Gear Reduction

A gear reduction drive assembly is utilized to provide the required power to a 5-axis machine’s rotary axes by changing the ratio of the rotation of two moving parts. The performance of the machines rotary drives is in a large part determined by this reduction drive. Key factors to consider include:

• Reduction ratios and gear materials.
• Backlash reduction.
• Drive mass, inertia, acceleration and
          velocity.
• Losses, efficiency & torque.

The interface between the motor and the axis rotary assembly must be of high precision and made of high-strength materials with high resistance to wear and slippage.

Fixture/Workpiece Support

Fixtures should be of high-precision, constructed of high strength steel and be fully-supported on both ends to assure accuracy, eliminate vibration to provide complete stability. Good jigs and fixtures provide:

• A higher degree of positioning
           precision and repeatability.
• A greater accuracy for the positioning
           of precise hole centers.
• Tighter tolerances at micron levels
           with higher-quality fit & finish.
• Increased cutting tool life.
• Preserve gingival margin integrity.

Tolerance Stack

The typical rotary configuration utilized in dental milling machines consists of a trunnion with an A- and B-axis part rotation assembly mounted in the XY In order to multi-axis motion—it is necessary to "stack" each additional axis on top of another.’

• Each "stack" adds a point of
          connection or fastening.
• Each connection can increase the
          chance of positioning errors. The
          further out in the stack, the weaker
          each element of the added axis
          becomes.
• The machine and spindle together
          need the capability to contour fast
          and accurately at high cutting rates.
          As the “stack increases, achieving
          stability and dynamic accuracy
          becomes extremely difficult.