Powder Coating Advantages

Article From: Products Finishing, , from Powder Coating Institute

Posted on: 6/1/1997

Acme needed a new finishing system, so it researched its options...

Like most manufacturing companies, Acme Fabrication Company (AFC) is constantly looking to improve its profitability by streamlining manufacturing processes and associated costs. Coincidentally, its existing liquid finishing system had reached the end of its useful life and needed replacing. So, AFC considered replacing its low-solids finishing system with powder coating. However, before the company could make a final decision in favor of powder coating, it evaluated other finishing technologies and associated capital and operating costs.

Products. Various formed and welded sheet metal products fabricated in accordance with customers' specifications and designs. These parts exhibit average finishing difficulty. The substrate is a combination of steel and aluminum. The maximum part size for this operation is five ft high by three ft wide by 10 ft long.

Application. Both sides of the fabricated parts must be coated using automatic applicators. Because of the complexity of some parts, manual touch-up is required to aid in providing complete coverage of the part. All of the products produced in this facility will be coated at one to two mils film thickness using one of two proprietary AFC colors.

Production Rate. Approximately 2.5 million sq ft of surface area will be coated per year. Production at this facility will be performed on a one-shift basis, five days per week, for 250 working days per year. The conveyor line speed required to attain this production rate has been calculated at 10 fpm.

Equipment Requirements. After some consultation with finishing experts, AFC has determined that most of the finishing equipment is the same for its application. For instance, the parts must be cleaned, pretreated, dried, cured and conveyed without regard to the finish applied. Therefore, the company is restricting its process comparison to the equipment required to apply low-solids and high-solids coatings, waterbornes and powder coatings.

Each of these finishing systems requires applicators to spray the coating, spray booths to isolate coating operations from the plant environment, and specialized ancillary equipment to meet code and safety requirements.

Table I (below) shows the uninstalled capital costs for each of the various finishing systems that AFC is investigating. These figures are based upon actual costs provided by various industry suppliers.

TABLE I -- Uninstalled Capital Costs
Finishing System Equipment Capital Costs
(not installed)
Low-Solids 2 water wash booths $200,000.00
  1 dry filter booth  
  8 electrostatic automatic spray guns  
  2 electrostatic manual spray guns  
  2 reciprocators  
  Fire detection and shutdown system  
  Water waste separator  
  Solvent incinerator $350,000.00
  TOTAL $550,000.00

High-Solids 2 water wash booths $204,000.00
  1 dry filter booth  
  8 electrostatic automatic spray guns  
  2 electrostatic manual spray guns  
  2 reciprocators  
  Fire detection and shutdown system  
  Water waste separator  
  Paint heaters  

Waterborne 2 water wash booths $240,000.00
  1 dry filter booth  
  8 electrostatic automatic spray guns  
  2 electrostatic manual spray guns  
  2 reciprocators  
  Fire detection and shutdown system  
  Water waste separator  
  Isolation and protection devices  

Powder Coating 1 powder coating cartridge booth $165,000.00
  8 electrostatic automatic spray guns  
  2 electrostatic manual spray guns  
  2 oscillators  
  Fire detection and shutdown system  
  2 reclaim modules with rotary sieves  

AFC, in consultation with its local environmental agency, determined that it would need to install a solvent abatement system if it was going to continue to use low-solids coatings. To be in compliance with air quality standards, it would have to install a solvent incineration system.

AFC was surprised to learn that the capital costs for powder coating were competitive with other finishing methods. This is especially true when it compared the capital costs of powder coating to low-solids liquid spray, including the solvent incineration system.

Operational Costs. Capital costs alone are not a fair comparison of these finishing technologies. So, AFC embarked on a comparison of operational costs. These operational costs consist of several parameters such as coating material, labor, cleanup and maintenance, energy and rework. Each of these categories needs to be examined separately to determine which finishing technology is least costly to operate.

Coating materials represent approximately two-thirds of the total operating cost of any finishing system. These costs vary widely between the different finishing technologies. Table II (below) provides the details of its analysis.

TABLE II -- Coating Material Costs
Cost Item Low-Solids High-Solids Waterborne Powder Coating
Material Cost, $/gal $18.00 $22.50 $17.50 $3.00 *
pct Solids 35 63 35 98
Specific Gravity N/A N/A N/A 1.4
Theoretical Coverage 561.4
sq ft/gal
1010.5
sq ft/gal
561.4
sq ft/gal
134.6
sq ft/gal
pct Utilization 50 50 50 89
Film Thickness 1.20 mils 1.20 mils 1.20 mils 2.00 mils
Actual Coverage 233.9
sq ft/gal
421.1
sq ft/gal
233.9
sq ft/gal
59.9
sq ft/gal
Applied Cost, $/sq ft $0.0770 $0.0534 $0.0748 $0.0501
* (substitute pounds for gallons)

AFC compared materials using application efficiencies and film thicknesses in standard industry practice. Because powder coating is easily recycled, its applied cost is less. This is true even in light of the slightly higher film thickness associated with powder coatings.

Because of the continuing rise in labor costs, the operational, cleanup and maintenance labor costs are of keen concern to AFC. Table III (below) shows the results of the comparison.

TABLE III -- Associated Costs
Cost Item Low-Solids High-Solids Waterborne Powder Coating
Line Supervisors 1 1 1 1
Supervisor Cost $20.50 $20.50 $20.50 $20.50
Supervision Total/hr $20.50 $20.50 $20.50 $20.50
Line Operators 2 2 2 2
Operator Cost $10.25 $10.25 $10.25 $10.25
Operators Total/hr $20.50 $20.50 $20.50 $20.50
Clean Up Time per Shift (hrs) 1.5 1.5 1.5 1
Clean Up Cost $10.25 $10.25 $10.25 $10.25
Hours per Shift 8 8 8 8
Hours per Year 2,000 2,000 2,000 2,000
Clean up Total/hr $1.92 $1.92 $1.92 $1.28
Waste Generated/hr 0.9 gal 0.9 gal 0.9 gal 2.2 gal
Sludge Disposal Cost/gal $45.00 $45.00 $45.00 $0.00
Sludge Total/hr $42.08 $42.08 $42.08 $0.00
Maintenance Hours 125 125 125 75
Maintenance Cost $10.25 $10.25 $10.25 $10.25
Replacement Parts $5,000 $5,000 $5,000 $2,500
Maintenance Total/hr $3.14 $3.14 $3.14 $1.63
Cost per Filter $1.00 $1.00 $1.00 $50.00
Filters per Year 120 120 120 6
Filter Cost per Hour $0.06 $0.06 $0.06 $0.15
Total Costs/hr $88.20 $88.20 $88.20 $44.07

Unfortunately, AFC realized that there is not any savings in operational labor costs since its system is designed to use automation as the main method of application. However, it did see a large reduction in maintenance labor and replacement part costs. This is largely due to the fact that powder coating systems have fewer moving parts and do not rely on mechanical pumps to feed the automatic applicators. Furthermore, the filters for powder coating systems are more expensive, but require changing less frequently. Sludge disposal is completely eliminated with powder coating, since waste powder is classified non-hazardous and can be handled by services that normally deal with non-hazardous wastes. When all of these factors were evaluated, it became clear that AFC would see a savings of more than 50 pct in maintenance and sludge disposal costs with a powder coating system.

Energy costs were also a concern. So it compared these different finishing technologies on a basis of energy usage. Table IV (below) shows the results.

Table IV -- Energy Use
Cost Item Low-Solids High-Solids Waterborne Powder Coating
Spray Booth Exhaust 200,640 Btu 200,640 Btu 200,640 Btu N/A
Cure Oven Exhaust 148,033 Btu 84,216 Btu 148,033 Btu 111,441 Btu
Total Load Loss 1,348,500 Btu 1,348,500 Btu 1,348,500 Btu 1,784,437 Btu
Oven Make-Up Air 12,123 Btu 6,897 Btu 12,123 Btu 6,897 Btu
Incineration Energy 738,390 Btu N/A N/A N/A
Flash Tunnel Exhaust 10,000 cfm N/A N/A N/A
Flash Tunnel Line 209,000 Btu N/A N/A N/A
Total Btu per Hour 2,656,687 1,640,253 1,709,297 1,902,775
Total Gas Energy Costs/hr $11.21 $6.92 $7.21 $8.03

Since powder coatings require slightly higher cure temperatures, the "Total Load Loss" or Btu's required to heat its product is higher for powder coating. However, AFC noticed that there was no need for spray booth exhaust, flash tunnel exhaust or solvent incineration for a powder coating operation. These three areas present AFC with significant energy savings over liquid finishes. When comparing total energy costs, powder coating is less costly to operate than low-solids coatings and slightly more expensive than high-solids or waterborne coatings.

It was time for AFC to total all the various operational costs for the different finishing technologies. It was here that powder coating was proven to be the finishing technology of its future with substantial operational cost savings when compared to liquid finishes. Table V (below) shows the results of these summations.

Table V -- Cost Summary
Cost Item Low-Solids High-Solids Waterborne Powder Coating
Material $192,376 $133,595 $187,032 $125,206
Labor, Clean up and Maintenance $176,410 $176,410 $176,410 $88,131
Energy $22,434 $13,851 $14,434 $16,068
Rework $31,298 $25,908 $30,230 $4,588
Total Annual $422,518 $349,764 $408,106 $233,993
Cost/sq ft $0.17 $0.14 $0.16 $0.09

This table clearly shows the advantages for AFC of operating a powder coating system as compared to other spray finishing methods. One of the most interesting aspects of powder coating is its forgiveness during application. Because it is almost impossible to cause a run or sag when applying a powder coating material, the cost for reworking rejected parts is dramatically reduced.

Payback. As with any capital equipment project, AFC is concerned with the amount of time it will take to amortize the initial cost of installing a new finishing system. AFC compared the operational cost of each spray finishing technology to its existing low-solids liquid spray operational cost to determine the annual operating cost savings. The savings, if any, were then divided into the capital cost for installing the new spray technology to determine the payback (in years) of converting to that technology. The results of this payback analysis are depicted in Table VI (below).

Table VI -- Finishing Payback System
Finishing System Capital Cost Annual Operating Cost Annual Operating Savings Payback In Years
Low-Solids $550,000 $422,518 $0.00 N/A
High-Solids $204,000 $349,764 $72,754 2.80
Waterborne $240,000 $408,106 $14,412 16.65
Powder Coating $165,000 $233,993 $188,525 0.88

Although all the spray finishing technologies offer some annual operational cost savings over low-solids liquid spray, powder coating offers the most dramatic reduction in annual operating costs. Additionally a powder coating system, in this example, is less expensive to install than all the other spray application technologies. AFC's capital costs of installing a new powder coating system will be paid back in operational savings within the first year of operation.

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