Precision CNC machining

CNC machining services

CNC machining or CNC milling is a subtractive manufacturing process that uses 3-axis, 4-axis and 5-axis indexed machining processes to cut solid plastic and metal blanks into end use parts. With a range of CNC machines, Additive Engineering can deliver CNC machining and CNC turning services to high precision for machined tools, prototypes and low volume production. Tight tolerances are +/- 0.5mm for metals and +/- 0.2mm for plastics. If you need a different tolerance, please contact us.

CNC machining services include :

Grinding machines for materials with high hardness including quenched steel and brittle materials including glass and ceramics. Dimensional accuracies are at 0.05 microns. Sizes range from 3,200×1,600mm to 12,500×6,300mm.

Electrical discharge machines are used for hard materials, for precision injection moulds, complex parts with deep holes and cavities, curved surfaces, narrow slits and thin walls.

Quality assurance

Additive Engineering is an ISO9001 certified facility and has passed supplier audits for medical devices customers to ISO13485 standards. Besides standard inspection reports, we can also provide 3D scanning for inspections as a service.

Design for CNC Machining

For precision CNC machining, there are a few design guidelines that will help improve your CNC design and will improve the functionality of the parts delivered by this low volume manufacturing method. The following are some examples:

  • Hole depth to diameter ratio is recommended to be 10:1 or less. Deeper holes would require additional post-processing.
  • pockets and cavities will have internal radii, add radius of more than 1/3 of the depth.
  • Metal walls are recommended to be at least 0.8mm and plastic walls to be at least 1.5mm. Thin walls are less structurally sound and are prone to warp.
  • Thread length is recommended to be 3 times the diameter of the hole. We accommodate and cut both metric and imperial threads, please ensure the standards used are clearly marked in your drawings provided.
design for cnc machining

CNC Machining or 3D printing for production?

To CNC machine or 3D print? This is a common enquiry for 3D printing service bureaus especially for one-off components, prototypes and low volume production. Most would associate CNC machining as the manufacturing process for mass production and 3D printing as the rapid prototyping solution. Each manufacturing method has its strengths and understanding the differences will help in the selection process, whether for plastic parts or metal parts.

Subtractive vs Additive manufacturing

The key difference between CNC machining and 3D printing is that CNC is subtractive manufacturing while 3D printing is Additive manufacturing. CNC technology start with a blank block of material, and computer numerical control of the CNC milling machine cuts away at the material to create a finished part. Cutters and rotating tools are used to shape the part.

3D printing technology or additive manufacturing involves creating parts in layers of material ( nylon powder or liquid resin for plastic parts) and metal powder for metal 3D printing. A laser energy source in the 3D printer combines the layers to form the 3D printed part. 3D printing does not require tooling or fixtures like a CNC mill.

Subtractive vs additive manufacturing
Subtractive vs Additive manufacturing (3D Printing)

CNC machining advantages

  • High dimensional accuracy
  • Excellent repeatability
  • Mechanical properties of metal is equal to wrought 
  • More expertise available on demand

CNC milling disadvantages

  • High waste of raw material
  • Long leadtimes 
  • labour-intensive, needs operator to choose tools, speeds, cutting path, repositioning
  • Doesn’t work with TPU and some superalloys (inconel is difficult to machine)

3D printing advantages

  • Good dimensional accuracy
  • Good repeatability 
  • Complex geometry or complex parts possible
  • Easier to set up, no need for tooling/ fixtures
  • No need operator to monitor process ( lights-out manufacturing)

3D printing disadvantages

  • High cost of 3D printing machines (especially metal)
  • Mechanical properties is not equal to wrought metal
  • Some post-preocessing involved for different finishes, heat treatment for metal
  • For large volumes, more cost effective to manufacture with injection moulding

What is the selection criteria between CNC machined or 3D printed parts?

As a rule of thumb, there are about 5 key factors to consider.

Complex geometry

If it is a complex part, lattice structures, a topology optimised part, part created by generative design, 3D printing as an additive process tends to be better than CNC machining. This is because of the machine tool access and clearances on cnc lathes, hold or mount points on cnc machining equipment and an inability to machine square corners due to tool geometry. Even 5-axis systems have its own limitations. An operator is required to rotate the part so the tools can access different angles. Jigs and fixtures are required for repositioning and adds to processing time and final part price. The limitations with a 3D printing process are much more manageable. Even the processes that require support structures do not diminish advantages with design freedom.

Dimensional accuracy

If tolerances to microns are required, cnc machining may be a better option. There is also the option to 3D print the near net shape to be further cnc machined to required tolerances. The minimum wall thickness of 3D printed parts are restricted by the laser spot size.


CNC machining

Metal 3D printing (DMLM)

Plastic 3D printing (SLS)


± 0.025-0.125mm

± 0.1mm

± 0.2mm

Min. wall thickness

0.8mm for metal and 1.5mm for plastic



Typical build volume

2000x800x1000mm; Lathe Ø 500 mm

100x100x100 mm to 440x220x320mm

200x250x300mm to 600x330x550mm


Costwise, it usually depends on the material required, the geometry (can it be done any other way), the part volume and the number of units required which impacts the post-processing time and cost. We have found 3D printing inconel and titanium to be more cost-effective than CNC machining inconel and titanium as these are notoriously difficult to machine.

Turnaround time

Need fast turnaround? 3D printing is usually much quicker. There is no need for machine tool set up. CNC workflows tends to be more labour-intensive. The operator needs to decide on tool selection, spindle speed, cutting path and repositioning. Post processing steps also factor into the build time. These include bead blasting, anodising and powder coating.

For 3D printing, the workflow involves a digital file, choosing orientation, adding supports if necessary and the printer creates the slices required to build the part. There’s post-processing involved as well such as cleaning of loose powder, heat treatment for metal parts and removal of support structures, which can be labour-intensive. Other processes include sanding and polishing.

The turnaround time also depends on the required material and the number of parts needed.

Number of parts

When you need one-offs and small volumes, 3D printing tends to be more cost effective. When the numbers start increasing to hundreds, CNC machining may become comparable and in thousands, injection molding is the most cost effective, assuming the part geometry can be manufactured using other processes. This is a general guide, part geometry and size of parts are factors in volume batches. Additive Engineering provides all of the following services, ask us for a quote.

Number of parts




3D print 

3D print


CNC machine or investment casting

CNC maching or injection moulding


investment or die casting

injection moulding

The Cool Parts Show

3D printed tool for CNC Machining

Additive manufacturing is complementary to CNC machining as demonstrated in this epsiode of The Cool Parts Show. This tool is 3D printed to be lightweight and is used in the manufacture of the motor housing in an electric car. 

an end mill for precise metal cutting (typically aluminium) and used to be made with machining. Metal 3D printing made contoured internal channels possible for more effective delivery of coolant, improving machining.

Start time and content

1:02 How this 3D printed machining tool works

2:48 Conventional tool weight versus 3D printed tool

4:33 the 3D printed sections of the tool

6:10 Another 3D printed cutting tool with coolant channels

7:50 Different features of the tool

9:00 Three cutting tools in one

In a hurry? Stephanie Hendrixson does a minute summary from 12:12-13:28.

Inspired to 3D print your own tools or need CNC services? Contact the Additive Engineering team with your requirements.

3D printing cnc machining tool
Credit : 3D printed CNC machining tool from Kennametal

Video courtesy of  Stephanie Hendrixson and Peter Zelinkski of Additive Manufacturing Media, do subscribe to The Cool Parts Show!

CNC machining and 3D printing are complementary processess

In conclusion, which manufacturing you choose would depend on the priorities you place on the various factors highlighted. Additive Engineering can help in the decision-making process by providing quotes for both CNC machining and 3D printing as well as technical guidance to the manufacturability of your product based on the material, tolerances and expected mechanical performance.

Materials for CNC machining


  • Aluminium (Al6061, Al7075)
  • Brass
  • Copper
  • Inconel
  • Magnesium
  • Stainless steel
  • Carbon steel
  • Titanium



  • ABS
  • Nylon
  • PMMA / Acrylic
  • Polycarbonate
  • Polypropylene
  • PEEK


If there is a material that is not listed, contact us with your requirements.


Design for manufacturability assistance
Additive manufacturing conducted in a clean-room environment
Manufacturing modelled to meet AS9100 standards and client-audited to meet ISO13485 standards for medical devices
Powder to product traceability
Product inspections
DMLM in bio-compatible titanium Ti6Al4V, stainless steel 17-4PH, CoCr alloy, Inconel Nickel 718, Hastelloy, SLS in medical grade PA2200
Tamper-proof packaging
Heat treatment
Hot isostatic pressing
CNC Machining
Polishing and full finishing
Injection moulding
Vacuum casting
Our certified powders undergo stringent quality control to meet performance requirements. We offer mechanical data for material selection and an optimised design to manufacture process.

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