For those who work in CNC, they often encounter 29 difficult solutions that can be easily collected and used!

1. The impact on cutting temperature: cutting speed, feed rate, back cutting amount;
The impact on cutting force: back feed, feed rate, cutting speed;
The impact on tool durability: cutting speed, feed rate, and back cutting amount.
When the back cutting amount doubles, the cutting force doubles;
When the feed rate doubles, the cutting force increases by approximately 70%;
As the cutting speed doubles, the cutting force gradually decreases;
That is to say, if G99 is used, the cutting speed will increase and the cutting force will not change too much.
3. It is possible to determine the cutting force and whether the cutting temperature is within the normal range based on the discharge of iron filings.
When the actual value X measured is greater than 0.8 compared to the drawing diameter Y, the concave arc of the car may rub against the R produced by the turning tool with a secondary deviation angle of 52 degrees (which is the commonly used turning tool with a main deviation angle of 35 degrees and 93 degrees) at the starting position.
5. The temperature represented by the color of iron filings:
White less than 200 degrees
Yellow 220-240 degrees
Dark blue 290 degrees
Blue 320-350 degrees
Purple black is greater than 500 degrees Celsius
Red color greater than 800 degrees
6. FUNAC OI mtc generally defaults to the G instruction:
G69: Not very clear
G21: Metric Size Input
G25: Spindle speed fluctuation detection disconnected
G80: Fixed loop cancellation
G54: Default coordinate system
G18: ZX plane selection
G96 (G97): Constant linear speed control
G99: Feed per revolution
G40: Knife tip compensation cancellation (G41 G42)
G22: Store Travel Detection On
G67: Macro program modal call cancellation
G64: Not very clear
G13.1: Cancellation of Polar Interpolation Method
7. The external thread is generally 1.3P, and the internal thread is 1.08P.
8. Thread speed S1200/pitch * safety factor (usually 0.8).
9. Manual tool tip R compensation formula: Chamfer from bottom to top: Z=R * (1-tan (a/2)) X=R (1-tan (a/2)) * tan (a)) Chamfer from top to bottom by changing the subtract to add.
10. For every 0.05 increase in feed, the rotational speed decreases by 50-80 revolutions per minute. This is because reducing the rotational speed means a decrease in tool wear, and the increase in cutting force is relatively slow, thus compensating for the impact caused by an increase in feed that increases cutting force and temperature.
11. The influence of cutting speed and cutting force on the tool is crucial, and excessive cutting force is the main cause of tool collapse. The relationship between cutting speed and cutting force: When the cutting speed is faster, the feed remains unchanged, and the cutting force slowly decreases. At the same time, the faster the cutting speed, the faster the tool wear, resulting in greater cutting force and higher temperature. When the cutting force and internal stress are too high for the blade to withstand,. There will be a landslide knife (of course, there are also reasons such as stress and decrease in hardness caused by temperature changes).
During CNC machining, special attention should be paid to the following points:
(1) For the current economic CNC lathes in China, ordinary three-phase asynchronous motors are generally used to achieve stepless speed change through frequency converters. If there is no mechanical reduction, the output torque of the spindle is often insufficient at low speeds. If the cutting load is too large, it is easy to get stuck. However, some machine tools are equipped with gear gears, which effectively solve this problem;
(2) Try to ensure that the tool can complete the machining work of a part or a work shift as much as possible, and pay special attention to avoid changing the tool midway during the precision machining of large parts to ensure that the tool can be processed in one go;
(3) When using CNC lathe to turn threads, it is advisable to use a higher speed as much as possible to achieve high-quality and efficient production;
(4) Use G96 as much as possible;
(5) The basic concept of high-speed machining is to make the feed exceed the heat conduction speed, so as to discharge the cutting heat along with the iron chips and isolate the cutting heat from the workpiece, ensuring that the workpiece does not heat up or heats up less. Therefore, high-speed machining selects a high cutting speed that matches the high feed while selecting a small back cutting amount;
(6) Pay attention to the compensation of the tool tip R.
13. Vibration and tool breakage often occur during slotting, and all of these root causes are increased cutting force and insufficient tool rigidity. The shorter the tool extension length and the smaller the back angle, the larger the blade area and the better the rigidity, which can increase with the larger cutting force. However, the larger the width of the slotting tool, the greater the cutting force it can withstand, but its cutting force also increases. On the contrary, the smaller the slotting tool, the smaller the force it can withstand, But its cutting force is also small.
14. Reasons for vibration during vehicle groove operation:
(1) The extended length of the cutting tool is too long, which leads to a decrease in rigidity;
(2) If the feed rate is too slow, it will increase the unit cutting force and cause significant vibration. The formula is: P=F/back cutting amount * f P is the unit cutting force F is the cutting force. In addition, if the rotation speed is too fast, the tool will also vibrate;
(3) The rigidity of the machine tool is insufficient, which means that the cutting tool can bear cutting force, but the machine tool cannot bear it. In other words, the machine tool cannot move. Generally, new beds do not have such problems. Beds with such problems are either old or often encounter machine tool killers.
15. When driving a piece of goods, it was initially found that the dimensions were all good, but after a few hours of operation, it was found that the dimensions had changed and were unstable. The reason for this may be that the cutting force was not very high at the beginning due to the new knives. However, after driving for a period of time, the cutting tools worn out and the cutting force increased, causing the workpiece to shift on the chuck, resulting in old and unstable dimensions.
16. When using G71, the values of P and Q cannot exceed the sequence number of the entire program, otherwise an alarm will occur: the format of the G71-G73 instruction is incorrect, at least in FUANC.
There are two formats for subroutines in the FANUC system:
(1) The first three digits of P000 0000 refer to the number of cycles, and the last four digits are the program number;
(2) The first four digits of P0000L000 are the program number, and the last three digits of L are the number of cycles.
18. If the starting point of the arc remains unchanged and the endpoint is offset by a mm in the Z direction, then the position of the bottom diameter of the arc is offset by a/2.
19. When drilling deep holes, the drill bit does not grind the cutting groove to facilitate chip removal.
If using a tool holder to drill holes, the drill bit can be rotated to change the diameter of the hole drilled.
21. When drilling stainless steel center holes or drilling stainless steel holes, the drill bit or center drill must be small, otherwise it cannot be moved. When drilling with cobalt drill, do not grind the groove to avoid annealing of the drill bit during the drilling process.
22. According to the process, cutting is generally divided into three types: one material per batch, two goods per batch, and the entire bar material per batch.
23. When an ellipse appears during threading, it may be due to loose material. Use a tooth cutter to cut it a few more times.
In some systems where macro programs can be inputted, macro programs can be used instead of subroutine loops, which can save program numbers and avoid many troubles.
25. If the drill bit is used for reaming, but the hole has a large bounce, the flat bottom drill can be used for reaming, but the Fried Dough Twists drill must be short to increase rigidity.
26. If a drill bit is directly used to drill holes on a drilling machine, there may be deviation in the diameter of the hole. However, if the size of the hole is enlarged on the drilling machine, it generally does not run. For example, if a 10mm drill bit is used to enlarge the hole on the drilling machine, the expanded diameter is generally around a 3-wire tolerance.
27. When in the small hole (through hole) of the car, try to continuously roll the chips and then discharge them from the tail. The key points of chip rolling are: -, the position of the knife should be appropriately raised, and secondly, the appropriate blade angle, cutting amount, and feed rate. Remember that the knife should not be too low, otherwise it is easy to break the chips. If the secondary deviation angle of the knife is large, even if the chips are broken, the tool holder will not get stuck. If the secondary deviation angle is too small, the chips will get stuck on the tool holder after the chips are broken, which is easy to cause danger..
28. The larger the cross-sectional area of the tool holder in the hole, the less likely it is to vibrate. Additionally, a strong rubber band can be attached to the tool holder as it can absorb vibration to a certain extent..
29. When turning the copper hole, the tool tip R of the knife can be appropriately large (RO.4-R0.8), especially when the taper is under the car, the iron parts may be nothing, and the copper parts may be too laggy..