Roughing, Smoothing…CNC Expert’s Machining Experience!

Roughing: Under the maximum load of the machine tool, in most cases, the largest possible tool should be selected, the largest possible feed amount, and the fastest possible feed. In the case of the same knife, the feed is inversely proportional to the amount of feed. Under normal circumstances, the load of the machine tool is not a problem. The principle of tool selection is mainly based on whether the two-dimensional angle and three-dimensional arc of the product are too small. After selecting the knife, the knife will be fixed length, the processing principle is longer than the depth of the knife, large parts have to consider whether there is interference chuck.
Light knife: The purpose of light knife is to meet the processing requirements of the surface finish of the workpiece and reserve an appropriate margin. Similarly, the light knife should be as large as possible, and the time as fast as possible, because the fine knife needs a longer time, use the most suitable feed and feed. Under the same feed, the larger the transverse feed, the faster, the surface feed is related to the finish after processing, the size of the feed is related to the surface shape of the surface, and the smallest margin is left without hurting the surface. Use the largest knife, the fastest speed, and the appropriate feed.

1. All clamps are horizontal and vertical.
2. Vise clamping: The clamping height should not be less than 10 mm, and the clamping height and processing height must be specified when processing the workpiece. The processing height should be about 5 mm higher than the vise plane, the purpose is to ensure firmness, while not hurting the vise. This kind of clamping is a general clamping, and the clamping height is also related to the size of the workpiece. The larger the workpiece, the higher the clamping height.
3. Clamping of the splint: the splint is coded on the worktable, and the workpiece is locked on the splint with screws. This kind of clamping is suitable for workpieces with insufficient clamping height and large processing force, generally medium and large workpieces, and the effect is better .
4. Code iron clamping: when the workpiece is large, the clamping height is not enough, and the wire is not allowed to be locked at the bottom, the code iron is used for clamping. This kind of clamping needs to be clamped twice, first yard the four corners, process the other parts, and then yard the four sides and process the four corners. During the second clamping, do not let the workpiece loose, yard first and then loosen. You can also code both sides first and process the other two sides.
5. Clamping of the tool: the diameter is above 10mm, and the clamping length is not less than 30mm; the diameter is less than 10mm, and the clamping length is not less than 20mm. The clamping of the tool must be firm to prevent collision with the tool and direct insertion of the workpiece.

1: Classified by material
White steel knife: easy to wear, used for thickening copper and small steel materials.
Tungsten steel knife: used for corner cleaning (especially steel) and smooth knife.
Alloy knife: similar to tungsten steel knife.
Purple knife; used for high-speed cutting, not easy to wear.
2: According to the cutter head
Flat-bottomed knife: used for flat and straight sides, clear flat corners.
Ball knives: used in various curved surface light and light knives.
Bull nose knife (one-sided, two-sided and five-sided): used for roughing steel materials (R0.8, R0.3, R0.5, R0.4).
Coarse leather knife: used for roughing, pay attention to the remaining method (0.3) of the margin.
3: According to the tool bar
Straight bar knife: The straight bar knife is suitable for various occasions.
Inclined bar knife: But it is not suitable for straight face and the slope less than the slope of the rod.
4: According to the knife edge
Two-edged, three-edged, four-edged, the more the number of blades, the better the effect, but the more work done, the speed and feed will be adjusted accordingly, and the more blades will have a longer life.
5: The difference between a ball knife and a flying knife
Ball knife: when the concave ruler is smaller than the ball ruler, and the flat ruler is smaller than the ball R, the light is not available (the bottom corner is not clear).
Flying knife: The advantage is that it can clear the bottom corner. Comparison of the same parameters: V=R*ω, the speed is much faster (flying knife), things that are powerful and bright are bright, and the flying knife is mostly used for contour shapes, and sometimes the flying knife does not need the light. The disadvantage is that the size of the concave surface and the flat ruler are smaller than the diameter of the flying knife.

1. In the absence of a ready-made processing surface, the plane is divided into four sides, the center is to the origin, the top surface is zero, and when the top surface is not flat (for copper), a margin of 0.1 is left, that is, when the number is touched, the actual value is 0 (z ), which is 0.1 on the graph.
2. When there is a ready-made machined surface, make the ready-made face on the drawing 0 (z), and the plane can be divided into the middle, otherwise the actual height and width of the machined surface should be checked by the number of ready-made edges (single side). , The length is different from the drawing, and it is programmed according to the actual material. In general, first process to the size on the drawing and then process the shape on the drawing.
3. When multiple positions are required for processing, the first position (standard position) must be the benchmark gongs of the other positions, and the length, width and height must be gongs. All the next processing benchmarks must be processed last time. The surface shall prevail.
4. Positioning of the insert: Put it in the whole, padded the bottom to a certain height, and then the drawing will also raise this height. The plane is divided into the whole, and the height is locked with screws at the bottom of the picture; you don't want to work on the bottom, but want to get rid of the status quo If it is square and square, it can be divided directly; a rougher point can be divided into the largest shape; cut a fixture, according to the fixture, determine the relative position of the insert drawing and the fixture, and then place the origin of the drawing at the center of the fixture.

1. Curved groove
1) The key is the choice of scope and the choice of surface
The area of ​​tool path processing is: the selected surface in the selected range is the end surface, and all the places where the tool can go from the highest point to the lowest point are the principle. The selected surface is best to be the entire surface, and the boundary can only be the area to be processed. The area where there is no surface extends less than half the distance of the tool diameter. Because the other surfaces have enough margin, they are automatically protected; it is best to extend the lowest line, because There is an R gong at the lowest point.
2) Knife selection: If the tool cannot enter in a spiral or diagonal line, or the area that cannot be machined, the area where the knife cannot enter is sealed and left for the second roughing.
3) Before the light knife, be sure to make all the uncut areas thick, especially small corners, including two-dimensional corners, three-dimensional corners and sealed areas, otherwise the knife will be broken. Secondary roughing: generally use three-dimensional grooving to select the range, flat-bottomed knife, can use flat grooving and contour toolpath, use the tool center to the selected boundary without hurting other surfaces, generally do not refine the boundary The fast two-way angle depends on the situation, the spiral feed, the angle is 1.5 degrees, and the height is 1. When the shape of the groove is strip, and the blade cannot be screwed down, use the diagonal line to feed, generally open the filter, especially the curved surface thickening, the feed The plane cannot be low to avoid hitting the knife, and the safety height cannot be low.
4) Retraction: Generally, relative retraction is not required, but absolute retraction is used. When there is no island, relative retraction is used.
2. Plane trenching
Milling various planes, concave flat grooves, when milling a part of an open plane, you need to define the boundary, in principle, it can feed (more than one tool diameter), and the open part is more than half the tool diameter outside, and the periphery is closed.
3. Shape
When the selected plane is suitable for the shape layering, use the shape layering to lift the knife (planar shape). When the knife lift point and the knife point are one point, there is no need to lift the knife. Z plane generally lifts the knife, try not to use the relative height; the compensation direction is general Right compensation (shun knife).
4. Tool path setting for mechanical compensation
The correction number is 21, the computer correction is changed to the mechanical correction, the feed is vertical, and the place where the tool cannot pass is changed to a large R without leaving a margin.
5. Contour shape
It is suitable for the closed face. If the open face has four turns, the face must be sealed. If it is within four turns or not, select the range and height (a certain arc-shaped feed to make thicker) for thickening. Circumstances: The machining distance in any plane is less than one tool diameter, if it is greater than one tool diameter, a larger tool or two contours of equal height should be used.
6. Surface streamlines
With the best uniformity and crispness, it is suitable for the light knife and can replace the contour shape in many cases.


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