What are the compensation methods for machining centers?

During the processing of a CNC machining center, due to factors such as the shape of the cutting tool, trajectory problems may occur. This is not a big deal. We can solve it by using compensation methods. Generally, there are three compensation methods.

1.Length compensation of the cutting tool

Data input for CNC machining center programming, start specifying the part machining center, establish the workpiece programming coordinate system, this coordinate system is only the workpiece coordinate system, zero. The length compensation of the CNC machining center is only related to the Z coordinate, unlike programming zero in the X and Y planes. The tool is positioned by the taper hole of the spindle without change, and the length of the Z-coordinate part is different.

The machining center needs to drill a hole 50mm deep and then drill in a depth of 45mm. A 250mm long drill bit and a 350mm long tap are respectively used. When setting the workpiece zero point on the machining center, even if the lengths of the tap and the drill bit are different, due to the existence of compensation, when the tap is called to work, The zero point Z coordinate automatically compensates the length of the tap to Z+(or Z), ensuring that after the zero point of the machining center is set, even if the lengths of the tap and the drill bit are not the same, due to the existence of compensation, when the tap is called to work, the zero point Z coordinate automatically compensates the length of the tap to Z+(or Z), ensuring that after the zero point of the machining center is set, even if the lengths of the tap and the drill bit are different, due to the existence of compensation, When the tap is called to work, the zero point Z coordinate automatically compensates the length of the tap to Z+(or Z) to ensure the correctness of the processing zero point.

2. Radius compensation of the cutting tool

The CNC machining center has tool radius compensation. When compiling the processing program, the diameter of the cutting tool is not taken into consideration. Tool length compensation is applicable to all tools, while tool radius compensation is generally only used for milling cutters. When milling the outer or inner contour of a workpiece with a milling cutter, tool radius compensation can be used. When using an end face milling cutter to process the end face of a workpiece, only tool length compensation is required.

Tool radius compensation for CNC machining centers is a command that is difficult to understand and use, and thus they are reluctant to use it in programming. In fact, understanding and mastering the usage still bring great convenience to programming and processing. When preparing to write a program for processing the shape of a workpiece with a milling cutter, the first step is to carefully calculate the coordinate values based on the shape, size and radius of the workpiece to clearly define the path of the tool center. The radius of the tool used is only the radius value of the milling cutter. After editing, it was found that the milling cutter was not suitable for changing to tools of other diameters. At this point, it is necessary to recalculate the coordinate values of the tool center path, as this is extremely difficult for molds with complex shapes. The shape processing of workpieces is divided into rough machining and finish machining. Therefore, rough machining is completed after the rough machining program is compiled.

The shape and size of the rough-machined workpiece have changed, and then calculating the center coordinate values of the finishing tool is too much work. If tool radius compensation is used, the tool radius can be ignored. Program according to the workpiece size, and then place the tool radius as radius compensation in the radius compensation register. When temporarily changing the milling cutter or performing rough and finish machining, only the tool radius compensation value needs to be changed to control the shape and size of the workpiece. The program basically does not need to be modified slightly.

3. Offset compensation of fixtures

When a CNC machining center processes small workpieces, several workpieces can be clamped at once without considering the coordinate zero points of each workpiece. Just program according to the G92 instructions and then use the fixture to offset, and the programmed zero point positioning of each workpiece can be achieved. Fixture offset is achieved by using fixture offset. It can be executed using fixture offset instructions G54 to G59, or the coordinate system can be set using the G92 instruction. After processing one piece, when processing the next one, reset the new workpiece with G92.