automating coating process
TRANSCRIPT
Automating the Coating Process Presented by:
Nguyen Quang Vu Business Development Manager
Finishing Brands UK
Automating the Coating Process
• Applicator Technologies
• Spray Characteristics
• Automation: Reciprocators & Robotics
• Product Presentation
• Production Requirements & Cycle Time
• Calculating Coating Volume Needs
• Selecting Automation
Applicator Technologies
Air Atomization
Hydraulic Atomization
Centrifugal (Rotary) Atomization
Electrostatics
Automating the Coating Process
Air Atomization Technology
Conventional Air Spray
• Low Volume High Pressure
HVLP
• High Volume Low Pressure
LVMP (TransTech \ Compliant)
• Low Volume Medium Pressure
Applicator Technologies
Conventional, HVLP, LVMP • Functional mechanics are all the same
• Air impinging on fluid stream to create droplets
Atomization air exits
from center holes of
air cap and creates
droplets
Fan (Pattern) air
exits from horns of
air cap and shapes
pattern into elliptical
shape
Conventional “Air Spray”
• The most established method of air atomizing used on spray guns
• Uses high pressure and low volume of air to provide good atomization of the material
• This process creates a high particle velocity resulting in lower paint transfer efficiencies due to “bounce-back” and “overspray” generated.
Applicator Technologies
Applicator Technologies
HVLP (High Volume Low Pressure)
• Compliant technology developed in the 80’s when environmental legislation was first introduced.
• Uses larger compressed air volumes at lower pressures to atomize coating materials.
• Can yield higher transfer efficiency than conventional air spray, however, quality of finish may be negatively impacted.
LVMP (Trans-Tech \ Compliant)
• Introduced in the 90’s and is a combination of Conventional and HVLP atomization methods.
• Trans-Tech utilizes more compressed air for the atomization process producing smaller droplet than HVLP.
• Can yield higher transfer efficiency than conventional air spray, with better quality than HVLP.
Applicator Technologies
Conventional • Spray at Any Pressure / CFM
• Air cap pressures typically 30 – 60 psi
HVLP • Meets USA Regulatory Requirements
• Air cap pressure less than 10 PSI
• Requires air cap test kit
LVMP (TransTech, Compliant) • Meets European Requirements
• Air cap pressures typically 20 – 40 psi
Applicator Technologies
Conventional, HVLP, LVMP • Comparison of air consumption, efficiency and particle size
Particle Size
150
300
450
600
750
900
20 40 60 80 100
HVLP
LVMP
Air
Air
Co
ns
um
pti
on
( l/m
in)
Transfer Efficiency %
Applicator Technologies
Conventional, HVLP, LVMP
Applicator Technologies
Applicator Technologies
Hydraulic Atomization
• Material at a high pressure is forced through a fixed orifice.
• The material is atomized by shear
• Spray pattern size is based on angle ground into tip
• Flow rate is based on fluid pressure developed by pump
Applicator Technologies
Hydraulic Atomization Airless & Air Assisted
• Airless
Typically 1000 - 4000 psi
High flow capability
Used with wide variety of
coating materials
Applicator Technologies
Hydraulic Atomization Airless & Air Assisted
• Air Assisted Airless
Typically 300 - 1500 psi
Air used to improve spray
pattern uniformity
Applicator Technologies Hydraulic Atomization Airless & Air Assisted
Applicator Technologies
Air and Hydraulic Atomization
Applicator Technologies
Centrifugal (Rotary) Atomization
• Rotary atomizers were developed by Harold Ransburg in the 1940’s.
• The term “Bell” comes from the shape of the original atomizers that were driven at low speeds 900 -1800 rpm with electric motors.
• The rotation was used to distribute coating evenly around the perimeter and the atomization process was purely due to the electrostatic charge applied to the “bell”.
Applicator Technologies
Centrifugal (Rotary) Atomization
• High speed rotary atomizers, utilize mechanical shearing action to atomize coatings materials.
• Rotational speeds vary from 15,000 – 100,000 rpm
Applicator Technologies
Centrifugal (Rotary) Atomization
• Atomized droplet size is based on bell cup diameter and rotational speed.
• Various diameters used based on flow rate and coating materials
• Bell cup design vary
Serrated edge
Non-serrated edge
Applicator Technologies
Centrifugal (Rotary) Atomization
• Shaping air is used to provide forward direction to the spray pattern
• Various shape air technologies used
Single shape function
Dual shape function
Vortex style
Combinations
• lower particle velocities associated with higher transfer efficiencies when compared to air atomization
Applicator Technologies
Centrifugal (Rotary) Atomization
Applicator Technologies
Centrifugal (Rotary) Atomization
• TurboDisk operates at speeds of 6,000 - 40,000 rpm
• Various disk platters available
Serrated edge conical available in 6, 9 or 12”
Smooth edge uni-disk available in 6, 8, 10 & 12”
• lower particle velocities associated with higher transfer efficiencies when compared to air atomization
Applicator Technologies
Centrifugal (Rotary) Atomization
• TurboDisk is a specialized applicator that works well with
High production systems
Minimal color changes
Batch run parts
• Markets used in:
Aluminum Extrusion Industry
Door manufacturers
Propane or cylinder manufacturers
Car or truck filter
Shock absorbers
Sporting equipment
Applicator Technologies
Centrifugal (Rotary) Atomization
Applicator Technologies
Electrostatics Definition: Method of paint application in which a
high voltage charge is used to dramatically increase
transfer efficiency.
• Coating is negatively charged as it is atomized
• Product coated is at ground potential, and appears to be opposite charge
• Opposites attract - coating is drawn to grounded product.
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Applicator Technologies
Electrostatic: Two Methods
• # 1 Process: External or Indirect Charge
Fluid supply and application equipment at ground potential
Wire grid is electrically charged
Product coated is grounded through conveyor system
Applicator Technologies
Electrostatic: Two Methods
• # 1 Process: External or Indirect Charge
Applicator Technologies
Electrostatic: Two Methods
• # 2 Process: Direct Charge
When first developed, atomization process was based on electrostatic repulsion, like particles repel.
Optimal atomization was obtained at a maximum fluid flow rate of 10 ml/inch of circumference
Today atomization process is either mechanical shearing action (rotary and hydraulic atomizers) or air impingement.
Applicator Technologies
Electrostatic: Two Methods
• # 2 Process: Direct Charge
With disk and bell applicators, charge is transferred from disk platter or bell cup.
Air atomized applicators utilize an electrode in the fluid stream
Applicator Technologies
Electrostatic Applicators • All atomization technologies are
available with electrostatics in manual and automatic versions
Non - Electrostatic applicator applying coating material to tubular target.
Back side of tube targets after being coated
Fluid flow rate set at 200 cc/min
Applicator Technologies
Non-Electrostatics Application
Electrostatic air atomized applicator applying coating material to tubular target.
Fluid flow rate set at 200 cc/min Back side of tube targets after being coated
Applicator Technologies
Electrostatics Application
Electrostatic rotary atomizer applying coating material to tubular target.
Fluid flow rate set at 200 cc/min Back side of tube targets after being coated
Applicator Technologies
Electrostatics Application
Applicator Technologies
Electrostatics
• More forgiving application
• Better uniformity
• Electrostatic “wrap” as opposed to “line of sight”
• Increased transfer efficiency Decreased coating cost Decreased booth maintenance Decreased emissions Decreased waste disposal
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0
20
40
60
80
100
Bells Air Elec. Air Conv.
Min
Max
0
20
40
60
80
100
Bells Air Elec. Air Conv.
Typical Transfer Efficiency on Metal Substrate
Typical Transfer Efficiency on Plastic Substrate
Applicator Technologies
Electrostatics
• Increased transfer efficiency
• The best way to reduce coating usage is to minimize the volume of material that is sprayed.
Applicator Technologies
Electrostatics
• You pay for paint 4 times!
You pay somebody to buy it
You pay somebody to apply it
You pay somebody to clean it up
You pay somebody to dispose of it
Applicator Technologies
Electrostatics can effectively be used on non-conductors
1. Conductive Sensitizers
2. Conductive Primers
3. Conductive Adhesion Promoters
4. Inherent Conductivity (moisture content)
5. Misting
6. Imaging Techniques
7. Conductive Additives
8. Metal Deposition
Applicator Technologies
Electrostatics: Eight techniques used to make non-conductors conductive:
Spray Characteristics
Applicator technologies can be used across a wide range of markets and applications
Transportation Wood Metal Special Coatings
Urethanes Latex Two-Component Epoxies
Toners Stains NGR Stains Topcoats UV Materials
Primers Base Coats Clear Coats Aerospace
specific coatings
Waterborne Adhesives Mold release Ceramics Enamels
Spray Characteristics
Classification of Atomization Technologies: • Finish Quality
Ro
ugh
---
----
----
- Fi
ne
Large -------------------------------------------- Small
Fin
ish
Qu
alit
y
Atomized Droplet Size
Airless Air Assist
HVLP LVMP
Conventional
Disk Bell
Spray Characteristics
Classification of Atomization Technologies: • Transfer Efficiency
Low
---
----
----
----
Hig
h
Conventional -------------------------------- Rotary
Tran
sfe
r Ef
fici
en
cy
Applicator Technology
Airless Air Assist
HVLP LVMP
Conventional
Disk Bell
E-Stat Gun
Note:
Spray Characteristics
Classification of Atomization Technologies: • Speed of Application
Slo
w--
----
----
----
-- F
ast
HVLP ------------------------------------------ Airless Spe
ed o
f A
pp
licat
ion
Airless
Air Assist
HVLP
LVMP
Conventional
Disk
Bell
Applicator Technology
Comparison of Rotary and Air Atomization Technology
43
Spray Characteristics
Normal: 200 – 250mm
Normal Spray Pattern Cut-in Areas
44
Dual Shaping Air Spray Pattern - can be optimized for coverage
into deep recessed areas or larger surfaces.
Cut-in: 75 – 100mm
Spray Characteristics
Automation: Reciprocators and Robots
Machines and robots installed in spray booths must be approved for operation in hazardous area (Class 1, Division 1).
• Machines \ Hard Automation Short Stroke Reciprocators Long Stroke Reciprocators Smart Reciprocators Special Machines (Rotary Spray)
• Robots \ Flexible Automation Electric robots, highly reliable
Automation: Reciprocators and Robots
• Short Stroke Reciprocators A reciprocator increase the effective
coating area of the applicator.
Typical stroke range 7 – 14”
Blends round spray patterns together providing very good coating uniformity.
Improves coverage by changing presentation of the applicator to the part.
Rotary atomizer, 30 cycles per minute
Air atomizers, 60 cycles per minute
Automation: Reciprocators and Robots
• Long Stroke Reciprocators A reciprocator increase the effective
coating area of the applicator.
Typical stroke length 3’ – 14’
May be equipped with “toeing” feature that angles applicators in direction of travel.
Rotary atomizer, 180 ft/min maximum
Air atomizers, 280 ft/min maximum
12 cyc 1 min
50% Spray Pattern Overlap
Automation: Reciprocators and Robots
• Long Stroke Reciprocators Machine must be
synchronized with conveyor to get uniform finish
50% or 75% spray pattern overlap most commonly used
50% overlap: conveyor speed (in) / pattern width (in) = machine cycle rate
75% overlap = above X 2
Assume: • 14 ft/min
• 12 in spray pattern
Conveyor Travel A
pp
licat
or
Trav
el
14 ft 1min
12in 1 ft
1 cyc 12 in
X X @ 50% Overlap
Automation: Reciprocators and Robots
• Long Stroke Reciprocators
Used with disk system
Typical stroke range 3’ – 24’
Recommend a minimum of 4 strokes on part while in disk loop
Maximum speed 4ft/sec, recommend slower.
Automation: Reciprocators and Robots
• Long Stroke Reciprocators
“S” loop conveyor configuration
Allows access to both sides of part
Automation: Reciprocators and Robots
• Smart Reciprocators
• Special Machines (Rotary Spray)
Similar to long stroke style reciprocator
Additional axis of movement incorporated
Variable stroke length
Multiple atomizer mounted on rotary axis
Product coated conveyed on belt beneath atomizers
Integrated system to reclaim material
Automation: Reciprocators and Robots
• Robots
Flexible automation, programmed to accommodate product coated.
Ability to maintain optimal distance between applicator and substrate.
In most cases more cost effective than designing custom “hardware” solution
Robot selection made based on work envelope “reach” and payload capability
Automation: Reciprocators and Robots
• Robots
Automation: Reciprocators and Robots
• Robots
Automation: Reciprocators and Robots
• Robots
Product Presentation
Product presentation is most often dictated by • Manufacturing process
• Size or weight of the product coated
• Desire to coat new product in existing system
Conveyor Systems
• Overhead
• Floor mounted
• Chain on edge
• Power and Free (indexing)
• Horizontal belt or web
Product Presentation
Part Presentation
• Single or multiple parts per fixture
• Fixture may index on 90˚ or 180˚ increments
• Fixture may continuously rotate
• Rotation may be reversed in each spray zone
Product Presentation
Part Presentation
• Repeatability
• Grounding
Product Presentation
Part Presentation
Production Requirements
• Following information is need to make equipment recommendations
Conveyor speed (ft/min)
Rack centers (ft)
Parts per rack
Hours per shift
Shifts per day
Days per week
Weeks per year of operation
2’
Calculating Coating Volume Needs
Calculating Coating Volume Needs
Calculating Coating Volume Needs
65
Comparison of application technology impact on transfer efficiency
Calculating Coating Volume Needs
Evaluate the “Givens”
• Greenfield project?
• New program in existing finishing system
• Production requirements
Selecting Automation
Prioritize the requirements
• Finish quality
• Production level
• Coverage
• Transfer efficiency
• Environmental
Bring in the Experts
• Use equipment suppliers applications labs
Selecting Automation
Thank-you
Nguyen Quang Vu Business Development Manager
Finishing Brands UK 0933993335