Types of CNC machines

Some types of CNC machines

There are so many types of CNC machines are present in the industries to manufacture the products. Generally, there are six types of CNC machines, they are used for different purposes :

1. CNC milling machines: In fact, they might be the most popular type of CNC machines used today. Milling machines utilize rotary cutters to shape workpieces as requested. They can be programmed to provide the required depth, angle and cutting direction.

2.CNC Lathes: A lathe is utilized to develop highly precise conical and spherical shaped parts. This particular machine uses turning centers wherein the cutting tool shaves off the excess material while the material is rotating on a spindle.

3.CNC Routers: A CNC router is like a CNC process. It accompanies the capacity to utilize PC numerical control to course instrument ways that empower the machine to work. CNC router diminish waste and increment efficiency, creating different things in a considerably shorter measure of time than utilizing different machines.

4.CNC Plasma Cutters: Plasma cutters uses a plasma beam to cut the materials into 2D shapes.

5.CNC Grinders: This type of machine utilizes a rotary wheel that abrades the material into the desired shape by repeatedly grinding it.

6.CNC Electric Discharge Machines: Electric discharge machining, or EDM for short, includes making a particular shape inside a specific material by utilizing electrical releases or starts. The material is expelled from a particular workpiece by a progression of repeating electrical releases between two anodes. These anodes are isolated by a dielectric liquid, which regularly gets an electric voltage.

What is CNC Machining

CNC machining is a type of manufacturing process to produce the machined parts, products, items by using CNC machines. CNC Stands for Computer Numerical Control or Computerized Numerical Control. 

While a CNC machine is an electro-mechanical device, it comprises of the computer acted as the control unit, which directs the machine tools to perform various machining operations as per the program of instructions fed by the operator. CNC machine works like the Robot, which has to be fed with the program and it follows all your instructions.

The basic CNC machining process for producing machined part can be broken down into 3 steps.

1. Design the CAD model of the part. 

2. Transfer the CAD model file into a CNC program (G-code) and set up the machine. 

3. The CNC system executes all machining operations to remove material and create the machined part.

A short video of precision machining process on our machine shop.

If you want to know more about CNC machining, please check our website.

8 Tips to Optimize Design for CNC Machining Parts

CNC machining process is widely used to produce custom machined parts with strong strength and tight tolerance. It is the fast and cost-effective way to manufacture prototypes and production parts. An optimized designed CNC machined part will help to accelerate production time while saving cost.

To fully optimize your design for CNC machining parts, you should look at below design tips:

1. Round the Internal Corners

The CNC machining tools – such as an end mill or milling cutter – will leave rounded inside corners. The corner radius can be reduced by using a smaller diameter machining tool, but it requires both a smaller tool to machine away material and more passes – often at a lower speed to reduce the risk of deflection or tool breakage – Resulting in more machining time.

So we would suggest to add an inside corner radius of at least 1/3 of the depth of the cavity and use the same radius in all internal edges, This helps eliminate tool changes, which adds complexity and can increase run time significantly.

2. Avoid Deep Cavities

The end mill cutting tools have limited cutting length, they typically work best when cutting cavities with a depth of up to 2-3 times their diameter. To minimize cost, we suggest limiting the depth of the cavity to the 4X diameter of the tool to ensure good results. Anything greater than that will increase the cost, as special tooling or multi-axis CNC systems are required.

If larger cavity depth is required, consider designing parts with a variable cavity depth.

3. Increase the Thickness of Thin Walls

CNC parts with thin walls have a tendency to chatter, which slows down machining speeds. They can also cause distortion, which makes it difficult to machine them accurately. The result can be an additional machine time and cost.

In order to keep machining costs low, thin walls should have a minimum width of 0.8mm for metal parts, and 1.5 mm for plastic parts.

4. Optimize the Depth of Tapped Holes

Regarding the Tapped holes, by increasing the length of thread in a hole does little to hold the bolt tighter. It’s really just the first two or three turns that do all the work. Going deeper just increases the risk of tap breakage and adds time to the tapping operation.

So we don’t suggest to thread a hold to more than 3 times of the hole’s diameter, normally, the thread length would be from 1.5X to 3X of the hole’s diameter.

5. Limit Use of Tight Tolerances

Typically, only a few surfaces of a part are critical to its function. The more features with tight tolerances, the more expensive a part to be manufactured. Because it increases the machining time and cost.

So we would suggest to only assign tight tolerances on some critical features and surfaces, other less significant features should be controlled by standard tolerances of ± 0.125 mm, which is sufficient for those features.

6. Reduce Small Features

Small features such as micro-holes (less than 2.5mm in diameter) will increase the machining difficulty and machining time, thus should be avoided unless absolutely necessary.

7.Split Up Complex Parts

Machining multiple simple parts are less costly than machining one complex part. especially for parts with deep pockets, which would require hours of machining time to remove material, plus additional material costs. And most shops will charge a premium for more complicated parts. This is because if a mistake occurs it is costlier to redo a complex part than it is to redo a simple one.

So we would suggest to split up the complex parts to some simple parts and assemble them together if possible.

8. Design Holes with Standard Size

Holes can be CNC machined fast and to a great accuracy using standard drill bits.  it won’t need end mills or reamers to finish the hole size to a non-standard dimension. This will helps reduce machine time and lower the cost. Also, limit the depth of all holes to 4 times their diameter. 

Contact us if you aren't familiar with standard drill bits sizes.