Powder Coatings---8. Economics of Powder Coating

andrewfei

Powder Coatings
8. Economics of Powder Coating
Complete Guide to Powder Coatings
Issue 1 – November 1999 27
Coating costs are questioned now more than ever
before. Many coaters want to know how powder
coating compares to liquid coating economically?
To answer the question, each and every individual case
must be assessed. There are many aspects and factors
that should be considered in order to judge the entire
economics of a project.
Some aspects are tangible and are specific such as
technical, technological and investment factors. Others
are intangible, for example hazard, risk and quality.
The following offers guidance in the selection of
powder coating.
Advantages of Powder Coating
1. Powder is immediately ready for use:
􀀹 There is no need to mix powder with solvents or
catalysts, or make any adjustment prior to use
􀀹 This eliminates any risk on the factory floor or in
the paint shop and reduces rejects due to mistakes
in the adjustments needed for wet paint prior to
use.
2. Reduction of fire risks:
􀀹 No solvent is used which reduces the risk of fire.
This presents cost savings on both regulatory safety
measures and a reduction of insurance premiums
􀀹 It eliminates the need for protected wiring and
special light and power supplies in the storage area
and application booths
􀀹 Care should be taken to ensure that naked flames
and heat soures do not come into contact with the
powder coating material.
3. No solvent waste problems:
􀀹 Powder coatings do not use solvents for thinning,
spraying or cleaning thus reducing waste disposal
problems
4 No solvent/paint waste disposal costs.
4. Reduced health risk in case of operator
exposure:
􀀹 The ommission of solvents in powder coatings
reduces the amount of inhalable hazardous
materials
􀀹 Contact with skin produces less hazourdous effects
and is easily washed off
􀀹 No need to use solvents or emulsifying soap to
clean skin. Barrier cream is sufficient to prevent
infection or irritation upon contact.
􀀹 A face mask will prevent powder-dust from being
inhaled
􀀹 Very little smell (if any) is produced, reducing the
need for ventilation.
5. Low waste of powder in the application process:
􀀹 Utilisation factors of 96 to 98% are possible, using
a well maintained recovery and recycling system in
the spray booth.
􀀹 No powder emulsions or powder sludge need to be
discharged. No costly waste of solvent and no
need for expensive solvent recovery systems.
􀀹 Unused powder can be collected and recycled,
reducing potential environmental problems.
6. Superior powder film properties:
􀀹 Improved performance can be achieved in
comparison with many conventional paints
􀀹 Improved appearance and performance can be
achieved using one coat application
􀀹 Adhesion and corrosion resistance are improved as
a result of easier curing control
􀀹 Powder film has minimal shrinkage during curing
resulting in excellent edge cover. Polymer weight
loss during stoving is less than 1%.
􀀹 More uniform and higher film thickness (35 upto
250 microns) can be obtained and controlled
without special training
􀀹 Provided the related equipment is well controlled it
will ensure that the required film thickness is
maintained and repeatable in automated production
􀀹 High gloss, semi gloss, matt, metallic and textured
coatings can be achieved in one application.
7. Easy powder-film repair:
􀀹 If one or more spots of the film are damaged before
curing the powder can easily be removed from the
surrounding area with air or a vacuum
􀀹 Rectification of the damaged area takes place by
re-spraying
􀀹 The removed powder can also be recycled and reused.
8. Housekeeping:
􀀹 The powder coating booth is easily cleaned using
air or a vacuum. Simple cleaning tools can be used
to clean booth walls and floors
􀀹 It is not necessary to use cleaning solvents and rags
as with liquid coating booths
􀀹 Manufacturers safety instructions must always be
followed
􀀹 Good housekeeping practices must be maintained
at all times.

andrewfei

9. Additional capital investment and economic
advantages:
􀀹 Simple automatic equipment enables easy
application
􀀹 Less need for skilled sprayers and operator training
􀀹 Simple pretreatment will normally suffice. For
most applications degreasing and phosphating will
be suffucient
􀀹 Processing time is generally reduced (in
comparison to liquid coatings) as a result of not
having to ‘flash off’ the solvents before curing
􀀹 Less space is required for equipment because there
is no ‘flash off’ period
􀀹 No solvents or hot solvent laden air needs
evacuation which reduces energy requirements
􀀹 ‘Flash off’ dust is not created and therefore does
not adhere to coatings reducing surface defects and
rejects
􀀹 Less air is required for replacement in the oven and
plant resulting in reduced heat loss
􀀹 Less storage space is requird for powder coatings
without special fire precautions such as anti flash
fittings
􀀹 No special solvent stores are required as powder is
ready for use
􀀹 A powder plant is simpler and cheaper to operate
than a liquid paint application plant.
In conclusion, the major benefits for selection of
powder coatings are:
1) Tangible capital cost reductions
2) Tangible operationl cost reductions (energy,
labour, efficiency)
3) Intangible technological cost reductions (quality,
hazards, environmental).
Specific cost considerations - At the end of the coating
line the most important figure is the all-in net cost per
m² for a powder coating film. To evaluate this cost we
should consider and analyse the entire powder coating
system starting at the raw material entrance of the
application plant and finishing with storage and
shipping activities. This is a very difficult task.
Table 11 illustrates how such calculations are carried
out:
Table 11: Simplified calculation of powder coating material cost and consumption per m²
(As powder coatings contain no solvent and require no mixing or thinning, it is relatively easy to calculate the
weight of powder required to coat a given work-piece surface. From this the cost can also be calculated):
Specific Gravity x Film thickness (microns) =Grams of powder per square meter coated
- Given a white powder with a specific gravity of:
- Volume of powder on 1m² with 1 micron thickness:
- Assuming a film thickness of 60 microns the amount of powder
per m² equals:
- The area covered with 1 kilo of this powder would be:
1.65g/c³
1c³
1 x 1.65 x 60.00 = 99 grams
1000/99 = 10.10m²
When all operations and equipment in the plant are well maintained and controlled a theoretical powder utilisation
of 97% could be expected in continuous production. This efficiency factor must also be taken into account.
- Thus giving:
- We assume that the powder is purchased for a net price of:
- The final coating cost is therefore:
97/100 x 10.10 = 9.797m² coated surface
Euro 15
15/9.797 = Euro 1.531/m²
Notes:
1. Errors can be made in calculating the surface area that requires coating. The total surface area must include
both sides of the component back and front, or if one side coating is required the wrap around effect must be
included in the calculation eg. with a multipication factor per running meter edge length
2. Inefficiencies take pace in every plant at certain times in in varying degrees. For short runs it may not be
feasible to optimise the efficiency factors
3. Akzo Nobel are able to provide technical assistance to optimise plant efficiencies.

andrewfei

Table 12: Powder Material Cost
Line Determining Factor Reference Case 1 Case 2 Case 3
1 Powder cost NLG per kg 15.00 16.50 16.50
2 Specific gavity G/c³ 1.65 1.65 1.65
3 Volume of powder c³/m² With thickness of 1 micron 1 1 1
4 Film thickness in microns Average 60 60 70
5 Theoretical coverage m²/kg 1000 / (line 3 x line 2 x line 4) 10.10 10.10 8.66
6 Theoretical material efficiency in % Normal range 95 – 98 97 97 97
7 Theoretical coverage in m²/kg Line 6 / 100 x line 5 9.80 9.80 8.40
8 Material cost NLG/m² Line 1 / line 7 1.53 1.68 1.96
Table 12 shows the same analysis in the form of a
matrix calculation. The advantage of this method of
calculation is clear when used for several cases at the
same time (See Case 1, 2 and 3 to follow). A selected
determining factor can be varied and the final result is
available immediately.
We recommend an identical analysis and calculation
matrix for each of the following steps in your powder
coating application process. Akzo Nobel can provide
technical assistance to help optimise the calculations
for your own plant.
Chemical cost for pretreatment - In most
pretreatment processes, chemicals are used such as
cleaners, surfactants, ion exchange chemicals and
phosphates etc
Energy cost - This represents the additional cost of
large energy consumables such as:
Curing oven: The powder curing oven requires less
exhaust air than the liquid coating alternative.
Although powder formulations typically need higher
curing temperatres, the overall energy requirement is
still less than with liquid coatings.
Conveyor system: Not only is energy required to drive
the conveyor it is also required to compensate for heat
loss to the conveyor and parts.
Energy for air circulation: Powder systems circulate
air but do not require make up air which has to be
heated. A powder coating application system requires
that a specified circulation of air is maintained in the
spray booth, through the recovery, air filter systems and
back into the building.
General utilities costs - Is dependant on the heating
method used in the curing oven ie. natural gas, oil or
electricity. Additionally, compressed air, water and a
general quota for electric power consumption for other
consumables would be required.
Labour and maintenance costs - Working hours and
hourly labour costs for operations and maintenance
would be a factor to be included here, if necessary split
per process step. Also replacement parts (filter
elements, sieves) and parts (bearings, conveyor, pump,
spray gun, instrumentation parts) need to be
incorporated.

andrewfei

Table 12: Powder Material Cost
Line Determining Factor Reference Case 1 Case 2 Case 3
1 Powder cost NLG per kg 15.00 16.50 16.50
2 Specific gavity G/c³ 1.65 1.65 1.65
3 Volume of powder c³/m² With thickness of 1 micron 1 1 1
4 Film thickness in microns Average 60 60 70
5 Theoretical coverage m²/kg 1000 / (line 3 x line 2 x line 4) 10.10 10.10 8.66
6 Theoretical material efficiency in % Normal range 95 – 98 97 97 97
7 Theoretical coverage in m²/kg Line 6 / 100 x line 5 9.80 9.80 8.40
8 Material cost NLG/m² Line 1 / line 7 1.53 1.68 1.96
Table 12 shows the same analysis in the form of a
matrix calculation. The advantage of this method of
calculation is clear when used for several cases at the
same time (See Case 1, 2 and 3 to follow). A selected
determining factor can be varied and the final result is
available immediately.
We recommend an identical analysis and calculation
matrix for each of the following steps in your powder
coating application process. Akzo Nobel can provide
technical assistance to help optimise the calculations
for your own plant.
Chemical cost for pretreatment - In most
pretreatment processes, chemicals are used such as
cleaners, surfactants, ion exchange chemicals and
phosphates etc
Energy cost - This represents the additional cost of
large energy consumables such as:
Curing oven: The powder curing oven requires less
exhaust air than the liquid coating alternative.
Although powder formulations typically need higher
curing temperatres, the overall energy requirement is
still less than with liquid coatings.
Conveyor system: Not only is energy required to drive
the conveyor it is also required to compensate for heat
loss to the conveyor and parts.
Energy for air circulation: Powder systems circulate
air but do not require make up air which has to be
heated. A powder coating application system requires
that a specified circulation of air is maintained in the
spray booth, through the recovery, air filter systems and
back into the building.
General utilities costs - Is dependant on the heating
method used in the curing oven ie. natural gas, oil or
electricity. Additionally, compressed air, water and a
general quota for electric power consumption for other
consumables would be required.
Labour and maintenance costs - Working hours and
hourly labour costs for operations and maintenance
would be a factor to be included here, if necessary split
per process step. Also replacement parts (filter
elements, sieves) and parts (bearings, conveyor, pump,
spray gun, instrumentation parts) need to be
incorporated.