It is not uncommon for machining centres to have automatic tool changing devices to automate the tool changing process. Newer models exhibit quicker tool changing times. If you’re trying to minimize cycle time, there may be some things you can do to reduce tool change time.
Reducing tool changing time will make the machine more productive. Taking into consideration how many tool changes a machining center will make during its lifetime, minimizing tool change time should be an important priority for any CNC-using company
Spindle Orientation
Most automatic tool changers require that the keyways in the cutting tool shank be aligned with the keys in the tool changing arm before a tool change can be made. This angular spindle position is called the spindle’s orient position.
Spindle orientation takes one to six seconds, depending upon the machine. Don’t wait until the machine is at the tool change position before performing the spindle orient. A special M code (M19) can be used to cause the spindle to rotate to its orient position during the motion to the tool change position.
How Far Does the Machine Have to Move?
With most machining centers, the automatic tool changer arm is in a fixed location – and the machine must be sent to a special position in X, Y , and/or Z in order to make a tool change. With vertical machining centers, for example, the tool change position is commonly the Z axis zero return position. For horizontal machining centers, it is commonly the Y and Z axis zero return position.
Should you place tools in the tool changer magazine in sequential order?
Today’s machining centers have random-access tool changers. This, of course, means that tools can be placed in the tool changer magazine in any fashion, yet they can be accessed in any order. This is a wonderful feature, allowing great flexibility in tool placement. But watch out for a time-wasting trade-off.
This is especially true for machines that have a single arm tool changer. With these machines, the cutting tool just used must be placed back in the tool changer magazine before the magazine can rotate to the next tool. Magazine rotation, of course, is not instantaneous. Magazine rotation time is a non-productive on-line task that can be minimized if tools are placed in the magazine in a sequential manner.
How heavy are your tools?
The actual act of tool changing requires a synchronized series of actions. We think of these actions as fixed and unchangeable – and with some machines, they may be. But remember that machine tool builders always strive to have their machines deal with the worst case scenario. If a machine tool builder claims that the automatic tool changer on a given machine can change a fifty-pound tool, they have designed the automatic tool changer mechanism accordingly – including the speed related to each action of the tool change.
Maybe you have a machine that has been designed to change a fifty-pound tool , but your heaviest tool is less than twenty pounds. It is possible that the machine tool builder can speed up your machine’s automatic tool changer to match your heaviest tool.
