Financial Payback Overview
The financial analysis of any coating removal operation has several components:
- Capital cost of necessary equipment, structures and enclosures.
- Labor cost, including man-hours for setup, operations, cleanup, training, anticipated on-the-job injuries, and labor overhead.
- Waste disposal cost including collection, containment, storage, transportation, tipping, related labor, taxes, and any fees related to hazardous materials.
- Out-of-service cost for the equipment being serviced.
- Cost of damage to the equipment being serviced.
- Processing costs including tools, supplies, materials and power if required.
Published studies abound comparing laser ablation to traditional means of coating removal and surface preparation. One factor, the relative stripping rate, can have a significant effect on operational readiness, inventory availability, and production line flow. One set of studies produced the following comparative results:
| Technology | Effective Strip Rate | |
|---|---|---|
| Media Blast |  |
0.03 — 0.22 ft2/ minute |
| Chemical Application |  |
0.002 — 0.05 ft2/ minute |
| Hand Sanding or Grinding |  |
0.0017 – 0.07 ft2/ minute |
| Water Blast |  |
0.05 – 0.07 ft2/ minute |
| Laser Ablation |  |
0.80 ft2/ minute |
- Effective Strip Rate: Fully burdened costs for media blast, chemical application, hand sanding, and water blast from USAF AFRL Joint Group on Pollution Prevention Study, 2001. All strip rates normalized to 1 mil thick coatings.
- Laser Ablation: Laser ablation rates depend upon average pulsed power of laser system. The approximate formula for laser ablation removal of most paint and other coatings is:
Strip rate in square feet per minute = 2 X (laser power in KW) / (coating thickness in mils)
where one mil = .001”
Therefore a Q-switched laser with an average pulsed power of 400W strips at 0.80 ft2 per minute.
Laser ablation strip rate advantages stem in large part from the elimination of all set-up and all clean-up time. Laser ablation simply requires “point and strip”.
Several studies of the total effective cost of aircraft fuselage decoating are summarized as follows:
| Study | Aircraft | Method | Effective Cost/ Sq. Ft. |
|---|---|---|---|
| 1 | T-45 Trainer | Chemical Solvent | $22.00 |
| 2 | T-38 Trainer | Chemical Solvent | $18.00 |
| 2 | T-38 Trainer | Hand Sanding | $13.00 |
| 1 | T-45 Trainer | Plastic Media Blast | $11.00 |
| 3 | F-4 Fighter | Chemical Solvent | $10.00 |
| 3 | F-4 Fighter | Plastic Media Blast | $5.00 |
1 AMTIAC Newsletter, Winter 1001: http://amtiac.alionscience.com/pdf/AMPQ5_4.pdf#ART02
2 Joint Services Pollution Prevention Handbook: http://p2library.nfesc.navy.mil/P2-Opportunity_Handbook/8_1_7.html
3 Pollution Prevention Opportunity Data Sheet: http://www.p2pays.org/ref/01/00597.pdf
Fully burdened “effective costs” included labor, preparation time, damage prevention precautions, power consumed, amortized equipment costs, consumable material costs, and residue disposition costs. All costs are based on published sources and normalized to contemporary times as per the references.
By comparison, Lasertronics’ laser ablation fully burdened, effective costs average $3.00 to $4.00 per square foot dependent on specific site variables. This reduction in cost from current stripping methods yields rapid payback. Many other benefits of laser ablation can be vitally important such as reduction in potential for damage, reduction in toxics exposure, reduction in operator harm, improvement in operational readiness, and abilities to process surfaces otherwise impossible to treat. Examples of the latter include complex, irregular, inaccessible, and fragile surfaces, all of which are difficult or impossible to strip with any traditional methods.
Obviously, each situation is unique. We would be pleased to address specific inquiries.
Labor Cost:
For manual Lasertronics’ ablation systems, the total labor required is one operator per system, for the hours the system is operated. This operator can both operate and maintain the system. Operating maintenance consists primarily of checking and changing as-needed the particulate filter. Semi-skilled labor can operate the system efficiently. Training time is about an hour. The number of man-hours required to complete a stripping job depends on the stripping rate of the laser being used, which in turn is determined by the power output of the laser.
Additional labor considerations for comparison with other methods include:
Reduction in injury rate. Abrasive methods (sanding, scraping) frequently lead to repetitive motion injuries. These are eliminated with the Lasertronics system.
Protective clothing. Most conventional methods (sanding, scraping, media blast, and solvents) require protective clothing, and in some cases respirators or supplied air systems. Even with the protective clothing and breathing protection, toxics exposure and array of resultant costs and operator impacts often still result. The Lasertronics system requires no protective clothing beyond eyewear (glasses or goggles) that costs about $200 per operator.
Waste Disposal Cost
A unique benefit of the Lasertronics ablation system is the potential it presents to capture stripped particulate material in a paper filter. This capability vastly simplifies the entire waste disposal problem. Instead of capturing, controlling, shipping, and disposing of potentially tons of contaminated media or liquid solvents, with Lasertronics the operator need only monitor and, as needed, change a paper HEPA filter that captures the ablated material. The contaminated filter containing the captured particulate is the only waste requiring disposal.
Toxic waste generation: Stripping one pound of paint generates very different volumes of waste, depending on the stripping method chosen
Lasertronics stripping generates about 12% (by weight) as much waste as does media blast, and about .3% as much as solvent stripping. Perhaps more important, Lasertronics enables capturing the waste in easy-to-handle, dry paper filters, making proper waste disposal far simpler, much cheaper, and a lot more likely to actually happen than with other methods.
Out-of-Service Cost
This cost takes the form of either the cost of loss of service, or the cost of providing extra equipment to fill in the anticipated out-of-service periods. In most situations where Lasertronics’ ablation system is a good fit in other regards, it is also faster than conventional approaches, resulting in a net reduction in out-of-service costs. A tenfold reduction in out-of-service time is common. Specifics can be estimated on a case basis.
Potential for Damage
This is another area where Lasertronics ablation shines, because it is nearly impossible to damage a substrate using Lasertronics’ ablation technology. Other methods of stripping are problematic:
Media blast is known to pose a damage risk to fragile substrates such as thin aluminum or composite fuselages. For that reason, aircraft can generally be blasted only once in their lifetime. In contrast, there is no limit to the number of laser ablation cycles.
More durable substrates, such as ships’ hulls, often must be blasted twice: once to remove the coating, and once again to restore the profile needed to optimize acceptance of a new coating. Lasertronics ablation, by contrast, removes only the coating and leaves the substrate surface in virgin condition, ready to accept new coatings without further processing. Alternative laser ablation processes that do not have Lasertronics’ controls have caused surface reflows of high strength steels that, as as consequence have decreased ductility, increased hardness and overall decreased strength.
Solvents and Scrapers are typically used on fuselages per the OEM maintenance manuals. If incorrectly used, scrapers can inadvertently cause surface damage leading to fracture. Alternatively, solvent-softened aluminum can obscure pre-existing cracks thereby rendering them undetectable during non-destructive testing. Highly concentrated solvents react with metal substrates to weaken the structures.
Lasertronics’ ablation systems prevent surface damage by use of sophisticated in-line real-time sensing of the target coating before every pulse. When the sensors detect a surface condition (color, shininess, roughness, or other condition that has been predetermined), the pulse is prevented from ever firing.