Productivity, cost per part, back-working capability, and quality all can be positively affected by adding a turning center with a second spindle to your shop floor.
“Dual-spindle machines increase productivity by reducing part handling by automatically transferring parts from one chuck to another for secondary operations,” explained Milton Ramirez, product technical specialist - turning products for machine tool manufacturer Haas Automation.
To further enhance productivity, these machines can be combined with robotic part feeding and extraction, or with bar feeders for long, unattended part runs.
“Also, with its part-transferring capabilities, these machines can produce a finished component machined on both faces by using secondary operations such as drilling and tapping on both faces [axially] or sides [radially],” said Ramirez.
Cost per part can be reduced because the part no longer sits idle, waiting for a secondary operation to be performed. The ability to work on the back side of the part is due to the control that machinists have over the secondary spindle. The secondary spindle can be programmed to approach the part and remove it from the main chuck, allowing the back-work machining.
This “done-in-one” style of machining is very common in two-spindle machines.
“Operations that are usually done on two or three machines can be done on one, reducing the time it takes for a particular part to be machined completely. It allows for quicker out-the-door machined products,” said Ramirez.
Part quality and consistency also are improved by decreasing the number of times a part is handled.
“Even though the cost to machine a part might not be reduced drastically, the machining process becomes much more controlled, and therefore the quality is increased, passing on the added value to the customer,” said Ramirez.
For those shops that have a goal of running unattended operation, Haas has a feature in its control called advanced tool management. This feature allows the operator to set up groups of tools for redundancy usage and automatically replaces worn or expired tools in the same group. This enables longer runs, better finished components, and more tolerance precision control, the company reports. Another feature is a dedicated tool life-monitoring system, a plug-and-play screen for Haas bar feeders, and robot-ready options for simple connectivity and communication.
The addition of a second spindle to the work envelope affects part programming in terms of complexity and special attention is needed in these cases.
“The spindle rotation and the toolpath direction are reversed, so the Z axis gets programmed in positive numbers instead of negative from part zero,” said Ramirez.
Also, different codes command the secondary spindle chuck to open, rotate, stop, and orient.
“The Haas control has a special code, called G14, that reverses or mirrors the complete program so a programmer does not have to worry about programming the secondary spindle differently than the main spindle,” said Ramirez. “This avoids the confusion of having to use so many different codes and numeric positioning values.”
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