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Cnc Programming

The CNC machine tool is a configuration of mechatronics processing with a high degree of technical integration and automation. It is a comprehensive application of high-tech products such as planning machines, active control, active detection and precision machines. With the growth and spread of cnc machine tools, the demand of modern enterprises for skilled personnel who understand cnc processing skills and can perform cnc processing and programming will continue to grow. The cnc lathe is one of the most widely used cnc machine tools today. This article explores the headings of step styles in CNC lathe parts processing.

There are two kinds of cnc programming essentials: manual programming and automatic programming. Manual programming refers to a programming process that is manually completed in all steps from part pattern analysis process processing, data planning, writing step lists, input steps to step verification. It is practically used for point processing or processing of parts with less or less chaotic shapes, as well as sites where the planning is relatively large, the steps are few, and the programming is easy to implement. But to deal with how many parts with chaotic shapes (especially those composed of spatial curved surfaces), and how many parts are not chaotic but require a large number of styles and steps, because the labor of planning values in programming is quite tedious, the labor is large, and the steps are easy to fall. The verification is also difficult, and it is difficult to complete with manual programming, so take active programming. The so-called active programming means that most or all of the step-by-step style labor is completed by a planned machine, which can effectively handle the processing of chaotic parts, and it is also the future growth trend of cnc programming. At the same time, it must be considered that manual programming is the foundation of active programming. Many core experiences in active programming come from manual programming, and the two complement each other.

Programming Steps

After getting a part drawing, finally analyze the part drawing to determine the processing process, that is, determine the processing essentials of the part (such as the use of jigs and fixtures, clamping and positioning essentials, etc.), and the processing path (such as feed path, tool setting, etc.) Point, tool change point, etc.) and process parameters (such as feed rate, spindle speed, cutting rate and depth of cut, etc.). Secondly, numerical planning should be carried out. Most local cnc systems have a tool compensation function. You only need to figure out the coordinate value of the intersection (or tangent point) of the adjacent elements of the shape, and get the coordinate value of the starting point end of each element and the center of the arc. Finally, according to the planned coordinate values of the tool movement path and the determined machining parameters and help actions, combined with the coordinate command codes and the step section patterns used by the cnc system law, the part processing step list is compiled section by section, and input into the CNC device’s memory in.

The Analysis Of Case Studies

CNC lathes are mainly used to process reversing and rotating parts, and the typical processing appearance is nothing more than outer cylinder, outer cone, thread, arc surface, grooving, etc. For example, it is more appropriate to use manual programming methods to process parts whose appearance is as shown in the overview diagram. Because the programming instruction codes of different cnc systems are different, programming should be carried out according to the configuration category. Taking the Siemens 802Scnc system as an example, the following controls should be implemented.

(1) Determine the processing path

The machining diameter is determined according to the principle of first main, then second, roughing first and then finishing. The external shape is roughed by a stable cycle command, and then finished, then the tool recess is turned, and the thread is finally processed.

(2) Clamping essentials and selection of tool setting points

A three-jaw self-centering chuck is used for self-centering and clamping, and the tool setting point is selected at the intersection of the right end surface of the workpiece and the reversing spread axis.

(3) Select tool

According to the processing requirements, four tools are selected. No. 1 is a roughing external turning tool, No. 2 is a finishing external turning tool, No. 3 is a grooving tool, and No. 4 is a threading tool. Adopt trial cutting method to set the knife, and process the end surface at the same time.

(4) Determine the cutting amount

Outer circle, rough turning spindle speed is 500r/min, feed rate is 0.3mm/r, fine turning spindle speed is 800r/min, feed rate is 0.08mm/r, when grooving and threading, the spindle speed is 300r/min, the feed rate is 0.1mm/r.

(5) Step style

Determine the intersection of the axis line and the center of the ball head as the programming origin. The processing steps of the part are as follows:

Main step

  • N05 G90 G95 G00 X80 Z100 (tool change point)
  • N10 T1D1 M03 S500 M08 (external rough turning tool)
  • -CNAME=”L01″
  • R105=1 R106=0.25 R108=1.5 (Configure the blank cutting cycle parameters)
  • R109=7 R110=2 R111=0.3 R112=0.08
  • N15 LCYC95 (call blank cutting cycle for rough machining)
  • N20 G00 X80 Z100 M05 M09
  • N25 M00
  • N30 T2D1 M03 S800 M08 (External precision turning tool)
  • N35 R105=5 (Configure blank cutting cycle parameters)
  • N40 LCYC95 (call blank cutting cycle finishing)
  • N45 G00 X80 Z100 M05 M09
  • N50 M00
  • N55 T3D1 M03 S300 M08 (grooving turning tool, tool width 4mm)
  • N60 G00 X37 Z-23
  • N65 G01 X26 F0.1
  • N70 G01 X37
  • N75 G01 Z-22
  • N80 G01 X25.8
  • N85 G01 Z-23
  • N90 G01 X37
  • N95 G00 X80 Z100 M05 M09
  • N100 M00
  • N105 T4D1 M03 S300 M08 (Triangular thread turning tool)
  • R100=29.8 R101=-3 R102=29.8 (Configure thread cutting cycle parameters)
  • R103=-18 R104=2 R105=1 R106=0.1
  • R109=4 R110=2 R111=1.24 R112=0
  • R113=5 R114=1
  • N110 LCYC97 (call thread cutting cycle)
  • N115 G00X80 Z100 M05 M09
  • N120 M00
  • N125 T3D1 M03 S300 M08 (Block cutting tool, tool width 4mm)
  • N130 G00 X45 Z-60
  • N135 G01 X0 F0.1
  • N140 G00 X80 Z100 M05 M09
  • N145 M02


  • L01.SPF
  • N05 G01X0 Z12
  • N10 G03 X24 Z0 CR=12
  • N15 G01 Z-3
  • N20 G01 X25.8
  • N25 G01 X29.8 Z-5
  • N30 G01 Z-23
  • N35 G01 X33
  • N40 G01 X35 Z-24
  • N45 G01 Z-33
  • N50 G02 X36.725 Z-37.838 CR=14
  • N55 G01 X42 Z-45
  • N60 G01 Z-60
  • N65 G01 X45
  • N70 M17

To realize cnc processing, programming is the key. Although this article only has a programming analysis of a CNC lathe machining part, it is certainly representative. Because CNC lathes can process chaotic surfaces that ordinary lathes cannot process, with high machining accuracy, easy quality assurance, and a very broad growth prospect, the processing and programming skills of controlling CNC lathes are particularly tense.

The Precautions Of Cnc Programming

  • The speed of the white steel knife should not be too fast.
  • For coppersmiths, use white steel knives less frequently, and more use flying knives or alloy knives.
  • When the workpiece is too high, you should use different length cutters to roughen it in layers.
  • After roughing with a big knife, use a small knife to remove the remaining material to ensure that the remaining amount is consistent.
  • Flat-bottomed knives are used to process planes, and ball knives are used less to reduce processing time.
  • When the copper worker cleans the corner, first check the size of the R on the corner, and then determine the size of the ball knife to use.
  • The four corners of the calibration plane should be flat.
  • Where the inclination is an integer, use an inclination knife to process, such as pipe position.
  • Before doing each process, think about the margin left after the previous process is processed, so as to avoid empty cutters or excessive processing.
  • Try to take simple toolpaths, such as shape, grooving, one-sided, and avoid the surrounding height.
  • When walking WCUT, if you can go FINISH, don’t go ROUGH.
  • When the shape of the light knife is rough, polish it first, then polish it. When the workpiece is too high, polish the edge first, then polish the bottom.
  • Set tolerances reasonably to balance processing accuracy and computer calculation time. When roughing, the tolerance is set to 1/5 of the margin, and for light knife, the tolerance is set to 0.01.
  • Do more procedures to reduce the time of empty knife. Do a little more thinking to reduce the chance of error. Do a little more auxiliary line auxiliary surface to improve the processing condition.
  • Establish a sense of responsibility and carefully check each parameter to avoid rework.
  • Diligent in learning, good at thinking, and continuous improvement.
  • For non-planar milling, use ball cutters more, use end cutters less, and don’t be afraid of receiving cutters;
  • Clear the corners with a small knife and intensively repair with a big knife;
  • Don’t be afraid of making up the noodles. Proper noodle making can increase the processing speed and beautify the processing effect.
  • The rough material has high hardness: up-milling is better
  • The rough material has low hardness: down milling is better
  • The machine tool has good precision, good rigidity, and finishing: more suitable for down milling, and vice versa.
  • Climbing milling is strongly recommended for finishing of inner corners of parts.
  • Rough machining: up-milling is better, finishing: down milling is better
  • The tool material has good toughness and low hardness: more suitable for rough machining (large cutting amount machining)
  • The tool material has poor toughness and high hardness: it is more suitable for fine machining.

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