Problems faced in building a paint shop

Air flow Compressed air Heat Electricity

Volume of air going across the booth

12000 cfm commercial booths…. U require a lot of power……

Paint booth exhaust: up the roof…… at the end of the building…..

Semi down draft paint booth: Up the roof- air intake filters…… at the end of the booth- air exhaust filters…..

Less expensive booth-- Cross transfer booth: Inlet and outlet both at the end of the booth…. Efficient use of shop floor space…… most economical of all the booths…..

Side down draft booth:

Down Draft booth:

Reverse flow spray booth: chance of contamination is greatly reduced…..

Infra cure booth: much like side down draft booth…… but infra lamps mounted on the side parts…..

Deluxe trucks booths:

Open front paint booths: for painting parts…..

HOW TO MIX AUTO PAINT::::

Paint wont harden properly…….. It wont spray properly…… Not right viscosity to work in your gun…….

Paint mixed with one type of thinner and hardener on top of that……. Sometimes mixed with reducer….

Paint cup…. Tells the ratio of the paint and the thinner to be mixed…….

HOW TO SAND THE AUTOMOBILE BODY::::

Making the panel flat after primer to give a base for the top coat….

Don’t use hands but use a block to sand the body…..

Price installation…….. Safety…… efficiency all play a vital role…….

Automatic Painting System

Autocoat Engineering (I) Pvt. Ltd. is already in manufacturing of painting plant on Turn Key Basis having supplied many large Spray Painting Booth & Conveyorised Phosphating & Painting plant all over India, Bahrain, Dubai, Saudi Arabia, Egypt etc. 

To increase productivity, reduce cost of painting, Automatic Painting Machines are designed, developed in Japan, Taiwan & China and are extremely popular resulting competitive products. Autocoat is now offering great opportunities to Indian manufacturers with such versatile Automatic Painting Machines

An Automatic Painting System has a Painting Booth composed of a partition having side Walls, a Ceiling, and a Floor which jointly define

a working space isolated by the partition from exterior space for accommodating a work piece to be painted in a position therein. The partition has air inlet and outlet ports opening into the working space.

A movable painting mechanism such as a Automatic Spray Gun is disposed adjacent to the work piece position and controlled by a control unit disposed outside of the Painting Booth and including a Drive source. The control unit and the movable painting mechanism are interconnected by an arm accommodated in an arm housing extending through the partition with a sealing member hermetically sealing a gap between the arm housing and the partition.

A door is mounted on the partition in the vicinity of the work piece position for transfer of the work piece into and out of the painting booth

Automatic Painting Machine should

Eliminate skilled Painter or Operator Deliver consistent quality of painting on product Simple to operate High productivity of Paint consumption Finally cost per unit is lowest due to Be of International quality

- Less space- Less power- Less heating- Less manpower cost, paint consumption cost etc.- Less rejection

Lastly highly economical & reliable 

High volume Automatic Painting machines are very popular in China & vide rage of models are competively priced for good quality product. 

Automatic Painting System Introduction

 Autocoat offer precision engineered range of Auto painting system widely used for the purpose of spray painting and immediate drying.

Booth resistance to corrosion increases operator efficiency, making it applicable for a number of application, mainly small sized products, and other industries. Depending upon the type of usage paint consumption and production capacity needed. The automatic painting line can be availed in various sizes suitable for unique or standard application.

Autocoat have tie up with “HUAN YU", an ISO 9001 Company, and leading manufacturer for Automatic Painting Machines, Automatic Painting Lines, Auto Spray Painting Line with out Robot, Portable Auto Painting Machine.

These machines can be added on with small air supply units and infrared and UV ovens. The basic need for automatic painting machine is that the quality of painting can not be matched with manual spray painting, high production capacity can be achieved a comparatively less cost when compared with the painting practice in India.

These products are completely imported, tested as per international standards, and we stand in hand to hand with these products. Before tieing up, Autocoat & Huan Yu had carried out detailed exercises so that our customer in India are benefited: 

QUALITY PRODUCT  in terms of life , workmanship & standardisation M/s. Huan Yu has been credited with the “Certificate for Excellence” in contract and credit, “Certified for Quality” by the Guangzhou Municipal Board of Quality and Technology Supervision and the Guangzhou Municipal Bureau of Environmental Conservation, ISO 9001:2000 Certified, QMS CE. 

AVAILABILITY OF SPARES  during life of equipment: Annual production capacity is 3000 sets. 

TRAINING OF AUTOCOAT ENGINEERS AT M/S. HUAN YU, who inturn look after equipments and after “Sales & Services”,

The products are imported, tested as per international standards, and backed by Autocoat Technical Guidance & Expertise, after sales service and technical expertise. 

TO ANSWER EVERY TECHNICAL QUESTION from Customer in India without need of contacting with M/s. Huan Yu, unless for major questions.

More about Huan Yu Company -:

Dongguan Huanyu Automatic Machine Co., Ltd. (Taiwan – funded) is a cooperative company of strategy and technology of Taiwan and Japan. The company is located in Jiaoli Donghe Industrial Zone, Zhongtang Town, Dongguan, covering an area ofr 20000m2 , with its headquarter in Taiwan. The company combines the experience and technology of Taiwan and Japan and wins consistent favors from various customers by advanced technology and high quality.

Since its establishment, holding an innovative concept and professional experience together with reformed technology, updated devices, excellent technicians as well as outstanding processing technology and first-rank capability of development of engineers, Huanyu Automatic Machine Co., Ltd dedicates itself in the research and development of various special machines to meet customers’ demand on spray devices and in the design and production of various painting devices of high quality and productability applicable in the industries of plastic electronics, hardware, sports equipment, appliance, vacuum plating etc. Company strive for making progress with you.

This company holds the tenet of “High Efficiency, Fine Quality, Good Faith” Under outstanding researchcapability, scientific programming, advanced technology and improved after service.

The Auto Spray Painting Machine or the Auto Spray Painting line is suitable for Plastic, ABS, FRP, etc that is we can also call this painting line as

Mobile Phone Painting Line

Toys Painting Line Helmet painting line Television painting line LCD Painting line Gift articles painting line Plastic painting line ABS painting line FRP painting line Clock Frame Painting line Shoes Painting Line Wheel Cover Painting Line Wooden door painting line Wooden frame painting line Automatic Plastic Painting Line

Huan Hu believe in always uphold the concept of a breakthrough, the accumulated expertise, superior technology and processing engineers and development capabilities, to develop all kinds of special models for our customers to be on the stringent requirements of spraying equipment, Widely applicable to the design and production of,

Plastic Electronics Hardware Sports Equipment Household Appliances Vacuum Coating Industries Such as various types of high-yield, high-yield high-quality

automation can paint equipment.  Mixing Station

Mixing and storing paint materials in the open shop environment invite and practically guarantee faulty finishes. Investing in a dedicated mixing and clean area will save many hours of corrections later. In this section, we show details about this clean area, and how it and the practices used within help avoid dirt in the finish.

2.1.1 Fingerprint ID

Even though the images were magnified to make them easier to see, the

contaminants they portray were visible to the naked eye as little specks or bumps on the surface or in the finish itself. Today's finishes and clearcoats are more sophisticated than ever, and the characteristics that enhance the paint finish — the super-smooth finish, the incredible clear depth of topcoats — serve to also magnify contaminants trapped on the surface during the finishing process.

The presence of these contaminants in the finish usually requires that the finish undergo additional buffing and polishing to minimize their visibility — known as "cut-and-buff" in the shop. Once embedded, nothing short of actually stripping the finish can really remove the particles. The key is to do everything possible to make sure few particles make it to the surface finishing in progress. Contaminants come from all quarters. Some are easier to manage, control or suppress than others. Keeping the "dirt" out of the finish in the first place through good practices and vigilance minimizes cut-and-buff, which pays off in big dollar savings.2.1.3 Investigative Tools

  During the investigation of suspected contaminants, it is critical to really see the nature of the contaminent. Each contaminant has its own "signature", which helps in tracking down the source.

A microscope is a must — this is your "dirt cam", your window into the world of the nearly-invisible. Although people tend to say, "my booth isn't working," what they're really saying is "my finishes used to be great, now they're terrible, so it must be the booth." Our experience has shown that it is almost never "the booth". We have instead found that practices used or not used in the shop, steps taken or not taken to prepare the vehicle, the quality of materials used, etc., were really making all the difference in the finish. 

If "the booth" really is the last suspect, then one must probe the clues left behind in order to solve finish problems. There really is no other way. You have to examine the evidence with magnification. Although we show a traditional laboratory microscope and camera setup, inexpensive microscopes which send their images to a desktop or laptop computer are available today. Image quality is excellent: in fact, most of the 60x images for these pages were made using a famous-maker "toy" digital microscope plugged into an office laptop via USB. With the portability of a laptop, you can literally take the microscope to the finish problem. 

1.1.1 The History of the Spray Booth 

The genesis of the spray booth came about through the effects of several inventions during the late 1800's. In 1887 maintenance supervisor Joseph Binks invented a cold-water paint spraying machine to apply whitewash to the subbasement walls of his employer, Chicago's Marshall Field & Co department store. The next year Civil War veteran Dr. Allen DeVilbiss invented the atomizer for medical use. The road from

 

these inventions more than a century ago to today's sophisticated finishing systems is a dramatic one. 

 The spray gun developed from those concepts as early as 1907. It was a timely idea since Henry Ford introduces his Model T the next year and mass production was just starting to evolve. The spraying of paint was first used in the furniture industry.

   

 When spray guns were first used on the assembly line, finishing times were slashed to just eight days. Then, DuPont introduced nitrocellulose lacquer, derived from a plentiful supply of World War I surplus gun cotton. The advantage of this unique new lacquer was its fast drying time that cut the finishing times down even more.

The new material proved virtually impossible to apply with a brush, but it was discovered that spray guns could transfer the lacquer smoothly and quickly. Finishing operations could now be completed in just 3 days, and the spraying of paint replaced hand brushing, a revolutionary automotive achievement. Detroit rapidly emerged as the largest single consumer of paint spray equipment.

   

 Natural products filling the expanding needs of the finishing industry came after that first spray gun, including exhaust canopies, like that shown on the right, which we now know as spray booths. In

   

order for the companies making spray application systems to sell their products, they found it to their advantage to design and build overspray collection systems integrated with their spray equipment, usually for very specific industrial and automotive manufacturing applications. That in turn spawned technologies we now take for granted in spray booth design, such as water wash,downdraft airflow and many others. 

 "Air wash" used to be the phrase that described what we know today as dry filter technology. How many other changes have there been? In these images one can see the awareness developing for finish quality improvement and other improvements as well. For example, only a few of the old pictures show painters or applications specialists using respirators or other protection. Today, manufacturers and other employers must comply with strict regulations concerning worker safety and health. Moreover, there have been vast changes to what finishers can exhaust into the planet's air or other ecological systems.

Spray booths and their systems have been critical to our hemisphere's development and defense for nearly a century. They appear in every type of industry imaginable, not only here, but all over the world, and their enhancement of the products produced has meant a higher quality of life for everyone1.1.2 Who Needs a Spray Booth?

 

Is the finishing or refinishing operation in question clean and energy-efficient? Does it meet the business's production standards and levels?

Or, is there evidence everywhere of paint or coating overspray, and an odor which proclaims that there are paint and coatings evaporating into the air?

Is production time spent on re-dos due to dust or dirt contamination or uneven curing, rather than meeting production timelines?

 

Modern paint and coatings require spray booths with the right technology — pre-engineered filtered heated air and precise temperature controls for all relative cycles, or equally sophisticated water wash impingement, or perhaps powder recovery or other technology.

 

The days of OEM finishes or refinish product applied in a "homemade" spray booth, or none at all, are swiftly coming to an end all over the world. With concerns about greenhouse effect, global warming and the prevention of atmospheric and other pollution on the agenda of every government, manufacturers and others who include finishing as part of their process are finding that they must comply with new, more stringent rules.

 

Another driver is the never-ending quest for quality in production. Competition centers on who can get what to the market with the least cost and highest profit. Those refinishers and manufacturers who can reliably reach their quality standard on the first pass are the ones who will dominate their field.

 

How are these two influences impacting our world? It will work this way. Only those manufacturers or refinishers that can bring their processes in line with current regulatory demands in their region will continue to operate. And of those that continue to operate, only those who can achieve a high-grade finish on the first attempt will prosper.

 

When the time comes to acquire a spray booth system for the first time, a few

decisions have to be made. The cost and ultimately, the final configuration, of a spray booth system is affected by the requirements of the object to be finished, such as size and portability, the materials the booth itself is constructed of, and the type of airflow required to adequately power the process. These three factors together determine the investment required

 

For example, an non-insulated single skin configuration will cost less than a dual skin insulated model. A larger booth will cost more than a smaller booth. A crossdraft system will cost less than a pressurized or downdraft system. When the benefits of one choice versus another are negligible, as with single vs. dual skin, why spend money for the unneeded feature? When it comes to airflow, however, choices really do affect the quality of the finish. "Is a premium finish really required?" then becomes a critical question.

 

How can products such as those offered by Global Finishing Solutions help? Equipment engineered specifically for isolating and enhancing finishing operations, while at the same time complying with the myriad of requirements established relating to safety and health, is the solution. Additionally, equipment such as ours can help the manufacturer / refinisher achieve a superior finish in one pass, a fundamental requirement of fiscal prosperity. Global Finishing Solutions's Automotive, Industrial and Truck / Heavy Duty Spray Booths provide a safe and efficient working environment for all coating applications. Today's technology combined with over 100 years of proven experience ensures a high-production facility with years of dependable service.

 

Our Equipment Features:

 

Flexible modular design

-Multiple width, length and height combinations allows for expansion from 24' to

unlimited lengths

 

Pre-engineered heated air management systems

 

-Downdraft

-Pressurized Crossdraft

-Crossdraft

 

Quality construction

 

-18-gauge pre-coated and 14-16 gauge structural steel components-Precise tolerance engineering-Wall-mounted 6-tube ETL approved Class 1 Division 2 fluorescent light fixtures for superior illumination-Equipment installation by certified (S.I.S.) Sales, Installation and Service distributors

More choices to meet your requirements

 

Wall designs

-Single (non-insulated)-Double (insulated)

Booth configurations

-Drive-Thru-Split-Solid Back-Combinations-Curing ovens-Custom engineering for special applications-2-axis and 3-axis man lifts-Indoor/outdoor spray booth systems-Indoor/outdoor heated air makeup systems

 

Who needs a spray booth? Virtually everyone who applies coatings of any kind. Spray booths offer quality and efficiency, and help prevent environmental pollution.

1.1.3 There are Four Critical Reasons to use a Spray Booth:

 

 

Reason 1: Confine the application of a hazardous material to a restricted controlled environment 

Reason 2: Prevent hazardous overspray and volatiles from escaping confinement and causing fire or explosion to nearby operations. 

Reason 3: Control air fuel/mixture so that a combustible combination cannot occur. 

Reason 4: Provide a clean environment in which to paint.

.1.4.a Components of Spray Booths

 Whether complicated or simple, booths have several basic features in common: 

-Working Chamber, Exhaust -Intake

-Air Make-up -Accessories

.1.5.a How Booths WorkBy design, a spray booth collects solids known as particulate emissions. Filtration media, which can be filter pads or water, and moving air, are the primary tools in this collection. A spray gun or similar device, with either human or robotic assistance, applies the coating material. The airstream moving through the booth gathers the solids and transports them to the filtration medium. The force and direction of the air, the efficiency of the filtration, and the characteristics of the coating equipment — these three elements — determine not only the overall efficiency of the coating operation, but also the quality of the finish. 

Prep workstations and mix room systems work in similar fashion. Moving air transports solids to filtration. In a mix room, the moving air stream also transports harmful and dangerous evaporants out of the working area, minimizing worker injury and hazard of explosion.

2.4.1 Mixing Area

 1. Use only fine nylon or metal strainers.2. Tighten lids on partially used containers.3. Replace spray gun cup strainer weekly.4. Store throwaway mixing cups in a dust–free container, use once and

discard.5. Use only metal mixing sticks.6. Place paint strainer directly over paint cup, keeping airborne dust from

entering cup.7. Provide a clean surface during all mixing of material.8. Store painter's suit in clean, filtered mix room, or in a storage cabinet just

outside the booth. Prior to any spray operation, this suit must be completely free of all lint, overspray and airborne contamination. A thorough cleaning and blowing off outside the booth is mandatory.

9. Pressure rinse all spray guns with clean solvent (never wipe out interior of cup) and store with lid attached.

2.4.2 Paint Spray Booth

 1. Close all doors. Keep booth operating in balanced spray mode when not in

use.2. Leave the booth running in the paint mode while loading and unloading

each vehicle.3. Replace compressed air hose to hanger when not in use.

Remember, for best results:   Change burner and floor filters on a regular schedule.  Maintain uniform airflow across the entire length of grating.

2.4.3 The Process

 We're assuming that the vehicle has been properly treated and repaired, ready to be brought into the spray booth for refinishing. By following the steps below, you'll be containing and confining the greatest sources of contamination to outside of the final refinish area. ***OUTSIDE THE BOOTH*** 1. Chemical wash the repair surface, outside the spray booth. Use only the highest-

quality lint-free towels available.

2. Blow off with high pressure (100% of vehicle).

3. Paper and tape around repair area with 18” high quality masking paper.

4. Repeat the chemical wash procedure.

5. Blow-off with high pressure (100% of vehicle).

6. Tack repair area and 18" masking paper.

7. With spray booth operating in the paint mode, load vehicle, centered over grates front–to–back and side–to–side.

***INSIDE THE BOOTH***

8. Close all doors, blow-off vehicle and masking paper with 40 psi.

9. Tack six feet of compressed air hose closest to gun connection and place on hose rack.

10.

Bag vehicle, placing the paper over the plastic bag and tape paper to plastic.

Paper or plastic cover should not extend more than 6 inches below the vehicle.Never cover any wheel well 100%. Use throw-away or reusable wheel covers.

11.

Observe spray booth balance gauge. Needle must be set at balanced to remove any airborne contamination during the spray mode.

12.

Blow-off repair area and paper with 40 psi.

13.

Chemical–wipe surface and paper with pre–saturated wipers for optimum surface conditioning prior to painting.

14.

Tack repair area and masking paper with new OEM (or equal) tack rag.

15.

Prepare and store enough base material in spray booth to complete the number of coats for proper coverage (only if mix room is not connected to spray booth).

16.

Prior to first coat of base, blow off and tack the paint suit inside the booth away from the repair area.

17.

In proper attire (a clean painter's suit), apply first base coat per paint manufacturer instructions.

18.

Apply additional coats of base as required.

Blow-off (40 psi) and tack repair area and masking paper between each base coat.After the last coat of base has been applied and properly dried, blow off (40 psi) and tack the surface with a new tack rag. 

19.

Prior to applying the first coat of clear, blow off and tack the painter's suit inside the booth away from the repair area.

20.

Prepare and store enough clear material in spray booth to complete the number of coats for proper coverage (only if mix room is not connected to spray booth).

During this phase, never leave the spray booth enclosure.

21.

In proper attire (a clean painter's suit), apply first clear coat per paint manufacturer instructions.

22.

Apply additional coats of clear.

23.

Allow the spray booth to flash at least three minutes before changing over to the cure cycle.

This flash of three minutes allows for the clear overspray to be removed from the

cabin, providing a clean atmosphere for curing.

24.

Allow the spray booth to cool down for a minimum of five minutes after the bake cycle before removing.

Remember, the spray booth must be operating in the spray cycle with only one set of entrance/exit doors open when unloading the vehicle.

.3.1 Top 10 Common Causes of Contamination

  

#1 Not understanding the importance of THE PROCESS when preparing a vehicle.

#2 Poor surface preparation and inability to see contamination on vehicle prior to spraying.

#3 Chemical wipe fibers left on or in doors, hood or track joints.#4 Poor quality of tack rags and tacking techniques.$5 Poor maintenance of spray gun and gun cleaning procedures.#6 Booth balance (too positive/ too negative).#7 Uneven velocity around vehicle.#8 Low air movement around vehicle.#9 Poor quality of paint strainers.#10 Contamination of booth walls or floor.

3.3.5 Paint Mix Rooms In-house paint mixing systems offer many benefits including:

1. Waste reduction. You mix only the amount of paint you need.2. Time savings. Your paint is ready when you need it.3. Versatility. You can match thousands of factory colors. Paint mixing machines come in many different sizes. You will also need digital scale, label printers, computer, and quart and gallon agitators. Your paint supplier will help you choose the right equipment for your application. Paint mix systems must be installed in a clean, well-ventilated room. You should put your mixing machine and accessories in a pre-engineered paint mix room. A typical paint mix room is constructed of sheet-metal panels much like those used in spray booths. It should have color-corrected artificial lighting and downdraft ventilation.

Paint mix rooms are generally located next to the spray booth to maximize painter productivity. Your local jurisdiction will probably have codes regulating your paint mix room size, proximity of paint mix room door to the spray booth door and ventilation requirements. Several suppliers, including Global Finishing Solutions, offer vestibule kits to enclose this area. Some manufacturers offer exhaust-only models, while other manufacturers may have both input and exhaust blowers. The input blower will pressurize the paint mix room to push airborne dust away from the door when it is opened. This option will help maintain a cleaner mix room environment and cleaner vehicle paint work.

3.4.1 Sample Floor Layout in a Small Collision Facility

 Even smaller shops can take advantage of good planning and modern equipment. In this case:

1. A wall or partition separates the spray booth from the metal working area — an effective substitute for the distance that might separate it in a large shop.

2. The versatility of a prep station helps keep air clean and boosts productivity in a small space by allowing priming and parts jamming to take place outside the main booth.

3. An estimate area, kept clean and well lit, can double as a final inspection and delivery area.

4. Parking angles and drive widths are planned to make the best use of limited space. 

3.4.2 Sample Floor Layout in a Large Collision Facility

 The design you see here offers most of the features this guide recommends: 

  1. Metalworking is located well away from the paint shop, so dirt and dust from sanding and grinding operations can’t contaminate new paint jobs.

2. Prep stations or limited finishing workstations located just before the spray booth improves the prepping operations' need to match factory paint finishes. They control dirt and let you do priming, so your spray booth can be kept free for assembled vehicles.

3. A floor-rail and dolly system lets you move cars sideways, backward and forward without starting their engines or remounting their wheels.

4. The paint mixing room is located next to the spray booth for

convenience, and separated from it to comply with NFPA regulations. A vestibule between the two allows access to either the booth or mix room without being exposed to the shop environment.

5. Cool down / unmasking / re-assembly take place just outside the spray booth.

6. Detailing is right after the reassembly area. This is the best work to show off to your customers because it demonstrates your close attention to the finishing touches.

7. Parts storage is right next to the production manager’s office, so he can easily track the parts status of each job.

8. Final inspection/delivery area has easy access to a meeting room/office for final discussions on the outcome of a job.

Best Practice for the Paint Mixing Room

Cut Shop Waste and Pollution

Reduce Health and Safety Hazard

Save Money

Keep All Containers Covered

Install a Ventilation System or Prefabricated Mixing Room

Wear Air Purifying Respirators

Wear Chemical-Resistant Gloves, Clothing, and Eye Protection

Practice Waste Reduction

Use An Automated Gun Cleaner

Keep all Containers Covered 

An open container of paint or solvent contaminates the air and wastes money. By putting a lid on it you will keep harmful vapors out of the air that you and your co-workers breathe. You'll also save materials and money by not letting your expensive paints and coatings evaporate away or be ruined by exposure to air.

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Install a Ventilation System or Prefabricated Mixing Room

Inadequate ventilation, common in many paint mixing rooms, poses a serious health and safety risk. A well-designed ventilation system will pull harmful vapors away from you and significantly improve air quality in the mixing room. To get the most protection from your ventilation, make sure you position vapor-generating materials and equipment in front of or near an exhaust outlet (e.g., install an exhaust hood behind the mixing table). A prefabricated mixing room has built-in ventilation. Prefab units come in a range of sizes and designs for convenient placement in the shop. Be sure to set up equipment such that the ventilation draws vapors away from work stations.

Remember: all electrical equipment in the paint mixing room (e.g., switches, ventilation fans, lights, telephones) should be approved for Class I, Division 1 (explosive) environments.

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Wear Air-Purifying Respirators

Vapor-generating materials and equipment pack most paint mixing rooms. A painter in a respirator is much less likely to breathe the harmful vapors in paints and solvents. When working in the mixing room, always use an air-purifying respirator with organic vapor cartridges. This respirator should provide adequate protection for typical mixing room tasks.

Remember: for a tight-fitting air-purifying respirator to work properly, you must: (1) Make sure it forms a tight seal on your face (a clean shave where the mask touches your face is step one, followed by a "fit test" from a safety professional); and (2) Change the cartridges on a regular schedule, as specified by the manufacturer—once vapors saturate the cartridges, the respirator won't protect you! Your employer should have an implemented filter change schedule as specified in 29 CFR 1910.134(d)(3)(iii).

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Wear Chemical-Resistant Gloves, Clothing, and Eye Protection

Your skin and eyes also need protection from hazardous paint materials. Many chemicals in coatings and solvents are not only strong irritants, but can pass through your skin and damage your body's internal organs. Be aware of the variety of chemicals you use in the mixing room and choose chemical-resistant gloves and paint suits that offer adequate protection.

 

 For gloves, nitrile or butyl rubber make the grade, latex does not. Remember: even a more protective glove has a limited life span, especially if you use it when handling certain strong solvents—so, always follow the manufacturer's recommended change schedule and never use a torn or punctured glove.

Warning: Isocyanates, the hardening component in

  most clear coats, are strong skin and lung irritants—and the leading cause of occupational asthma. Recent studies indicate that skin contact with isocyanates may trigger an allergic reaction in your lungs.

And don't overlook your eyes! A full face piece respirator will provide eye protection, however, goggles or a face shield should be worn with a half-mask respirator (as described above). The respirator or goggles/face shield will keep strongly irritating and toxic chemicals from splashing in your eyes and face—and keep you from mistakenly rubbing your eyes with a contaminated hand. An eye wash station is a must for any auto refinishing shop.

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Practice Waste Reduction

Shops that reduce waste do something good for the environment and their bottom line. In fact, more efficient use of paints and solvents lets you save twice: up-front, on the amount of materials you need per refinish job; and on the back end, in lower waste removal costs.

Mix only the amount of paints and coatings you need. High-volume, low-pressure (HVLP) spray guns, recommended for all painting tasks (and required by law in certain areas), transfer paint much more efficiently than conventional guns; the result: you use—and need to mix—far less paint.

Another good practice is to store and reuse left-over primers and basecoats. Computer mixing systems, offered free by many paint companies, make it easier to mix smaller quantities of paint and to track and reuse any left-overs.

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Use An Automated Gun Cleaner

An automated gun cleaner also saves you money—and improves health and safety in your shop. These devices help you get the most mileage from your cleaning solvent, reduce shop waste, and minimize your contact with hazardous solvents. Select a model with a lid that covers the entire basin. If you select a model that allows manual pre-cleaning in an open basin, make sure the basin is equipped with an exhaust fan to collect vapors before they escape into the room air.

Remember: if equipped with an exhaust fan, the gun cleaner should only be used when the fan is connected to an exhaust outlet that removes the vapors from the room. Regardless of the type of gun cleaner you select, make sure you frequently inspect and maintain the unit—leaking hoses and lids with a poor fit can contaminate your mixing room with harmful solvent vapors.

Before placing a used spray gun in the gun cleaner, pre-clean the gun cup to remove gross coating contamination. This practice extends the service life and effectiveness of the cleaning solvent used in the automated cleaning unit

How Clean Are Paint Shop Cleanrooms?

Although great strides have been made in paint shop cleanrooms, there are still major opportunities to improve their cleanliness, especially with improvements in the design and construction of the paint circulation and supply systems . . .

By S. Thomas Boyce and Jan PitzerHosco Livonia, MI

During the past 15 years, the automotive industry has developed a significant number of paint technologies to address the needs of the environment, product appearance and durability. Along with the development of new coatings, most new facilities have incorporated cleanroom environments in which these materials are applied.

The main reason for cleanrooms is to improve the quality of the paint finish by reducing sources of dirt contamination on a wet film. This dirt contamination causes some manufacturers to repaint the entire car rather than making spot or

panel repairs. But, by eliminating dirt contamination and the resulting defects, expensive repair procedures can be avoided.

Until recently, most of the emphasis on eliminating dirt contamination in cleanrooms has been focused on the people working in the paint shop. Early evaluation of the sources of paint defects indicated that 60% of these defects were caused by dust particles, lint, hair, dandruff, powder, cotton fibers and other pollutants carried by workers, supervisory personnel and visitors working around the paint shop (see Figure 1). Therefore, anyone entering a cleanroom must wear lint-free coveralls and a hair bonnet as well as pass through an air shower

compartment that may contain a shoe scrubber. These steps are designed to remove contaminants that can cause flaws in the paint finish. There is also a psychological benefit to this procedure because it conditions people to be aware of all sources of dirt and to think about their surroundings, which affect the quality of their work.

But, what about the other 40% of dirt sources, such as agglomerated paint particles, color carry over during the color change process and paint line cleaning? The newer high-solids and waterborne basecoat materials are much less forgiving than the older low-solids solvent-borne paints. They are more prone to shear degradation, agglomeration, foaming and skimming, all of which can contribute to a greater potential for introducing dirt into the paint circulation system.

From an equipment standpoint, much of the work in paint circulation systems during the past 10 years has been focused on the paint mix room. The development of lower shear pumps, low shear agitation methods, low shear regulators and new mix tank designs with liquid level controls and automatic filling have greatly improved the overall operation of the paint supply system. In addition, the choice of the proper grades of stainless steel and passivated systems has reduced or eliminated the gelling of paint caused by metal ions, lowering the potential for dirt to enter the paint supply system.

Figure 1

Figure 2 .

While there are some continuing refinements of the storage and pumping supply systems, most of the emphasis on the management of dirt has shifted in recent years to the piping system.

Figure 2 shows a typical circulating-to-gun paint circulation system found in many automotive plants. There are many variations of this basic system depending on the OEM customer and geographic location. In this example, a main supply pipe exits the paint mix room and winds around one booth with four spray stations. An automotive plant could have as many as 50-80 spray stations depending on the length and number of spray booths. The size of the supply pipe could be 1.0-2.5 inches depending on the plant.

The first station of a circulating-to-gun system includes a return piping network, which each subsequent station feeds, that eventually carries paint back to the paint mix room. The detail of one drop station is displayed showing a manual spray gun with connecting fittings and hoses, fluid control, mini-filter, fluid quick disconnect and stem.

Within the interior of the piping system network there are many areas that are often overlooked as potential dirt traps, cavities or dead rooms where paint particles can collect and eventually lead to a contaminated finish. There are also some exterior configurations of paint hoses that can be improved to reduce the flaking off of dry overspray, which can be carried by airflows in the spray booth to the surface of the vehicle creating a defect.

Spray Station Ball Valves

Normally four ball valves are used per color (two for supply and two for return) at each spray station. These valves are available in a variety of configurations, including threaded, compression fitted or tube stub. The booth wall mounted valves can be either bulkhead mounted or reverse bulkhead mounted depending on whether the customer prefers valve handles inside or outside the spray booth. Generally automatic station valves are mounted outside the booth for safety reasons to facilitate valve closing without interfering with the automation equipment.

Many ball valves used for spray station drops are not specifically designed for paint and contain medium to large size cavities around the ball that can trap

Figure 3

paint from previous or existing colors. Paint collects between the Teflon lifesaver seals and the interior of the valve body (see Figure 3). When the ball is rotated some of the sticky or agglomerated paint particles can break free, flow downstream to the applicator and create a defect. These areas are difficult, if not impossible, to clean during flushing or color change processes and represent one of the more significant sources of dirt in a paint system.

The preference in new paint shops is for valves that incorporate an encapsulated ball (see Figure 4). In these valves, the valve seats are placed on opposite sides of the ball and axially pressed together to form a substantially void free axial seal. This bearing cavity completely encapsulates the ball so that no paint can accumulate in the interface between the ball and the polymeric body of the valve. There are no crevices or threads to collect paint or dirt where it can harden

and later contaminate paint jobs. This valve also flushes cleanly during color change or pigging.

The last important consideration regarding valves is to closely match the bore of the valve with the inside diameter of the station drop to prevent any restriction or pressure drop in the system.

Transition Connections

Several types of transition connections are typically used in paint circulation systems. The most common stainless steel tubing connection is the compression style connection. This connection is made using a ferrule and nut mechanical type seal (see Figure 5). This type of connection has two main advantages:

1. The connection normally has a smooth bore internal diameter if the correct tubing wall thickness is used, eliminating internal shelf areas or dead spots. The smooth bore also maintains uniform fluid velocity and laminar flow in straight fitting configurations.

2. The connections can be disassembled for maintenance without significant effort or damage.

The primary drawback of compression fittings is that once the tubing is

Figure 4

Figure 5

connected, those fittings can’t be reused in another area.

The next most common type of connection in a paint circulation system is the ball and cone style connection (see Figure 6). These are available in NPS (National Pipe Straight) or BSP (British Straight Pipe). The design incorporates a 30-degree male seat on the side with the swivel nut and a 30-degree female seat on the other side of the connection, much like a JIC or a pipe union connection. These connections are most generally applied inside the spray booth for hose, color changer, regulator and gun connections and around filters and gages with sizes of 0.25 and 0.375 inch. This type of connection has several advantages:

1. The connection has a smooth internal bore diameter if the correct tubing wall thickness is used. The elimination of internal shelf areas or 

2. dead spots also helps maintain uniform fluid velocity and laminar flow in straight fitting configurations.

3. Ball and cone connections can be rotated and precisely positioned for neat and clean bundling of the paint hoses into and away from the applicator, color changer or bulkhead area.

4. The connections can be broken for maintenance or rearrangement reasons without significant effort or damage.

5. The connection can be reused many times, making rearrangement inexpensive and quick.

There are no known drawbacks of this connection type other than it is normally restricted to 0.25- and 0.375-inch connections. If right-angle hose fittings are used, particular attention should be paid to the internal construction. Many 90-degree fittings have a large dirt pocket in the back of the fitting, which is a major dirt contributor in paint systems (see Figure 7).

Another type of connection is NPT (National Pipe Tapered) or BSPT (British Tapered). Many of these connections have been eliminated in paint circulation systems except at pump, gage and filter joints. There is probably only one advantage to this connection type – it is readily available and well understood from an installation point of view. NPT has three major drawbacks:

1. The assembly of NPT components leaves many internal steps or shelves at

Figure 6 - Ball and Cone Design

the connection area. In addition, internal threads on female connections are exposed and provide many cracks and crevices for the paint to accumulate.

2. During assembly of components, especially with stainless steel, the tapered thread of the fitting will become tight and stop rotating at various and random angles. This is a problem particularly when the installer is working to make racks of lines appear uniform, to have precise locations of ball valve handles or to mount areas around color changers.

3. Also, with stainless steel connections there is a tendency for the two mating surfaces to gall, which damages the threads and makes each mating component unusable for rearrangement or system modification.

Last, is the recent application of sanitary clamp style fittings. These fittings are generally applied around larger line sizes like the compression fittings mentioned earlier. The sanitary clamp style is used around mix tanks, pump and filter areas and in overhead piping mains. It is the only welded fitting listed here. Its benefits and drawbacks are identical to the compression style fittings.

Color Changer and Automation Equipment Cavity-Free Connections

With the increased use of automation for paint application, it is increasingly important for the equipment builder, installer and owner to consider the pros and cons of connector types during the specification development and decision making of the project.

Automatic stations are becoming more compact and smaller due to the limited space inside machines and robots to mount color changers and route paint hoses. The resulting challenge for paint fitting manufacturers is to provide accessible connection points to machines and color changers within smaller areas and to increase line sizes to provide higher flow rates and reduce pressure loss and shear.

In response to these challenges, some new practices are important to consider.

1. Paint inlet and outlet points of color changers should

Figure 7 - Hose Connections

Figure 8

remain NPT or BSPT by NSP (M) straight fittings. This allows precise racking or routing of circulation hoses away from the color changer in a neat bundle, since the swivel nut on the NPS (F) hose connector can be positioned at any angle (see Figure 8). One potential pitfall of NPT connections to color change manifolds is the gap, or dirt trap, between the end of the fitting and the base of the manifold. O-rings or Teflon wafers should be used to eliminate these traps and keep the assembly drive cavity free.

2. Hoses, connectors and fittings used for the supply and return circulation lines to color changers should be smooth bore, sweep-type fittings that facilitate laminar flow (see figure 9). These fittings can be 90, 60, 45 or 30 degrees or straight depending on the application requirements. Smooth bore provides consistent fluid stream velocity and eliminates internal steps or shelves where paint can agglomerate. Every effort should be made to closely match internal bores between connecting components. Cavity free specifies that there be no machining steps or pockets (such as drill point pockets, which can occur in angle fittings) on the interior of the fitting body. Laminar flow requirements can eliminate abrupt flow path changes in small fittings that can degrade paint color or luster and can reduce pressure drop at the color changer. This is a major new area of improvement in fittings because circulating systems’ operating 

3. pressures are usually driven by the automatic stations and then color change time constraints. Any reduction in pressure loss within these stations provides direct benefit to the higher amounts of maintenance and expense related to seals and energy consumption.

4. Fitting and hose selection for color changer outlets to the applicator has an even more critical performance requirement to ensure optimized color change time, minimize solvent and air use and eliminate color carry-over from one color to the next. One important consideration is the use of FEP or PTFE Teflon as the hose material between the color changer and applicator to further improve performance.

Hose Management and Containment

Proper hose management and containment can have a significant impact on

Figure 9

defect-free paint finishes and minimizing reprocessing. Automotive paint circulating

systems generally circulate to the gun, which requires a two-hose arrangement to the spray gun or color changer. One hose supplies the station and the other hose returns the paint to the circulation loop.

It is important to keep in mind that paint hose is specified by its ID since it is critical to maintain paint circulation velocity within the recommended range by the material suppliers. Conversely, plastic tubing is specified by its OD to work properly with push-lok or compression style fittings. Specifying tubing instead of paint hose, while it seems a minor point, can create significant circulation problems that will eventually show up in problems with fluid delivery to the applicators, difficulty maintaining viscosity or paint temperature or formation and discharge of dirt from the system onto filters or parts being sprayed.

There are several methods of cinching twin hoses together that are practiced in the industry (see Figure 10). Some plants simply use masking tape to join hoses together. However, the tape gets sticky when exposed to solvent and picks up overspray. Eventually the dry overspray particles break free, become airborne and get carried to the painted surface creating a defect.

Another approach uses nylon ty-wraps as a substitution for tape. This method is more maintenance free than tape. However, the wraps have a tendency to snag on the booth grates and create motion difficulty for manual spray operators.

Metal spring steel clips are small, compact and low profile along the outside diameter of the hose. They provide a better snag-free alternative to ty-wraps and are much better than tape.

Plastic nylon clips are more compatible with paints and solvents. They are non-conductive for safe use in electrostatic zones. The clip design also separates the hose surface to facilitate full hose surface cleaning, minimizing overspray buildup between the two hoses.

Bonded twin line hose is either continuously or intermittently bonded along its length. This design eliminates the need for clips, tape or wrap to hold the hose

Figure 10

set. However, the bond seam along the hose creates a continuous crevice that is difficult to clean. Bonded hose also increases the structural rigidity, which is objectionable to some spray operators.

Monoline coaxial paint hose assemblies (hose within a hose) built in lengths up to 25 ft accomplish the same improvements as the bonded twin line hose, with one big advantage. It has just one hose surface, with no crevices or recesses for housekeeping. It is also the most aesthetically pleasing and one of the most ergonomically superior hose assemblies for use in manual stations.

For both robotic and bell automation zones, bundled hose with an exterior smooth cover provides excellent performance with regard to housekeeping, hose containment and hose life (see Figure 11). Bundled hose includes paint lines and pneumatic signal and trigger lines wrapped with a smooth, solvent-resistant exterior cover.

Advancements in extrusion capabilities and new economies of scale have enabled some suppliers to custom engineer bundled hose in quantities as low as 1,000 ft. Some users of these systems have adopted color-coded pneumatic lines to facilitate quick maintenance response in diagnosing station performance problems. Virtually any existing hose or tube size and material of construction can be assembled into a bundle to solve housekeeping, dirt-in-paint or hose kinking and containment problems using this new technology.

Manual Spray Station Accessories

Improvements in the design of manual spray gun accessory equipment have significantly contributed to reducing defects and reprocessing. No-spit paint quick disconnects, check-valve-style stems and mini-filters mounted on the spray gun are all examples of advancing technology in manual spray zones (see

Figure 12).

Ergonomics has also been a driver of new product developments to reduce fatigue for spray operators. Spray gun flow restrictors and quick disconnects are now available in durable composite materials that are 50% lighter and fully compatible with automotive paints and solvents.

Figure 11

Figure 12

Dirt-in-paint reduction is a continuous improvement process. Those automotive manufacturers who are committed to advancing the state-of-the-art cleanroom environments in new facilities have made improving the quality of their paint supply systems a priority.

With the variety of fittings and valves available in the market, OEM companies must take a more aggressive role in requiring turnkey systems integrators and designers to use cavity-free products designed specifically for paint. The benefits are enormous and include reduced dirt-in-paint defects, improved first run capability and reduced repair warranty.

Some automotive manufacturers have even created dirt-in-paint groups within their corporate paint engineering operations and are encouraging each plant to develop an ombudsman for dirt-in-paint reduction.