CNC Prototype: The Ultimate FAQ Guide

What exactly is CNC prototype? How is it different from rapid prototype? How does it work or What are its benefits? Is it cost-effective? If your mind is wandering to find the answer to all such questions, then stop worrying. Here I am to answer your every question regarding prototyping, especially regarding manufacturing in China.

We have assembled comprehensive guidelines in this article for you in order to help you in practicing with the best designs in CNC prototype. Each and every dimension of prototype is covered in it in order to make it extremely helpful for you. For your ease, related video guidance is also available in it with my answers.

So, if you’re confused and impatient to get all such questions answered, don’t forget to give a read to my Ultimate FAQ Guide about CNC Prototype.

How Does the CNC Machining Create Prototypes?

All the CNC machines are completely automated, which means that they only require digital files or software or a computer program according to which they perform cutting and tooling functions.

• First, designs are built-in digital tool libraries that then give instructions to physical machines to make those designs automatically based on those digital instructions.
• Creating prototypes starts by designing the parts inCAD software. The dimensions and properties of the final part are determined by a 3D model.
• After that, CAM software is used to prepare the model for the whole process. It also checks the errors in the model, and a CNC program is created for fabricating the physical part.
• Next, the selection of parameters takes place. In this step, voltage, cutting speed, RPMs, and configuration of the machine are decided.
• Lastly, the software is used to determine nesting in order to maximize material usage. Nesting plays the role of accurate placement and orientation of parts relative to the raw material.

How to Design Rapid Prototypes by CNC Machining?

Designing your favorite parts is the most interesting function in prototypes as it plays a key role in giving you the most accurate output. This includes 3 simple steps.

• First, you have to export your model into a CNC compatible format
• Second, prepare a technical engineering drawing
• Third, get an instruction command from an online system

If you want to learn some amazing tips and tricks for improving your designs and reducing the cost, you can check out several videos on YouTube.

Or you can also watch this video for details, CNC Machining – Designing Quality Parts.

What Are The Different Diverse Categories of CNC Machines?

Wondering which type of CNC prototyping machine is best for you? Usually, there are many different types of CNC machines but the ones discussed here are the five major ones,

CNC Milling Machine

CNC Milling Machine is the most common type of CNC Machine. This machine has built-in tools for drilling and cutting. Once the materials are placed in the CNC milling machine, the computer will guide the tools to cut or drill them.

Milling machines are mostly available in 3-to-6 axis configuration.

CNC Plasma Cutting Machine

CNC Plasma Cutting Machine is particularly designed for cutting the materials using a plasma torch. A high-powered torch is present in it, which can easily cut rough materials like metal. As compared to electric welding, which cuts metals at 10,000 degrees Fahrenheit, CNC Plasma Cutting can cut metal at a temperature of up to 50,000 degrees Fahrenheit.

CNC Lathe Machine

One of the most advanced forms of CNC Machines is CNC Lathe Machine, which can rotate the materials during operation. They are more compact and smaller because of fewer axes. Lathe machines have a lathe in the center that moves and manipulates the materials into the computer programming position.

Laser Cutting Machine

Laser cutting Machines are best for cutting tough materials. Unlike CNC Plasma Cutting machines, Laser Cutting Machines use a laser to cut the materials. Although lasers provide accurate cutting, they are not strong as plasma torches. Following are some types of lasers,

1. Neodymium (Nd)
2. CO2
3. Yytrium-aluminium-garnet (Nd: YAG)

CNC Electric Discharge Machine

CNC Electric Discharge machines are also called CNC Spark Machines. Spark Machines are a special type of machine that uses an electric spark to mold the materials into the desired shapes.

The electric spark or electric discharge can deform any material to which it is exposed as it has an erosive effect. In order to best reshape the material, the controlled spark is used. Material is placed between the top and bottom electrodes for which the computer dictates the amount of electric discharge.

How Much Does CNC Prototype Cost?

The cost of CNC prototype is mostly dependent on your usage purpose. But before buying its machines, you really need to look at your overall budget. Do a project planning and finalize in advance the purpose and the process of using CNC parts.

For buying a CNC  machine, keep the following things in your notice,

• The cost of your specific order
• The cost of different CNC Machines
• Cost of labor
• Complexity of model
• Additional completion costs

Once you decide to buy CNC machines, its cost also largely depends on its designs’ complexity. If you are thinking of creating more intricate parts, then it will definitely cost you high. A complex design may also require a longer time for designing and a few intricate pieces.

Your order volume may also cause variation in your cost. Although a smaller order is cheaper than the bigger one, the cost of bigger order reduces per individual item. The reason behind this is that once a digital design is created, the company can re-use it many times with no extra cost. This will ultimately reduce your overall cost.

What Are The Different Tips to Reduce Cost?

Here are some of the beneficial tips which will certainly help you in reducing your manufacturing cost,

• Add the undercuts for sharpening the edges and maximize the size of fillets.
• Minimize the total machine orientations
• Before buying, consider the material cost

Furthermore, if you want to watch a detailed guidance video regarding the reduction of cost of prototyping, watch the following video.

Watch video: CNC Machining – Reducing Costs

Which Rules Should be Followed in CNC Prototype?

There is a detailed guidebook for telling you the details of CNC Prototype rules, but I am sharing the few most important ones with you.

Pockets and Cavities: Use large diameter cutting tools for machining deeper pockets and cavities that will affect the fillets of the edges present on the internal side.

Internal Edges: The fillet should be larger for vertical internal edges, while edges on the floor of the cavity should be sharp.

Minimum Wall Thickness: A large wall thickness is necessary because plastics are prone to thermal softening and warping. So, the wall thickness must be reduced, which lowers achievable tolerances.

Holes: Holes must be with standard diameters. On the other hand, use an end mill tool to machine non-standard diameter holes.

Threads: The threads which are the largest possible are easy to machine. They should not cross the limit of 3 times. Otherwise, they will be unnecessary. Always include a technical drawing to your order and design threads as cosmetics in your

CAD package.

Tall Features: Its standard is smaller than 4. Since tall features are prone to vibration, so they are difficult to machine accurately. For this, consider the overall geometry of the given part.

Small Features: The recommended size for cavities and holes is 2.5mm. Using cutting tools, this can be machined CNC. If there is something below, that will be considered as micro-machining, and that must be avoided.

Tolerances: For the tolerance, the standard is 0.125 mm. Avoid over-tolerance, and all the tolerances (geometric, interference, bilateral or unilateral) should be defined on critical features.

Maximum Part Size: The part size of CNC Milling should be 400 x 250 x 150 mm, while CNC Turning should be 500 mm x 1000 mm.

Is CNC Machining Good For Prototyping?

The most dominant form of rapid prototyping is 3D printing, but CNC Prototyping is also very useful for the creation of prototype parts. As a requirement of the product development process, companies highly need production prototypes or engineering prototypes that look and function like final parts.

For this, the parts formed by CNC machining acts as a substitute for real things. Not only this, but it is also more affordable than 3D printing.

The suitability of CNC parts depends on the prototype, the material used, and the purpose of making that prototype. These all factors guide users to opt for the most appropriate method of prototyping.

What Are The Advantages of CNC Prototype?

A large number of advantages make it the best method to use, which include quality of parts, the option of materials, speed of production, and especially similarity of the final part.

From a digital 3D design to an exactly similar machined prototype

The best part about CNC Prototype is its “CNC Element.” NC Prototyping creates the digital designs of different parts that give the machine instructions to mold the raw material into exactly similar shapes as designed by the computer. The final part, created, has identical dimensions.

Another good thing is that a design, once created, can be used multiple times to form a large number of identical parts.

Besides this, if a prototype machine or a design has some flaw in it, it can simply be corrected to give the best quality real prototype designs.

Durable and Strong Materials

CNC Prototype offers a wide range of strong, compatible, and durable materials, including different types of metals. It also possesses the ability to 3D print those metals at a low cost.

Mostly used CNC materials include,

Best Consistency and Quality

CNC prototyping is computer-controlled, so it always functions the way it is supposed to do, unlike many prototype processes that rely on human skill. So, there are very low chances of error, nearly impossible. It follows every minute of instructions.

The most important thing is that it can do that function again and again with exact accuracy. This is particularly useful in creating copies of a prototype on a massive scale, each with exactly similar dimensions and consistency.

The Disadvantages of CNC Rapid Prototyping:

Expensive than 3D Printing

The most prominent drawback of CNC Prototype is none other than the cost of the prototyping process. Its machining centers are heavy and large pieces of machinery that require greater human supervision and greater human power than a 3D printer. Not only this, its special material like metals are also expensive to buy.

Because of such financial constraints, CNC Machinists and engineers opt for alternative prototyping processes such as rapid prototyping. It is also understandable that sometimes, businesses need to cut their expenses during the early prototyping stage.

Wastage of Material

CNC Prototype is a subtractive process that requires more material than what is actually needed. The leftover material is in the form of metal or plastic chips, which can be sold or properly disposed of. As compared to this, in additive prototyping, there is no material wastage.

At times, the prototyping process can cause high costs due to large-scale material usage and wastage. But since, the process gives recyclable chips, so it is beneficial as it has no environmental impact as well as selling those chips reduces the material cost.

Geometrical Restrictions

As far as geometric flexibility is concerned, 4-axis and 5-axis centers are very flexible, but still, they have their limitations. So, for complex internal geometries and elaborate structures, additive prototyping is more suitable as it is not restricted by the angles of drilling and cutting tools. If flexibility can be replicated on the final part, only then is geometrical flexibility helpful.

What is CNC Machining?

It is a process of manufacturing containing pre-programmed computer software that dictates the functioning and movement of machinery and different tools. This manufacturing process is used to control a large variety of machineries such as lathes, mills, routers, and grinders.

A three-dimensional cutting task can also be completed in a single set of prompts using CNC Machining.

When a system of CNC Machining is activated, the required cuts are programmed in the form of software that dictates corresponding machinery and tools to carry out the specific dimensional tasks like a robot.

Who is the father of CNC Machining?

John T. Parsons is considered the father of numerical control machining. He first calculated airfoil coordinates on an IBM 602 A multiplier. That was the first numerical control machine that was used for manufacturing goods that were helicopter blade templates using punch cards based on pre-programmed instructions.

How CNC and NC are Distinguished?

CNC stands for Computer Numerical Control. On the other hand, NC stands for Numerical Control. The programs in it are fed into the punch card, but in CNC, the programs are fed into the computer directly using a small traditional keyboard.

What is the Difference Between the Process of CNC and DNC?

DNC stands for Direct Numerical Control. It is a broad system of networking of many CNC machines. This program is sent to individual machines after its completion externally.

How Will You Compare CNC Milling and CNC Lathe?

Lathes are used for round parts, and the tools are held stationary in this case. While milling can be used for any shape of parts and tools, do the movements, and the material is held stationary by the milling machines. Lathe works with 2-axes, while milling machines usually work with 3-axes.

What is the Difference Between the Techniques of CNC and VMC?

A CNC machine is an automated, computer-controlled system. While VMC is a type of CNC Prototype that is specifically used for cutting metals.

What is the difference between the processes of CNC and PLC?

CNC (Computer Numerical Control) is conditional and is the final execution processed from the program, while PLC (Programmable Logic Controller) is a sequential and programmed process.

What is the Role of CNC Machinists?

CNC Machinists work with heavy machinery of CNC Prototype almost during all operations from initial setup to operation and production of different parts and tools from plastic, metal, and other materials. The final step includes drilling, grinding, and cutting of the material based on the instructions guided by CNC Machinist.

What is a Part Program?

It is the set of instructions to describe the work to be done under CNC software. A standard program sheet from a raw drawing sheet is prepared. The machining data is compiled and translated into a language understandable by the control system.

This data includes the classification of the process of machining sequence, spindle speed, cutting conditions, coolant, and selection of cutting tools.

What is G-Code used by CNC Machines? (Master of Actions)

• Code is used as the basic code during CNC Prototype which is the most popular CNC programming language. G stands for geometry. A number follows the G-code, which is the command to change the geometry of the final product. Following are some codes as examples:

G00: Rapid Movement

G01: Linear Movement

G02: Clockwise Movement

G03: Counter-Clockwise Movement

What is M-Code used by CNC Machines? (Organizer of Functions)

• M stands for Machine. M-codes are usually used for non-geometry machines functions such as start and stop, spindle rotation, and pallet change. For example,

M00: Stop function

M03: Clockwise Spindle Rotation

M08: Flood coolant command ON

M09: Flood coolant command OFF

What is Meant by the 5 axes on a CNC Machine?

The term axis represents the direction of movement of the cutting tool. In a 5-axis machine, the drilling or cutting tool rotates on A and B while moves on X, Y and, Z linear axes and approach the work-piece in any direction.

What Makes CNC Prototyping Better Than Rapid Prototyping?

There are a few of the points discussed below, which are meant to compare the pros and cons of the two different forms of prototyping,

• As the precision and repeatability of final parts are concerned, CNC has the edge over rapid prototyping.
• The best part about CNC machining is that it can handle an unlimited range of material which is not possible in the case of rapid prototyping.
• Besides this, rapid prototyping is more affordable and cost-effective.
• People can easily learn and start working on production through rapid prototyping.
• Regarding geometric flexibility, rapid prototyping is extremely flexible in its designs with unlimited complexity compared to CNC prototype, where this function is not possible or difficult to perform.

What Kind of Services a CNC Machining Offers?

A CNC machining process can offer a wide range of services, including threading, turning, milling, drilling, prototyping, tapping, part design, and reverse engineering, parts dispatching, and limited material warehousing.

Which Are The Various Applications of Quality CNC Parts?

The greatest thing about CNC parts is that it has evolved a wide range of applications with time. At times, professionals from different industries have used prototypes for manufacturing their required products. These industries include Space, Aerospace, Automotive, Design, Electrical, Industrial, and Sports.

What Are the Differences between CNC Prototyping and 3D Printing?

Both CNC Prototyping and 3D Printing are suitable for different situations and are unique and exceptional processes to be used by an engineer.

CNC Prototyping is a subtractive manufacturing technology, while 3D Printing is an additive technology. CNC offers high accuracy, excellent repeatability, and a wide

Range of surface and material finishes. While 3D printing is highly cost-effective, reduces time, and creates more complex designs.

What Are the Surface Finishes for CNC Rapid Prototypes?

After the production of the final parts, surface finishes are applied. They can change the hardness, chemical resistance, surface roughness, and appearance of the parts produced.

But the machined parts possess the tightest tolerance, so they are already manufactured with the natural finishing touch with zero extra cost for the purpose.

Which Are Some Types of Surface Finishes?

If you are looking for which surface finishing method is best for your products, then the following are the most commonly used surface finishing methods,

Bead Blasting

Bead blasting is usually very useful for aesthetic purposes. It removes all the tool marks and adds a satin surface or uniform matte on a machined part. What good is that it is a low-cost finish, but it affects surface roughness and critical dimensions?

Anodizing

Anodizing increases the wear and corrosion resistance of aluminum surfaces or parts by adding a non-conductive, hard, and thin ceramic coating. Anodizing is durable, can be applied to cavities, and can also be colored to any tone. But its drawback is that it is only suitable for titanium and aluminum and is brittle than powder coating.

Hard coat Anodizing

Hard coat anodizing is a high-density and thicker ceramic coating that provides excellent resistance against corrosion. It is mostly suitable for functional applications. It contains a normal coating thickness of 50 micrometers with no colors applied. Its limitation is that it is only suitable for aluminum, but it has high wear resistance.

Powder Coating

Powder coating is a corrosion-resistant, thin and protective polymer paint applied to any produced part or surface, which is available in a variety of colors. The best part about powder coating is that it is compatible with all the metals with high impact resistance and corrosion coating.

On the other hand, its drawback is that it is not suitable for small components, and it cannot be applied to internal surfaces.

Silk Screening

Silk screening is a cheap method to print logos and texts on the final parts machined by CNC for aesthetics. What’s best about it is that it is available in many colors, low cost, and can only be applied to flat surfaces.

Finally, this was my Ultimate FAQ Guide. Since most of the queries have been addressed in this article in detail, now you can kick start working with CNC Prototype very efficiently.