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Fully Automated Electrophoretic Coating (E-Coat) Line

MOQ:	1
Price:	USD2000-USD10000/SET
Standard Packaging:	With regular Film and Carton
Delivery Period:	15 DAYS After Deposit
Payment Method:	T/T
Supply Capacity:	500SET/MONTH

Detail Information

Product Description

Detail Information

Place of Origin

China

Brand Name

CoatTech

Certification

Model Number

CT-ED-7200

NAME:

Fully Automated Cathodic E-Coat Line

Power Supply::

220V/50HZ/1Ph Or Other Option

Using Energy::

Electric Or Other Option

Motor::

Chinese Brand Or Import Brand

Control Sytem::

Switch Style Or PLC Touch Screen Control

Color::

White Or Other Option

Application::

Metallic Products

Dimention::

As Require

Product Description

Fully Automated Electrophoretic Coating (E-Coat) Line

Continuous cathodic E-coat for automotive chassis components — 72 m overhead conveyor line,

| Location: P*****d, Central Europe | Client name withheld under NDA

PROJECT AT A GLANCE

Item	Detail
Client	Tier-2 manufacturer of automotive chassis and suspension components (stampings and welded assemblies)
Workpieces	Control arms, spring seats, subframe brackets, cross-member reinforcements, seat-frame stampings
Substrate	Cold-rolled steel, hot-rolled pickled steel, some zinc-coated brackets
Max. workpiece envelope	1,200 × 800 × 600 mm · max. 45 kg per hanger
Process	7-stage immersion pre-treatment → cathodic electrophoretic deposition (CED) → 3-stage UF counterflow rinse → DI rinse → drain + air blow-off → gas-fired convection cure
Line configuration	Single-loop overhead chain conveyor, continuous, fully automatic, load/unload only manual
Conveyor path / footprint	72 m process path · 72 m × 11 m installed footprint
Chain speed	0.4 – 2.0 m/min (VFD, stepless), nominal 1.2 m/min · hanger pitch 400 mm
Design throughput	180 pcs/h · 2,880 pcs/day (2 shifts) · 720,000 pcs/year (250 working days)
Dry film thickness	20 ± 3 μm (measured mean 20.3 μm, range 18.4 – 22.1 μm)
Cure schedule	Metal temperature 175 ± 5 °C for 25 min (3-zone gas convection oven, 900,000 kcal/h)
ED tank	30 m³ working volume, cathodic epoxy dispersion, 316L tubular diaphragm anodes
Utilities	Installed power 480 kW · natural gas 900,000 kcal/h · DI water 2 m³/h · compressed air 6 bar
Manning	2 operators per shift (load / unload) + 1 process technician per day
CoatTech scope	Process design, manufacture, FAT, shipment, installation, commissioning, operator training, 12-month process support
Project timeline	Contract Nov 2025 → engineering 4 wks → fabrication 10 wks → FAT 1 wk → installation 6 wks → commissioning 3 wks → SOP Mar 2026

01 THE CHALLENGE

The client supplied control arms, spring seats and subframe brackets to two European OEM assembly plants. All parts were finished on a manual air-spray line with a solvent-borne two-component primer: six sprayers per shift, two shifts a day. The line had become the constraint on the whole plant, and — more seriously — the source of a recurring quality dispute with its customers.

Five problems had to be solved at the same time:

· Cavities and weld seams were not being coated. Air spray cannot reach inside box sections, hem flanges or the back of weld beads. Salt-spray panels cut from finished parts rusted at 240 h against an OEM specification of 720 h.

· Film thickness scatter. Measured dry film ran 25 – 70 μm depending on operator and part geometry; heavy areas sagged, shadowed areas were starving. Consumption of primer was therefore far higher than the theoretical requirement.

· Capacity ceiling. The manual line delivered 110 pcs/h against a firm customer requirement of 180 pcs/h for the 2026 model year. Overtime and weekend shifts were already running.

· Yield. First-pass yield sat at 90.2%; 9.8% of parts needed rework and 2.1% were scrapped outright, mostly for runs, dry spray and misses.

· Environmental permit. Solvent use put the site at 42.6 t/a of VOC against a permit ceiling that would drop to 5 t/a at the next renewal. There was no credible path to compliance with solvent-borne spray.

Measured baseline before the project

Metric	Manual air spray (baseline)	OEM / permit requirement
Throughput	110 pcs/h	180 pcs/h
First-pass yield	90.2 %	≥ 98 %
Scrap rate	2.1 %	≤ 0.5 %
Dry film thickness	25 – 70 μm (± 22 μm spread)	18 – 25 μm
Cavity / weld coverage	Inconsistent; bare metal in box sections	100 % coverage
Neutral salt spray	240 h (red rust at welds)	≥ 720 h
Paint utilisation	≈ 45 %	—
VOC emissions	42.6 t/a	≤ 5 t/a
Direct operators	12 (6 per shift × 2 shifts)	—
Unit coating cost	€ 1.85 / pc	—

02 WHY CATHODIC E-COAT AND NOT ANOTHER SPRAY LINE

CoatTech evaluated three routes against the client's five requirements — cavity coverage, thickness control, capacity, VOC and unit cost. Only electrophoretic deposition satisfies all of them at once, because deposition is driven by an electric field rather than by line of sight.

Requirement	Air / airless liquid spray	Electrostatic powder	Cathodic E-coat (selected)
Cavity & weld coverage	Poor — line-of-sight only	Poor — Faraday cage effect	Excellent — field-driven, 21 cm Ford-box throwing power
Thickness uniformity	± 22 μm observed	± 8 – 15 μm typical	± 2 μm across the whole part
Edge coverage	Thins at edges	Thins at edges	Edges coat first — field concentrates there
Automation & capacity	Operator-limited	Good	Excellent — continuous conveyor, 180 pcs/h
VOC	42.6 t/a (solvent-borne)	Near zero, but overspray waste	< 5 t/a — waterborne, low co-solvent
Corrosion performance	240 h	500 – 700 h on edges	1,008 h verified
Material utilisation	≈ 45 %	≈ 95 % with recovery	96.5 % with UF closed-loop recovery
Unit cost	€ 1.85 / pc	Higher film build cost	€ 1.15 / pc

Decision: a continuous cathodic electrophoretic line. Cathodic (not anodic) deposition was specified because the workpiece is the cathode — the substrate is not attacked, no metal ions dissolve into the bath, and corrosion performance is typically two to three times that of anodic systems on the same film build.

03 THE SOLUTION

3.1 Process flow — 13 stations, 72 m of conveyor

Stn	Station	Method	Key parameter	Function
1	Pre-degrease	Immersion	Alkali 5 – 7 %, 55 – 60 °C, 3 min	Removes bulk press oil and handling soil before the main bath
2	Main degrease	Immersion + circulation	Alkali 5 – 7 %, 55 – 60 °C, 6 min	Complete removal of drawing compound and weld anti-spatter
3	Rinse 1	Immersion, overflowing	Tap water, ambient, 1 min	Strips carry-over degreaser
4	Surface conditioning	Immersion	Titanium phosphate colloid, ambient, 1 min	Creates dense nucleation sites so the phosphate film is fine and even
5	Phosphating	Immersion	Zinc phosphate, 40 – 45 °C, 8 min, 2.5 – 4.0 g/m²	Grows the conversion layer that carries adhesion and under-film corrosion resistance
6	Rinse 2	Immersion, overflowing	Tap water, ambient, 1 min	Removes phosphate liquor
7	DI rinse	Immersion + spray	Deionised water, ambient, 1 min, < 25 μS/cm	Last barrier — stops salts and phosphate entering the ED bath
8	Drain	Free drain over bath	2 min	Reduces drag-in dilution of the ED bath
9	Cathodic E-coat	Full immersion, DC field	30 m³, 28 ± 1 °C, solids 19 ± 1 %, pH 6.0 – 6.7, 1,300 ± 300 μS/cm, 180 – 220 V ramped, 150 s	Deposits a 20 μm wet film with full cavity coverage
10 – 12	UF rinse (3 stages)	Spray + immersion, counterflow	UF permeate, ambient, 30 s per stage	Recovers un-deposited paint to the ED bath, removes loose film; permeate cascades back stage by stage
13	DI rinse	Spray, fresh	Deionised water, 30 s	Removes UF liquor so the cured film is free of water spotting
14	Drain + air blow-off	Air knives	2 min	Clears pockets and blind holes — prevents boil-out craters in the oven
15	Cure oven	Gas convection, 3 zones	Metal temperature 175 ± 5 °C, 25 min	Cross-links the film to its final mechanical and chemical resistance

3.2 Key subsystems that make the process stable

· Anode membrane system — tubular diaphragm anodes in 316L stainless separate the anodes and anolyte from the bath. It isolates dissolving metal and removes the acid generated by electrolysis, which is what keeps bath pH from drifting down. Anolyte conductivity is held at 400 ± 100 μS/cm.

· Bath temperature control — deposition is exothermic and the bath is circulated continuously. A plate heat exchanger coupled to a 120 kW chiller holds 28 ± 1 °C; the UF loop is cooled on the same circuit so permeate never exceeds 33 °C and the membrane does not age prematurely.

· Ultrafiltration — four spiral-wound modules produce 1.8 m³/h of permeate. Permeate is the rinse medium for stations 10 – 12 and returns the recovered paint to the ED tank, which is what lifts utilisation to 96.5 % and makes the rinse section a closed loop.

· Filtration — 50 μm bag filters followed by 25 μm cartridges on the main circulation; filters are changed on differential pressure, not on a calendar.

· Rectifier — 400 A / 300 V DC with less than 5 % ripple and soft-start voltage ramping. Ramping the voltage rather than applying it in one step is what prevents pinholing on complex stampings.

· Deionised water plant — RO + EDI at 2 m³/h, product conductivity below 10 μS/cm, feeding the final rinse and bath make-up.

· Control — S7-1500 PLC with a 15-inch HMI. Recipe management per part family, live trending of bath temperature, pH, conductivity, rectifier volts/amps, chain speed and all oven zones, plus batch traceability and alarm history to SCADA.

3.3 Equipment scope of supply

Package	Supply
Pre-treatment	7 immersion tanks in PP / SUS304, 28 m³ total, steam-heated with automatic temperature control, oil skimmer on degrease tanks, sludge screw press for phosphate
E-coat section	30 m³ ED tank with overflow weir, circulation pumps, plate heat exchanger, 316L tubular diaphragm anodes with anolyte loop, 400 A / 300 V rectifier
Rinse & recovery	3-stage UF counterflow rinse, 4 spiral-wound UF modules (1.8 m³/h permeate), fresh DI spray station, air-knife blow-off
Cure oven	30 m gas-fired convection oven, 900,000 kcal/h, 3 independently controlled zones, 150 mm insulated panels, forced air circulation, heat recovery to pre-treatment make-up
Conveyor	Heavy-duty overhead chain conveyor, 72 m, 45 kg per hanger, VFD 0.4 – 2.0 m/min, automatic lubrication, overload and jam protection
Utilities & environment	RO + EDI water plant (2 m³/h), bag and cartridge filtration, exhaust collection from tanks and oven with VOC abatement, drip trays and bunded chemical storage
Control & safety	S7-1500 PLC, 15" HMI, SCADA data logging, recipe management, CE-compliant guarding, emergency stop circuits, gas leak detection and burner flame safeguard
Services	Process design and tank sizing, manufacture, FAT at CoatTech Guangzhou, shipment, site installation, commissioning, operator and laboratory training, 12 months of process support

04 PROCESS CONTROL WINDOWS AS AGREED IN THE SPECIFICATION

The line is run against the following windows. Values are logged per shift and are the contractual acceptance criteria, not averages of convenience.

Parameter	Unit	Target window	Check frequency	Why it matters
Bath solids (105 °C, 1 h)	%	19 ± 1	Every 2 days	Too low → thin film and poor hiding; too high → poor flow and rough film
Bath pH (25 °C)	—	6.0 – 6.7	Daily	Low → violent electrolysis and pinholes; high → resin flocculation and poor throwing power
Bath conductivity	μS/cm	1,300 ± 300	Daily	High → rough film and pinholes; low → low throwing power and insufficient build
Bath temperature	°C	28 ± 1	Continuous	Every 1 °C up raises deposition 8 – 12 % and shortens bath life
Anolyte conductivity	μS/cm	400 ± 100	Daily	Tracks acid removal; rising value means diaphragm fouling
MEQ (neutralisation equivalent)	—	Per paint supplier	Weekly	Drift signals bath ageing or contamination
Solvent content	%	< 3.5	Weekly	Low → orange peel and poor flow; high → abnormal build and higher VOC
Ash / pigment-to-binder ratio	%	21 ± 3	Weekly	Controls film appearance and corrosion balance
Deposition voltage	V DC	180 – 220, ramped	Per recipe	Ramping avoids pinholes on complex stampings
Deposition time	s	150	Per recipe	Sets film build together with voltage and bath temperature
Phosphate coating weight	g/m²	2.5 – 4.0	Weekly	Below range → adhesion and salt-spray loss; above → rough film
Final rinse conductivity	μS/cm	< 25	Daily	The main defence against salt contamination of the bath
Oven metal temperature	°C	175 ± 5	2 × daily + furnace tracker monthly	Under-cure → low gel fraction; over-cure → discoloration and brittleness
Dry film thickness	μm	20 ± 3	Every batch	Contractual and cost driver simultaneously

05 PROJECT EXECUTION

Phase	Duration	Milestone
Process design	4 weeks	Bath and tank sizing from real throughput, heat balance and oven profile signed off by client and paint supplier
Fabrication	10 weeks	Tanks, oven, conveyor and control cabinets built and pre-assembled at CoatTech, Foshan / Guangzhou
FAT	1 week	Dry run of the full line at our works: conveyor, rectifier, burners, PLC logic and interlocks witnessed and signed off
Shipment & installation	6 weeks	11 × 40 ft containers; mechanical and electrical erection on the client's prepared foundation
Commissioning	3 weeks	Bath make-up and maturation, rectifier ramp trials, oven profiling with a Datapaq tracker, first articles
Validation	2 weeks	Salt-spray, cross-cut, impact, thickness and throwing-power testing against the acceptance protocol
Training & handover	1 week	Operators, laboratory and maintenance trained; bath control sheets and SPC templates handed over

06 RESULTS — BEFORE AND AFTER

Figures below were recorded during commissioning and the first six months of series production (March – September 2026) and are taken from the client's own SPC records.

+64 %

THROUGHPUT — 110 → 180 pcs/h

99.1 %

FIRST-PASS YIELD — was 90.2 %

96.5 %

PAINT UTILISATION — was ≈ 45 %

1,008 h

NEUTRAL SALT SPRAY — was 240 h

−93 %

VOC EMISSIONS — 42.6 → 3.1 t/a

14 mo

PAYBACK ON INVESTMENT

Metric	Before (manual spray)	After (E-coat line)	Change
Throughput	110 pcs/h	180 pcs/h	+64 %
Annual capacity (2 shifts, 250 d)	440,000 pcs	720,000 pcs	+64 %
First-pass yield	90.2 %	99.1 %	+8.9 pp
Rework rate	9.8 %	0.9 %	−91 %
Scrap rate	2.1 %	0.25 %	−88 %
Film thickness spread	± 22 μm	± 2 μm	−91 %
Neutral salt spray	240 h	1,008 h (creepage ≤ 1.2 mm)	+320 %
Coverage in cavities / welds	Partial, bare metal present	Complete — 21 cm Ford-box throwing power	Resolved
Paint utilisation	≈ 45 %	96.5 %	+114 %
Paint per 1,000 pieces	148 kg	70 kg	−53 %
VOC emissions	42.6 t/a	3.1 t/a	−93 %
Direct operators	12 (6 per shift)	4 (2 per shift)	−67 %
Labour per 1,000 pieces	109 man-hours	22 man-hours	−80 %
Energy per 1,000 pieces	€ 310	€ 214	−31 %
Unit coating cost	€ 1.85 / pc	€ 1.15 / pc	−38 %
Unplanned line stoppages	4.2 h / week	0.6 h / week	−86 %
Overall equipment effectiveness	62 %	89 %	+27 pp

07 VALIDATION AND TEST DATA

Acceptance testing was carried out on production parts, not on laboratory panels, with the paint supplier present. Test methods follow the standards named in the client's OEM approval package.

Test item	Method / standard	Specification	Result
Dry film thickness	Magnetic gauge, ISO 2808	18 – 25 μm	Mean 20.3 μm; range 18.4 – 22.1 μm
Throwing power	Ford box method, HG/T 3334	≥ 18 cm (premium grade)	21 cm
Cross-cut adhesion	ISO 2409, 1 mm spacing	Class 0	Class 0
Neutral salt spray	ISO 9227 / GB/T 10125	≥ 720 h	1,008 h; single-sided creepage ≤ 1.2 mm, no blistering
Impact resistance	ISO 6272	≥ 50 kg·cm	Pass at 50 kg·cm
Pencil hardness	ISO 15184	≥ 2H	2H
Cupping (Erichsen)	ISO 1520	≥ 5 mm	6.2 mm
Gel fraction	Solvent extraction	≥ 90 %	94.5 %
Bath solids	Gravimetric, 105 °C	19 ± 1 %	19.3 %
Bath pH	pH meter, 25 °C	6.0 – 6.7	6.35
Bath conductivity	Conductivity meter, 25 °C	1,300 ± 300 μS/cm	1,420 μS/cm
Bath temperature	Inline PT100, logged	28 ± 1 °C	28.4 °C, spread 0.6 °C over 24 h
Cure — metal temperature	Datapaq furnace tracker, 6 probes	175 ± 5 °C × 20 min minimum	176 °C held for 25 min; all probes within window
Edge coverage	Cross-section microscopy	No thinning at edges	Edge build equal to or above face build

08 ENVIRONMENTAL AND ECONOMIC BENEFIT

Environmental

· VOC cut from 42.6 t/a to 3.1 t/a — the site is now inside its permit ceiling with headroom, and the solvent-based primer store was decommissioned.

· The rinse section is a closed loop: UF permeate carries recovered paint back to the ED tank, so the only discharge is spent permeate and occasional filter backwash, both routed to the existing effluent plant.

· Oven exhaust heat is recovered to pre-treatment tank make-up water, which is where most of the 31 % energy saving comes from.

· Phosphate sludge is dewatered on a screw press before disposal, reducing hazardous waste volume by roughly 70 % compared with the previous wet sludge handling.

Economics

· Unit coating cost fell from € 1.85 to € 1.15 — driven by material recovery, not by cheaper paint.

· Direct labour on finishing dropped from 12 operators to 4; the released headcount was redeployed to assembly, so the saving was taken in full.

· Rework and scrap together fell by roughly 90 %, which removed two internal cost streams that had never been properly measured before.

· Combined annual saving of € 412,000 against an installed project cost of € 481,000 gives a simple payback of 14 months; the figures are before any revenue effect from the extra 280,000 parts of annual capacity.

The larger commercial effect was not the cost saving but the qualification: at 1,008 h salt spray the client now clears the OEM's 720 h requirement with margin, which removed the audit exception that had been blocking new part nominations.

09 IN THE CLIENT'S WORDS

“What surprised us was not the corrosion result — we expected that. It was the consistency. Our film thickness spread went from 22 microns to under 2, and first-pass yield has not dropped below 99 % in six months. We stopped talking about coating as a problem and started quoting it in tenders.”

— Head of Manufacturing Engineering, Tier-2 chassis components supplier, P*****d

10 WHY COATTECH

· One supplier from process design to production support — the tank sizing, the bath control windows, the oven profile and the PLC recipes were engineered together, so no interface was left to the client to resolve.

· The complete line was dry-run at our works before shipment. FAT covered conveyor, rectifier, burners, PLC logic and safety interlocks, which is why on-site commissioning took three weeks instead of the usual two months.

· Bath control sheets, SPC templates and laboratory procedures were handed over with the line; the client's own team runs the bath, not ours.

· A process engineer stayed on site for the first month of production, with remote support for 12 months afterwards.

· Spare parts package, filter and membrane consumables, and a named service contact for the life of the line.

Youtube Video Link as follow

https://youtube.com/shorts/Ov19gypUkog?si=pVBIy_BJVYnRvs0n

Fully Automated Electrophoretic Coating (E-Coat) Line

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Fully Automated Electrophoretic Coating (E-Coat) Line

MOQ:	1
Price:	USD2000-USD10000/SET
Standard Packaging:	With regular Film and Carton
Delivery Period:	15 DAYS After Deposit
Payment Method:	T/T
Supply Capacity:	500SET/MONTH

Detail Information

Product Description

Detail Information

Place of Origin

China

Brand Name

CoatTech

Certification

Model Number

CT-ED-7200

NAME:

Fully Automated Cathodic E-Coat Line

Power Supply::

220V/50HZ/1Ph Or Other Option

Using Energy::

Electric Or Other Option

Motor::

Chinese Brand Or Import Brand

Control Sytem::

Switch Style Or PLC Touch Screen Control

Color::

White Or Other Option

Application::

Metallic Products

Dimention::

As Require

Minimum Order Quantity:

Price:

USD2000-USD10000/SET

Packaging Details:

With regular Film and Carton

Delivery Time:

15 DAYS After Deposit

Payment Terms:

T/T

Supply Ability:

500SET/MONTH

Product Description

Fully Automated Electrophoretic Coating (E-Coat) Line

Continuous cathodic E-coat for automotive chassis components — 72 m overhead conveyor line,

| Location: P*****d, Central Europe | Client name withheld under NDA

PROJECT AT A GLANCE

Item	Detail
Client	Tier-2 manufacturer of automotive chassis and suspension components (stampings and welded assemblies)
Workpieces	Control arms, spring seats, subframe brackets, cross-member reinforcements, seat-frame stampings
Substrate	Cold-rolled steel, hot-rolled pickled steel, some zinc-coated brackets
Max. workpiece envelope	1,200 × 800 × 600 mm · max. 45 kg per hanger
Process	7-stage immersion pre-treatment → cathodic electrophoretic deposition (CED) → 3-stage UF counterflow rinse → DI rinse → drain + air blow-off → gas-fired convection cure
Line configuration	Single-loop overhead chain conveyor, continuous, fully automatic, load/unload only manual
Conveyor path / footprint	72 m process path · 72 m × 11 m installed footprint
Chain speed	0.4 – 2.0 m/min (VFD, stepless), nominal 1.2 m/min · hanger pitch 400 mm
Design throughput	180 pcs/h · 2,880 pcs/day (2 shifts) · 720,000 pcs/year (250 working days)
Dry film thickness	20 ± 3 μm (measured mean 20.3 μm, range 18.4 – 22.1 μm)
Cure schedule	Metal temperature 175 ± 5 °C for 25 min (3-zone gas convection oven, 900,000 kcal/h)
ED tank	30 m³ working volume, cathodic epoxy dispersion, 316L tubular diaphragm anodes
Utilities	Installed power 480 kW · natural gas 900,000 kcal/h · DI water 2 m³/h · compressed air 6 bar
Manning	2 operators per shift (load / unload) + 1 process technician per day
CoatTech scope	Process design, manufacture, FAT, shipment, installation, commissioning, operator training, 12-month process support
Project timeline	Contract Nov 2025 → engineering 4 wks → fabrication 10 wks → FAT 1 wk → installation 6 wks → commissioning 3 wks → SOP Mar 2026

01 THE CHALLENGE

Five problems had to be solved at the same time:

· Capacity ceiling. The manual line delivered 110 pcs/h against a firm customer requirement of 180 pcs/h for the 2026 model year. Overtime and weekend shifts were already running.

· Yield. First-pass yield sat at 90.2%; 9.8% of parts needed rework and 2.1% were scrapped outright, mostly for runs, dry spray and misses.

Measured baseline before the project

Metric	Manual air spray (baseline)	OEM / permit requirement
Throughput	110 pcs/h	180 pcs/h
First-pass yield	90.2 %	≥ 98 %
Scrap rate	2.1 %	≤ 0.5 %
Dry film thickness	25 – 70 μm (± 22 μm spread)	18 – 25 μm
Cavity / weld coverage	Inconsistent; bare metal in box sections	100 % coverage
Neutral salt spray	240 h (red rust at welds)	≥ 720 h
Paint utilisation	≈ 45 %	—
VOC emissions	42.6 t/a	≤ 5 t/a
Direct operators	12 (6 per shift × 2 shifts)	—
Unit coating cost	€ 1.85 / pc	—

02 WHY CATHODIC E-COAT AND NOT ANOTHER SPRAY LINE

Requirement	Air / airless liquid spray	Electrostatic powder	Cathodic E-coat (selected)
Cavity & weld coverage	Poor — line-of-sight only	Poor — Faraday cage effect	Excellent — field-driven, 21 cm Ford-box throwing power
Thickness uniformity	± 22 μm observed	± 8 – 15 μm typical	± 2 μm across the whole part
Edge coverage	Thins at edges	Thins at edges	Edges coat first — field concentrates there
Automation & capacity	Operator-limited	Good	Excellent — continuous conveyor, 180 pcs/h
VOC	42.6 t/a (solvent-borne)	Near zero, but overspray waste	< 5 t/a — waterborne, low co-solvent
Corrosion performance	240 h	500 – 700 h on edges	1,008 h verified
Material utilisation	≈ 45 %	≈ 95 % with recovery	96.5 % with UF closed-loop recovery
Unit cost	€ 1.85 / pc	Higher film build cost	€ 1.15 / pc

03 THE SOLUTION

3.1 Process flow — 13 stations, 72 m of conveyor

Stn	Station	Method	Key parameter	Function
1	Pre-degrease	Immersion	Alkali 5 – 7 %, 55 – 60 °C, 3 min	Removes bulk press oil and handling soil before the main bath
2	Main degrease	Immersion + circulation	Alkali 5 – 7 %, 55 – 60 °C, 6 min	Complete removal of drawing compound and weld anti-spatter
3	Rinse 1	Immersion, overflowing	Tap water, ambient, 1 min	Strips carry-over degreaser
4	Surface conditioning	Immersion	Titanium phosphate colloid, ambient, 1 min	Creates dense nucleation sites so the phosphate film is fine and even
5	Phosphating	Immersion	Zinc phosphate, 40 – 45 °C, 8 min, 2.5 – 4.0 g/m²	Grows the conversion layer that carries adhesion and under-film corrosion resistance
6	Rinse 2	Immersion, overflowing	Tap water, ambient, 1 min	Removes phosphate liquor
7	DI rinse	Immersion + spray	Deionised water, ambient, 1 min, < 25 μS/cm	Last barrier — stops salts and phosphate entering the ED bath
8	Drain	Free drain over bath	2 min	Reduces drag-in dilution of the ED bath
9	Cathodic E-coat	Full immersion, DC field	30 m³, 28 ± 1 °C, solids 19 ± 1 %, pH 6.0 – 6.7, 1,300 ± 300 μS/cm, 180 – 220 V ramped, 150 s	Deposits a 20 μm wet film with full cavity coverage
10 – 12	UF rinse (3 stages)	Spray + immersion, counterflow	UF permeate, ambient, 30 s per stage	Recovers un-deposited paint to the ED bath, removes loose film; permeate cascades back stage by stage
13	DI rinse	Spray, fresh	Deionised water, 30 s	Removes UF liquor so the cured film is free of water spotting
14	Drain + air blow-off	Air knives	2 min	Clears pockets and blind holes — prevents boil-out craters in the oven
15	Cure oven	Gas convection, 3 zones	Metal temperature 175 ± 5 °C, 25 min	Cross-links the film to its final mechanical and chemical resistance

3.2 Key subsystems that make the process stable

· Filtration — 50 μm bag filters followed by 25 μm cartridges on the main circulation; filters are changed on differential pressure, not on a calendar.

· Rectifier — 400 A / 300 V DC with less than 5 % ripple and soft-start voltage ramping. Ramping the voltage rather than applying it in one step is what prevents pinholing on complex stampings.

· Deionised water plant — RO + EDI at 2 m³/h, product conductivity below 10 μS/cm, feeding the final rinse and bath make-up.

3.3 Equipment scope of supply

Package	Supply
Pre-treatment	7 immersion tanks in PP / SUS304, 28 m³ total, steam-heated with automatic temperature control, oil skimmer on degrease tanks, sludge screw press for phosphate
E-coat section	30 m³ ED tank with overflow weir, circulation pumps, plate heat exchanger, 316L tubular diaphragm anodes with anolyte loop, 400 A / 300 V rectifier
Rinse & recovery	3-stage UF counterflow rinse, 4 spiral-wound UF modules (1.8 m³/h permeate), fresh DI spray station, air-knife blow-off
Cure oven	30 m gas-fired convection oven, 900,000 kcal/h, 3 independently controlled zones, 150 mm insulated panels, forced air circulation, heat recovery to pre-treatment make-up
Conveyor	Heavy-duty overhead chain conveyor, 72 m, 45 kg per hanger, VFD 0.4 – 2.0 m/min, automatic lubrication, overload and jam protection
Utilities & environment	RO + EDI water plant (2 m³/h), bag and cartridge filtration, exhaust collection from tanks and oven with VOC abatement, drip trays and bunded chemical storage
Control & safety	S7-1500 PLC, 15" HMI, SCADA data logging, recipe management, CE-compliant guarding, emergency stop circuits, gas leak detection and burner flame safeguard
Services	Process design and tank sizing, manufacture, FAT at CoatTech Guangzhou, shipment, site installation, commissioning, operator and laboratory training, 12 months of process support

04 PROCESS CONTROL WINDOWS AS AGREED IN THE SPECIFICATION

The line is run against the following windows. Values are logged per shift and are the contractual acceptance criteria, not averages of convenience.

Parameter	Unit	Target window	Check frequency	Why it matters
Bath solids (105 °C, 1 h)	%	19 ± 1	Every 2 days	Too low → thin film and poor hiding; too high → poor flow and rough film
Bath pH (25 °C)	—	6.0 – 6.7	Daily	Low → violent electrolysis and pinholes; high → resin flocculation and poor throwing power
Bath conductivity	μS/cm	1,300 ± 300	Daily	High → rough film and pinholes; low → low throwing power and insufficient build
Bath temperature	°C	28 ± 1	Continuous	Every 1 °C up raises deposition 8 – 12 % and shortens bath life
Anolyte conductivity	μS/cm	400 ± 100	Daily	Tracks acid removal; rising value means diaphragm fouling
MEQ (neutralisation equivalent)	—	Per paint supplier	Weekly	Drift signals bath ageing or contamination
Solvent content	%	< 3.5	Weekly	Low → orange peel and poor flow; high → abnormal build and higher VOC
Ash / pigment-to-binder ratio	%	21 ± 3	Weekly	Controls film appearance and corrosion balance
Deposition voltage	V DC	180 – 220, ramped	Per recipe	Ramping avoids pinholes on complex stampings
Deposition time	s	150	Per recipe	Sets film build together with voltage and bath temperature
Phosphate coating weight	g/m²	2.5 – 4.0	Weekly	Below range → adhesion and salt-spray loss; above → rough film
Final rinse conductivity	μS/cm	< 25	Daily	The main defence against salt contamination of the bath
Oven metal temperature	°C	175 ± 5	2 × daily + furnace tracker monthly	Under-cure → low gel fraction; over-cure → discoloration and brittleness
Dry film thickness	μm	20 ± 3	Every batch	Contractual and cost driver simultaneously

05 PROJECT EXECUTION

Phase	Duration	Milestone
Process design	4 weeks	Bath and tank sizing from real throughput, heat balance and oven profile signed off by client and paint supplier
Fabrication	10 weeks	Tanks, oven, conveyor and control cabinets built and pre-assembled at CoatTech, Foshan / Guangzhou
FAT	1 week	Dry run of the full line at our works: conveyor, rectifier, burners, PLC logic and interlocks witnessed and signed off
Shipment & installation	6 weeks	11 × 40 ft containers; mechanical and electrical erection on the client's prepared foundation
Commissioning	3 weeks	Bath make-up and maturation, rectifier ramp trials, oven profiling with a Datapaq tracker, first articles
Validation	2 weeks	Salt-spray, cross-cut, impact, thickness and throwing-power testing against the acceptance protocol
Training & handover	1 week	Operators, laboratory and maintenance trained; bath control sheets and SPC templates handed over

06 RESULTS — BEFORE AND AFTER

Figures below were recorded during commissioning and the first six months of series production (March – September 2026) and are taken from the client's own SPC records.

+64 %

THROUGHPUT — 110 → 180 pcs/h

99.1 %

FIRST-PASS YIELD — was 90.2 %

96.5 %

PAINT UTILISATION — was ≈ 45 %

1,008 h

NEUTRAL SALT SPRAY — was 240 h

−93 %

VOC EMISSIONS — 42.6 → 3.1 t/a

14 mo

PAYBACK ON INVESTMENT

Metric	Before (manual spray)	After (E-coat line)	Change
Throughput	110 pcs/h	180 pcs/h	+64 %
Annual capacity (2 shifts, 250 d)	440,000 pcs	720,000 pcs	+64 %
First-pass yield	90.2 %	99.1 %	+8.9 pp
Rework rate	9.8 %	0.9 %	−91 %
Scrap rate	2.1 %	0.25 %	−88 %
Film thickness spread	± 22 μm	± 2 μm	−91 %
Neutral salt spray	240 h	1,008 h (creepage ≤ 1.2 mm)	+320 %
Coverage in cavities / welds	Partial, bare metal present	Complete — 21 cm Ford-box throwing power	Resolved
Paint utilisation	≈ 45 %	96.5 %	+114 %
Paint per 1,000 pieces	148 kg	70 kg	−53 %
VOC emissions	42.6 t/a	3.1 t/a	−93 %
Direct operators	12 (6 per shift)	4 (2 per shift)	−67 %
Labour per 1,000 pieces	109 man-hours	22 man-hours	−80 %
Energy per 1,000 pieces	€ 310	€ 214	−31 %
Unit coating cost	€ 1.85 / pc	€ 1.15 / pc	−38 %
Unplanned line stoppages	4.2 h / week	0.6 h / week	−86 %
Overall equipment effectiveness	62 %	89 %	+27 pp

07 VALIDATION AND TEST DATA

Acceptance testing was carried out on production parts, not on laboratory panels, with the paint supplier present. Test methods follow the standards named in the client's OEM approval package.

Test item	Method / standard	Specification	Result
Dry film thickness	Magnetic gauge, ISO 2808	18 – 25 μm	Mean 20.3 μm; range 18.4 – 22.1 μm
Throwing power	Ford box method, HG/T 3334	≥ 18 cm (premium grade)	21 cm
Cross-cut adhesion	ISO 2409, 1 mm spacing	Class 0	Class 0
Neutral salt spray	ISO 9227 / GB/T 10125	≥ 720 h	1,008 h; single-sided creepage ≤ 1.2 mm, no blistering
Impact resistance	ISO 6272	≥ 50 kg·cm	Pass at 50 kg·cm
Pencil hardness	ISO 15184	≥ 2H	2H
Cupping (Erichsen)	ISO 1520	≥ 5 mm	6.2 mm
Gel fraction	Solvent extraction	≥ 90 %	94.5 %
Bath solids	Gravimetric, 105 °C	19 ± 1 %	19.3 %
Bath pH	pH meter, 25 °C	6.0 – 6.7	6.35
Bath conductivity	Conductivity meter, 25 °C	1,300 ± 300 μS/cm	1,420 μS/cm
Bath temperature	Inline PT100, logged	28 ± 1 °C	28.4 °C, spread 0.6 °C over 24 h
Cure — metal temperature	Datapaq furnace tracker, 6 probes	175 ± 5 °C × 20 min minimum	176 °C held for 25 min; all probes within window
Edge coverage	Cross-section microscopy	No thinning at edges	Edge build equal to or above face build

08 ENVIRONMENTAL AND ECONOMIC BENEFIT

Environmental

· VOC cut from 42.6 t/a to 3.1 t/a — the site is now inside its permit ceiling with headroom, and the solvent-based primer store was decommissioned.

· Oven exhaust heat is recovered to pre-treatment tank make-up water, which is where most of the 31 % energy saving comes from.

· Phosphate sludge is dewatered on a screw press before disposal, reducing hazardous waste volume by roughly 70 % compared with the previous wet sludge handling.

Economics

· Unit coating cost fell from € 1.85 to € 1.15 — driven by material recovery, not by cheaper paint.

· Direct labour on finishing dropped from 12 operators to 4; the released headcount was redeployed to assembly, so the saving was taken in full.

· Rework and scrap together fell by roughly 90 %, which removed two internal cost streams that had never been properly measured before.

09 IN THE CLIENT'S WORDS

— Head of Manufacturing Engineering, Tier-2 chassis components supplier, P*****d

10 WHY COATTECH

· Bath control sheets, SPC templates and laboratory procedures were handed over with the line; the client's own team runs the bath, not ours.

· A process engineer stayed on site for the first month of production, with remote support for 12 months afterwards.

· Spare parts package, filter and membrane consumables, and a named service contact for the life of the line.

Youtube Video Link as follow

https://youtube.com/shorts/Ov19gypUkog?si=pVBIy_BJVYnRvs0n

Fully Automated Electrophoretic Coating (E-Coat) Line

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