Summary Of 12 CNC Machining Experience (2)

6. How To Monitor And Adjust During CNC Machining?

After the workpiece is aligned and the program is debugged, it can enter the automatic processing stage. In the automatic machining process, the operator should monitor the cutting process to prevent abnormal cutting from causing workpiece quality problems and other accidents.

The following aspects are mainly considered for monitoring the cutting process:

1. Machining Process Monitoring

The main consideration for rough machining is the rapid removal of excess margin on the surface of the workpiece. In the automatic machining process of the machine tool, according to the set cutting amount, the tool automatically cuts according to the predetermined cutting path. At this time, the operator should pay attention to observe the cutting load changes in the automatic machining process through the cutting load table, and adjust the cutting amount according to the bearing capacity of the tool to maximize the efficiency of the machine tool.

2. Monitoring Of Cutting Sound During Cutting

In the automatic cutting process, generally when starting cutting, the sound of the tool cutting the workpiece is stable, continuous, and brisk. At this time, the movement of the machine tool is stable. As the cutting process progresses, when there are hard spots on the workpiece, tool wear, or tool clamping, the cutting process becomes unstable. The unstable performance is that the cutting sound changes and the tool and the workpiece collide with each other. Sound, the machine tool will vibrate. At this time, the cutting amount and cutting conditions should be adjusted in time. When the adjustment effect is not obvious, the machine tool should be suspended to check the condition of the tool and workpiece.

3. Finishing Process Monitoring

Finishing is mainly to ensure the processing size and surface quality of the workpiece, the cutting speed is higher, and the feed rate is larger. At this time, attention should be paid to the impact of built-up edge on the machined surface. For cavity machining, attention should also be paid to over-cutting and cutting at corners. To solve the above problems, one is to pay attention to adjusting the spray position of the cutting fluid to keep the machined surface in a cooling condition at all times, the other is to observe the quality of the machined surface of the workpiece, and adjust the cutting amount to avoid quality changes as much as possible. If the adjustment still has no obvious effect, the machine should be shut down to check whether the original program is reasonable. Special attention should be paid to the position of the tool when the inspection is suspended or stopped. If the tool stops during the cutting process, a sudden stop of the spindle will cause tool marks on the surface of the workpiece. Generally, consider stopping the tool when it leaves the cutting state.

4. Tool Monitoring

The quality of the tool largely determines the processing quality of the workpiece. In the automatic machining and cutting process, it is necessary to judge the normal wear condition and abnormal damage condition of the tool through methods such as sound monitoring, cutting time control, pause inspection during cutting, and workpiece surface analysis. According to the processing requirements, the tools should be processed in time to prevent the processing quality problems caused by the tools not being processed in time.

cnc machining center process

7. How To Choose Processing Tools Reasonably? What Are The Major Factors Of Cutting Amount? How Many Kinds Of Materials Are There For Knives? How To Determine The Speed, Cutting Speed, And Cutting Width Of The Tool?

  1. When plane milling, you should choose non-reground hard alloy end mills or end mills. In general milling, it is best to use the second pass to process. The first pass is best to use the end mill for rough milling, and continue to pass along the surface of the workpiece. The width of each pass is recommended to be 60%-75% of the tool diameter.
  2. End mills and end mills with carbide inserts are mainly used for processing bosses, grooves and box mouth surfaces.
  3. Ball knives and round knives (also known as round nose knives) are often used to process curved surfaces and variable bevel contours. The ball knife is mostly used for semi-finishing and finishing. Round knives inlaid with cemented carbide tools are mostly used for roughing.

8. What Is the Function Of The Machining Procedure Sheet? What Should Be Included In The Machining Procedure Sheet?

  1. The processing procedure sheet is one of the contents of the CNC machining process design, and it is also a procedure that needs to be observed and executed by the operator. It is a specific description of the processing procedure. The purpose is to let the operator clarify the content of the procedure, the clamping and positioning method, and the processing The tool selected by the program should not only be paid attention to, etc.
  2. In the processing program list, it should include: drawing and programming file name, workpiece name, clamping sketch, program name, tool used in each program, maximum cutting depth, processing nature (such as roughing or finishing) , Theoretical processing time, etc.

9. What Preparations Should Be Made Before CNC Programming?

After determining the machining technology, you must understand before programming:

  1. Workpiece clamping method;
  2. The size of the workpiece blank —- in order to determine the scope of processing or whether multiple clamping is required;
  3. The material of the workpiece-in order to choose which tool to use for processing;
  4. What are the stocked knives?-Avoid modifying the program during processing because there is no such tool. If you must use this tool, you can prepare it in advance.

10. What Are The Principles For Setting The Safety Height In Programming?

The principle of setting the safety height: generally higher than the highest surface of the island. Or set the programmed zero point on the highest surface, so as to avoid the danger of hitting the knife to the greatest extent.

11. After The Tool Path Is Compiled, Why Is It Necessary To Post-process?

Because the address code and NC program format that can be recognized by different machine tools are different, the correct post-processing format must be selected for the machine tool used to ensure that the compiled program can run.

12. What is DNC Communication?

The way of program delivery can be divided into CNC and DNC. CNC means that the program is delivered to the memory of the machine tool through media media (such as floppy disk, tape reader, communication line, etc.) for storage, and the program is called out from the memory during processing. Processing. Because the memory capacity is limited by the size, when the program is large, the DNC method can be used for processing. Since the machine tool directly reads the program from the control computer during DNC processing (that is, it is done while sending).

  1. There are three main elements of cutting parameters: depth of cut, spindle speed and feed rate. The general principle of selecting cutting parameters is: less cutting, fast feed (that is, the cutting depth is small, the feed speed is fast)
  2. According to the classification of materials, cutting tools are generally divided into ordinary hard white steel knives (materials are high-speed steel), coated knives (such as titanium plating, etc.), alloy knives (such as tungsten steel, boron nitride knives, etc.).

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