CNC Prototype Rapid Manufacturing Process Overview

product development, prototyping

Prototyping holds a crucial role in the production lifecycle, serving as a pivotal step for designers and engineers to validate and optimize their part designs prior to commencing manufacturing. CNC prototype is one of various prototypes while as a initial tool, employed to exhibit proof-of-concept or assess particular material and performance attributes. CNC machining is a better way to manufacturing the prototype, when especially not mostly required in large quantities. At Sungplastic, our CNC prototype service is full-range and delicate to excellence.
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Learn more about our CNC prototype manufacturing expertise and capabilities.

What is CNC Prototype?

CNC prototype refers to the process of creating prototypes using computer numerical control (CNC) machining techniques. CNC machining is a subtractive manufacturing method that utilizes computer-controlled machines to precisely remove material from a solid block or sheet of material, resulting in the creation of a CNC prototype with high dimensional accuracy and intricate details.

In CNC prototyping, a CAD (Computer-Aided Design) model is used as a digital representation of the desired prototype. The CAD model is then converted into a format compatible with CNC machines, typically in the form of G-code instructions. The G-code provides the machine with precise instructions on tool paths, cutting depths, and other parameters required to produce the CNC prototype.
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Why is CNC Machining Good for Prototyping Processes?

There are several compelling factors that establish CNC machining as the optimal choice for prototyping. To begin with, CNC machining offers an unparalleled level of precision and accuracy, owing to its utilization of computerized controls that meticulously oversee the motion of both the workpiece and cutting tool. These computerized controls meticulously account for every facet of your design, guaranteeing that the resulting CNC prototype is an exact replica.

Additionally, CNC machining excels in terms of speed, setting it apart from processes like injection molding, where manufacturers and product developers may endure a months-long wait for tolerances and molds to be prepared.

Within the CNC system, the prototyping process commences with the creation of a 3D CAD model of the final product, subsequently translated into CAM files. These CAM files contain the essential G-code, dictating the CNC machine’s precise movements during the prototyping fabrication process.

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Advantages of CNC Rapid Prototyping

CNC machining is highly regarded as a beneficial method for prototyping processes due to several key advantages it offers.

  • High Precision and Accuracy
    CNC machining provides excellent precision and dimensional accuracy, allowing for the creation of CNC prototype that closely matches the design specifications. The computer-controlled nature of CNC machines ensures consistent and repeatable results, minimizing variations between multiple prototypes.
  • Wide Range of Materials
    CNC machining supports a broad range of plastic materials, including engineering-grade plastics, thermoplastics, and thermosetting plastics. This versatility allows for the selection of materials that closely replicate the properties and characteristics of the intended final product.
  • Complex Geometries and Intricate Details
    CNC machining can produce prototypes with intricate details and complex geometries. The ability to precisely remove material from a solid block or sheet enables the creation of CNC prototype with fine features, undercuts, sharp corners, and intricate surface textures.
  • Quick Turnaround Time
    CNC machining offers relatively fast turnaround times for CNC prototype. Once the CAD model and machining instructions are prepared, the CNC machine can efficiently carve out the prototype, reducing the overall lead time compared to other manufacturing methods.
  • Iterative Design and Rapid Modifications
    CNC machining allows for easy iteration and modifications during the prototyping process. CAD models can be adjusted quickly, and the updated instructions can be sent to the CNC machine for machining the revised prototype. This flexibility facilitates rapid design iterations, enabling faster refinement and optimization of the product design.
  • Functional Prototypes
    CNC machining can produce functional prototypes that closely resemble the final product’s mechanical properties and behavior. This enables testing and validation of the prototype’s functionality, fit, and performance under realistic conditions. Functional prototypes can help identify design flaws, optimize performance, and gather valuable feedback before moving to mass production.
  • Cost-Effective for Low to Medium Volumes
    CNC machining is cost-effective for low to medium volumes of prototypes. While the initial setup costs for CNC machining can be relatively high, the per-unit cost decreases as the volume increases. This makes CNC machining a viable option for producing a small batch of prototypes or low-volume production parts.
  • Compatible with CAD Software
    CNC machining seamlessly integrates with CAD software, allowing for direct transfer of design files to the CAM software for programming the machining instructions. This compatibility streamlines the prototyping process, reduces errors, and ensures accurate translation of the design intent into the physical prototype.

CNC machining offers precise, versatile, and efficient prototyping capabilities, making it a popular choice for creating functional prototypes, concept models, and small-batch production runs. Its ability to produce prototypes with high accuracy, intricate details, and a wide range of materials contributes to its effectiveness in the prototyping process.

Disadvantages of CNC Rapid Prototyping

While CNC rapid prototyping offers numerous advantages, it also has certain limitations and disadvantages. Here are some of the drawbacks associated with CNC rapid prototyping.

  • Cost for Complex Designs
    CNC rapid prototyping can be expensive for complex designs or prototypes with intricate geometries. The cost of CNC machining is often determined by the amount of material removed and the complexity of the machining process. Prototypes with complex designs may involve more machining time, multiple setups, and additional tooling, resulting in higher costs compared to simpler designs.
  • Design Limitations
    CNC machining is a subtractive manufacturing process that removes material from a solid block or sheet. This limitation means that certain design features, such as internal cavities or overhangs, may be challenging or impossible to achieve with CNC rapid prototyping alone. Additional post-machining or assembly steps may be required to incorporate such features, increasing complexity and cost.
  • Difficulty with Soft or Flexible Materials
    CNC machining is more suitable for rigid materials, and it may be challenging to achieve precise results with soft or flexible materials. These materials can deform or deflect during the machining process, leading to less accurate and less reliable prototypes.
  • Limited Scalability
    CNC rapid prototyping is well-suited for low to medium volumes of prototypes. However, when it comes to large-scale production, CNC machining may not be the most efficient or cost-effective option. The setup and machining process for each individual prototype can be time-consuming, making it less suitable for high-volume production.
  • Waste Material Generation
    CNC machining is a subtractive process that involves removing excess material from a larger block or sheet. This results in a significant amount of waste material, especially for complex designs. Proper disposal or recycling of the waste material is necessary, which can add to the overall cost and environmental impact.

CNC Machining Materials For Prototyping

Materials commonly used in CNC machining for prototyping can be broadly categorized into two main types: plastic and metal. These materials offer diverse properties and characteristics that cater to different prototyping needs.


  • ABS (Acrylonitrile Butadiene Styrene)
    ABS is known for its excellent impact resistance and is often used for functional prototypes, particularly in the automotive and consumer goods industries.
  • Nylon
    Nylon is a versatile thermoplastic known for its strength and durability. It’s used in applications where parts need to withstand wear and tear, such as gears and bearings.
  • Polycarbonate
    Polycarbonate offers high impact resistance and optical clarity. It’s used for prototypes requiring transparency, like lenses and visors.
  • Polypropylene
    Polypropylene is lightweight and has good chemical resistance. It’s commonly used for prototypes in the packaging and medical industries.
  • PVC (Polyvinyl Chloride)
    PVC is often used for prototypes requiring resistance to chemicals and weathering, such as pipes and fittings.
  • Polyethylene (PE)
    Polyethylene is known for its low friction properties and is often used for prototypes of products like bottles, toys, and plastic bags.
  • Polyoxymethylene (POM) or Acetal
    POM is a strong and rigid plastic with excellent dimensional stability. It’s chosen for prototypes of precision parts like gears, bushings, and clips.
  • Polyurethane (PU)
    Polyurethane is a versatile material known for its flexibility and impact resistance. It’s used for prototypes of products like foam padding, gaskets, and wheels.
  • Polystyrene (PS)
    Polystyrene is lightweight and has good electrical insulating properties. It’s commonly used for prototypes in the electronics industry, including housings for electronic devices.
  • Polyethylene Terephthalate (PET)
    PET is a strong and lightweight plastic with good chemical resistance. It’s often used for prototypes of containers, bottles, and packaging materials.
  • Polyvinylidene Fluoride (PVDF)
    PVDF is a high-performance plastic known for its excellent chemical resistance and low friction properties. It’s chosen for prototypes in demanding environments, such as chemical processing.
  • Polyether Ether Ketone (PEEK)
    PEEK is a high-performance thermoplastic with exceptional mechanical properties and resistance to high temperatures. It’s used in prototypes for aerospace, automotive, and medical applications.
  • Polyimide (PI)
    Polyimide is a heat-resistant plastic often used for prototypes in the electronics and aerospace industries, where resistance to extreme temperatures is essential.


  • Aluminum
    Aluminum is a lightweight metal with good strength-to-weight ratio. It’s widely used for prototypes in aerospace, automotive, and consumer electronics due to its versatility and corrosion resistance.
  • Steel
    Steel offers exceptional strength and durability. It’s used in prototypes for heavy-duty applications, such as machinery and structural components.
  • Brass
    Brass is valued for its corrosion resistance and aesthetic appeal. It’s used in prototypes for decorative or precision components, like musical instruments and jewelry.
  • Titanium
    Titanium is known for its high strength-to-weight ratio and corrosion resistance. It’s chosen for prototypes in industries like aerospace and medical, where these properties are critical.
  • Copper
    Copper is an excellent conductor of electricity and heat. It’s used for prototypes in electrical and electronic applications, such as connectors and heat sinks.
  • Stainless Steel
    Stainless steel offers corrosion resistance and high-temperature stability. It’s employed in prototypes for applications where hygiene and durability are essential, like medical devices and kitchen equipment.

The choice of material depends on the specific requirements of the prototype, including mechanical properties, aesthetics, environmental factors, and cost considerations. CNC machining provides the flexibility to work with a wide range of materials, making it a versatile choice for prototyping across various industries.

Different CNC Prototyping Operations

CNC prototyping involves various operations that are performed during the CNC machining process. The specific operations required for a prototype depend on the design requirements, the type of material being machined, and the desired outcome.


Milling is a fundamental CNC operation where a rotating cutting tool removes material from a workpiece to create the desired shape or features. It can be performed using different types of milling cutters, such as end mills, ball mills, or face mills. Milling operations include contouring, pocketing, slotting, and drilling holes.


Turning is a CNC operation primarily used for cylindrical or rotational parts. It involves the rotation of the workpiece while a cutting tool removes material to create the desired shape. Turning operations can be performed on a lathe machine and include processes like facing, turning, boring, threading, and grooving.


Drilling is a CNC operation that involves creating holes in the workpiece using a rotating drill bit. CNC drilling machines can accurately position and drill holes of different diameters and depths. Drilling operations can be performed as a standalone operation or as part of other machining processes.


Tapping is a CNC operation used to create internal threads in a pre-drilled hole. A tap is used to cut the threads into the workpiece. The CNC machine controls the rotational speed and feed rate to ensure precise and accurate threading.


Reaming is a CNC operation performed after drilling to improve the accuracy and surface finish of the drilled hole. A reamer with multiple cutting edges is used to remove a small amount of material and refine the hole dimensions.


Boring is a CNC operation used to enlarge or refine an existing hole. It is performed using a single-point cutting tool that removes material from the inner diameter of the workpiece to achieve the desired size and surface finish.


Facing is a CNC operation that involves machining the end face of a workpiece to create a smooth and flat surface. It is often performed as an initial operation to prepare the workpiece for subsequent machining processes.


Contouring is a CNC operation where the cutting tool follows a predefined path to create complex shapes or contours on the workpiece. It is commonly used for creating curved surfaces, profiles, and intricate details.


Engraving is a CNC operation used to etch or engrave text, logos, or patterns onto the surface of a workpiece. It is performed using specialized engraving tools that remove material to create the desired design.

Surface Finishing

Surface finishing operations, such as sanding, polishing, or applying coatings, may be performed after the primary CNC machining operations to achieve the desired surface texture, appearance, and aesthetic qualities of the prototype.

CNC Prototyping Process

CNC prototyping process involves several steps as followed.


  • Design Preparation
    Create a detailed 3D CAD model of the prototype using computer-aided design software or obtain a CAD model from another source.
  • CAM Programming
    Convert the CAD model into machine-readable instructions using computer-aided manufacturing (CAM) software. This step involves defining the tool paths, cutting strategies, and other machining parameters.
  • Material Selection
    Choose the appropriate plastic material for the prototype based on its mechanical properties, desired appearance, and functional requirements. Common plastic materials used in CNC prototype include ABS, acrylic, nylon, and various engineering-grade plastics.
  • Machine Setup
    Set up the CNC machine by securing the chosen plastic material onto the machine bed or vice and installing the necessary cutting tools, such as end mills or drills.
  • CNC Machining
    The CNC machine follows the programmed tool paths and removes material from the plastic block or sheet according to the specified design. The cutting tools rotate at high speeds, controlled by the CNC machine, to precisely carve out the prototype’s shape and features.
  • Finishing Operations
    Once the primary machining is complete, additional finishing operations may be performed to achieve the desired surface finish. This may include sanding, polishing, or applying surface treatments to enhance the aesthetics of the CNC prototype.
  • Quality Control and Inspection
    The CNC prototype is inspected and measured to ensure it meets the required specifications, tolerances, and quality standards. Any necessary adjustments or refinements can be made at this stage.

Considerations and Tips for CNC Prototyping

When engaging in CNC prototyping, there are several considerations and tips that can help ensure a successful outcome.
Here are some key points to keep in mind.

  • Design for Manufacturability
    Design your CNC prototype with manufacturing in mind. Consider the capabilities and limitations of CNC machining and optimize your design accordingly. Avoid features that are difficult or costly to machine, such as sharp internal corners, deep undercuts, or thin walls. Design parts with proper tolerances, appropriate fillets, and draft angles to facilitate machining and improve the overall quality of the CNC prototype.
  • Material Considerations
    Select the appropriate material for your CNC prototype based on its intended function, mechanical properties, and visual requirements. Consider factors such as strength, durability, heat resistance, chemical resistance, and aesthetics. Consult with your CNC machining service provider or material supplier to determine the best material option for your specific application.
  • Prototype Size and Complexity
    Understand the size limitations of the CNC machine and the maximum workpiece dimensions it can accommodate. Complex designs with intricate features may require additional setup time and machining operations. Consider the machining time, tool changes, and setup requirements when planning your CNC prototype to ensure efficient and cost-effective manufacturing.
  • Tool Selection
    Choose the right cutting tools for your CNC machining operation. Consider factors such as material type, hardness, and the desired surface finish. Select appropriate end mills, drills, taps, reamers, and other cutting tools to achieve the desired precision and quality.
  • Surface Finish Requirements
    Determine the required surface finish for your CNC prototype. CNC machining can achieve varying levels of surface roughness, but additional post-machining operations like sanding, polishing, or coating may be necessary to achieve the desired surface texture and appearance. Communicate your surface finish requirements clearly to your CNC machining service provider.
  • Prototype Quantity
    CNC machining is well-suited for low to medium volume production. Consider the quantity of CNC prototype you need and discuss it with your CNC machining service provider. They can guide you on the most cost-effective approach, whether it’s machining multiple CNC prototypes in a batch or using different machining strategies based on volume requirements.
  • Iterative Design and Testing
    Take advantage of the iterative nature of CNC prototyping. Create multiple CNC prototypes to test and validate your design. Use the feedback and insights gained from each iteration to refine and optimize your product design. CNC machining allows for quick design modifications, so use this flexibility to your advantage during the prototyping phase.
  • Communication with CNC Machining Service Supplier
    Maintain clear and open communication with your CNC machining service provider. Provide them with detailed design specifications, material requirements, surface finish expectations, and any other necessary information. Regularly discuss your project progress, address any concerns, and seek their expertise to ensure a smooth and successful CNC prototyping process.

By considering these factors and following these tips, you can enhance the effectiveness of your CNC prototyping process and increase the likelihood of achieving high-quality CNC prototype that meet your design requirements.

Applications of CNC Machining Prototype

The versatility, precision, and ability to produce functional prototypes make CNC machining a valuable tool in various industries, including automotive, aerospace, consumer goods, medical devices, and many others. CNC machining prototype finds applications in various industries and can be used for a wide range of purposes.


  • Product Development
    CNC machining prototype is widely used in product development to create functional prototypes that closely resemble the final product. It allows engineers and designers to validate the design, test functionality, and gather feedback before moving to mass production. CNC prototype enables iterative design improvements and help identify any design flaws or performance issues early in the development process.
  • Concept Models
    CNC machining is often employed to create concept models that showcase the aesthetic design and overall form of a product. These models are used to evaluate the visual appeal, ergonomic aspects, and overall concept of the product before proceeding with further development.
  • Functional Prototypes
    CNC machining can produce functional prototypes that closely mimic the mechanical properties and behavior of the final product. These CNC prototypes enable testing and validation of the product’s performance, functionality, and fit. Functional prototypes can be subjected to various tests, such as stress testing, assembly testing, or functionality testing, to ensure that the product meets the desired requirements.
  • Engineering Validation
    CNC machining prototypes are utilized for engineering validation purposes, allowing engineers to verify the design’s suitability for manufacturing and assembly. CNC prototype can be used to evaluate the structural integrity, dimensional accuracy, and assembly feasibility of a product to ensure that it can be successfully manufactured and assembled in large-scale production.
  • Design Verification
    CNC prototype is employed to verify the design of a product, ensuring that it aligns with the intended specifications and meets the desired requirements. Design verification involves assessing the form, fit, and function of the CNC prototype and comparing it to the original design intent.
  • Custom Components
    CNC machining prototype is used to create custom components or parts for various applications. It allows for the production of complex geometries, precise tolerances, and intricate features that might be challenging to achieve with other manufacturing methods. CNC machining can produce one-off or low-volume custom components efficiently and accurately.
  • Tooling and Molds
    CNC machining prototypes are used in the production of tooling and molds. CNC prototype can be machined to create molds for casting processes or as patterns for injection molding. CNC machining allows for the creation of highly accurate and detailed molds, ensuring the production of high-quality parts in subsequent manufacturing processes.
  • Presentation Models
    CNC machining is utilized to create presentation models that are used for marketing, sales, and presentations. These models showcase the final product’s appearance, texture, and overall aesthetics, giving stakeholders and potential customers a realistic representation of the product.

CNC Prototype vs. Injection Molding Prototype

CNC machining is a subtractive manufacturing process where material is removed from a solid block or billet to create the prototype. It is a versatile and precise method suitable for a wide range of materials.
Injection molding is a formative manufacturing process where molten material is injected into a mold cavity to create the prototype. It’s ideal for mass production but requires expensive molds.


  • Part Tolerance
    Injection-molded prototype exhibits part tolerances that span from ±0.1 to 0.7mm. The relatively modest tolerance levels achieved in injection molding stem from post-injection shrinkage.CNC prototype boasts an exceptionally high tolerance level of ±0.01mm, underscoring the precision and accuracy intrinsic to the machining procedure.
  • Prototype Material
    Injection-molded prototypes predominantly feature plastics or elastomers. This preference arises from the necessity of introducing molten materials into molds for prototype formation.CNC prototype can comprise materials such as wood, plastic, or metal, contingent on the manufacturer’s material selection.
  • Surface Quality
    While the injection molding process is characterized by precision, the resultant prototypes may exhibit minor imperfections, including warping, sink marks, flow lines, weld lines, vacuum shots, short shots, and jetting. These imperfections can detract from the visual appeal of injection-molded prototypes.CNC prototype showcases superior surface finishes attributable to the extensive tooling intricacies involved in the machining process.
  • Setup and Tooling Changes
    CNC machines can quickly adapt to design changes without significant tooling costs. It’s flexible for iterative prototyping.Changing the mold for design iterations can be costly and time-consuming in injection molding, making it less suitable for rapid design changes.
  • Quantity and Scalability
    CNC machining is ideal for producing small to medium quantities of CNC prototypes and is easily scalable.Injection molding is best suited for large-scale production and may not be cost-effective for low quantities.
  • Complexity
    CNC machining excels at producing CNC prototype with intricate details and complex geometries.Injection molding is suitable for complex parts but may have design limitations due to mold constraints. It’s less versatile for highly detailed prototypes.
  • Cost
    CNC machining can be cost-effective for low to medium quantities of CNC prototypes. Material costs and machining time impact pricing.Injection molding is cost-effective for high-volume production but requires significant upfront mold costs, making it less economical for prototypes and small runs.

CNC Prototyping vs. 3D Printing

CNC (Computer Numerical Control) machining is a subtractive manufacturing process. It starts with a solid block of material, and a CNC machine precisely removes material to create the CNC prototype.
3D printing, also known as additive manufacturing, builds prototypes layer by layer from a digital file by adding material, which is an additive process.

  • Material Consumption
    Compared to CNC prototype machining, 3D printing boasts minimal material waste. It employs only the necessary material during the manufacturing process. In contrast, CNC machining subtracts excess materials from a solid block to achieve the desired shape.
  • Prototyping Cost
    CNC processes tend to be more expensive than 3D printing. This price differential arises from the various accessories essential for the optimal functioning of a CNC machine, encompassing fixtures, cutting tools, and cutting fluid delivery systems. Additionally, the substantial initial investment required for acquiring a CNC prototype machine contributes to the higher cost of prototypes produced through machining, rendering them notably pricier.
  • Supported Materials
    CNC machining accommodates a diverse spectrum of materials, spanning wood, plastic, metals, and alloys. In contrast, 3D printing primarily supports thermoplastics due to their malleability under heat and suitability for reformation.
  • Part Tolerance and Toughness
    CNC machines exhibit an exceptional tolerance level of ±0.01 mm, while advanced 3D printing technologies like DMLS (Direct Metal Laser Sintering) offer a tolerance level of ±0.1 mm. Additionally, CNC prototype machines fabricate parts characterized by greater toughness compared to those generated by 3D printing.
  • Speed and Lead Time
    CNC machining typically has shorter lead times, making it suitable for rapid prototyping. It doesn’t require complex setup or curing times.
    3D printing can be slower, especially for larger and more complex prototypes. Printing times can vary widely depending on the size and complexity of the object.
  • Design Iterations
    CNC machining allows for rapid design changes without significant tooling costs. It’s flexible for iterative prototyping.
    3D printing is also well-suited for iterative design changes, as digital files can be easily modified and reprinted.
  • Surface Finish
    CNC machining provides a wide range of surface finishes, from rough to mirror-like, depending on post-processing techniques.
    3D printed prototypes may require additional finishing to achieve a desired surface quality.
  • Scalability
    CNC machining is ideal for producing small to medium quantities of prototypes and is easily scalable.
    While 3D printing is suitable for small batches, it becomes less cost-effective for large-scale production due to longer printing times.

The choice between CNC prototyping and 3D printing depends on factors like material selection, design complexity, speed, cost, and desired end-use properties. Each method has its strengths and limitations, making them suitable for different prototyping scenarios.

FAQs about CNC Prototype

  • Are there better options for prototyping than CNC prototype machining?
    While CNC prototype machining is an excellent choice when durability is paramount, the choice of prototyping method depends on various factors. Material selection, desired structural robustness, and several other criteria will heavily influence your decision.
  • What factors affect the cost of CNC prototype?
    Several factors contribute to the cost of CNC prototype. These factors encompass the complexity of the design, required tolerances, material selection, the type of CNC machine utilized, and the chosen surface finishing method.
  • What is the price of CNC prototype manufacturing?
    Depending on the specific needs of the prototype, the price of a CNC prototype can vary significantly. Typically, the price for 3-axis CNC machines starts at around $35 per hour and can up to $120 per hour for a CNC prototype that needs a CNC machine with additional cutting axes. The number of axes needed will depend on how complicated the CNC prototype is.
  • How long does it take to make a prototype of CNC machining?
    Prototypes made with CNC machining are frequently ready in a few hours or days. Traditional prototyping techniques can take many weeks or even months.

Sungplastic: Best CNC Prototype Service You Need

Utilize our CNC manufacturing capabilities to craft CNC prototype boasting exceptional dimensional precision and superb mechanical attributes, all crafted from metals and plastics. By entrusting your production to our CNC machines and following our meticulous CNC prototype process, you can swiftly obtain the precise prototype parts you desire with the help of CNC prototype service from Sungplastic.

The process for our CNC prototyping is straightforward: furnish us with your CAD file, collaborate with our seasoned engineers to fine-tune your design, and transition to production once your project is primed for implementation.

For more information you want, please contact us.

About Sungplastic

About Sungplastic

Sungplastic is a plastic product manufacturer with rich experience in injection molding. According to the different product development requirements, we flexibly adjust the manufacturing process to achieve high quality, high efficiency and more economical.

We offer a variety of manufacturing services: Rapid Prototyping, Tool Making, Injection Molding, Product Design and Development, CNC Machining and Metal Stamping. You can choose from a variety of plastics, silicone rubber, or metal for your product. Regardless of mass production or small batch customization, Sungplastic has always been committed to providing assured, efficient and more economical one-stop processing services for your projects.

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