What is a custom CNC machined part?

Materials used in aerospace CNC machining

Custom CNC machining parts are parts that are accurately machined using CNC machines according to the customer’s part drawing requirements. These parts are used in a variety of industries and fields such as aerospace, automotive, medical, electronics, and more.

How to design machining parts?

When designing machined parts, you need to consider the part material, structure, and machining difficulty to ensure that the part functions and performs as expected. The following points are noted during the design process:

Material selection

Select the appropriate material according to the usage environment and functional requirements. For example, for parts that need to withstand high pressure or high temperature, you need to choose high-strength, high-temperature-resistant materials. Machined parts are usually made of metal and plastic.

Part structure

Design a reasonable part structure, including shape, size and connection method, etc., to ensure the stability and durability of the parts.

Machining Requirements

The machining difficulty and accuracy requirements of the parts depend on the design of the part structure, which is programmed and machined according to the part structure in the subsequent machining process to achieve efficient and accurate machining.

Custom CNC machining parts material selection

The selection of material for custom CNC machined parts is an important aspect that directly affects the performance, service life and manufacturing cost of the parts. When selecting the material, it is necessary to comprehensively consider a number of factors, including the use of the part, the working environment, stress load, dimensional tolerances, machining performance and economic factors.

Aluminum Alloy

Characterized by lightness, corrosion resistance, and high strength. Due to its low density and light weight, it is often used in aerospace, automotive and other industries that require weight reduction. Its good thermal and electrical conductivity also makes it widely used in the manufacture of electronic components.

Stainless Steel

Stainless steel has good corrosion resistance and mechanical properties. Choose stainless steel for parts that work in wet or corrosive environments to ensure stability and durability.

Carbon Steel

High strength and hardness. Carbon steel parts are commonly machined using turning and milling techniques.

Titanium Alloy

Has the advantages of high specific strength, high specific stiffness and high temperature strength. Titanium alloy materials have a wide range of applications in aerospace and shipbuilding, and the excellent performance enables titanium alloy parts to maintain stability in extreme environments.


With good thermal and electrical conductivity, it is suitable for the manufacture of high-precision electronic components. Copper material processing usually use cutting and milling and other technologies.


Ceramic materials such as alumina and air boron are widely used in high-precision, high-temperature, high-pressure, wear-resistant CNC parts because of their thermal stability, wear resistance and corrosion resistance.


It has excellent corrosion resistance, insulation and processing performance. In the manufacture of CNC parts, polyethylene is often used to manufacture some non-load-bearing, non-stressed parts.


Engineering plastics with high strength, wear resistance, impact resistance and other characteristics. Nylon parts in the need to withstand certain mechanical stress and friction occasions have a wide range of applications.

There are many other materials available, such as polyamide, brass, zinc alloy and so on.

Types of Custom CNC Machining?

  1. Milling processing: milling cutter to cut the workpiece, suitable for processing flat, curved surfaces and complex shapes of the parts.
  2. Turning: cutting of workpieces with rotary tools, suitable for machining cylindrical parts.
  3. Drilling: The rotating drill bit drills holes in the workpiece, suitable for processing hole parts.
  4. Grinding: grinding of workpieces using grinding wheels to improve the surface quality and accuracy of parts.

What are the finishing operations for machined parts?

Finishing of machined parts mainly includes the following aspects:


grinding the surface of the parts by grinding wheel to remove burrs and uneven parts produced during the machining process to improve the surface quality of the parts.


Use polishing tools to polish the surface of the parts to make them smoother and brighter.


Further fine processing of the surface of the part to further improve the accuracy and surface quality of the part.


Plating a thin layer of metal or alloy on the surface of the parts to enhance the corrosion resistance, appearance of finish and electrical conductivity of the parts, as well as to improve the hardness and wear resistance.


through the spraying equipment will paint (such as paint, powder, etc.) evenly coated on the surface of the parts, in order to achieve anti-corrosion, anti-wear, high temperature and other special properties, and to achieve a beautiful appearance.

Chemical treatment

change the nature of the surface of the parts. For example, pickling removes oxidized skin and dirt, increases surface roughness, and provides better adhesion and lubrication.

Heat Treatment

Through processes such as heating, holding and cooling, the structure and properties of the material are altered to optimize the hardness, strength, toughness, etc. of the part and improve its fatigue and wear resistance.


removing a part of the material surface using chemical or electrochemical means to achieve the effect of etching patterns or text, applicable to different kinds of metal materials.

There are also surface treatment methods for specific materials or needs, such as anodizing (for aluminum and aluminum alloys), electrophoresis (for stainless steel and aluminum alloys), and PVD vacuum plating (for metal-ceramic coatings).

How to outsource CNC machined parts?

Product developers often outsource hardware to CNC machining specialists. Even for prototypes, it often makes more sense to use a third-party CNC machining company rather than an in-house solution due to the factory space and personnel skills required to operate the machining equipment.

When you need to outsource CNC machining parts, you can follow the steps below:

Understand the Requirements

Define your part requirements, including the material, size, accuracy, and quantity of parts to be machined.

Get certified

ISO certifications in particular are a good guide to identifying a competent machining company, although they will not tell you the extent of the company’s capabilities.

Factory Visits

If possible, visit your potential outsourcing partner to see how they machine parts. In some cases, a manufacturing agent can be hired to arrange visits to multiple locations in a given region.

Communicate and Negotiate

Communicate in detail with the supplier to clarify details such as machining requirements, pricing, delivery dates, etc. and sign a contract for machining.

Quality Inspection

Upon receipt of the completed machined parts, quality inspection is conducted to ensure that the parts meet the design requirements and quality standards.

Follow DfM guidelines

Ensure your digital part design follows machining guidelines: no thin walls, limited depth holes, etc.

Use common standards

Submit complete technical drawings with your digital files to eliminate ambiguity and use common standards to avoid miscommunication.


Sign a non-disclosure agreement when outsourcing machined parts. This legally prevents manufacturers from disclosing or reusing your designs.

Transportation Time Factors

Outsourced parts take longer to arrive than in-house parts, so consider shipping time if deadlines are tight.

Preparing for payment

For initial orders, manufacturers may require payment in advance, but you can buy on credit for subsequent orders.

Please note that when outsourcing CNC machining parts, make sure to choose a reputable and experienced supplier to ensure the reliability of machining quality and delivery date. At the same time, both parties should establish a good communication and cooperation mechanism to jointly promote the smooth progress of the project.

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