CNC machining is a manufacturing process for producing precise and accurate plastic parts, Polycarbonate is a wide-use material in various industries. You may have questions as listed below, I will show you the answers later on.
What is Polycarbonate?
Polycarbonate is a thermoplastic polymer containing carbonate groups.
Its price is in the middle range, also, it has unique properties, such as high impact strength, good dimensional stability, and highly transparent, therefore, polycarbonate is popular in a variety of applications.
Some of the applications are covers, housings, glazing, rear and side car windows, appliances, and car exterior parts.
Can Polycarbonate be CNC machined? What is the Machining Tips?
Polycarbonate rods and plates are easy to be machined by regular machining processes, like saw cutting, drilling, and CNC milling, etc.
Saw cutting is one of the cheapest ways for cutting the PC sheets, you can opt for either circular or band saws. in this process, to avoid melted edges and chipping of the polycarbonate sheets, you should ensure the blade is sharp enough, select an appropriate cutting speed and feed rate, use a suitable lubricant, and clamp the polycarbonate sheets properly. Don’t forget to wear safety gear when operating the saw-cutting process as well.
Laser cutting is another cutting method to produce more precise cuts, it is more efficient and reliable than the saw-cutting process, but the laser-cut polycarbonate workpiece may look burnt, due to the high temperature of the laser cutting light.
Drilling machining is a process where a machine uses drill bits to make holes in the polycarbonate part but doesn’t use the drill bits designed for drilling metals to make holes in the polycarbonate workpiece. The standard drill bit for metals is different from the drill bits for polycarbonate, as shown in the below photo.
Milling is another popular machining process , it removes the material from a workpiece by using a rotating cutter. You can use a CNC router or milling machine to cut a polycarbonate sheet to achieve tight tolerances and various shapes.
To achieve a more accurate size and smoother finishes on the polycarbonate part when CNC machining, here to list some tips :
- Use a very sharp uncoated cutting tool to minimize the stress during machining.
- Adopt appropriate machining parameters, such as cutting speed, feed rate, and cutting depth.
- Choose suitable coolants, it can take away the cutting heat, as well as extend the tool life. But you need to Ensure to avoid certain coolants which will dissolve the polycarbonate, recommend to use non-aromatic, water-soluble coolants.
- Clamp the workpiece properly, the polycarbonate machined part will crack or warp if it is clamped too tight during machining, so well clamping is important for machining polycarbonate.
- Anneal after machining, the PC machined part is prone to stress cracking under the high heat generated and tensile load during machining, to achieve a quality and precision machined part, it is very crucial to do the annealing process to reduce the stresses.
What Are the Other Manufacturing Processes for Polycarbonate Sheets?
As mentioned above polycarbonate is easy to be machined by using the common machining method, such as cutting, drilling, turning, and CNC milling etc.
Besides those machining methods, the polycarbonate structure or shape can be manipulated by some other fabrication processes, like bending, injection molding, and thermoforming.
For a polycarbonate sheet, there are two kinds of methods for bending it to the required shapes, one is cold bending, the other is hot bending.
Cold bending
It is a very simple process, in which a certain magnitude of force is applied to the polycarbonate sheet to form the curved shapes. In this process, make sure to choose the appropriate bent radius and control the force well.
Hot bending
It is the opposite of cold bending, in this process, a small amount of heat will be applied to the polycarbonate sheet, you can use a heat gun or electric heater to heat the PC sheet during the bending process. The heat will soften the polycarbonate sheet to make the bending process easier.
Injection molding
It is the most common method to produce polycarbonate parts with complex shapes and tight tolerances. In this process, the small pieces of polycarbonate material will be heated and melt in the barrel of the injection molding machine, then the molten polycarbonate will be injected under high pressure into the mold, it will cool down and harden on the mold cavity to form the desired shape. The injection molding process is suitable for mass production of polycarbonate parts, due to its fast cycle time and good dimensions repeatability.
Thermoforming
It is a process easily to be confused with injection molding, in this process, the polycarbonate sheet is heated to be soften but not melt, then use either a female or male mold to form a suitable shape. Normally, you can opt for either a vacuum-forming or pressure-forming process.