The problem and the project planning were already a challenge in themselves: 3,900 drilled holes 25 mm deep per hour at the circumference of rounds, four different workpieces with a retooling time between articles of less than a minute, fully automated, three shifts, measured, and controlled - everything in the one system.

Twelve tonnes of drill dust must be extracted every year through a suction unit connected directly to the system. Six conveyor belts supply and return the workpieces. The supplied parts are inspected and controlled with a camera. Wrong or damaged workpieces are ejected, and the drilling position on the parts defined for further machining. A six axis robot takes the workpiece and supplies it to one of the four structurally identical, rotary machining stations that have already received the camera's data. Here, the deposited workpiece is clamped and measured with a laser to a precision of 1/100 mm.

The drilling operations take place on a total of eight Suhner high speed machining spindles BEX 4 at speeds up to 40,000 rpm. Every nine seconds ten holes have been drilled and a part is ready. The dust tight BEX 4 machining spindles work virtually free of vibrations for extremely reliable operations. Specifically the high concentricity of less than 0.002 mm safeguards precisely drilled holes with hard metal tools at huge feed rates of up to 3 m/min. Every drilled hole is measured with laser technology to a precision of 1/100 mm immediately they leave the system. Every nine seconds ten holes have been drilled and a part is ready.

Sixteen user programmable CNC axes safeguard the precise positioning of the drilled holes, eight others power the feed, four rotate the workpieces, and eight servo drives rotate the Suhner BEX 4 spindles. Together with the robot, the system controller coordinates 42 axes. Covering 24 m? of floor space, the system tips the scales at 5,500 kg, of which 250 kg are the electrical cables alone.

The fascination of this system lies in its speed - the rate at which the system can process data is scarcely imaginable in the real world. Servo positions and the measurements from the camera and laser are "frozen" within a thousandth of a second, processed, and coordinated for further machining. For this purpose, a special evaluation unit has been developed and implemented for laser measuring systems. The result is drilling precisions to a hundredth of a millimetre!

Desert-like conditions prevail in the machine room when 3,900 drilled holes 25 mm deep are worked every hour into the pressed material. The clamped workpiece is measured with a laser to a precision of 1/100 mm.

(Suhner India Private Limited, Bangalore. Tel: 080-27831108. Fax: 91-80-27831109. Email: automation.in@suhner.com)