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Everything you need to know about plastic CNC machining
2021.07.23
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CNC machining is one of the most common manufacturing methods. Rapid prototypes and low-volume parts rely on the advantages of precision, size and cost from CNC machining. Learn plastic CNC machining can let you understand your project more specifically. Does your project need CNC machined plastic parts? What plastic material should be used for CNC machining? This article can answer all your questions.
 
Outline here:
Plastic CNC Machining
Plastic 3D printing
Plastic CNC Machining VS Plastic 3D Printing
Quantity of Plastic CNC Machining

CNC Plastic Material Options
 

Plastic CNC Machining


CNC machining is subtractive manufacturing. CNC plastic machining cuts the plastic block until it to be an ideal shape and precision. Depending on the factors of plastic material, complexity, and precision requirement, engineers will choose 3-axis, 4-axis, or 5-axis CNC machine to process the workpiece. More axis CNC machine allows more moving paths and cutting surfaces. The machining speed and precision become higher with a more-axis CNC machine.
 
3-axis CNC machine: The most common CNC machine which can produce simple geometries without multiple rotations of the workpiece. It is usually used for drilling, milling slots or machining previse edges.
4-axis CNC machine: Allowing access to an additional side of the workpiece for drilling, milling slots or machining previse edges.
5-axis CNC machine: The highest CNC machine can produce a more precise workpiece and use multidimensional rotation to access the full sides of the workpiece. Parts made from a 5-axis CNC machine can achieve complex designs and tight tolerance. 5-axis CNC machining is widely used for industries of aerospace, medical, automotive, and consumer products.
For detailed description of 3/4/5-axis CNC machining, quick visit
 

Plastic 3D printing


Plastic 3D printing is an additive manufacturing method. According to your CAD files, 3D printing can build the prototype or volume parts by sintering powder. The most used 3D printing methods are SLS 3D printing and SLA 3D printing.
 
SLS 3D printing: Selective Laser Sintering. Forming the part nylon powder with laser technology. SLS 3D printing doesn’t need supporting material while printing, which is best suited for functional parts and moving parts from prototypes.
SLA 3D printing: Stereo lithography Appearance. The printing process cures the photopolymer layer by layer by UV light. It is best suited for prototypes, concept models, and translucent prototypes.
For detailed description of the 3D printing process,quick visit
 

Plastic CNC Machining VS Plastic 3D Printing


When considering rapid prototyping and low volume production, it is no doubt that low cost, fast delivery, and superior quality are the ideal manufacturing method. Prototyping and volume production are complicated involved multiple factors. The following are the 7 kinds of comparisons for a better understanding.
 
Precision - Plastic CNC machining
Model complexity - 3D printing
Speed - 3D printing
Size - Plastic CNC machining
Strength - Plastic CNC machining
Material - Plastic CNC machining
Environmentally friendly - 3D printing
 

Precision

CNC machined plastic parts are well known for precision. CNC machining controls the cutting tool and movement by programming. Every precise cutting has been calculated. Although 3D printed parts are made by computer and can achieve precision, the precision isn’t reliable.
 

Model complexity

Plastic CNC machining can process many complex parts but require more labor time for programming, which results in a higher price. 3D printing has less restriction on geometry.
 

Speed

3D printing is exceptional in producing time. Parts can be produced under unattended once files are ready and set up properly. Plastic CNC machining requires a more experienced operator to programming and then start to produce, which extends the producing time.
 

Size

Plastic CNC machining and 3D printing have no restriction on small size parts. For large size parts, 3D printing can only split the design into multiple components to produce. Assembling or welding the components together after printing. CNC machine occupies a larger physical footprint to machining. Parts can be made at a time without assembling.
 

Strength

The interior structure of the plastic CNC machined part is compact to be integrity, which shows better mechanical and thermal properties. On the contrary, the structure of the 3D printed part may occur structural weaknesses between layers. The weak layer will weaken the part strength.
 

Material

CNC machining can produce parts in almost all plastic materials. Even the 3D printing material options are growing, but it still limits.
 

Environment friendly

As subtractive manufacturing, CNC machining must waste part of the material when cutting.
 

Quantity of Plastic CNC Machining


Plastic CNC machining is usually used for low-volume plastic production. It has few possibilities of economies of scale and is in no need of tooling cost. Once the programming process is finished, CNC machining has the capability to build identical parts. When the part’s geometry is complex that needs to rotating or resetting the workpiece, production cost and time per part will increase.
 
The following figure shows suitable manufacturing methods for parts of different quantities. Keep in mind that you need to consider other reasons completely if you have special requirements of materials, etc.


different manufacturing methods for different quantites
 

CNC Plastic Material Options

 
Material Color Machinability Features
ABS Black, Ivory, Transparent ⭐⭐⭐ High impact strength
Low heat resistance
Flame retardant 
PMMA/Acrylic Black, white, Transparent High transmittance / weather resistance / cold tolerance / abrasion resistance
Brittle
PC/Polycarbonate Black, white ⭐⭐ High toughness / impact strength
Can be colored and be transparent after FUME
POM/Acetal Black, white ⭐⭐⭐⭐ High fatigue strength / wear resistance / electrical insulation / self-lubrication
Low acid resistance / adhesiveness / weather resistance / moisture absorption
HDPE Black, white High chemical resistance / electrical insulation / impact strength
Low moisture absorption
Lightweight
PP/Polypropylene Black, white ⭐⭐ High heat resistance / flexible life
Lightweight
PPS Beige The machinability for pure PPS is low, especially for the impact strength. Fiberglass will be filled to improve the machinability
High electrical insulation / heat resistance
Hard and brittle
Nylon/PA/PA6 Black, white High impact strength / chemical resistance / abrasion resistance / moisture absorption
PEEK White ⭐⭐ High dimensional stability / impact strength / chemical resistance / heat resistance
PVC Black, white ⭐⭐ High toughness / weather resistance / geometric stability
TEFLON  Silver white ⭐⭐⭐⭐ High heat resistance / chemical resistance

2fprototypes provides manufacturing services to help your project. Please feel free to contact our pro engineers if you still have questions about plastic CNC machining and 3D printing.
 

 

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