After having good ideas and product design, you want to know you’re using the best equipment and leading your business forward. To make prototypes out of your design and even to have mass production, computer numeric control (CNC) machining and 3D printing are two common choices here in Hemtom Prototyping. Which one is better for your needs?

CNC machining and 3D printing each has unique benefits. You would want to use them  regarding cost and availability under varying circumstances. Now let’s find out their differences and strengths to find which is right for your prototype.

1.Working principle
SLA is an industrial 3D printing, or additive manufacturing, process that builds parts in a pool of UV-curable photopolymer resin using a computer controlled laser. The laser is used to trace out and cure a cross-section of the part design on the surface of the liquid resin. The solidified layer is then lowered just below the surface of the liquid resin and the process is repeated. Each newly cured layer adheres to the layer below it. This process continues until the part is completed.
Also a 3D printing method. During the SLS process, a computer-controlled CO2 laser draws onto a hot bed of nylon-based powder from the bottom up, where it lightly sinters (fuses) the powder into a solid. After each layer, a roller lays a fresh layer of powder on top of the bed and the process repeats.
CNC machining starts with a block of material and shapes it with a rotating tool. Following the program, it carves away excess until you have the finished product.
2.Materials usage for CNC and 3D printer

SLA: Thermoplastic-like photopolymers
These kind of resins are not as strong as engineering-grade plastics so the parts made using SLA have limited use for functional testing.

SLS: Nylon, TPU
SLS parts are more durable than SLA parts but have limited resin choice.

CNC:Most commodity and engineering-grade thermoplastics and metals
CNC machining works with a variety of materials. They can use: ABS, ,ABS+PC, Polycarbonate, Polycarbonate, Acrylic, Nylon, PP, PA6+GF30%, POM, PE, TEFLON, PEEK,PPE, Aluminum Alloy, Stainless steel, Red Copper, Bronze, Brass,Wood, Glass, Corian, etc…

In general speaking, CNC machines are better for prototypes that can withstand structural tests because they carve the design from the target material. Structural tests and alterations will be more accurate because they use the target material.
3.Precision level
CNC machining is more precise and consistent than 3D printing because they have a higher tolerance for heat. 3D printers end up with distorted products when there’s too much heat.
CNC machines don’t heat the material and reform it. The material stays strong and has a better structural integrity than 3D printers, which have to heat the material to build the intended product.
4.Surface finish
3D printed parts have a grainy or sandy texture.
CNC machines provide better surface finish than 3D printing because the materials don’t deform during the process. The rigid material and cutting action keeps the product together and has fewer chances for mistakes or deformations to occur.
Both 3D printing and CNC machining are fast prototyping methods. They produce part within days or even hours.
In condition that you need fine finish for your product, CNC machining can be easier and faster because the surface is already quite smooth. 3D printed products require a lot of washing and polishing work after they’re built.
6.Geometry limitations
3D printing can produce parts with complex geometries.But, 3D printers can only use the area of the printing bed for making parts so large-scale parts might not fit in that space.
There may be some geometry limitations associated with CNC machining. Because CNC machining is a subtractive process, milling undercuts can sometimes be tricky.

These are the main difference between 3D printing and CNC machining regarding prototying.
Hemtom Prototyping has been focused on this field for decades. Our engineers and expert machinists will provide outstanding work that will help you reach your design goal. We make products with excellent finish for you. Please feel free to contact us if you have any needs or inquiries.
Follow Us
Follow Hemtom and stay informed with industry news
Contact our team
Tel: (+86) 755 33319633