Machine Design

A better way to keep paint out

A cable-pass-through seal from Roxtec Inc. of Tulsa, Okla., keeps paint from gumming up the works inside spray-painting robots.

The Roxtec RG M63/4 cablesealing system keeps paint spray out of Fanuc Robotics spray-painting robots. The M63 modular system consists of peel-away layers that accommodate any size wire or cable.

A cable-pass-through seal from Roxtec Inc. of Tulsa, Okla., keeps paint from gumming up the works inside spray-painting robots.

Electric sparks in misty spray-paint booths have been known to cause explosions. And wet paint can bollix up encoders, electric motors, and bearings. That's why the Robotic Paint Shop Automation Div. of Fanuc Robotics America Inc., Rochester Hills, Mich., wanted to keep the inside of its robots paint-free despite the numerous holes where wires enter or exit the robot and spray booth.

Standard cord grips with gasket seals originally plugged the holes but caused problems.

Installers had to remove connectors to slide the grip onto the cable, snake the cable through the booth penetration plate, and then slip the nut over the cable to fasten the grip. In some cases installers enlarged the cable jacket to fit the grip by applying multiple layers of shrink-wrap. This often damaged connectors and disconnected wires.

Cables enter the robot through a purge chamber. Positive pressure in the chamber helps keep paint out of the robot; but cobbled-together cable installations made seals leak requiring cable replacement.

Fanuc engineers came up with a better way through a plug-andplay cabling. They redesigned the cable ends for mounting outside the spray booth using connectors from Harting Inc., Elgin, Ill. The other end of the cable is routed, terminated, and tested inside the robot's purge cavity. The cable-sealing system from Roxtec lets cable ends pass through bulkheads without removing the connector.

The Roxtec seal consists of several multidiameter modules, a mounting frame, and a compression unit. The split multidiameter modules have peel-away inner layers that adapt the module to any cable. Installers remove layers until the module halves fit the cable snugly. Connectors on the cable ends pass easily through the large frame opening with the multidiameter modules resting in the frame. With all modules in place, the compression unit squeezes the frame contents to produce an air, water, and dusttight seal.

Fanuc uses the Roxtec Gland M63/4 on its robot controllers and system control consoles for power and communication cables handling DeviceNet, Profibus, and similar formats. The RG M63/4 helps maintain NEMA-12 requirements.

Harting Inc. of North America, (877) 741-1500,
Fanuc Robotics America Inc., (800) 477-6268,
Roxtec Inc. North America, (800) 520-4769,

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