WHAT IS CNC MACHINING
A CNC machine is a kind of drilling machine which the move are commanded by a computer, CNC meaning “Commanded Machine Computer”. In short you can imagine a drill that instead being directed and move by a people, is actually commanded by some servo and motor piloted by a computer. This give advantage of having an automatic drilling being done by a machine removing the possibility of human error and following striclty the aseignment given by a computer.
The magic of CNC is, although being a kind of drilling machine, it allow to dig into material several axis. On this base you can dig and remove material not only according to a single translation but also in 3D.
There are many different kind of CNC machining present on the market. Most of what differentiate them are the accuracy of positioning of the tool, and the number of axis (3,4,5 axis) which the arm holding the tool can go, and the speed. On this base, depending on which accuracy you are really to accept you may choose one machine or another one.
CNC Machine used for rapid prototyping activity are usually very accurate and are quite often dedicated for this activity; You may find CNC machine for manufacturing but we recommend always to use machine for prototyping rather than manufacturing to perform rapid prototyping because quite often the accuracy is sharper.
There are many different size of machine and depending on the size, you can prototype rather big parts. Standard volume size for prototyping is up to 1800mm*600mm*500mm on this base we can machine part until 1700mm
WHY USE CNC MACHINING FOR RAPID PROTOTYPING
CNC milling is an ideal way to turn your CAD design into a three dimensional prototype, because of its accuracy and solid production of prototype building.
The main advantages of CNC face to other process is that we use a block of real material which we dig inside to remove material to create a part. On this base you can take a real block of acrylic, aluminum, ABS or another other material and realize a part in this same material making it look, weight and feel the same as the original that will be produced during the manufacturing phase.
This is not the case with SLA, SLS or even 3D printing were some special material have to be used such as resin, additive, simulant or another type of plastic which make the part being not as realistic as what they will be during mass production.
Finally, CNC machining is a cost-effective, consistent and accurate method of producing prototypes from actual production-grade materials. This makes it possible to use many materials, including plastics and metals, and also undercuts and double bended surfaces are feasible.
PROCESS OF CNC MACHINING WHEN DOING RAPID PROTOTYPING
CNC machine are drill commanded by computer. On this base the machine is supposed to read file for computer to know in which direction to go to remove material step by step. The drill is using CAM file which is a special format for CNC machine indicating what is the path the tool should follow to realize the part shape which is needed.
On your side, most of time, you will have generated a CAD file in STEP or IGES format. So, if you plan to use CNC machining, your file will need to be transformed in a CAM file and we will need to verify that your design is compatible with CNC machining (as not all the design can be done with CNC machining.
You will need to provide us with your CAD file, so we can “feed” our process to verify and generate a CAM file that can be read by our machines.
Finally, it all starts with a 3d program or CAD program of the prototype. A product cannot be done without a three dimensional CAD-program.
Once the machine finished the part, quite often there are some slight mark due to to the tool. For this reason we usually recommaend to perform a finishing process, which at minimum require polishing.
ADVANTAGES OF CNC MACHINING FOR RAPID PROTOTYPING
When producing prototypes through the CNC Machining process, the materials used for creating the prototype are limitless as long as they exist.
CNC machining is fast, accurate and cost effective and with parts produced from production materials this makes it the perfect choice for many projects.
CNC machines are accurate
Also the final structure looks like it is real injection molded or casted, mass manufactured
LIMITATIONS OF CNC MACHINING FOR PROTOTYPE
Some very special and complex shape can not be achieved and in this case you will need to turn to other technics such as SLA or SLS
MATERIALS AVAILABLE FOR CNC MACHING PROTOTYPE
Due to limitless possibility of material, you can easily perform rapid prototype with a CNC machine for the following materials:
- Acrylic (PMMA)
- PC +30%GF
- PA+30%GF PP
- PP +20%GF
- 94V0 flame retarding ABS
- NYLON 6
- NYLON 66
- Stainless Steel
- Mild Steel
- Aluminum (paticularly 6061, 7075)
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This post is also available in: French