Testing Report on Turbine-Powered Spray Guns

Article From: Products Finishing, , from Gardner Business Media

Posted on: 6/1/2001

United Defense FSE REPORTProject Engineer: Tom BraswellDate: 03 November 2000Objective: Beta testing of high-performance HVLP on York production line Background As a result of a technical literature search, the Can-Am HVLP (compressor-less) spray system was investigated as a possible solution to the cessation of the recycling thermal oxidizer on site at York.The system showed the most promise based on the supporting documentation in the form of research projects performed by the Hughes Aircraft Co. and the California South Coast Air Quality Management District.

United Defense FSE REPORT
Project Engineer: Tom Braswell
Date: 03 November 2000
Objective: Beta testing of high-performance HVLP on York production line

Background

As a result of a technical literature search, the Can-Am HVLP (compressor-less) spray system was investigated as a possible solution to the cessation of the recycling thermal oxidizer on site at York.

The system showed the most promise based on the supporting documentation in the form of research projects performed by the Hughes Aircraft Co. and the California South Coast Air Quality Management District. Selection of the system was also based on the considerable list of customers serviced by the company.

Alpha Testing Stage I

CARC coatings used at UDLP York and test coupons were sent to the supplier for a compatibility test with its equipment. The supplier's personnel prepared all of the test coupons with the CARC coatings (unreduced) and returned them to York for evaluation. The test coupons were evaluated for appearance and film thickness. When compared to York production test coupons, the CARC 686 Tan test panels looked smoother. The MIL-C-22750 white epoxy sprayed by the turbine-powered HVLP spray guns had a better distinctness of image (DOI). And, the MIL-P-53022 epoxy primer was free of orange peel we normally see with other HVLPs.

Alpha Testing Stage II

A project engineer and two CARC painters traveled to the supplier plant site in Livonia, MI, to test the spray application of CARC coatings first hand using the company's equipment. The CARC coatings were sprayed unreduced onto 36 test coupons, 24 5-gal steel pails and lids and an after-market Jeep fender assembly.

The supplier's HVLP spray guns atomized the unreduced CARC coatings superior to the solvent reduced CARC coatings applied by HVLP spray guns we currently use at York. (We cannot spray unreduced CARC topcoat with our equipment.) It also performed better than the spray guns we use on our small parts line at York.

Both painters were pleased with the performance of the gun and the ergonomics of the system. We measured on site, 25-30% less liquid paint used over our current equipment. However, the measured DFT was averaging 25-35% heavier. This anomaly will also contribute to paint savings once the painters get used to the high transfer efficiency of the turbine-powered HVLP spray guns and apply less paint. The test coupons and the buckets were free of defects and were very smooth.

Beta Testing at York

All of the Alpha testing showed that Can-Am's equipment is a promising compliant system for our paint operations at York. We invited the supplier's crew into the plant for a three-day Beta test run on our production lines.

Summary of the Beta Test

We were able to spray the most difficult coatings we have, MIL-C-53039 Tan 686 and Green 383, without solvent reduction. We painted product on the large parts paint production line for two days with four painters and one day in small parts paint with four painters with no problems.

Paint consumption was reduced by 42-45% using the turbine-powered HVLP spray guns. Painters completed events 9-15% faster as well. The equipment was easy to use and produced paint finish quality better than our HVLPs and other spray guns.

Findings (Comments from painters)

1.Less overspray fog in confined spaces such as drivers compartment. I could see what I was painting very easily.
2.Better coverage back into holes and crevices.
3.Use fewer paint shields (one as compared to three or four) during a C2V hull paint job.
4.Use less paint. I don't have to refill as often. We used about half the paint we normally use.
5.Sprays wetter. Easier to maintain a wet edge
6.Less dry spray. Almost none in areas where we always get dry spray
7.Blisters are gone. There are no blisters, even where we have heavy coverage.
8.This gun is fast. We can paint as fast as we want without the equipment holding us back.
9.Can be used to spray topcoat CARC with no thinner. We can't do that with our HVLPs.
10.The gun and hoses feel lighter than what we have and are more manageable after the air hose warms up.

FSE Findings

1. The paint atomization with the turbine-powered HVLP spray gun is superior to any equipment we have.
2. The visible overspray is minimal. The difference was very dramatic when we switched back to the current HVLP during our comparison.
3. Coverage with the tested HVLP was better, especially in difficult-to-reach areas like pockets and holes.
4. The overall appearance of the products painted was better than that painted with our HVLP.
5. We used a measured 42-45% less liquid paint. The parts we painted were coated heavier than normal (about 25% in some areas) because the painters were not used to the transfer efficiency. This will also add to the paint savings when the painters become more proficient with the turbine-powered HVLP spray guns.
6. The rate at which the tested equipment can apply paint is faster than our HVLPs. The average was 9% faster with the unreduced paints and 10-15% faster with the CARC coatings reduced 10% with acetone.
7. Grille doors, a part that always has blisters in the CARC topcoat on the fin edges, had none.
8. The painters used 75% fewer face shield protectors because of less overspray.
9. The painters went in the small parts spray booth in white cover-alls and came out with white cover-alls. The much reduced overspray helped keep the painters from painting each other.
10. The electric power to the tested equipment is necessary only while spraying. It can be turned off after the painters blow out their guns.
11. The Quality Control Auditor performed all of the normal checks on the events painted with no findings.
12. The painters want to use the turbine-powered HVLP equipment.

Information

1. The cost to install the equipment in all five of our booth locations is approximately $149,000. A spare's package is an additional $7,386.

The breakdown for the Can-Am costs is as follows:

  • Large Parts Booth no.1 $32,228.60
  • Large Parts Booth no.2 $32,228.60
  • Large Parts Booth no.3 $32,228.60
  • Small Parts Prime Booth $23,559.20
  • Small Parts Topcoat Booth $28,768.80
  • Spares $7386.40

2. In year 1999, we used 7,928 gallons of paint in Bldg. 8 (according to our integrated coatings supplier). The cost of that paint was $245,744.65. Since the tested equipment can reduce our paint consumption by at least 40%, we could have saved over $98,000 during that year if it was in place at all spray painting positions.
3. This is a compressor-less system. The air for the spray guns is supplied by a 7.5 hp turbine. This turbine produces over 200 cfm at 8.75 psi. At maximum output, the gun uses 28 cfm at 8.75 psi. (Our painters can spray at 5 psi or less with this equipment.) This unit will drive three guns at maximum output with the CARC coatings. The turbine was supplying 11.2 cfm per 1 hp.
4. The current HVLP guns we use need 18-23 cfm to operate efficiently. Each 1 hp produces 4 cfm. Each gun at maximum output uses 5.75 hp. The energy required to run the turbine-powered HVLP was less than half our current system. And, the turbine can be turned off between painting events, saving energy.
5. The painters will need training to apply the proper amount of coating. Each painter needed time to adjust to the higher transfer efficiency.
6. All of the support equipment for our current HVLP's can be used. The compressors will not be needed for atomization air.

Recommendation

Purchase the turbine-powered HVLP equipment to replace the HVLP and other spray guns we now use. The paint RMC savings based for year 1999 (at 40%) could have been $98,297.86. Or, purchase the units in increments as justified.

 


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