CNC Machining Vs SLA & SLS: Which One is Better?

Posted on: Nov 8, 2017, | By Steve, WayKen Project Manager

CNC machining is very common in the rapid manufacturing industry. From plastic parts to metal parts, it can be seen anywhere. Before we jump to the topic, let me briefly show you the pros and cons of different technologies.

Ways for CNC Machining

There can be no doubt that CNC machining is still the most effective and popular way to manufacture a rapid prototype today. The advent of additive manufacturing has added another layer, literally, to rapid prototyping to be sure but CNC still provides the best way to develop functional prototypes from plastic or metal with perfectly finished surfaces and intricate detail.

To better understand this type of prototyping, check out the following machining ways that can be used to create your perfect rapid prototype.


A piece of material is turned while the machining tool cuts it into shapes or adds detail to the piece. The material can be moved up and down as well as the turning process continues. This process of machining does exactly what it sounds like and is the oldest type of machining known.


The prototype material is held still with a vise while rotating cutting tools move and change cutting away at the metal or plastic. Multiple tools can be used to shape and perfect each prototype. These tools are guided by CAD designs and their designs, notches, and holes are extremely precise.

Sanding and Polishing

We remove product defects such as the burr, machine line and adhesive mark from the product surface via the efficient hand sanding from the custom prototypes. The flatness of the part will be improved and roughness will be reduced to meet a smooth and perfect appearance.

The hand polish process is to be used for a mirror finish on normal plastic, metal parts and clear acrylic parts, as well as vapor polishing polycarbonate to achieve a professional-grade glossy for your prototype finishing, and to enhance the clarity of clear parts. Whether your project requires a Machined Finish, Matt Finish, Clear Finish, Mirror polish, Brushed polish, or Sand Blasting, WayKen will offer you one-stop services.

The Advantages of CNC Machining as below:

  • When it comes to complex-shaped parts, only fewer machining tools are needed. If you want to change the shape and size of parts, just modify the programming procedures of parts, it is suitable for new product development and modification.
  • With Stable quality, high precision and high repetition accuracy, CNC machining can be widely used in many areas, even in the aerospace industry with so many strict standards.
  • In terms of multiple types and low-volume production, CNC machining has higher production efficiency which can reduce the time in your preparation stages such as machine tool adjustment and the process inspection.
  • Even the complex and some unobservant parts are possible to machining which can’t be achieved in the traditional way.

However, CNC machining can’t deal with tool presetting and special shape parts.

Rapid prototyping was first introduced in the late 1980s, as a high-tech manufacturing technology based on additive manufacturing, it’s considered to be a major achievement in the manufacturing sector in the past 20 years. SLA and SLS are mainly used in Rapid Prototyping.

What is SLA?

SLA is Stereo Lithography Apparatus. Stereolithography is an additive manufacturing process that works by focusing an ultraviolet (UV) laser on a vat of photopolymer resin. With the help of computer-aided manufacturing or computer-aided design(CAM/CAD) software, the UV laser is used to draw a pre-programmed design or shape onto the surface of the photopolymer. Photopolymers are sensitive to ultraviolet light, so the resin is photochemically solidified and forms a single layer of the desired 3D object. This process is repeated for each layer of the design until the 3D object is complete.

SLA has the advantages of rapid-forming speed, a high degree of automation, forming any complex shape and high dimensional accuracy, and is mainly applied to the rapid prototyping of complex and high-precision fine workpieces.

What is SLS?

SLS is Selective Laser Sintering. SLS involves the use of a high-power laser (for example, a carbon dioxide laser) to fuse small particles of plastic, metal, ceramic, or glass powders into a mass that has a desired three-dimensional shape. The laser selectively fuses powdered material by scanning cross-sections generated from a 3D digital description of the part (for example from a CAD file or scan data) on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed.

The method has the advantages of the simple manufacturing process, a wide selection of materials, low cost and fast forming speed.


Comparing to CNC machining, SLS and SLA have some drawbacks. The strength and accuracy of the parts by SLA & SLS are not as good as CNC. Rapid Prototyping technology is a good choice for low-cost and high-efficiency prototypes, while demand for higher intensity and accuracy you should try CNC machining. It depends on the circumstances, finding out your best solution thus to create the best prototype.

WayKen Rapid Manufacturing offers several rapid prototyping technologies, including SLA and SLS, 3D printing, vacuum casting, rapid injection molding, and CNC machining of both metal and plastic. Our facilities comprise 20,000 square feet in total. More than 60 employees work for the company, each with a wealth of experience in rapid prototyping. WayKen emphasizes its ability to help customers at every stage of product development.

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