12 experience summary of CNC processing, machined people must!

Due to the complexity of CNC machining (e.g. different machine tools, different materials, different tools, different cutting methods, different parameter settings, etc.), decided to engage in CNC machining (whether processing or programming) to reach a certain level, must go through a relatively long period of time, this manual is the engineer in the long-term actual production process summed up, the selection of CNC processing processes, processes, common tool parameters, monitoring and other aspects of the experience, for reference.

One. Q: How do I divide the machining process?

A: The division of CNC processing operations can generally be carried out according to the following methods:

(1) Tool centralized sequencing method is to divide the operation according to the tool used, with the same tool to finish all the parts can be completed. In the use of a second knife, the third to complete the other parts of them can be completed. This reduces the number of knife changes, compresses the air time, and reduces unnecessary positioning errors.

(2) According to the processing parts sequencing method for parts with a lot of processing content, the processing parts may be divided into several parts according to their structural characteristics, such as internal shape, shape, surface or plane, etc. Generally first processing plane, positioning surface, and then processing holes, first processing simple geometry, then processing complex geometry, first processing low precision parts, and then processing precision requirements of higher parts.

(3) to rough, finishing sequencing method for parts prone to processing deformation, due to the deformation that may occur after roughing and need to be corrected, so generally speaking, all to carry out roughing, finishing should be separated from the process.

To sum up, in the division of the process, we must depend on the structure and process of the parts, the function of the machine tool, the number of parts nuncically controlled processing content, the number of installations and the production organization of the unit flexible grasp. It is also suggested that the principle of process concentration or the principle of process dispersion should be determined according to the actual situation, but it must be reasonable.

Two. Q: What principles should be followed in the arrangement of the processing sequence?

A: The arrangement of the processing order should be considered according to the structure and blank condition of the part, as well as the need for positioning clamping, with emphasis on the rigidity of the work piece not being destroyed. The order should generally be carried out in accordance with the following principles:

(1) the processing of the upper process can not affect the positioning and clamping of the next process, interspersed with a common machine tool processing process should also be considered comprehensively.

(2) The inner cavity plus process is carried out first, and then the forming process is carried out.

(3) in the same positioning, clamping mode or the same knife processing process is best connected to reduce the number of repeated positioning, the number of knife changes and the number of moving pressure plate.

(4) In the same installation of multiple operations, should first arrange for the work piece rigid damage small operation.

Three. Q: What aspects should be noted in determining the way the work parts are clamped?

A: There are three points to be aware of when determining the positioning benchmark and clamping scheme:

(1) Strive to design, process, and programmatic calculation of the benchmark.

(2) Minimize the number of clamps, as far as possible after a positioning can be processed all the surface to be processed.

(3) Avoid the use of the machine-d'or manual adjustment scheme.

(4) The fixture should be open smoothly, its positioning, clamping mechanism can not affect the tool in processing (e.g. collision), in such cases, can be used with tiger pliers or a bottom plate screw way clamping.

Four. Q: How can I be sure that the knife point is reasonable? What does the workman coordinate system have to do with the programmatic coordinate system?

1． The knife point can be located on the machined part, but pay attention to the knife point must be the base or has been refined part, sometimes after the first operation of the knife point is processed and destroyed, will lead to the second operation and after the knife point can not be found, so in the first operation of the knife to the knife to set a relative fixed size relationship with the location of the location of a relatively fixed position, so that according to the relative position relationship between them to retrieve the original pair of knife points. This relative pair of knife positions is usually located on the machine bench or fixture. The selection principles are as follows:

1) It's easy to find right.

2) Easy programming.

3) Small error on the knife.

4) Easy to check during processing.

2. The origin position of the work piece coordinate system is set by the operator himself, and after the work part is clamped, it reflects the distance position relationship between the work part and the machine zero point by determining the tool. Once the work item coordinate system is fixed, it is generally not changed. The workware coordinate system and the programming coordinate system must be unified, that is, the workware coordinate system and the programming coordinate system are consistent during processing.

Five. Q: How do I choose a knife route?

The knife route is the trajectory and direction of the tool relative to the part being processed during exponential processing. The proper choice of machining route is very important because it is closely related to the processing accuracy and surface quality of the part. The following points are mainly considered in determining the route of the knife:

1) To ensure the processing accuracy of the part requirements.

2) Convenient numerical calculation, reducing programming workload.

3) Seek the shortest processing route and reduce empty knife time to improve processing efficiency.

4) Minimize the number of segments.

5) To ensure the roughness requirements of the surface of the workman's contour, the final contour should be arranged for the last knife to be processed continuously.

6) The cutter's forward and backward (cut-in and cut-out) routes should also be carefully considered in order to minimize the stop at the contour (the sudden change in cutting force resulting in elastic deformation) and leave a knife mark, but also to avoid vertical lowering the knife on the contour surface and scratching the work piece.

Six. Q: How do I monitor and adjust during processing?

After the work part is found and the program debugging is completed, it can enter the automatic processing stage. During the automatic machining process, the operator monitors the cutting process to prevent the quality problems and other accidents caused by abnormal cutting.

Monitoring the cutting process takes into account the following:

1． Process monitoring roughing is mainly concerned with the rapid removal of excess excess on the surface of the work piece. During the automatic machining of the machine, the tool is automatically cut according to the predetermined cutting trajectory according to the set cutting amount. The operation is at this point

The person should pay attention to observe the change of cutting load during automatic machining through the cutting load table, adjust the cutting amount according to the tolerance of the tool, and make the maximum efficiency of the machine.

2． The monitoring of cutting sound during cutting process In the automatic cutting process, when cutting is generally started, the sound of the cutting work piece of the tool is stable, continuous and light, at this time the movement of the machine is smooth. With the cutting process, when the work piece has a hard point or tool wear or tool clip and other reasons, the cutting process appears unstable, unstable performance is the cutting sound changes, the tool and the work piece will be impact sound, the machine will vibrate. At this time, the cutting amount and cutting conditions should be adjusted in a timely manner, when the adjustment effect is not obvious, the machine should be suspended to check the condition of tools and work parts.

3． Finishing process monitoring finishing, mainly to ensure the processing size of work parts and the quality of the processing surface, high cutting speed, large intake. At this time should pay attention to the impact of chip tumor on the processing surface, for cavity processing, should also pay attention to the corner processing cut and give the knife. For the above-mentioned problem solving, one is to pay attention to adjust the spray position of the cutting fluid, so that the processing surface is always in the best) cooling conditions, and the other is to pay attention to observe the quality of the finished surface, by adjusting the cutting amount, as far as possible to avoid quality changes. If the adjustment still has no obvious effect, then the original procedure should be stopped to determine whether it is reasonable.

In particular, pay attention to the position of the tool when pausing or shut-down inspections. If the tool is stopped during cutting, a sudden spindle stop will cause a knife mark on the work surface. Shutdown should generally be considered when the tool leaves the cutting state.

4. The quality of the tool monitoring tool determines the machining quality of the work piece to a great extent. In the process of automatic machining cutting, the normal wear and tear condition of the tool and the abnormal breakage condition of the tool should be judged by means of sound monitoring, cutting time control, pause inspection during cutting, and surface analysis of work parts. According to the machining requirements, the tool should be handled in a timely manner to prevent the problem of processing quality caused by the tool not being processed in time.

Seven. Q: How do I choose a machining tool? What are the major elements of cutting usage? What are the tools for several materials? How to determine the speed of the tool, cutting speed, cutting width?

1． Flat milling should be selected without re-grinding carbide end milling or end milling cutters. General milling, as far as possible the use of secondary tool processing, the first cutter is best to use end milling rough milling, along the surface of the work piece continuous knife. Each knife width is recommended at 60%-75% of the tool diameter.

2． End mills for end mills and carbide blades are mainly used to machine bosses, grooves and box surfaces.

3． Ball knives and round knives (also known as round nose knives) are often used to process surfaces and bevel profiles. Ball knives are mostly used for semi-finishing and finishing. Round knives with carbide-encrusted tools are mostly used for coarse opening.

Eight, Q: What is the role of the processing procedure list? What should be included in the processing procedure list?

A: (1) The processing procedure is one of the contents of the CNC process design, and it is also the procedure that needs to be observed and executed by the operator, which is the specific description of the process, in order to make the operator clear the content of the program, the clamping and positioning method, the tools selected by each machining program should pay attention to, etc.

(2) In the machining program list, it shall include: drawing and programming file name, work piece name, clip sketch, program name, the maximum depth of tool, cutting, machining properties (such as roughing or finishing), theoretical machining time, etc.

Nine, ask: CNC programming before what to do to prepare?

A: After determining the processing process, before programming to understand: 1, work parts clamping method------------

10. Q: What are the principles for setting the safety height in programming?

A: The principle of safety height: Generally higher than the highest surface of the island. Or set the programming zero point to the highest surface, which also minimizes the risk of hitting the knife.

Eleven, Q: After the toolpath is made up, why do we have to do the post-processing?

A: Because different machine tools can recognize the address code and NC program format is different, so for the machine used to choose the correct post-processing format to ensure that the program can run.

Twelve. Q: What is DNC communication?

A: The mode of program delivery can be divided into CNC and DNC, CNC refers to the program through the media media (such as floppy disk, tape reader, communication line, etc.) to the memory of the machine to store, processing from the memory to transfer the program for processing. Because the capacity of the memory is limited by size, so when the program is large can be processed by DNC method, because the DNC processing machine directly from the control computer to read the program (i.e., side-by-side), so the capacity of the memory is not limited by size.

There are three main elements of cutting usage: cutting depth, spindle speed and intake speed.

The overall principle of choice of cutting dosing is:

Less cutting, fast-forwarding (i.e. small cutting depth, fast forwarding speed)

According to the material classification, the tool is generally divided into ordinary hard white steel knife (material is high-speed steel), coated tool (e.g. titanium plating, etc.), alloy tool (e.g. tungsten steel, boron nitride cutter, etc.).