A POWDER COATING LINE AUDIT

-00 2 y/6 9

PdF

Roger CummingslMike Huddleston Area Sales Manager/Technical Representative

H.B. Fuller Company Oakdale, Minnesota

Presented at: FINISHING '95 CONFERENCE AND EXPOSITION

September 18-21, 1995 Cincinnati, Ohio

MINI-AUDIT REPORT POWDER COATING SYSTEM

PREPARED FOR

The In Trouble Corporation Hometown, US

September 10,1995

PREPARED BY The Concerned Company

Close, us

THE PART Description: Computer diskdrive cabinets

Material:

Dimensions: Weight:

N o t w

Cold-Rolled, 'Readywar galvaneal sheet steel

Cabinet - 6' high by 3.5' wide by 1 .S deep Cabinet - 125 pounds (approx) Moderate to severe faraday cage areas are present. Film thickness spec5cation - 1.5 to 2.5 mils generally, except UL compliance requires 100% coverage at 1.5 mils minimum on interior surfaces of electronics box. Five colors total, all epoxy, primary color black texture eccounting for 85% of production volume.

consbuction: Sheared, brake-formed and spot-wlded

SYSTEM SURVEY

BOOTH

Type: "Twin Air-Belt"

Model: CE1-84.40.15K Mfg: Containment Equipment Inc.

Dimendons: Part profile: collection: Cy-Cart mini-cydondCartridge collector system

Environment:

12' high X 6 wide X 40 long 8' high X 4' wide

Enclosed room, temperature and humidity controlled

GUNS

Type: (I 2) 1 OOKV automatic - wlintegrated power supply (2) 8OKV manual - whemote power supply

Mfg: Sprayzit Corporation Yodel: Automatics: Sz-I OOA

NoPles : Round diffuser on autos Manuals: Sz8oM

Flat fan on manuals (2) Reciprocators on dollies Manual reinforcement prior to automatics

Gun Mover: Amnged:

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1

WASHER

Type: Mfg/lnstaller:

Material: Risers:

Note:

Length:

Water: Chemistry:

Chemical Supplier: Product:

concentration: pH:

ptessure: Temperature:

Nozzles: Length:

Dwell:

Length: Dwell:

Misters:

Wetgl.: TDS

pH: Pressure:

Temperature: Nozzles: Length:

Dwell:

5-Stage power spray General Process Systems Canopy and all tanks stainless steel PVC in all stages No rinse stages back-flowed

Entrance Vestibule

114"

Stage I - Clean

On-site welllchamal filtered Alkaline Atlas Chemicals Inc. Super-clean X l 3.0% 10.5 25 PSI 125F Clip-on V-Jet 180 inches 90 seconds

Drain Section

90 inches 45 seconds Interlocked with conveyor

Stage 2 - Rinse

City servidraw 1325 PPMDS 7.75 15 PSI Ambient Clip-on V-Jet 90 inches 45 seconds

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Drain Section

Length: Dwell:

Misters:

Water: Chemistry:

Chemical Supplier: Produck

Concentration: pH:

Pressure: Temperature:

Nozzles: Length:

Dwell:

Length: Dwell:

Misters:

Water: TDS:

pH: Pressure:

Temperature: Nozzles: Length:

Dwell:

Length: Dwell:

Misters:

60 inches 30 seconds Interlocked with conveyor

Stage 3 - Conversion Coat

City servicelraw Iron phosphate Atlas Chemicals Inc. Super-prep XL 3.5% 3.25 12 PSI 115F Clip-on Swirl-Jet 120 inches 60 seconds

Drain Section

60 inches 30 seconds Interlocked with conveyor

Stage 4 - Rinse

City servicelraw 975 PPMDS 7.0 15 PSI Ambient Clip-on V-Jet 60 inches 30 seconds

Drain Section

60 inches 30 seconds Interlocked with conveyor

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i

Water: TDS:

pH: Pressure:

TemperatUN?: Noules: Length:

Dwell:

Length: Note:

Type: Mfgllnstaller: Configured:

Dwell: Set-Point: Indicated:

Note:

Type: Mfgllnstaller: Configured:

Dwell: Set-Point: Indicated:

Stage 5 - Final Rinse

City servicelDe-ionized 9 PPMDS 6.75 12 PSI 115F Clip-on Swirl-Jet 90 inches 45 seconds

Exit Vestibule

1 5 including a 180 degree tum Incorporates a water blow# section prior to the tum, using low volumelhigh velocity, unheated air-knives

DRY-OFF OVEN

Floor level, gas-firedlconvection High-Temp Equipment Co. Bottom f M o p retum 15 minutes at 10 FPM 385F

Parts arrive at booth at 95F 376-394F

CURE OVEN

Overhead, gas-firedlconvection High-Temp Equipment Co. Bottom feemop retum Parts enterlexit through bottom of oven 25 minutes at I O FPM 400F 396-404F

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OBSERVATIONS and RECOMMENDATIONS

COMPRESSED AIR SUPPLY

Observations

0 Air quality is excellent. No gross water, water vapor, or oil vapor is detectable.

0 The traps and drains are clean. There is no oily residue on the U.V. detector windows

0 Pressures and temperatures indicated on the refrigerated airdryer are normal

Recommendations

1. Add a drip leg and automatic drain just prior to the particulatelcoalescing filter set that is suspended from the ceiling in the powder room

2. Install an interlock that will prevent start-up of the powder coating system (or at least trigger an audible or visual alarm) if the air filters become loaded or the air dryer is inoperative.

POWDER DELIVERY

POWDER PUMPS

Observations

0 Delivery from one gun was intermittent, ofilonIMlon, and cycling at a very constant rate!

0 Delivery from two guns was surging erratically

Note: It was determined that both problems were caused by the "FLOW to "ATOMIZING" air pressure balance not being adjusted properly. With the first gun, this imbalance caused the check valve in the FLOW rate air line at the powder pump to continuously cycle opened and closed. With the two surging guns, the improperly adjusted air flows allowed powder to settle in the powder hoses. Both conditions were corrected by properly adjusting the delivery air pressures.

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Recommendations

1. Review proper powder delivery air-control adjustment procedures

POWDER HOSES

0 bservations

0 All hoses are unnecessarily long 0 No extemal wear or damage is visible on auto gun hoses 0 No intemal powder buildup is evident 0 The manual gun hoses are laying on the moving filter belt and being abraded 0 Some hoses are 'VY ID and some are 5/8" ID

Recommendations

I. Shorten all hoses

2. Correct routing and anchor points to eliminate traps, pinched areas and kinks

3. Suspend and anchor manual gun hoses so they do not lay on the filter belt

4. Put 112 hose on the manual guns and 5/8" hoses on at1 auto guns

PARTS GROUNDING

Observations

0 Between parts and ground - generally less that 500K ohms 0 Between parts on adjacent load bars - generally less that 250K ohms 0 Some cabinets measured greater than 2 megohms - part-to-ground 0 Many door frames measured greater than 2 megohms - part-to ground

Note: Continuity measurement - Resistance >I megohm is unacceptable. All measurements made while parts were in front of guns. All measurements made at 1000 VDC.

Comment: Current parts grounding is not adequate. Poorly grounded parts result in poor transfer efficiency and therefore wastes powder, especially with the spray-to-waste colors. Poor ground also causes light coverage and thus rejected parts. Most seriously, ungrounded parts present a safety hazard, especially when they are as massive as these. If an ungrounded cabinet discharged suddenly after becoming fully capacitized, it would deliver a

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substantial shock, and provide an excellent ignition source. Don’t test your fire detection system in this manner; ground the parts!

Recommendations

I. Eliminate the load bars, but especially the swivel hooks, if possible

2. Implement a hanger bum-off program that will ensure adequate and consistent parts grounding

3. Monitor parts grounding on a regular schedule by measuring continuity

BOOTH

Observations

0 Booth is containing powder effectively

0 Face velocities are normal for a belt booth (Velocities expressed in the form: rangelaverage in FPM)

Measured at:

Entrance vestibule 50-60155 Exit vestibule 50-60155 Conveyor slot 45-65/55 West side operator opening 25-35/30 East side operator opening 4030/45 West side auto gun slots 45-55/50 East side auto gun slots 45-55/50

0 Airflow at the parts is normal (Airflow expressed in the form: rangelaverage in FPM)

Measured:

Horizontally Vertically

0 Collection system is operating effectively 0 Static pressures are within spec

0-010 0-1 015

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,

GUNS

Observations

0 One defective gun selector switch and two faulty H N adjust potentiometers 0 All air controls function normally 0 Electrostatic output (As indicated by meters, not measured)

AUTOMATIC GUNS

- SCI

1 1 10uA 2 120 3 90 4 50 5 95 6 90 7 110 8 85 9 105

10 85 11 110 12 105

MANUAL GUNS

Q& - SCI

East Side 1 OOuA West Side 95

VOLTAGE

97Kv 100 90 65 93 87

I00 80 97 85 97 93

VOLTAGE

80KV 75

Recommendations

1. Replace the VOLT/AMP meter for Gun #I

2. Replace the defective switch and potentiometers

3. Adjust or repair guns with low SCI values to bring their E.S. output up to spec

Note: The SCI (Short Circuit Current) reading for these guns should fall in the 100 -1 25uA range.

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APPLICATION PERFORMANCE

Observations

0 Film thickness measurements

Note: Three cabinets were selected that were coated during different production runs, on different shifts. Each of the surfaces was measured at twelve points. The same surface was measured on each of the three cabinets. The resulting 36 measurements were then averaged and reported.

Surface Averaqe Thickness

Side panel - leftlexterior Side panel - righuexterior 2.4

2.3 mils

Back panel - exterior 3.5 Top panel - exterior 2.1 Electronics box wall - interior Electronics box floor - interior 318 flange around door opening

3.5 2.0 6.3

Note: The average film thickness on these parts, excluding the relatively insignificant surface area represented by the 6.3 value, is 2.63 mils. The powder film on most surfaces could be reduced by 0.5 mil and still meet spec

Recommendations

1. Shut off the automatic guns that coat the door openings

Note: The auto guns are applying powder to surfaces that must be coated manually due to the adjacent faraday areas. The additional powder being applied by the auto guns is unnecessarily increasing the film thickness on those surfaces. The manual guns are providing adequate coverage while attending to the faraday areas. Shutting off the auto guns will also reduce overall average film thickness and thereby reduce the cost per coated part.

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FIRE DETECTION SYSTEM

Observations

0 When we arrived, the UV detector controller displayed a ‘4-0 fault

Note: A ‘4-0‘ fault indicates detector #4 has recognized low level UV radiation. This is most likely the result of an arc from a poorly grounded part to its hanger.

0 When the operator pressed RESET to cleat the fault, the controller cycled to an indicated ‘3-4‘ fault. The original 4-0 fault did clear.

Note: A ‘3-4‘ fault indicates a short-circuit condition exists in the ‘C’ lead coming to the controller from detector #3.

0 During production on the second day we noticed the UV detector controller displayed a ‘4-8‘ fault.

Note: A ‘4-8 fault indicates the UV detection system has been placed in BYPASS mode. In this condition the detection system is inoperative. The powder coating system must not be operated with the UV detection system in BYPASS.

0 The technician was asked to turn the key switch from BYPASS to NORMAL mode and press RESET. All faults cleared and the controller indicated a normal operating condition.

0 Both detectors at the exit end of the booth have been intentionally covered with duct-tape.

Recommendations

1. Remove the duct-tape covering the detectors

2. Have a qualified service technician repair and test the UV DetectionlFire Protection system as soon as possible.

3. Remove the key for the NORMAUBYPASS key switch in the controller, and consign it to the care of an appropriate manager.

4. Review the purpose, operation, control and maintenance of the UV DetectionlFire Protection system with the operator technicians.

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5. Implement a hanger bum-off program that will ensure adequate and consistent parts grounding. (See: PARTS GROUNDING/Recommendations 2.) The intent is to eliminate false alarms so there is no incentive to disable the UV detection system by covering the detectors with tape.

Note: The situations with the tape covered detectors and the controller in bypass, were immediately brought to the attention of the operating technicians in the powder coating room as well as to XYZ Corporation management. We reviewed with them the exact purpose of the UV Detection System. It was explained why disabling it or allowing it to become ineffective through neglect creates a very serious safety issue.

CURE OVEN

Observations

0 The curve shows a very poorly balanced oven. (See the attached printout) 0 The entrance and exit air seals are not operational 0 Cold air is flowing between the entrance and exit vestibules (They are both in

the floor of the oven about 40 apart)

Comment: The deficiencies are severe enough to adversely affect the degree and consistency of parts curing. The uneven heat distribution necessitates the use of a higher than would otherwise be required set-point, and overall average oven temperature, and that is a waste of energy and money.

0 Evaluation of parts cure

Note: Three cabinets were selected that were each cured during different production runs, on different shifts. Surfaces selected for testing included some located higher in the oven and some that were lower. Surface areas on both light gauge sheet metal and heavy brackets were tested.

(Test method: MEK rub - 50 X 2 This is an epoxy)

Surface or Panel Result

Side panel - Top of part profile Slight gloss reductionlNo transfer Side panel - Center of part profile Slight gloss reductionlNo transfer Side panel - Bottom of part profile Slight gloss reduction/No transfer Electronics box wall - Bottom of part profile Slight gloss reduction/No transfer Electronics box floor - Bottom of part profile Slight gloss reductionlNo transfer Door hinge box - Bottom of part profile Slight softeninghloderate transfer Hinge-pin boss - Bottom of part profile Moderate softeninglConsiderable transfer

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0 Full cure achieved on all sheet metal surfaces regardless of position in oven 0 Marginal cure achieved on areas of greatest mass positioned low in the oven

Note: Sample coupons made from the same materials as the parts, and coated and cured during normal production have been submitted to our lab for more comprehensive cure and physical testing. DSC tests will be conducted to provide a quantitative analysis of degree of cure. Taber Abrasion, Pencil Hardness and other tests will be conducted to assess mar and scratch resistance.

Recommendations

1. Relocate the burner control thermocouple from the return-air duct to a position where it directly monitors the temperature of the air coming into the oven from the hot air inlet duct. This change will signal the burner to cycle up and down within a tighter range, and thereby maintain a more constant temperature in the oven.

2. Restore the operation of the air seals at the entrance and exit vestibules

3. Install partitions to prevent the cold air that intrudes from the powder coating room, from flowing between the entrance and exit vestibules.

Comment: Correcting oven balance by improving airflow and burner control response will allow the set-point to be lowered significantly, and at the same time provide more complete and consistent parts curing. Improving the efficiency of the cure oven presents other advantages. At a given set-point, read: energy cosf, parts can be cured at a greater line speed. That means more efficient production, and a reduced cost per coated part.

Note: Before increasing line speed, consider other possible system limitations such as load/unload, and cleaninglpretreatment capability.

4. Inspect the exhaust fan blades for accumulated powder that may cause an out-of-balance condition and result in bearing or blade failure. Clean or replace as necessary.

5. Clean the accumulated powder residue and burner soot from the interior surfaces of the oven to minimize the potential for contamination of the cured powder film. Include this as a regular service in your preventive maintenance procedure.

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POWDER STORAGE

Observations

0 The powder is stored in a dedicated, climate controlled room. 0 Current ambient conditions in the storage room are about ideal at 65F and

55% humidity. 0 Two pallets of powder were left sitting outside the storage room during the

two day we were in the plant.

Recommendations

1. Place powder in the storage room immediately upon its arrival at the plant.

2. Arrange the storage room so that the powder inventory can be easily accessed an used in a first inlfirst out rotation.

“RIGHT TO KNOW STATION

Observations

0 MSDS and TDS documents were not obviously apparent,

Recommendations

1. Establish a Right to Know station near the powder coating operation where the appropriate Material Safety Data Sheets and Technical Data Sheets are

visible and accessible.

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CURE OVEN TEMPERATURE CURVE

CURING DATA DEG F MIN

HI TEMP: 375 'TIME: IO

LOW 'TEMP: 325 'TIME: 20 M I D 'TEMP: 3 5 0 TIME: 15

M I M TEMP: 325 MAX TEMP: 4.25

PROBE 1 DATAPAQ #: 334 PEAK TEMP 460 W".":,iifNl;: AE,OVE ?-In:*: .rEFlF FOrl e:&?

PROBE 2 DATAPAQ X: 127 PEAK TEMP 395

PROBE 3 DATAPAQ #: 153 PEAK TEMP 401

PROBE u DATAPAQ #: 189 PEAK ' r E w 419

THRESHOLD TEMPERATURE: 350 (F) PROBE ' T o m TIME # OF OCCAS

M1N:SEC 1 16:40 5 2 8:15 1 3 10:15 1 4 13:50 2

THRESHOLD TEMPERATURE: 375 (F) PROBE 'TOTAL TIME X OF OCCAS

MIN: SEC 1 14:45 5 2 4:50 1 3 6:25 1 4 9:50 2

PEAK TEMPERATURE PROBE HAX. TEMP " t E REACHED

F H1N:SEC 1 460 22:50

3 401 15:40 4 41 9 23:30

2 395 25 : 20

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Temperature (F)

,

P6:UaE 'I - RED A I R PROBE 2 - GREEN INSIDE HINGE BOX F'ROBE 3 - BLUE PAMEL DOIJBLER PROBE 4 - BLACK LOWER FLANGE

Transducer ID# A411 885 BQ Printed on (Date not set)

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