What is CNC Precision Machining? A Complete Guide | CNC Precision Machining Service

Published by worthyhardware at May 8, 2023

What is CNC precision machining?

CNC precision machining is a technique that makes use of computer-controlled machines to shape and cut materials into a specific shape or size. This subtractive manufacturing process can do everything from drilling holes to carving complex shapes with precision and accuracy.

In CNC precision machining, designers need to create accurate 3D drawings (Computer-aided Design (CAD)), while operators are responsible for turning these designs into physical parts (Computer-aided Manufacturer (CAM) ). The two roles rely on each other for a successful outcome.

Choosing the right cutting tool is crucial in CNC precision machining. The type of material being machined, the desired surface finish, and the required tolerances all play a role in determining the appropriate tool.

What are the tolerances of CNC precision machining?

CNC machines are very precise. However, because people run these CNC machines we call them the operators or machinists, plus we need to install the CNC machine cutting tools, which will be worn in the production process, so tolerances are necessary for CNC precision machining guarantee that the finished product satisfies the required requirements and performs as intended.

Without tolerances, there would be inconsistencies in the size, shape, and dimensions of the machined parts, resulting in a product that may not work as intended. Tolerances also ensure that the parts fit together correctly during assembly, reducing the risk of errors and malfunctions.

There are different types of tolerance measurement systems

Standard Tolerance Ranges

Tolerance type	Description	Example
Standard Tolerances	Standard tolerance can be described as linear and angular measures, as well as corner chamfers and rounded parts.	+/- (0.127 mm) or .005″
Bilateral Tolerances	The measurement of the part might differ on either side of the nominal value or actual profile in bilateral tolerance.	30 mm (nominal value) +0.05/-0.05 mm (refers to a maximum or minimum value respectively)
Unequally Disposed Tolerances	It shows variation from an actual profile that is permitted in the opposite dimension unequally.	30 mm (Actual drill hole size) Tolerance required (0.1 mm) Max and Min’s limits are like to be 30.09 or 29.99 respectively
Unilateral Tolerances	It permits the tolerance variation from the actual value in one direction.	30 mm (hole diameter) Tolerance required (0.2 mm) The lower limit is 30.2 mm, and the upper limit is 29.8 mm.
Limit Tolerances	It is simply a minimum and maximum allowance dimension specified on the drawing. The key element is that this standard is used in applications where parts must fit together.	30mm (base hole diameter) The upper and lower limits are 30.0 mm and 30.1 mm

Geometric dimensioning and tolerancing

GD&T is a system that uses symbols to describe a part’s geometrical parameters. It is a tolerance-defining method that assists designers and manufacturers in controlling variations in the manufacturing process. It is crucial to remember that you will always consult the standards whenever you want to apply GD&T.
GD&T is a feature-based approach that is classified into five primary categories:
v Form controls describe the shapes of the feature, which include:
Ø Straightness
Ø Flatness
Ø Circularity and roundness
Ø Cylindricity

v Profile controls help in explaining the three-dimensional tolerance zone around the surface by using the following two features:
Ø Line profile
Ø Surface profile

v Orientation controls help in setting up dimensions that depend on the orientation of the angle. It includes:
Ø Angularity
Ø Perpendicularity
Ø Parallelism

v Location controls are used to define the feature’s location with the help of linear dimensioning. It may include:
Ø Position of feature from the datum plane or axis
Ø Concentricity measures the distance between the feature axis and a datum plane
Ø The symmetry feature helps to ensure that the non-cylindrical portion is identical throughout a datum plane.

v Runout control helps to prevent a given feature that might deviate from the axis of rotation. Two main types of runout are listed below:
Ø Single runout
Ø Total runout

What is the working process of CNC precision machining?

Design the 3D model

Designers often use Computer-Aided Design (CAD) software to create 3D models of the part they want to machine. They can specify dimensions, angles, and other details of the part in the CAD software.

The software can also simulate the manufacturing process to ensure that the design is optimized for machining. Once the design is complete, the CAD file is typically exported in a format that can be read by the CNC machine.

Programming 3D models for CNC machines

In the programming stage, the design is transformed into a set of CNC machine instructions to follow. This is done using computer-aided manufacturing (CAM) software. The programmer enters information about the material, tooling, cutting speeds, and other parameters into the software, which then generates a code that the CNC machine can understand.

The code is usually in the form of G-code, a programming language that the CNC machine can interpret. The G-code tells the machine how to move the cutting tool and when to turn it on or off, as well as other details like the speed and feed rate of the tool.

Set up the machines

The CNC machine operator then sets up the machine, including installing the appropriate cutting tools, workholding devices, and measuring instruments. They also load the program into the machine’s computer and verify that everything is working correctly.

CNC Machining

With the machine set up and ready to go, the operator begins the machining process. The CNC machine follows the programmed toolpath to precisely cut or drill the part to the required specifications.

Inspection

Once the part is finished, it undergoes a thorough inspection to ensure that it meets the required tolerances and other specifications. This may involve using precision measuring instruments such as micrometers or laser scanners.

Finishing

Finally, the finished part may undergo additional finishing operations such as anodizing, polishing, painting, or plating before being shipped to the customer.

What are the common CNC precision equipment used ?

Precision CNC machining requires the use of specialized equipment that can accurately and efficiently fabricate parts with tight tolerances. These machines use advanced technology and precise tools to create complex shapes and designs with high levels of precision. In this section, we will explore the various types of equipment used in precision CNC machining and how they contribute to the overall process.

CNC Milling equipment

CNC milling machines use rotary cutters to remove material from a workpiece by moving it in different directions on multiple axes. They are mainly suitable for machining various parts, such as slots, pockets, and holes, as well as creating complex three-dimensional contours and shapes.

Meanwhile,there are several types of CNC milling machines, including vertical milling machines, horizontal milling machines, gantry milling machines, and drilling-milling machines.

CNC Turning equipment

CNC turning machines are specifically designed to produce cylindrical or round-shaped parts. Unlike milling machines, which move the workpiece to achieve the desired shape, turning machines rotate the workpiece while a cutting tool removes material to create the desired shape. Turning machines can also perform other operations such as drilling, boring, and threading.

CNC turning machines,also named CNC lathes, can be classified into several types, including horizontal lathes, vertical lathes, Swiss-type lathes, and multi-spindle lathes.Horizontal lathes are ideal for heavy-duty machining, while Swiss-type lathes are preferred for small, intricate parts. Vertical lathes are useful for large parts, and multi-spindle lathes are used for high-volume production.

CNC Drilling equipment

CNC drilling equipment uses specialized drill bits to create holes in metal or other materials.This equipment is typically used in the production of printed circuit boards, aerospace components, and medical implants.

CNC drilling employs a variety of drill bits, including twist drill bits, center drill bits, spot drill bits, countersink drill bits, and reamer drill bits.

Electrical Discharge Machines (EDM)

Electrical Discharge Machines (EDM),also named spark eroding, spark machining, die sinking, or wire burning,use an electrical discharge to remove material from a workpiece. It is a popular choice for manufacturing molds, dies, and other tooling components.

EDM is classified into two types: wire EDM, which uses a thin wire as the electrode, and sinker EDM, which uses a shaped electrode to create the desired shape in the workpiece.

CNC grinder equipment

CNC grinder equipment is used to precisely shape and finish parts by removing excess material using a rotating abrasive wheel.

There are several types of CNC grinder machines, including surface grinders, cylindrical grinders, and centerless grinders.

Benefits of CNC precision machining

Precision and repeatability are key factors when it comes to producing high-quality and cost-effective machined parts. CNC precision machining is an excellent solution that can help achieve both of these requirements, and it offers several advantages over traditional machining methods.

Increased Efficiency

The computer-controlled machines can work continuously without interruption, making them ideal for the mass production of identical parts. Additionally, the accuracy and precision of CNC machines ensure that each piece is created to the exact specifications required, minimizing errors and the need for manual adjustments. This saves time and resources, resulting in a more efficient and cost-effective manufacturing process.

Improved Accuracy and Consistency

The precision of the process is determined by the programmed instructions, which are followed precisely by the machine with little to no deviation. This eliminates the potential for human error, such as operator fatigue, and ensures consistent results. Additionally, CNC machines are designed to maintain high levels of accuracy over extended periods of use, providing reliable and consistent results with each use

Reduce the production cost

With traditional machining methods, it is common to have a significant amount of material waste due to errors in the production process. However, CNC machines are programmed to optimize the use of materials, which reduces waste and saves money. Furthermore, the precision and uniformity of CNC machining lower the chance of errors, which can save time and money on rework and corrections.

Application of CNC precision machining

CNC precision machining has a wide range of applications across various industries.

Aerospace Industry

The aerospace industry is one of the primary users of CNC precision machining. This industry demands high precision and accuracy in producing parts for airplanes, spacecraft, and other aerospace vehicles.

Some common aerospace applications of CNC precision machining include the production of turbine blades, structural components, and landing gear parts. The use of CNC machining in aerospace manufacturing helps to improve safety, increase efficiency, and reduce costs.

Medical Industry

CNC precision machining is vital in the medical industry, where precision and accuracy are critical. Medical devices such as orthopedic implants, surgical instruments, and prosthetics require the highest level of precision and quality, which can be achieved through CNC machining.

Automotive Industry

We could use the CNC machining to make various compartments, such as engine parts, transmission parts, and brake systems.

By utilizing CNC machining, automotive manufacturers can quickly produce high-quality prototypes and make necessary modifications to improve the design before launching the product in the market. This not only ensures product quality but also helps meet tight deadlines and stay ahead of the competition.

Military and Defense Industry

With the increasing demand for high-precision parts and equipments,such as engine components, gun parts, and navigation systems,CNC precision machining ensures that the components are manufactured to meet the exact specifications, making them reliable and efficient for use in military applications

Materials used for CNC precision machining

Here is a list of common materials that undergo precise machining:

Metals:

Aluminum,
Brass,
Bronze,
Copper,
Carbon steel,
Tool Steel
Stainless steel,
Titanium,
Special alloys such as Inconel, Monel, and Hastelloy

Plastics:

Acetal,
Acrylic,
Delrin,
Lexan,
Nylon,
PEEK,
PET,
Polycarbonate,
Polyethylene,
PTFE,
PVC,
Ultem

Composites:

Carbon fiber,
Fiberglass,
Kevlar

Wood

Hardwood:Black Walnut,Beech,Oak,Maple,Cherry,Mahogany,Birch,Ash,Teak
Softwood:Pine,Spruce,Cedar
Engineering wood:Bamboo,MDF,Plywood

Conclusion

In conclusion, CNC precision machining is a highly versatile and efficient manufacturing process that has revolutionized the way we produce complex and high-precision parts.

With the continuous development of new materials and technologies, CNC precision machining is poised to play an even more important role in shaping the future of manufacturing.

Absolutely, it’s important to take action and start exploring the benefits of CNC precision machining for your own manufacturing needs. Whether you’re in the aerospace, medical, automotive, or any other industry, CNC precision machining can help you achieve higher efficiency, accuracy, and cost-effectiveness in your production processes. Need to source a reliable CNC precision machining service provider? Try Worth Hardware, we are well equipment more than 50 sets of CNC machines and can help bring your ideas to life.