CNC machining method and tool selection

The following problems should be paid attention to in the process of CNC hand board processing

(1) Determine the processing content of CNC machining center, determine the installation base surface, processing base surface and machining allowance of workpiece, and organize the machining process with the intention of giving full play to the power of CNC machining center.

(2) As for complex parts, due to thermal deformation during processing, internal stress after quenching and deformation after parts clamping, it is difficult to complete the whole process after one clamping. At this time, it can be considered to clamp twice or repeatedly.

(3) The principle of “from rough to fine” should be followed in the organization of machining process. First, organize heavy cutting, rough machining, remove the machining allowance on the blank, and then organize the content with low machining accuracy.

(4) In order to reduce the influence of a large amount of heat on the machining accuracy, and to improve the tool life, large flow cooling method should be used actively.

CNC machining method and tool selection.

1. Try to use a big knife to cut thick, and then use a small knife to clear the corner. For example, the diameter of? 32 tool is 4 times that of? 8 tool, while the processing area is 16 times. Moreover, the large diameter tool has good rigidity, and the cutting depth and feed speed are significantly greater than those of the small diameter tool.
2. Try to use the fillet knife for roughening and flat bottom knife for corner cleaning. Because of the better force on the round blade, and it can be used repeatedly, the square grain can only be used twice.
3. Generally, the plane should not be processed with ball cutter, but with flat bottom knife. It is better to leave 0.2mm for polishing.
4. For straight wall groove processing, first finish the bottom surface of the workpiece, and then finish the side surface. For the side surface with height less than 50 mm, large number of reciprocating machining with carbide grain cutter shall be avoided as far as possible, and all straight shank cutters shall be selected for contour processing. (the depth of each tool is about the tool radius. )

CNC machining

1. Proper selection of forming tools to process regular shaped workpieces to improve power. For example: taper cutter milling slope, finger knife milling rib, fillet cutter (r0.3-r1) small fillet, etc.
2. In order to ensure the constant cutting load of the cutting tool, the layer by layer winding processing method should be selected as far as possible to avoid the upper and lower tool feeding.
3. The rigidity of the tool should be enough. Generally, the length diameter ratio (measured by the ratio of tool length to diameter) should not exceed 5. For example, the extension length of a 16mm diameter cutter should not be greater than 80mm, and a clamping length of 25-45mm should be reserved. Please refer to the tool specification table (Appendix 2) to select the machining tool to avoid over cutting due to lack of rigidity in the process of machining.
4. According to the shape of the workpiece, the programmer can select the self-made taper shank cutter or small cable head clamp to enhance the rigidity; for narrow groove and deep cavity dead angle, please use EDM, and do not have to force milling out.
5. If there are upper boss and pits in multi curved surface machining, please use a tool with small diameter to partially clean the corner, or make a protective surface to avoid bouncing.
6. Please process from center to corner. If the flat bottomed cutter is used for downward machining, please first use the ball cutter to cut the lower edge, or the horizontal feed part should be processed layer by layer to avoid the excessive allowance of the first cutter, resulting in over cutting of the “top and bottom”.
7. For the molding of the surrounding inclined plane and the bottom fillet, it is usually wound layer by layer with a ball cutter, and the fillet will appear “undercut” and affect the quality. Please use a flat bottomed cutter for semi finishing, and then use a ball cutter with a radius less than 1-2mm for finishing, or use a flat bottomed cutter to go back and forth for machining.
8. For the vertical or steep surface, please use the unidirectional cutting method to process from top to bottom, or use the winding method to process layer by layer downward.
9. For deep cavity or high column machining, please use ball cutter or R6 fillet cutter for winding and finishing layer by layer. Avoid using

When machining flat bottomed cutter or fillet cutter without R1, the tool tip of flat bottomed cutter is easy to wear, resulting in inaccurate shape, while the position of cutting contact point of ball cutter and fillet cutter changes with the change of machining position, and the wear is more uniform, which can ensure the machining quality.

1. For deep cavity or high column position (greater than 200 mm), please use square cutter for roughening, do not use R6 fillet cutter for roughening, because the contact surface of fillet cutter is large, it is easy to vibrate and spring the cutter.