infrared vs

7/26/2019 Infrared Vs

1/3

Infrared vs. Convection Curing

Many manufacturers face the challenge of product

piling up around their painting department, waiting to

cure. After all, depending on the paint being used, it

can take anywhere from a few minutes to a few hours

to achieve the degree of curing required for the

product to move to the next step of your

manufacturing process.

ne of the best ways to help reduce a bottleneck due

to slow throughput in your painting process is to reduce

the time it takes to cure your paint.

!ypical methods for speeding up the curing process

include Infrared curing and convection heat. "oth

options have their pros and cons, which we will review

so you can better determine which might be right for

your application.

Convection Curing

#or a variety of reasons, convection heat is one of the

most common methods of curing coatings. Convection

heating involves elevating the temperature of the

ambient air surrounding a product in order to speed upcuring. $olvent%based coatings& cure time can often be

reduced by '( percent or more using convection heat.

ne of the primary bene)ts of convection heating is

the opportunity for a low%cost initial investment. *aint

booths can be purchased with an elevated heat option

for curing, making the overall cost very reasonable.

$imilarly, convection curing ovens typically can be

purchased at a lower initial cost than infrared ovens.

An additional bene)t of convection heat is that it will

work with a large variety of coatings+as a general rule

of thumb, though, you should check with your coating

representative to make sure it&s a viable option.

A )nal bene)t of convection heat, in comparison with

infrared, is that convection will work with a greater

variety of product shapes.

Infrared Curing

Infrared curing involves infrared waves penetrating

through the coating and curing throughout. #or this to

happen most eciently, the infrared waves should

have a direct line to the surface that you are trying to

cure. !hat&s why infrared curing is best for -at

surfaces If your product has a lot of angular, round, or

non%-at surfaces, this method can present challenges.

!he largest bene)t of infrared curing is how much

faster it can cure a coating as compared with

convection curing. !his is due to the temperature

elevations associated with infrared curing. /epending

on the wavelength of infrared being used,

temperatures can be elevated in seconds up to a few

thousand degrees. !he end result is a rapid curing

time.

In addition to rapid curing, infrared can also have a

lower operating cost. In the convection method, a lot of

energy is used to elevate and maintain temperature in

a paint booth or oven. !his results in higher operating

costs. $ince infrared uses energy waves to elevate

temperature, curing begins almost immediately and

very little energy is wasted in the curing process.

An additional bene)t of infrared curing is that it can be

used to spot cure. $ince infrared curing uses energy

waves, you can purchase infrared panels that allow for

curing targeted areas. !his can be a useful application

for spot repair work when you want to accelerate the

curing time.

Infrared curing, though, can be used on fewer types of

coatings than convection. !his is largely because it

depends on the infrared waves to be able to pass

through the coating and re-ect o0 the substrate

causing heat elevation of the coating.

1o matter which technology you are leaning toward, it

is always recommended to have a coating baked using

that method as a 2trial run3 prior to deciding on an

equipment investment.

If a coating has certain properties, like being

excessively re-ective, the infrared waves may not

e0ectively penetrate the coating and may not cure the

coating well. Additionally, certain substrates will absorb

infrared waves, reducing the re-ection of the wave

back through the coating, which can signi)cantly

reduce the curing e0ectiveness of infrared.

/ue to the potential challenges of coatings, substrate

materials, and product con)gurations you should

always have your product tested to see if infrared

curing can potentially work for you. In fact, no matter

which technology you are leaning toward, it is alwaysrecommended to have a coating baked using that

method as a 2trial run3 prior to deciding on an

equipment investment to determine if you can improve

production time.

Making a /ecision

"efore you decide which tool might be ideal for you, it

is smart to coordinate with your coating representative

to verify whether convection or infrared curing will

work, evaluate the production improvement potential

of either solution, and evaluate the cost di0erences in

initial investment and operating costs.

4ltimately, convection and infrared curing both have

good uses. 5hich method will work well for your

application will depend on the substrate of your

products, the coating you apply, the amount you want

to invest, and your production priorities.


2/3

6lectrostatic *ainting 5hat 7ou 1eed to 8now

6lectrostatic painting is often not well understood in

the paint and coatings industry.

!o help clarify the electrostatic process, I want to

discuss what electrostatic painting is and how it works,

things you should consider, and how to determine if it

is the right )t for you.

!he electrostatic method is used in liquid and powder

coating, but I will focus on liquid coatings in this post.

5hat It Is, 9ow It 5orks

6lectrostatic painting is a process in which an

electrostatic charge is applied to both the substrate

and to the coating through the tip of the spray tool in

order to achieve eciency in painting the surface by

preventing overspray.

!he coating is pro:ected by an electrostatic charge

from a high%volume, low%pressure ;9 spray gun or

airless paint sprayer to the grounded, conductive

surface to be painted.

!he charged paint is attracted to the charged surface

in such a way that the pain essentially wraps around

the target and rather than leading to overspray.

!his translates into a high transfer eciency and

reduction of coating waste. !ypical ranges of

electrostatic transfer eciency are anywhere from ?(

to @( percent, depending on the target type and other

factors.

!his paint savings is often what makes electrostatic an

attractive solution, but there are a lot of things to

consider with electrostatic coating, such as the

coatings you use, the intended target, your equipmentmaintenance tendencies and safety.

Coatings and 6quipment

!he coatings you want to use are an important

consideration because of the unique requirements of

electrostatic equipment.

In the electrostatic process, the charged paint is

attracted to the charged surface in such a way that the

pain essentially wraps around the target and rather

than leading to overspray.

5aterborne coatings, for example, require special

spray guns when used for electrostatic painting. !his is

because waterborne coatings are conductive and tend

to carry a charge that can cause issues with

2grounding out3 when they are sprayed.

rounding out means that the electric charge+rather

than charging the paint at the tip of the gun+simply

passes back through the coating into the pressure pot

and, if the pressure pot is grounded, into the earth.

!his provides none of the bene)ts of electrostatic

application.

!he waterborne%speci)c electrostatic spray gun will

have an isolation block as part of the equipment to

prevent the electric charge from trying to return to the

pressure tank and ultimately stops the waterborne

coating from grounding out.

!his can be a highly expensive downside if you

routinely change between solvent% and water%based

coatings on your :obs because you will need two

di0erent types of electrostatic guns.

Additionally, many unique complications can occur with

this specialiBed process, so it is always best to have

someone test the equipment tested in your work area,

with your coating and under your normal

circumstances. 6lements such as humidity, the

grounded target, the coating itself and the solvent you

use can vary from one work area to the next and a0ect

the spray application.

It is also important to note that certain solvents are

more likely to work well with a solvent%based

electrostatic gun because they are less conductive

than other solvents. $ee the table below for more

information.

4ltimately, the goal is to have the coating be as

nonconductive as possible. !hat is why solvents like

xylene and toluene are good for electrostatic painting

they are nonconductive, which minimiBes the likelihood

of your coating grounding out.

8eeping in mind the unique requirements of

electrostatic coating, for the most part you can spray

:ust about any coating, but certain coatings like Bincs

will not take a negative charge well and therefore will

not be able to deliver the improved transfer eciency

electrostatic brings.

$urface Materials

!he surface you intend to paint also plays a signi)cant

role in determining if electrostatic spraying is a good

method to use.

*lastic, wood or )berglass surfaces won&t conduct a

charge without a preparation coating, for example. !his

means you will have to apply a prep coating before

your intended coating to allow for electrostatic

application.


3/3

Additionally, electrostatic application is sub:ect to a

phenomenon called the #araday Cage 60ect. !he

#araday Cage 60ect describes the tendency for

negatively charged particles to want to attract to the

nearest positively charged surface.

In electrostatic painting, this e0ect means that the

paint will want to adhere to the sides of the surface

material but not penetrate into any corners. 5ith this

in mind, an applicator needs to remember to turn the

electricity to the gun o0 in order to achieve thoroughcoverage.

$hop and 6quipment Maintenance

Another area to consider before investing in

electrostatic painting is how well you maintain your

shop and equipment.

6lectrostatic equipment is a lot more expensive than

9

infrared vs

Documents