Burr OAK Tool Inc. is a producer of dies used to produce two types of fins for window air conditioners. Evaporator fins on the side of the air conditioner inside the window transfer heat from the inside air to the cold refrigerant flowing through the evaporator coil. Compressor fins located on the side of the air conditioner outside the window move heat from the now hot refrigerant to the outside air. Burr OAK Tool dies progressively stretch and reform the fins through a series of metal forming operations that extrude and reduce the thickness of the fins. The very complex geometry of the dies must be controlled within +5/-0 ten thousandths of an inch in order to meet fin tolerances.
Until recently, the company finished and semi-finished form plates on a Makino Form Grinder because its machining centers could not hold the required tolerances. It took 9.2 hours to produce form plates with a waffle form and 11.3 hours for sinewave form plates. Burr OAK Tool recently purchased a Mazak VTC-800 4-axis vertical machining center with the goal of reducing machining time for these dies. The new machine is much more difficult to program than any of the machines used previously by the company. Adding to the challenge is the fact that parts are designed in 2-D because they have so many holes and other features that it would take prohibitively long to design them as solid models.