Conveyors and paint systems: choosing the right conveyor system ...

The selection of a paint or powder finishing system depends on a number of factors, including the types of parts being coated, the required surface-treatment process, size and weight of the parts, sequence of process steps and the flow of material through the entire fabrication process.

The finishing line layout should be planned based on the space requirement of the process equipment and the available space. Rout the conveyor so as to carry parts from the loading point in the fabrication area through the process system to the unloading point in the assembly/shipping area. This concept will minimize material handling/damaged parts and personnel required.

CONVEYOR SYSTEMS

For liquid-paint-process lines, mainly two types of conveyor systems are used.

Overhead monorail conveyors have the load-carrying and the drive function combined in one element--the endless chain. This chain is guided by a rail system based on either an I beam or an enclosed track. A take-up station overcomes chain slack caused by temperature variations or wear. A caterpillar drive or a sprocket in a turn drives the chain. Parts are suspended from the chain by special attachments or load bars. This conveyor can follow only one path--deviations are not possible. This system is simple and efficient but not very flexible.

Overhead power and free conveyors are two-rail systems. The load-carrying element, (trolley) and the driving element (chain) are separated. The trolleys use the lower "flee rail" and the chains are in the upper "power rail." Pusher dogs establish the connection between chain and trolley, and they can be engaged and disengaged as needed. The "free rail" can be equipped with switches, lifting stations or stops to allow the trolleys to follow several different paths, be lifted or lowered, stopped or moved at different speeds through the system. The entire conveyor system is PLC-controlled.

This system is more costly, but it is flexible enough to link fabricating processes, paint lines, assembly and shipping, and to accommodate process variations within these areas. This system will also reduce the number of personnel and the cost of transporting parts through several fabrication steps. Because of this, the danger of damaged parts through various manual handling steps is greatly reduced.

OTHER CONVEYOR SYSTEMS

Besides the two systems previously described, there are several other systems used to lesser extents for finishing processes:

* Automatic hoist systems for dip processes (typically e-coat and dip pretreatment).

* Square-transfer systems (applications similar to those for hoist systems).

* Inverted monorail or power-and-free conveyors.

* Roller conveyors for transporting skids of parts or assemblies.

* Dual-chain and drag-chain conveyors for dolly systems.

Any of the above conveyor types can be combined to provide the optimum paint system for a specific application. Conveyor systems will reduce manual handling of the parts, minimizing labor costs and the potential for damage.

PROCESS EQUIPMENT

In most cases, a paint or powder coating line consists of two portions: the pretreatment system and the coating section.

Pretreatment systems produce a substrate surface suitable to receive the coating. These systems are intended for cleaning, phosphating and similar treatments. Pretreatment chemicals are normally in aqueous solutions and may be used in steam-cleaning applications. Vapor degreasing/phosphating is also used. Mechanical cleaning, such as shot blasting, is another means for treating parts prior to cleaning.

Each pretreatment process starts with cleaning of the parts, followed by application of conversion coatings such as iron or zinc phosphates or chromates. The process sequence also includes the required rinses. Spray or dip or combinations thereof could apply the process steps mentioned here, depending on part configurations and process steps required.

A dry-off oven typically follows the pretreatment process. The oven normally operates at approximately 300[degrees]F and is heated by natural gas. If gas is not available, fuel oil, electricity or steam can be used. Note: dry-off ovens are not built to evaporate water puddles. All water collections must be drained prior to dry-off.

Ancillary equipment for pretreatment systems includes oil-water separators, sludge-removal systems such as filters or centrifuges, heating systems (hot water), chemical feed/metering systems and demineralizers/deionizers.

Different coating processes require specific pretreatment steps. Electrocoat, for example, requires a final rinse with deionized water before entering the e-coat tank.

LEARN MORE

INTEGRATING PAINT SYSTEMS

Industrial Finishing Technologies (IFT) neither manufactures finishing components nor is it a finishing job shop. Yet, IFT's Midwest and Southeastern divisions thrive right in the thick of the finishing industry. IFT represents a new generation turnkey finishing systems integrator, a small specialized corporation that is equipped to accommodate the exclusive needs of finishers moving into the 21st century.

CONVEYORS AND PAINT SYSTEMS

This article is reprinted from the 2006 PRODUCTS FINISHING DIRECTORY AND TECHNOLOGY GUIDE. Read the article in its entirety online.

Find the links to these article online at www.pfonline.com/articles/1006show.html. www.pfonline.com

PAINT SYSTEM

The MAX series servo-drive gantry systems can paint accurately in 2-, 3- and 4- axis applications without the complexity and cost of a six-axis robot. The system is designed for liquid paint, adhesive and powder applications. The controller uses the patented Windows-based Wetcoat software, allowing you to program paths and create part recipes quickly without the difficulty of learning robot programs. The System controls every movement of the spray gun path and allows complete control of variables that effect film build, gloss and colon It controls atomizing air, electrostatics, fluid delivery, rotary atomizer speed and any spray parameter can be changed at any point in the painting program. The Series has the payload capacity to manipulate multiple spray guns and can paint parts as small as a cell phone and as large as a motor coach.

For more information from ARTomation by Digital Coating, call 440-234-1988 or enter PF Direct code 111NX at www. pfonline.com

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PAINT FINISHING SYSTEM

The Paint Finishing System is a creative, cost-effective solution to tough finishing problems. The systems conform to the customer requirements for product finishing: powder, liquid spray, electrocoat and dip systems. The systems also conform to liquid to powder conversions with redesign of existing systems and compliance with environmental regulations.

Facilitating a turnkey approach, the systems can provide the total package: conveyor, surface preparation, paint application, oven, racks, permitting, abatement, waste treatment and training. The Paint Finishing System produces a quality finished product with rugged durability.

For more information from Herr Industrial Inc., call 717-569-6619 or enter PF Direct code 772PH at www.pfonline.com

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POWDER AND LIQUID COATING SYSTEMS

The company would like to reintroduce itself as Pneu-Mech Systems and R3 Technologies Mfg. LLC--your "Complete Systems House." These companies can provide complete engineering, fabrication, installation or integration of powder and liquid coating process equipment, systems and related services. Its projects range from a variety of pretreatment washers, convection ovens, infrared ovens, environmental rooms, conveyor systems, batch equipment, liquid coating booths, robot installation, make up air units, equipment relocations, system retrofits/upgrades and waste water management/filtration systems. The companies focus on getting to know each client and finding out exactly what their present and future goals are, while providing high quality products, service and support at a fair price. Its sales/engineering staff has a total of more than 250 years of experience and knowledge to rely on along with in house fabrication and eight installation crews.

For more information from Pneu-Mech Systems Mfg. Inc., call 704-873-2475 or enter PF Direct code 541WP at www.pfonline.com

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VERTICAL POWDER COATING SYSTEM

The unique design of the powered conveyor system of the vertical powder coating system allows color changes with no downtime or loss of production according to the company. Powder booths can be used in series or in parallel, providing the greatest amount of operating flexibility including the application of two different powder colors at the same time. Vertical powder coating system can apply thin film builds and offer costs competitive with traditional vertical liquid paint systems.

For more information from Tellkamp Systems Inc., call 562-802-1621 or enter PF Direct code 136QR at www.pfonline.com

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DRIVE FOR ENCLOSED TRACK CONVEYOR SYSTEMS

The Unibilt High-Efficiency 750# Caterpillar Drive is designed to provide maximum efficiency and flexibility for all enclosed track conveyor applications including overhead and inverted. According to the company, the drive is nearly 98% energy efficient because the high-efficiency helical bevel gear reducer is mounted to the drive shaft. It also is said to use fewer parts than the previous 600#drive, which reduces maintenance requirements and sends more power to the drive.

The compact 750# drive can replace or upgrade virtually any enclosed track conveyor drive currently in use. Benefits include reduced noise and increased durability and cut-off accuracy. The innovative torque arm assembly and proximity sensor offer precise full-range adjustment of the chain pull overload cut-off. The torque arm indicator provides visual confirmation of the overload chain pull cut-off setting.

For more information from Webb Co., Jervis B., call 248-553-1203 or enter PF Direct code 224PV at www. pfonline.com

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CONVEYOR COMPONENTS

The company provides high quality and very durable conveyor components and equipment at low prices. It offers a diversified line of products to help solve the most challenging material handling problems. Company provides monorail and enclosed track overhead conveyor components.

For more information from Ohio Valley Conveyors LLC, call 352-683-1287 or enter PF Direct code 193BB at www.pfonline.com

By Bernd Piel

Eisenmann Corporation