CNC Precision Machining for High-Quality Machined Parts

Ever wonder how those heavy-duty aluminum tools and engine parts are made by machinists? They most certainly did not cast them in a furnace or make them by hand. These machined parts are produced using a technique known as CNC precision machining.

For those who are unfamiliar with the manufacturing industry, computer programs are used in the process of CNC precision machining, which produces products that meet precise specifications.

We’ll describe the procedure, the tools utilized, their uses, and the programming and processing involved in this article. Continue reading to find out more, whether you want to become more knowledgeable about manufacturing or you’re just curious about this procedure.

What is CNC Precision Machining?

CNC precision machining, in essence, refers to the meticulous shaping of raw materials into a finished product by eliminating excess material based on a CAD or CAM blueprint. Whether employed in the production of toys, medical devices, automobiles, or even space shuttles, precision machining is integral to creating components with tight tolerances. Prior to manufacturing any product, CAD or CAM programs generate highly detailed 3D outlines that serve as a guide for the precision machining process. Utilizing CNC equipment, actions such as cutting, milling, turning, and electrical discharge machining are executed to achieve the desired final product. While skilled machinists oversee the process, much of the work is automated, with CAD and CAM software creating designs and translating them into machine-readable instructions. The final step involves the machinists loading these instructions into the CNC equipment to initiate the manufacturing process.

CNC Precision Machining Tolerances

While CNC precision machining tools boast remarkable accuracy, they cannot perfectly replicate the dimensions outlined in the CAD blueprint. Hence, machinists employ tolerances.

Tolerance refers to the allowable deviation in the dimensions of a part, aligning with conventional standards and synonymous with dimensional accuracy. Precision CNC tolerances lack a universal standard; instead, their stringency varies based on the specific manufacturing process. The precision of a measurement is indicated by the number of decimal places in the tolerance value.

Various Tolerance Measurement Systems

Choosing the appropriate tolerance for part manufacturing is crucial, especially for critical structural components that interface with other parts. While not every part requires tight tolerances, maintaining minimal deviation from the nominal value is imperative for structural integrity.

Unilateral Tolerance Measurement

In this approach, deviation is permitted only on one side of the nominal value. For instance, if the nominal value for a shaft intended to fit into a bearing is 20mm, a shaft larger than this would not fit. Consequently, machinists allow deviation only on the smaller side for such a shaft.

Limit Tolerances

This system establishes a tolerance range. For example, if the nominal value for a shaft is 15mm and the tolerance is 15 – 15.5mm, it signifies a limit tolerance.

Bilateral Tolerances

This tolerance type permits deviation on both sides of the nominal value, typically expressed as a +/- value. For instance, if a machined part measures 25mm with a tolerance of +/- 0.05mm, it implies the value can range from 24.95mm to 25.05mm.

Tolerances play a vital role in precision machining processes, contributing to cost reduction and faster turnaround times. Despite their significance, achieving precise tolerances demands skill and patience. The standard tolerance for CNC machines is 0.005 inches, but at Sungplastic, our 5-axis CNC machines can achieve tolerances as tight as 0.002”. We offer a variety of tolerances to cater to our customers’ specific needs, with standard tolerances for CNC machining metals compliant with DIN-2768-1-fine, and for plastics, it is DIN-2768-1-medium.

Types of Precision CNC Machining Equipment

The diverse nature of precision machining processes necessitates an array of specialized equipment to achieve optimal results. In some instances, these tools are integrated into a single precision CNC machine, streamlining the process for the machinist who only needs to initiate and conclude the operation. Alternatively, certain scenarios may require the deployment of tools across different machines, prompting the machinist to transfer the workpiece or raw material between them. Notable precision machining equipment includes:

CNC Milling Equipment

Milling entails the use of rotary cutters to eliminate excess material from a workpiece. This category encompasses various mills such as end mills, chamfer mills, and helical mills. Precision CNC-enabled mills include hand milling machines, plain milling machines, universal milling machines, and those with either horizontal or vertical orientations.

CNC Turning Equipment

Turning is a machining method that revolves around rotating the workpiece alongside a single-point cutting tool. Prominent tools for precision CNC turning processes include lathes like turret lathes, engine lathes, and engine-purpose lathes. Additional turning equipment covers straight turning, taper turning, external grooves, and threads.

CNC Drilling Equipment

Drilling utilizes rotating multi-point drill bits to create cylindrical holes in raw materials or workpieces. Specialized drill bits for CNC machining include spotting drills for shallow or pilot holes, peck drills for chip reduction, screw machine drills for precision hole production without a pilot hole, and chucking reamers for enlarging existing holes. The process is facilitated by drill presses designed for specific drilling tasks.

CNC Electric Discharge Machining Equipment

Electrical Discharge Machining utilizes electrical discharges to achieve precision CNC-machined products. The setup involves a tool electrode and a workpiece electrode separated by a dielectric fluid and subjected to electrical voltage. This process is alternatively known as spark machining, spark eroding, burning, die sinking, or wire erosion.

Applications of CNC Precision Machining

Precision machining is increasingly becoming integral in the manufacturing landscape, thanks to its versatility, cost efficiency, and time-saving attributes. This technique finds widespread applications across diverse industries, including:

Medical Industry

The dynamic field of medicine continually demands new equipment and high volumes of existing devices. CNC precision machining plays a crucial role in manufacturing various medical components, including orthotic devices, safe enclosures, implants, MRI machines, and research equipment.

Automotive Industry

In the ever-evolving automotive sector, where innovation is key, precision machining is essential for developing prototypes of CNC-machined parts before integrating them into the manufacturing line. This technology is not limited to automobiles but extends to other modes of transport, such as shipping vessels and transport trucks.

Aerospace Industry

Precision is paramount in the aerospace industry, where even the slightest error can have severe consequences for transportation planes and space shuttles. CNC precision machining is responsible for crafting critical components like landing gear ports, bushings, manifolds, and airfoils with meticulous accuracy.

Military and Defense Industry

In the realm of military and defense, where nations continually design new ammunition and defense systems, CNC precision machining is indispensable. This precise process brings various designs to life, producing components such as plane parts, transportation components, communication devices, and ammunition with accuracy and reliability.

Advantages of High Precision CNC Machining

Employing highly precise CNC machines in your manufacturing processes offers a multitude of benefits, including:

Reduced Production Costs:
Opting for CNC precision machining proves cost-effective, particularly for small to medium production runs. Unlike injection molding, CNC machining incurs lower upfront costs as there is no need for expensive mold creation.

Increased Operational Speed:
CNC machines operate at a faster pace compared to processes like injection molding. While the creation of molds in injection molding can take months, CNC machining can produce components within weeks, ensuring a quicker turnaround.

Rapid and Cost-effective Prototyping:
CNC machining services enhance the efficiency of prototype production. The versatility of CNC allows for working with a range of cost-effective materials, minimizing expenses on prototypes. The accelerated prototyping process translates to overall faster production. At Sungplastic, we deliver prototypes that not only meet manufacturing requirements but also adhere to high-quality standards.

How to Execute Precision Machining

Materials

CNC precision machining accommodates a diverse range of materials. At Sungplastic, we offer material certifications (SGS, RoHS, etc.) upon request. Some examples of metals and plastics for which certification is provided include:

Metals:

• Aluminium (Aluminum 6061, Aluminum 6061-T651, Aluminum 606, etc.)
• Stainless steel (201, 301, 303, 304, 316, etc.)
• Steel (1008, 1018, 1020, etc.)
• Brass (280, 260, 2680, etc.)
• Copper
• Bronze
• Titanium

Plastics:
ABS, PC, PMMA, POM, PA

This is just a selection of the materials available; Sungplastic offers a comprehensive range for custom prototyping and production. To explore the full list, upload your design for an instant quote and initiate your project.

Programming

Prior to initiating precision machining, machines must undergo programming to ensure seamless and error-free operations. The following steps outline the programming process:

• After the CAD software generates the 2D vector or 3D solid blueprint, export it to a CNC-compatible file format like STEP or IGES.
• The CAM system generates digital programming code, which controls the tooling and produces the custom-designed part.
• Two main programming codes are utilized: G-code (Geometric code), specifying machine movements, and M-code, controlling auxiliary functions.

Processing

Once the machine is programmed, the processing of raw materials begins to achieve exact specifications for the finished product. Various precise CNC processes are employed based on the product, including: CNC Milling, CNC Turning, CNC Drilling.

Surface Finishing

Surface finishing involves enhancing and beautifying the finished product by applying different materials. Sungplastic employs diverse finishing techniques such as anodizing, bead blasting, electroplating, powder coating, etc., to plate the surface of the product for added strength and aesthetic appeal.

CNC Precision Machining Service

Making your custom parts with CNC precision machining is probably the most efficient method. In addition to saving you money, it requires very little time and leaves little room for mistakes. Add this manufacturing procedure to your work right now!

We at Sungplastic make your CAD blueprints come to life in the most amazing way possible. With our extensive range of engineering experience and methodology, we guarantee strong manufacturing capabilities. We can execute your CNC designs, whether they involve creating custom prototypes for as little as one or producing parts that require months to produce, thanks to our 3, 4, and 5-axis CNC machines and a variety of auxiliaries. We also offer injection molding, 3D printing, sheet metal stamping and more services for your custom products.

Provide you with High-Quality Parts at Sungplastic.

FAQs

1. What is CNC Precision Machining?
CNC precision machining is the process of shaping a raw material or workpiece to meet specific and precise dimensions. This involves using blueprints created from CAD and CAM designs.

2. How much does a CNC mill cost?
The cost of a CNC mill varies depending on its size and the range of operations it can perform. Prices typically range from approximately $50,000 to $170,000.

3. How can I determine the accuracy of my CNC machine?
The accuracy of a CNC machine is quantified by the term ‘positional accuracy.’ To assess it, program the machine to move to a specific value, record its deviation from the programmed value, and take multiple readings. Calculate the statistical average value of these deviations to determine the positional accuracy. The average value for most CNC machines is around 0.02mm. If your machine’s value falls outside this range, it may indicate a lack of accuracy.