Cycle Time Reduction: Drilling with C-Axis Unclamped (Lathes)

In my previous blogs I’ve talked about ways to increase production on Okuma CNC lathes using cycle time reduction when commanding the spindle/M-spindle, and when indexing a lathe turret. Now I’d like to show you two ways you can improve cycle time when drilling multiple holes with a compound fixed cycle (G181).

When drilling and cutting forces are small, such as small diameters or in aluminum, cycle time can be reduced by drilling with the C-axis unclamped.

Both methods below allow compound fixed cycle drilling without clamping the C-axis, but one is ideal for high-volume low-mix production, while the other works better for low-volume high-mix. You can always reference your “OSP-P300L/P300S Operator’s Pocketbook” for this information, but I’m spotlighting it here to give you some quick, actionable tips.

Method 1: Change the Parameter Setting (Modal)

This method is ideal for high-volume, low-mix scenarios, where processes have already been proven to work without C-axis clamping.

Set the OPTIONAL PARAMETER: (MULTIPLE MACHINING) "C-axis clamp/unclamp in hole pro." parameter to "no effect".

Method 2: Use M-Code M141 (by block)

This method is ideal for low-volume, high-mix scenarios, where clamping the C-axis can only be omitted in some cases.

Use the M141 command in the program to disable the C-axis clamp/unclamp command in the block where the M141 command exists.

Warning

1. If you are drilling larger holes or in a situation where higher forces are exerted, the C-axis may be displaced by the cutting forces.
2. Since C-axis clamping and unclamping is not performed, the tool could interfere with the work piece if the retraction distance is not adequate and/or droop is not enabled. Set an appropriate retraction distance for the Z-axis and/or set the droop control of the feed axis to "enabled" and set a permissible value.

Where Half a Second Can Really Make a Difference

The shops that will benefit most from these techniques are those where seconds off a cycle equals tens of thousands of dollars saved over a year, but anyone armed with this knowledge can take advantage of these little time-savers.

Thoughts? Questions? Feel free to let me know in the comments below.

Cooper Ferguson is Applications Engineer, Okuma America Corporation.

Read the other blogs in Cooper’s series on Cycle Time Reduction:

Tips for Cycle Time Reduction: Spindle/M-Spindle

Cycle Time Reduction: Indexing Turret