The complete guide to CNC precision part

The complete guide to CNC precision part

CNC precision part are everywhere, and it’s easy to see why: CNC precision machining is suitable for a range of metals and plastics, and machined parts can be fabricated quickly and affordably with no tooling required.

With Tik precision, you can get machined parts and prototypes at fair prices with short lead times, and we have experience working with clients from various sectors. But why should you go for precision machined parts vs molded or 3D printed parts? Sometimes the choice is usually obvious, but sometimes it’s harder to decide. And how do you actually design parts for engineering, either in-house or outsourced to CNC precision part manufacturer?

This guide goes over the basics of CNC precision part: what they are, so why companies need them, the best machining materials, typical tolerances for made parts, how to design CNC precision part, and more.


What are CNC precision parts?

CNC precision part will be everywhere. From tiny metal fasteners to aircraft engine components, all sorts of parts possess been built using the process of machining. But what exactly is definitely engineering, and what therefore can be CNC precision part?

When we talk about made precision part, we mean something more specific than objects built using machinery. We mean specifically parts created using cutting machines such as mills, lathes, and routers. These devices almost all work in different ways, but their fundamental purpose is certainly the same: using a sharp trimming tool, they cut sections away from a block of material known as the workpiece.

Even within that definition, CNC precision part may be formed in various methods. The procedure of engineering can become manual, whereby a machinist (a skilled professional operator of architectural equipment ) handles a machine like a mill to manually slice the workpiece into the desired shape. Or it can end up being digital, in which case a motorized CNC machine automatically cuts the precision machined parts according to computer instructions.

Nowadays most complex or custom machined parts are made with CNC devices, yet machinists still perform manual machining for certain jobs, since it may become faster than creating a digital style and programming the digital gear.

CNC precision part might turn into metallic or perhaps plastic (sometimes other components too), but they must become made from supplies that can easily end up being minimized without drastically deforming.

Occasionally parts happen to be machined after being built with another manufacturing procedure. For instance, cast or shaped items may possibly possess certain details or features accuracy machined into them at a later stage. These may be described as partially made parts or perhaps CNC precision part.

Why use CNC precision part?

There are many reasons why companies, product designers, R&D departments, and other professionals might use machined parts, and many of the specific advantages of CNC precision part are explained in the following section.

In brief, CNC precision part have got excellent strength, as they are constructed from solid blocks of materials, and they can be produced in a wide range of shapes and thicknesses. They can include very detailed features, and they can become produced from an extremely wide variety of parts. Small quantities of made parts may turn out to be created quickly since they perform not require tooling, and tolerances can always be extremely tight if machining speeds are reduced.

Companies may well also make use of machined parts because machining is a tried-and-testing production technique that has been an industry standard for decades. CNC precision part are consequently likely to meet industry-specific standards and certifications.

Advantages of CNC precision part

CNC precision part offer particular benefits that may not turn into possible with, for example, injection-shaped parts or 3D imprinted parts. Some of the key benefits of accurately machined parts will be listed here.

1 . No MOQ

One of the principal benefits of CNC precision part is the ability to purchase them with simply no minimum order quantity.

For formed CNC precision part, it is necessary to fabricate steel tooling – a process that takes a long time and typically costs tens of thousands of dollars. Machined parts, however, happen to be cut directly from a blank workpiece, which makes it cost-effective to purchase incredibly small amounts or even one-off parts.

Of course, requiring an incredibly large quantity of ( plastic material ) parts might imply molding is usually a better proposition. But the executive is definitely virtually unique in offering high-quality parts with no MOQ, making it ideal for smaller businesses, little creation runs, and prototyping.

2 . Good prototypes

Some businesses choose to order shot molded prototypes, but it is typically only huge firms that can afford to carry out so. The cost of tooling can make prototyping prohibitively expensive.

CNC precision part are suitable and affordable as representative models since they could always be created because of one-offs. Machining is generally likewise much faster than molding, which means R & D departments can quickly iterate several versions of a component, then put it through whatever testing or perhaps assessment is certainly needed before moving on to creation.

The elements versatility of engineering also means corporations can, for example, order CNC precision part in several different metallic alloys or composite plastics to see which performs best under test conditions.

3. Design freedom

CNC machined part can easily currently have a wide variety of shapes and sizes. This could be because COMPUTER NUMERICAL CONTROL machining is unquestionably not really subject to extreme molding style constraints like thin walls and tapering; made parts can be thick and robust, however, features can also be fine and comprehensive.

Although CNC machined part have some limitations when it comes to, for example, internal sections and deep channels, machining continues to represent one of the most geometrically flexible production processes.

Molded parts, on the additional hand, must have slim walls and conform to more strict design criteria generally.

Actually, THREE DIMENSIONAL printing, generally seen as one of the best developing techniques in terms of design independence, has limitations this kind of mainly because avoiding overhangs. (And extensive support structures may become required for more complicated and sprawling designs, which need to be removed with costly post-processing steps. )

4. Quality

CNC machined part may become manufactured to a really high regular. Perhaps more importantly, customers can specify tolerances that require to turn into met by the machinist. This means the machinist or equipment owner may take an extra period upon tight-tolerance parts and individual features.

While injection molds may also be developed to limited tolerances, each individual molding cannot be held to this kind of high regular. Moldings made toward the end from the mold lifespan may lack the definition of earlier units.

5. Lead times

CNC precision parts can easily prove to be produced faster than parts built via various other production processes like molding.

This is partly due to the absence of labor-intensive tooling, but the making process itself is also highly efficient: some of the faster machining centers equipped with linear guide rails own rapid rates of around 4, 000 centimeters per minute (though parts should not actually be machined in those speeds).

The one-step nature of machining and the speed of CNC engineering centers combine to make CNC precision parts a few of the fastest to fabricate (in low volumes), reducing business lead times for shorter time-to-market and practical rapid prototyping.

6. Alterations

Because CNC machined parts are made from a digital CAD file, it really is feasible to make changes to that digital design and style right up until the moment of fabrication.

This is useful during R&D and prototyping when engineers might want to make fractional adjustments to the precision machined part or perhaps create multiple versions. It also reduces the possibility of waste, since defective parts are less probably to end up being generated.

This is a significant advantage for CNC machined part over-molded parts: tooling cannot easily always be changed, and it would be a huge waste of money to create a new mold if a last-minute alteration is required.

7. Strength

Precision machined parts are cut coming from solid pieces of material known as blanks, which usually contain typically been sturdy or extruded. This makes all of them very strong compared to, for example, 3 DIMENSIONAL published parts, which can be much weaker along one axis where one layer can be constructed upon the next.

Many CNC machined parts are also stronger than their cast equivalents, seeing that designed parts must have slim walls and are therefore limited with regards to mechanical performance.

8. Surface finish

CNC machined parts avoid the surface quality issues associated with molding this type of as flow lines, jetting, and flash for the parting line. With a moderate amount of post-processing, finely-detailed machined parts can become brought to an extremely large standard with regards to surface area complete.

Machining as well gives a far superior surface area complete to 3D IMAGES printing, in fact before any post-processing offers have been carried out. 3D printing, especially FDM printing, can leave visible coating lines on the area in the component which in turn must end up being smoothed more than via sanding or chemical treatment. Made parts carry out not really experience these level lines.

How to style CNC precision parts

It is always best to employ design intended for processing (DfM) principles: design parts based on the development method that will be used. Parts to get machining need to turn into designed differently, for instance, parts pertaining to 3D stamping.

Fortunately, CNC precision parts will certainly not be particularly difficult to style – just while lengthy because particular rules happen to be followed. These types of rules are outlined below.


Undercuts are slashes in the workpiece that are not able to become executed using common slicing tools (because a section of the element is obstructing this ). They want special reducing products — T-shaped ones, for example – and exclusive design and style considerations.

Since trimming tools will be made in standard sizes, undercut dimensions should be in whole millimeters to match the device. (For frequent slashes this doesn’t matter since the device can move back and forth in tiny increments. )

Undercut width might range from 3-40 mm, depending on the slicing application, with undercut depth up to twice the size.

If undercuts can be avoided altogether, the machined parts may possibly become manufactured much faster and with less effort.

Wall thickness

Contrary to molded parts, which will deform if walls are too sound, machined parts are unable to handle specifically skinny wall space. Designers should prevent thin wall space, or make use of treatment just like injection molding if slender surfaces happen to be integral to the style.


As with thin wall surface areas, tall protruding areas are difficult to machine, since the vibrations of the cutting gadget may damage the section or perhaps result in lower accuracy.

Cavities, holes, and threads

When designing CNC machined parts, it is important to remember that openings and cavities are dependent on the cutting equipment.

Cavities and pockets may well end up being precision-machined into a portion to an interesting depth of four occasions the cavity width. A deeper major will necessarily end up with fillets — rounded rather than razor-sharp edges – because of the required cutting instrument diameter.

Holes, which are made with drill bits, should also have got a depth of virtually no more than four instances of the exercise bit thickness. And hole diameters should, where feasible, correspond to normal exercise bit sizes.

Threads, utilized to incorporate fasteners like screws, execute certainly not will need to become deeper than three moments the diameter.


CNC machined parts are limited in size because they are fake within the building envelope of the machine. Milled parts should measure no more than 400 x 250 by 150 mm; turned parts ought to measure no more than Ø 500 mm by 1000 millimeters.

Larger sizes are possible with larger products, nevertheless, this should turn out to be discussed with the machinist prior to fabrication.

CNC machined part resources

CNC Machined parts can easily always be produced by many different products, including alloys and plastic materials.

However, a few elements will be easier to equipment than others. Very hard substances happen to be hard to penetrate with a minimizing system and may cause the software to vibrate more ( as a result lowering quality). Extremely soft pieces and materials with an extremely low melting point could deform upon contact with all the reducing units.

The most common made part factors are listed below. Other components may also be machined upon request from the producer.

Metal: Aluminum, Steel, Stainless Metallic (17-4, Inconel 625 & 718), Magnesium, Titanium, Zinc, Brass, Bronze, Copper.

Plastic: ABS, PC, ABS+PC, PP, PS, POM, PMMA (Acrylic), PAGF30, PCGF30, Teflon, DHPE, HDPE, PPS, PEEK. ( Less common: PA GF50, PPS GF50. )

CNC precision part area finishes

CNC precision part may turn into treated following machining in order to alter their surface area texture and appearance. Finishes can always be either functional or cosmetic.

As-machined: Simply no surface end added. This is normally ideal for many inner, non-cosmetic useful parts.

Bead blasted: The bead blasting process involves firing abrasive media in the precision machined part, leaving it having a matte appearance. The method can be adjusted to give a particular level of roughness. It might not become perfect for good features, seeing that bead blasting removes supplies and as a result affects the geometry with the precision machined parts.

Anodized: The electrolytic passivation procedure of anodization is unquestionably suited to aluminum-made parts, creating a scratch-resistant, colorful covering. Type II anodization creates a corrosion-resistant finish; Type III may be thicker and produces wear resistance in addition to corrosion degree of resistance.

Powder-coated: During the power coating technique, powdered paint (in the color of the designer’s choice) is certainly sprayed onto the machined component, which is after that baked in an oven. This creates a stable, wear-resistant, and corrosion-resistant coating that is obviously even more durable than regular color coatings.

CNC precision part tolerances

Machined parts can be produced to limited tolerances, which might become needed for critical mechanical parts that interact with additional ingredients. Looser tolerances may turn into chosen meant for prototypes and non-mechanical parts.

Applications of precision machined parts

Made parts are utilized in practically most industries, from aerospace to medicine. A few popular everyday and sector-agnostic parts will be played out beneath, followed simply by applications in particular industries.

Common made parts:

  • Fasteners
  • Valve bodies
  • Ball joints
  • Gears
  • Shafts
  • Housings
  • Brackets
  • Rollers
  • Aerospace

Machinable aerospace parts include prototype engine components, fuel panels, landing gear parts, and engine mounts.


Automotive machined parts include function screening elements these kinds of as lighting, engine, transmission & steering systems, as well as one-off customized parts.


Machined titanium and stainless steel parts consist of implants, medical gadgets, and surgical tools this sort as scalpels.

Consumer products

CNC machined part are found in household goods and appliances. Sporting gear may also prove to be CNC accuracy machined, while many precision machined steel and plastic-type material elements happen to be discovered in consumer electronics. Items this sort as laptop casings, connectors, and sockets can ever end up being accurately machined.

How to outsource CNC machined part

Hardware businesses huge and little often outsource their particular CNC machined part needs to a specialist. Also for prototypes, it frequently makes sense to employ a third-party CNC engineering company above an in-house solution, due to the factory space and human skills necessary to operate machining items.

Choosing a producer to CNC machined part might seem daunting, but focusing on the subsequent factors and practices may possibly help to make it simpler.

Certifications: ISO qualifications in particular are a great guideline designed for identifying competent machining companies, although they will not inform you of the scope of a company’s abilities.

Word of mouth: Talk to extra hardware businesses who own contracted manufacturers in the region and find aside their experiences outsourcing machined parts.

Demand information: Once you have established get in touch with an organization and keep asking questions until you are satisfied that they know how you can execute your project. If they cannot provide you with a clear answer, they most likely aren’t an appropriate partner for outsourcing.

Visit factories: If all the likely, visit the potential freelancing partner to observe how they machine parts. In some cases, it may be feasible to hire a creation agent to arrange visits to multiple sites in a given area.

RfQs: Send an RFQ to a number of shortlisted CNC machining businesses to get an idea of who can offer the greatest price.

When it comes to arranging the manufacture of the outsourced precision machined parts, it might be helpful to observe the following tips.

Follow DfM guidelines: Make sure your digital aspect design follows machining guidelines: zero slender walls, openings of limited depth, etc.

Use universal requirements: Submit a complete technical drawing with your digital files to remove ambiguity, and utilize universal specifications to prevent miscommunication.

NDA: Sign a non-disclosure agreement when outsourcing techniques machined parts. This legally prevents the maker from disclosing or reusing your styles.

Factor in shipping situations: Outsourced parts consider longer to arrive than in one facility parts, therefore factor in delivery instances if operating to restricted deadlines.

Prepare for payment: Intended for first-time orders, producers will probably require payment up-front, though you may be able to purchase after credit for subsequent orders.