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A Detailed Guide To the CNC Machining Parts

June 24, 2024

Computer Numerical Control (CNC) machining is a modern, efficient, and automated subtractive manufacturing process that allows cnc machining parts manufacturers to make repeatable parts with consistent quality from a wide range of materials such as plastics, metals, and composites. CNC machined parts are vital for many industries such as aerospace, automotive, and medical.

 

The history of CNC technology can be traced to a few key events. The first modern machining tools date back to 1775, when inventors developed a boring tool that made it possible to produce steam engine cylinders with greater accuracy and precision.

  

The technological precursors to modern computing that were developed in the textile industry earlier in the century were the first steps towards modern computing. In 1725, Basile Bouchon used a system of perforated holes in paper tape to encode data. After that, in 1805, Jacquard Joseph Marie improved this process by replacing the paper tape with punch cards which were durable. These cards were sequenced to give instructions on how to add the fabric to the loom, thus simplifying the process and being one of the earliest examples of programming. The Jacquard loom, therefore, can be viewed as a forerunner of modern computer and automation technologies.

  

This CNC machining guide will cover the workings of the modern CNC processes, including material options, design considerations, cost factors, and so on.


What are CNC Machined Parts?

Parts that are made by machining are everywhere, and they are produced by the process of machining, which is the removal of sections of the workpiece by using cutting machines such as mills, lathes, and routers. Machining can be done manually by a skilled machinist or digitally by using CNC (Computer Numerical Control) machines that follow computer-generated instructions for precision cutting. These components are usually made of different materials such as metals and plastics, and they have to be able to be cut without significant deformation. Besides, machined parts can be created after initial manufacturing processes such as casting or molding to add specific features. This feature of machining to produce exact, dependable parts is what makes it so important across industries, from the smallest of fasteners to the most complex of aircraft engine components.


Bed

The bed is the base of the CNC machine, which gives a stable platform for all other components. Generally, it is made of cast iron to provide durability and strength.

  

Input Device

The input device is the most crucial part of the machine as it is responsible for the delivery of programming instructions to the machine. Some of the most common types include punch tape readers, magnetic tape readers, and computers connected via RS-232-C.

 

Machine Control Unit (MCU)

The machine control unit is the brain of the CNC system. It interprets programming instructions and oversees key operations, such as:It interprets programming instructions and oversees key operations, such as:

 

● Tasks and starting and stopping.

● Adjusting spindle speed

● The direction of spindle rotation.

● Changing tools

● The feed rate control.

  

Control Panel

The control panel is the central custom cnc parts of the CNC machine, which takes the programming instructions and feeds them into the machine and makes sure that the tasks are executed properly.

 

Display Unit

The display unit has a monitor which is used to display important information like programs, instructions, and the status of the machine.

 

Machine Tools

Machine tools include a wide range of CNC elements, such as the sliding table and spindle. The table is manipulated by the X and Y axes, while the spindle is controlled by the Z axis. The machine needs the spindle drives and spindle motors which are the most essential elements for its operation.

  

Chuck

The chuck is a work-holding device that is attached to the main spindle and it is used for securing the tool in place.

 

Headstock

The headstock is the machine part where the workpiece, or the part being machined, is fastened.

 

Tailstock

The tailstock is used to provide extra support to the workpiece, which is very useful for activities like turning and threading.

  

Tailstock Quill

The tailstock quill is used to distribute the workpiece equally between the headstock and the tailstock.

 

Drive System

The drive system is composed of an amplifier circuit, ball drive motors, and lead screws. CNC servo drives and AC servo motors are used to provide smooth operation of CNC machines.

 

Feedback System

The feedback system monitors and provides the real-time data for the machining process to ensure the precision and accuracy.

 

Feedback System

The feedback system is composed of CNC elements, including position and motion transducers, which are used to track the tool movement and location. These transducers send the signals to the machine control unit (MCU), which then makes the necessary changes in the motion and position of the table and spindle for the required precision.

  

Footswitch or Pedal

The footswitch or pedal is used by the CNC machine operator for opening and closing the chuck


Key Industries Using CNC

 

CNC machining is one of the main tools in many industries, either in a direct or indirect way, influencing all those areas that are in need of component production. Here are some key industries and their uses of CNC machining:The following is a list of industries and examples of CNC machining:

 

Aerospace

The aerospace sector has to deal with parts that have a very high degree of precision and reproducibility. CNC machining is used to make turbine blades, tooling for manufacturing other parts, and the combustion chambers of rocket engines, among other essential components.

 

Automotive

Automotive and Machine Building In the automotive industry, CNC machining is considered as the main tool in order to make molds with high precision that are used in casting parts like engine blocks and machining parts with high tolerance like pistons. On the other hand, gantry-style CNC machines are used to shape the clay molds in the vehicle design stage.

 

Defense

The military utilizes CNC machining for the creation of high precision components with close tolerances, such as missile parts to gun barrels. CNC machines are the basis of accuracy and speed that are needed to create reliable military hardware.

 

Medical

The medical implants are often made from complex organic shapes with the help of advanced alloys. CNC machinery is a vital part of this field because manual machines are not capable of the needed precision and complexity for these medical devices.

 

Energy

Energy The energy field of engineering is quite broad ranging from steam turbines to the most modern technologies such as fusion. The blades of steam turbines require precision for balancing, whereas R&D of the fusion process involves CNC machining of complex shapes made of advanced material for the plasma containment chambers.

 

What to Include in Machining Parts. 

It is crucial to apply the DfM (Design for Manufacturing) principles when designing machined parts, using the manufacturing process as a guideline. The constraints for 3D printed parts are different from the ones for machined parts. The latter must be designed according to specific guidelines so as to guarantee manufacturability and efficiency.

 

Undercuts

Undercuts are the elements that cannot be produced by the standard cutting tools. The tool is obstructed by the part of the workpiece. They need the use of specific cutting tools in the shape of T and a special design of the workpiece.

 

Key points to remember about undercuts

 

Standard Sizes: Use whole millimeter dimensions so that the standard tool sizes could be matched. While standard cuts can be made in very small installments, undercuts need to be more precise in sizing.

 

Width and Depth: Undercut width can be between 3 and 40 mm, and the depth is twice the width, which is the cutting tool's depth.

 

Avoid When Possible: If undercuts can be eliminated, the manufacturing process is simplified, in a way that it becomes faster and less complex.

 

Through adhering to these considerations, designers can develop productive and manufacturable machined parts in line with CNC machining processes’ capabilities and limitations.

 

Wall Thickness

  

The difference between molded parts that can deform with excessive wall thickness and machined parts that struggle with especially thin walls is that the latter can be easily deformed. Designers should not use thin walls for machined parts and should choose injection molding if thin walls are necessary. In the case of machining, the minimum wall thickness is 0. 8 mm for metal and 1. 5 mm for plastic.

  

Protrusions 

The deep and tall sections are difficult to machine because they can cause the cutting tool to vibrate, and this can damage the part or reduce the accuracy. In order to avoid this, the height of protruding features should not be more than four times their width.

  

Cavities, Holes, and Threads

  

In the process of designing machined parts, it is necessary to take into account the constraints of cutting tools that are used for making cavities, holes and threads.

 

Cavities and Pockets: Such a depth should not be more than four times the cavity width. The cavities will be deeper and the fillets (rounded edges) will be unavoidable due to the cutting tool diameter.

 

Holes: The depth of holes must not be deeper than four times the width of the drill bit and their diameters must match the standard drill bit sizes when possible.

 

Threads: For the purpose of fasteners like screws, the depth of threads should not exceed three times the diameter of the screw.


Scale

 

Custom cnc machining parts are restricted by the build envelope of the machine. For milling, parts should not exceed dimensions of 400 x 250 x 150 mm. For turning, parts should be no larger than Ø 500 mm x 1000 mm. Larger parts can be machined with specialized equipment, however, this requires prior consultation with the machinist.


Machined Part Surface Finishes  

Machined components can be subjected to several post-machining processes to change their surface finish and look. They can be used for functional or cosmetic purposes.

  

As-machined: This finish is not a surface treatment and can be used for many internal, non-cosmetic functional components.

  

Bead Blasted: This process, which is done by firing abrasive media at the machined part, gives the part a matte appearance. The sandpaper grade can be changed as necessary. Nevertheless, bead blasting might not be the best option for small details, as it removes material and can change the geometry of the machined parts.

  

Anodized: Anodization is a process of electrolytic passivation which is suitable for aluminum machined parts. It provides a scratch-resistant and colorful layer. Type II anodizing provides a corrosion-resistant finish, while Type III is thicker and gives both wear and corrosion resistance.

 

Powder Coated: This procedure involves spraying the powdered paint of the chosen color onto the machined part that is then baked in an oven. This results in a hard, scratch-resistant, and corrosion-resistant layer that is more durable than the usual paint coatings.


Key Takeaways

In the environment of technological development that is quickly changing, it is thought that additive manufacturing will eventually replace CNC machining. However, the most probable thing is the formation of manufacturing centers that will consist of machines with different technologies combined into one. These processes, which are highly developed, include both subtractive and additive features, and this makes them capable of doing things that a single technology cannot achieve. Prototypes of the combined systems are already existing, and these models show the potential of this hybrid approach to production.

 


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Chuanghe Fastener Co., Ltd(CHE)is a professional manufacturing enterprise, Specialize in manufacturing precision fastener over 15 years. If you have a project then please get in touch and we can discuss your requirements and needs. View more cases we have accomplished to learn more details of our services

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