How to choose the cutting path in CNC machining?

The tool path refers to the movement trajectory and direction of the tool relative to the workpiece during CNC machining. The reasonable selection of processing routes is very important, as it is closely related to the CNC machining accuracy and surface quality of the parts. When determining the cutting route, the following points are mainly considered:

1. Ensure the machining accuracy requirements of the parts.

2. Facilitate numerical calculations and reduce programming workload.

3. Seeking the shortest CNC machining route to reduce empty tool time and improve CNC machining efficiency.

4. Try to reduce the number of program segments as much as possible.

5. Ensure the required roughness of the workpiece contour surface after CNC machining, and the final contour should be arranged for continuous machining with the last cutting tool.

6. The forward and backward path of the tool (cutting in and out) should also be carefully considered to minimize the occurrence of tool marks at the contour due to sudden changes in cutting force causing elastic deformation, and to avoid scratching the workpiece by vertically lowering the tool on the contour surface.

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What aspects should be paid attention to when determining the clamping method of workpieces for CNC machining

When determining the positioning reference and clamping scheme, the following three points should be noted:

1. Strive for consistency in design, process, and programming calculations.

2. Try to minimize the number of clamping times and achieve CNC machining of all the surfaces to be machined after one positioning.

3. Avoid using manual adjustment plans that occupy the machine.

4. The fixture should be open and its positioning and clamping mechanism should not affect the tool path in CNC machining (such as collision). When encountering such situations, it can be clamped using pliers or adding bottom plate screws.

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What principles should be followed in the arrangement of CNC machining sequence

The arrangement of processing sequence should be considered based on the structure and condition of the parts, as well as the need for positioning and clamping, with a focus on ensuring that the rigidity of the workpiece is not compromised. The order should generally follow the following principles:

1. The CNC machining of the previous process should not affect the positioning and clamping of the next process, and if there are universal machine tool machining processes interspersed in the middle, comprehensive consideration should also be given.

2. First, proceed with the internal cavity machining process, and then proceed with the external machining process.

3. It is best to connect the CNC machining process with the same positioning, clamping method or the same tool to reduce the number of repeated positioning, tool changing, and moving the pressure plate.

4. For multiple processes carried out in the same installation, the process with minimal damage to the rigidity of the workpiece should be arranged first.

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Main industries that use CNC machining

 Any industry involving component production will be directly or indirectly affected by CNC machining. Below are some of the main industries that use CNC machining.

Aerospace - Aerospace requires components with high precision and repeatability, including turbine blades in engines, tooling for making other components, and even combustion chambers used in rocket engines.

Automotive and Machine Manufacturing - The automotive industry needs to manufacture high-precision molds for casting components (such as engine mounts) or machining high tolerance components (such as pistons). The gantry machine can cast clay modules and is used in the design phase of automobiles.

Military Industry - The military industry uses high-precision components with strict tolerance requirements, including missile components, gun barrels, etc. All processed components in the military industry can benefit from the accuracy and speed of CNC machines.

Medical - Medical implant devices are typically designed to fit the shape of human organs and must be made of advanced alloys. Due to the lack of manual machines capable of generating such shapes, CNC machines have become a necessity.

The energy industry covers all engineering fields, from steam turbines to cutting-edge technologies such as nuclear fusion. The steam turbine requires high-precision turbine blades to maintain balance in the turbine, and the shape of the R&D plasma suppression cavity in nuclear fusion is very complex. It is made of advanced materials and requires the support of CNC machines.

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How to divide CNC machining processes

 The division of CNC machining processes can generally be carried out according to the following methods:

1. The centralized tool sorting method is to divide the processes according to the tools used, and use the same tool to CNC machine all the parts that can be completed on the part. Use the second and third knives to complete other parts that they can complete. This can reduce the number of tool changes, compress the travel time, and reduce unnecessary positioning errors.

2. For parts with a lot of CNC machining content, the machining part can be divided into several parts according to their structural characteristics, such as inner shape, outer shape, curved surface or plane, using the sorting method of machining parts. Generally, the plane and positioning surface are machined first, and then the hole is machined; Process simple geometric shapes first, and then process complex geometric shapes; First process the parts with lower precision, and then process the parts with higher precision requirements.

3. For parts that are prone to CNC machining deformation, the rough and fine CNC machining sequencing method is used. Due to the possible deformation that may occur after rough machining, shape correction is required. Therefore, generally speaking, all processes that require rough and fine machining must be separated. In summary, when dividing processes, it is necessary to flexibly grasp the structure and processability of the parts, the functions of the machine tool, the amount of CNC machining content for the parts, the number of installations, and the production organization status of the unit. It is also recommended to adopt the principle of process concentration or process dispersion, which should be determined based on the actual situation, but must strive for rationality.

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What Kind of Parts Can Use Turning-Milling Compound Machining?

 Turning-milling compound machining is a versatile process that can be used to produce a wide range of complex parts. This process is particularly suitable for parts that require high precision, accuracy, and repeatability, such as gears, impellers, turbine blades, and medical implants.

The turning-milling compound machining process can produce parts with complex geometries, fine surface finishes, and high tolerances. This process is suitable for the production of parts made of various materials, including metals, plastics, and composites.

The turning-milling compound machining process is widely used in the aerospace, automotive, medical, and electronics industries, among others. This process can produce parts that are difficult or impossible to manufacture using conventional machining methods.

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What Is Turning and Milling Compound

 Turning-milling compound machining is a manufacturing process that combines the advantages of turning and milling operations. This process involves the use of a single machine that can perform both turning and milling operations on a single workpiece. This method of machining is widely used in the production of complex parts that require high precision, accuracy, and repeatability.

In turning-milling compound machining, the workpiece is held in place by a chuck or a fixture, while a cutting tool moves in two axes (X and Y) to remove material from the surface of the workpiece. The tool is rotated in a clockwise or counterclockwise direction, while the workpiece is rotated in the opposite direction.

The cutting tool can be either a milling cutter or a turning tool, depending on the requirements of the part. This process is suitable for the production of parts with complex geometries, such as gears, impellers, and turbine blades.

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The Benefits of Swiss CNC Machining

 The good performance of Swiss CNC machining greatly benefits from the guide bushing and the geometry and mechanics that take place in the tool zone.

The chip-to-chip time from one tool to the next can be one second or less because the cutting tool operates near the guide bushing;

Capacity for 20 or more tools in the tool zone;

Shorter set-up times;

Often a single heavy cut helps to remove all the necessary material while preventing deflection;

Superior surface finish without the need for grinding;

Complex parts can be machined in a single cycle with more accuracy;

Multiple operations are performed on a part in a single machining cycle, making the part ready for shipment as soon as it is produced from the lathe;

Optimization of productivity-the right automatic bar feeder enables continuous, unattended, and even lights-out operation;

Tighter tolerances are realized by the sliding headstock & the guide bushing.

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What is Swiss CNC Machining

 Swiss CNC machining is a specialized process to machine small, high precision turned parts. A Swiss CNC machine, also referred to as a Swiss automatic lathe, Swiss screw machine, or Swiss-type lathe, was originally designed for the Swiss watchmaking industry. Over the years, the Swiss-style turning machine has been refined to be widely used in various industries for high-volume, high-precision manufacturing – and for good reason.

A Swiss-style lathe is a type of machine that cuts bar stock fed through a guide bushing while the tools keep stationary. The collet is recessed behind the guide bushing so that the bar stock held in it will have better support and will not directly be exposed to the lathe bed and the tooling, so the machine can process the material rapidly and tightly. Also, it plays a great role in decreasing tool deflection and vibration while increasing parts accuracy since the cutting tool can work nearer to the bushing.

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The advantages of 5-Axis CNC Machining

 Compared with the traditional three-axis machining center, the five-axis machining center has the following advantages:

1. Multi-axis machining capability: The five-axis machining center has five independent motion axes, including three linear axes and two rotary axes, which can realize multi-axis machining of complex curved surfaces. Through the combined motion of multiple axes, multiple surfaces can be processed in one clamping, which reduces the number of workpiece clamping times and improves machining efficiency.

2. Machining accuracy: The five-axis machining center can accurately cut the workpiece at different angles, which can avoid unstable machining caused by the complex shape of the workpiece. By machining multiple surfaces of the workpiece, higher machining accuracy and surface quality can be obtained to meet the requirements of high-precision machining.

3. Shortened tool length: Through the movement of the rotary axis, the five-axis machining center can adjust the relative position of the tool and the workpiece surface, shorten the tool length, reduce the influence of cutting vibration and tool bending, and improve the machining quality.

4. High flexibility: The five-axis machining center has a high degree of machining freedom and flexibility, and can process complex-shaped workpieces, such as spiral grooves, curved surfaces, etc. It is suitable for multi-variety and small-batch production, and can quickly adjust the machining path and tool trajectory to meet different machining needs.

5. Reduce manual intervention: The five-axis machining center has functions such as automatic tool change and automatic measurement, which can reduce manual intervention and improve production efficiency and consistency. At the same time, it can also optimize and verify the machining path through simulation software, reduce the time of trial tool adjustment, and improve machining efficiency.

In summary, the five-axis machining center has obvious advantages in machining accuracy, machining efficiency and machining freedom, and can meet the high-precision machining requirements of complex curved surface parts.

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What is 5-Axis CNC Machining ?

 5-axis machining center is a CNC machine tool with the ability to move five axes independently. It can realize the machining of workpieces at different angles through rotary axes (A and C axes) based on the three linear axes of X, Y, and Z. This type of machining center is usually used for the machining of complex curved surfaces, and can complete the machining of multiple surfaces in one clamping, improving machining efficiency and precision.

The five axes of the five-axis machining center are:

X axis: linear movement of the workpiece in the horizontal direction.

Y axis: linear movement of the workpiece in the longitudinal direction.

Z axis: linear movement of the workpiece in the vertical direction.

A axis: rotation around the X axis, also known as the rotary axis.

C axis: rotation around the Z axis, also known as the rotary axis.

Through the combined movement of these five axes, the five-axis machining center can achieve precise cutting and machining of multiple faces of the workpiece. Compared with the traditional three-axis machining center, the five-axis machining center has greater machining freedom and flexibility, and can complete more complex and delicate machining tasks. It is widely used in aerospace, automobile, mold, medical equipment and other fields, especially for machining complex curved surface parts and complex-shaped workpieces such as spiral grooves.

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What is CNC machining?

 In fact, it is a CNC milling machine, which many people call "CNC machining center" in the Guangdong, Jiangsu, Zhejiang and Shanghai areas. It is an automated machine tool equipped with a program control system. (CNC machine tool) is the general name for computer-controlled machine tools (Computernumericalcontrol). It is an automated technology machine tool controlled by a system.

The automatic control system can logically process programs with control numbers or other marked command requirements, decode them through the computer, and then move the machine tool and process the parts. Through CNC blade drilling, the rough materials are processed into semi-finished products and finished parts.

CNC machining (CNCMachining) CNC machining refers to processing using special processing tools of CNC machine tools. CNC index controlled machine tools are programmed and controlled by CNC machining language, usually G code. The CNC machining G code language tells the CNC machine tool which Cartesian position coordinates the CNC blade uses, and controls the CNC blade's cutting speed and spindle speed, as well as tool changer, coolant and other functions.

CNC machining has great advantages over manual machining. For example, the parts produced by CNC machining are very precise and precise; CNC machining can produce parts with complex designs that cannot be processed by manual machining. CNC machining technology has been widely promoted, and most machine shops have CNC machining capabilities. The most common CNC machining methods in typical machine shops include CNC machining centers, CNC machining centers and CNC machine tools EDM wire cutting (spark discharge). wire cutting).

The special tools used to carry out CNC machining centers are called CNC milling machines or CNC machining centers. The CNC lathe that performs CNC machine tool milling processing is called a CNC lathe center. CNC machining G codes can be programmed manually, but general machining shops use CAM (aided design and manufacturing) software to automatically load CAD (aided design) files and convert them into G code programs to control CNC machine tools. 

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CNC turning processing skills

 CNC turning is a high-precision, high-efficiency automated machine tool. The use of CNC lathes can improve processing efficiency and create more value. The emergence of CNC lathes has enabled enterprises to get rid of backward processing technology. The processing technology of CNC lathes is similar to that of ordinary lathes, but because CNC lathes are clamped once and continuously and automatically complete all turning processes, attention should be paid to the following aspects.

Reasonable selection of cutting parameters

For efficient metal cutting, the material to be processed, cutting tools and cutting conditions are the three major factors. These determine the processing time, tool life and processing quality. An economical and effective processing method must be a reasonable selection of cutting conditions.

The three elements of cutting conditions: cutting speed, feed rate and cutting depth directly cause tool damage. With the increase of cutting speed, the temperature of the tool tip will rise, which will cause mechanical, chemical and thermal wear. If the cutting speed is increased by 20%, the tool life will be reduced by 1/2.

The relationship between feed conditions and tool back wear occurs within a very small range. However, when the feed rate is large, the cutting temperature rises and the back wear is large. It has less impact on the tool than the cutting speed. Although the impact of cutting depth on the tool is not as great as cutting speed and feed rate, when cutting at a small cutting depth, the cut material produces a hardened layer, which will also affect the tool life.

Users should choose the cutting speed to be used according to the material to be processed, hardness, cutting state, material type, feed rate, cutting depth, etc.

The selection of the most suitable processing conditions is based on these factors. Regular and stable wear to reach the life is the ideal condition.

However, in actual operation, the choice of tool life is related to tool wear, change in the size of the machined part, surface quality, cutting noise, processing heat, etc. When determining the processing conditions, it is necessary to study according to the actual situation. For difficult-to-process materials such as stainless steel and heat-resistant alloys, coolants can be used or blades with good rigidity can be selected.

How to determine the three elements of cutting processing

How to correctly select these three elements is a major content of the metal cutting principle course. Metal processing WeChat has excerpted some key points. The basic principles for selecting these three elements:

1) Cutting speed (linear speed, circumferential speed) V (m/min)

To select the number of revolutions per minute of the spindle, you must first know how much the cutting linear speed V should be. The choice of V: ​​depends on the tool material, workpiece material, processing conditions, etc.

Tool material:

For carbide, V can be higher, generally more than 100 m/min, and technical parameters are generally provided when purchasing blades:

What material can be selected when processing how much linear speed. High-speed steel: V can only be lower, generally not more than 70 m/min, and in most cases less than 20~30 m/min.

Workpiece material:

High hardness, low V; cast iron, low V, when the tool material is carbide, it can be 70~80 m/min; low carbon steel, V can be more than 100 m/min, non-ferrous metal, V can be higher (100~200 m/min). Hardened steel, stainless steel, V should be lower.

Processing conditions:

Roughing, low V; finishing, high V. Poor rigidity system of machine tools, workpieces, and tools, low V. If the S used in the CNC program is the spindle revolutions per minute, then S should be calculated based on the workpiece diameter and cutting line speed V: S (spindle revolutions per minute) = V (cutting line speed) * 1000 / (3.1416 * workpiece diameter) If the CNC program uses a constant line speed, then S can directly use the cutting line speed V (m/min)

II) Feed (cutting amount)

F mainly depends on the surface roughness requirements of the workpiece. During fine machining, the surface requirements are high, and the feed rate is small: 0.06~0.12mm/spindle revolution. During rough machining, it can be larger. It is mainly determined by the tool strength, generally it can be more than 0.3. When the tool main clearance angle is large, the tool strength is poor, and the feed rate cannot be too large. In addition, the power of the machine tool and the rigidity of the workpiece and the tool should also be considered. The CNC program uses two units of feed rate: mm/min and mm/spindle revolution. The units used above are mm/spindle revolution. If mm/min is used, the formula can be used for conversion: feed rate per minute = feed rate per revolution * spindle revolutions per minute

3) Cutting depth (cutting depth)

During fine machining, it can generally be less than 0.5 (radius value). During rough machining, it is determined according to the workpiece, tool, and machine tool. Generally, a small lathe (maximum machining diameter is less than 400mm) turns 45 steel in the normalized state, and the radial cutting depth generally does not exceed 5mm. In addition, it should be noted that if the lathe spindle speed change adopts ordinary frequency conversion speed regulation, then when the spindle speed is very low (lower than 100~200 rpm), the motor output power will be significantly reduced, and the cutting depth and feed amount can only be very small.

Reasonable selection of tools

1. When rough turning, choose tools with high strength and good durability to meet the requirements of large back cutting amount and large feed rate during rough turning.

2. When fine turning, choose tools with high precision and good durability to ensure the requirements of processing accuracy.

3. In order to reduce tool change time and facilitate tool alignment, machine clamping tools and machine clamping blades should be used as much as possible.

Reasonable selection of fixtures

1. Try to use general fixtures to clamp workpieces and avoid using special fixtures;

2. The positioning reference of parts overlap to reduce positioning errors.

Determine the processing route

The processing route refers to the movement trajectory and direction of the tool relative to the part during the CNC machine tool processing.

1. It should be able to ensure the processing accuracy and surface roughness requirements;

2. The processing route should be shortened as much as possible to reduce the tool idle travel time.

The connection between the processing route and the processing allowance

At present, under the condition that CNC lathes have not yet been widely used, the excess allowance on the blank, especially the allowance containing forging and casting hard skin layers, should generally be arranged on ordinary lathes for processing. If CNC lathes must be used for processing, attention should be paid to the flexible arrangement of the program.

Key points for fixture installation

Currently, the connection between the hydraulic chuck and the hydraulic clamping cylinder is achieved by a pull rod. The key points for clamping the hydraulic chuck are as follows: First, use a wrench to remove the nut on the hydraulic cylinder, remove the pull tube, and pull it out from the rear end of the spindle, then use a wrench to remove the chuck fixing screws to remove the chuck.

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