter running two 8-colour flexo presses and one intermittent label press for self-adhesive labels, shrink sleeves and food packaging films. Their product mix includes thin BOPP and PE films with heat sensitive substrates, and roughly 40% of orders are short runs below 5,000 metres, which means frequent lamp cycling and high changeover losses.
The Challenge
The existing curing station used two 3 kW mercury (UV arc) lamps per press. The converter faced four recurring problems:
- Energy cost: mercury lamps drew about 6 kW per press continuously, because they cannot be switched off between jobs without a long re-warm cycle.
- Heat damage: substrate surface temperature reached 70°C at the curing station, causing film shrinkage and registration drift on thin shrink sleeves.
- Short lamp life: mercury tubes were replaced every 800-1,000 hours, each change requiring downtime, cooling and re-focusing of the reflector.
- Quality rejects: inconsistent UV dose at higher line speeds caused tacky surfaces and blocking in the rewinder, with a scrap rate of around 3.2%.
The Solution: CG-CT2-400x40-1000W Water Cooled LED UV Lamp
After a line audit, we recommended replacing each 3 kW mercury head with a CG-CT2 1000W water cooled LED UV curing lamp, mounted in the same position with an adapted bracket and water manifold. The CG-CT2 uses a 400x40mm wide beam emitting window, delivering 16-18 W/cm² at a 30-50mm working distance, with 0-100% dimming through a 0-10V signal tied to line speed.
Key configuration points of the retrofit:
- Two CG-CT2 1000W heads per press, giving 2,000W installed against 6,000W of mercury power.
- 395nm wavelength selected for the client's acrylic and cationic UV inks, with one 385nm spare head for deep-pigment white ink jobs.
- Instant on/off control, so lamps switch off during make-ready and wash-up instead of idling.
- A closed loop chiller at 22°C and 2.5 L/min flow per head, with a flow switch interlocked to the press.
- Dose tracking: the PLC raises lamp output automatically as line speed increases, keeping the UV dose constant from 40 to 90 m/min.
Before and After
| Performance item | Before (mercury UV) | After (CG-CT2 LED UV) |
|---|---|---|
| Installed UV power per press | 6,000 W | 2,000 W |
| Energy consumption at curing station | Baseline | 62% lower |
| Substrate surface temperature | About 70°C | About 42°C |
| Maximum line speed | 60 m/min | 90 m/min |
| Lamp service life | 800-1,000 hours | 20,000 hours rated |
| Scrap rate on thin film jobs | 3.2% | 1.1% |
| Warm-up and restart time | 2-5 minutes | Instant |
Results After Six Months of Production
Two presses ran the CG-CT2 retrofit for six months of two-shift production. Measured results were:
- 62% lower electricity consumption at the curing station, equivalent to roughly 26,000 kWh saved per press per year.
- 65% reduction in scrap on thin film and shrink sleeve jobs, because surface temperature dropped by about 28°C and dose stayed stable at high speed.
- 50% higher output on short runs, since lamps reach full intensity instantly with no warm-up and no shutter delay.
- Zero lamp replacements in the period, against an expected 5-6 mercury tube changes previously.
- No ozone extraction required, allowing the converter to remove one exhaust fan and reduce plant noise.
Payback on the retrofit was calculated at roughly 14 months on energy and scrap savings alone, before counting extra capacity released by higher line speed.
Why the CG-CT2 Was Selected
Three factors decided it. First, the 400x40mm wide beam covers the full 350mm print width of the label press with a single head, avoiding alignment loss between two narrow lamps. Second, water cooling held the LED junction temperature flat during 12 hour shifts, so irradiance did not fade between the first and last job of the day. Third, dimming by 0-10V allowed the converter to run light-coverage jobs at reduced output, which further lowered energy use on short runs.
Client Comment
"The biggest change is not the energy bill, it is that we stopped worrying about heat. Shrink sleeve jobs that used to distort now run at 90 metres per minute without registration drift. Installation took one weekend per press and the water connections were plug and play."
Scope for Further Projects
The converter is now evaluating the higher power CG-CT3 1500W model for a wide web flexo line, where a 400x30mm window at higher irradiance suits thick coating and adhesive lamination above 100 m/min. Both models share the same water cooling loop and control interface, so spares and training carry over.
Talk to Our Engineers
If your press still runs mercury UV lamps or you need faster curing on heat sensitive film, send us your press width, line speed, ink type and current lamp power. Our engineers will return a comparison of CG-CT2 and CG-CT3 configurations, energy estimate and payback calculation within one working day.