Gaining control of a blanchard grinder

Developed more than 100 years ago, Blanchard grinding has typically been a manual process for many shops. The simplicity of a Blanchard makes operation of the machine easy to learn and run. The old dials and handwheels found on Blanchard grinders still work well and get the job done.

However, there’s an even easier way to run a Blanchard: by adding a CNC.

Blanchard began adding controls to its machines in the 1990s. These early controls were plagued with problems. Many shops shy away from Blanchard grinders that have the original controls because of their reputation for being complicated to operate and maintain.

The work zone of a Blanchard 36HD-66 surface grinder,
which can grind parts up to 84″ in diameter. Image courtesy of Bourn & Koch

However, shops realize that Blanchard grinding is a highly efficient method of imparting an extremely flat surface to a workpiece made of virtually any material. The finish is produced by utilizing a vertical grinding spindle with a cylindrical grinding wheel and, generally, a flat magnetic chuck to hold ferrous material. As the magnetic chuck rotates, it carries the work under the first side and then the other side of the wheel face, which is fed down into the work to remove material. This action creates the characteristic crosshatch pattern that has come to be the best indication of a true “Blanchard grind.”

When Bourn & Koch Inc. acquired Blanchard in 2004, the machine tool builder immediately began building new Blanchard grinders and remanufacturing existing machines. Since then, Bourn & Koch has offered FANUC CNCs for the machines. The latest models have the FANUC 35i-Model B control. Bourn & Koch developed a human-machine interface to enable conversational programming. Therefore, programming a grinding process is a simple procedure.

The CNC controls both axes of the machine: X (horizontal table traverse) and Z (vertical grinding head travel). The addition of a CNC allows for precise control over the grinding head downfeed to increments of 0.0001″. Thus, extremely close tolerances can be held.

Adding a CNC to a Blanchard grinder also makes the machine easier to operate and maintain. Servomotors now drive the machine’s axes, eliminating the need for costly maintenance of noisy gearboxes. The grinders still have a heavy-duty lead screw to provide an adequate level of power behind the head downfeed.