As we know CNC Plastic Machining is an important part of the manufacturing industry, and it is important to know how plastic machining process is being carried out and how it influences our industry today.
Plastic Machining is an Art
With the rise in the cost of metal parts and manufacturing of plastic parts becoming more comfortable thanks to modern rapid prototyping techniques, more and more product designers now prefer plastic as the material of choice as opposed to any other material.
Though the equipment and the tools for plastic machining are similar to that for other materials, the cutting of plastic in some ways is far different from the cutting of the metal. Therefore it is essential that the manufacturer carries out their homework well in order to avoid time and money loses.
Quoting the price for the plastic parts is often more difficult as that to the quotation for the metal parts. It is primarily due to the difference in the raw stock as plastics are sold off in sheets and comes in a variety of different sizes as compared with metals which are sold by pounds.
Plastic Machining Process
As one of the leading plastic fabricators in the region, Wayken provides some of the most beautiful plastic turned components in the industry. With leaders in the industry, we implement state of the art machining process.
Machining process for plastic includes determining the speed and the feed for the machine. It is crucial to set this right since by having an incorrect setting may completely offset the final product aesthetics and integrity. While machining different plastics, it must also be made sure that the moisture absorption factor is also kept in consideration. Some plastics tend to absorb water and swell and then shrink out once they dry up. Under the machining process for plastic, tight tolerances must be maintained. In the machining of different plastic, air is used as a coolant as opposed to liquid coolants in cases of metals and other materials.
When machining plastics, the contamination of the plastic must also be carefully controlled and monitored. Plastic parts are often prone to metal contamination that is a result of small metal chips adhering to the sticky plastic surface and damaging the overall part. Once matching, the handling and the staging equipment and areas are carefully cleaned.
Methods of machining plastic materials
Besides CNC prototyping, there are several industrial processes for the machining of plastic parts. Some of the modern and rapid manufacturing techniques are discussed as follows;
1. Plastic Milling
Plastic milling is carried out to mill components with a high degree of consistency to very close tolerances without any burrs. No burrs in plastic parts mean that resources in post-processing are not wasted and ready to use plastic is available off the production line. Under plastic milling, the surface finish of the product can be improved via plastic polishing. Plastic milling is also fast and accurate as the parts can be directly manufactured off the CAD systems.
2. Micro Plastic Machining
Micro Plastic Machining is the plastic fabrication of microcomponent which is unable to be manufactured by the conventional techniques. This technique requires extremely high precision and accuracy in order to make sure that the parts are made as per requirements. Under micro plastic manufacturing, the tolerances are extremely high with as high as +/- 0.0005. Microplastic machining is a relatively new technique on which Wayken has a good experience in.
3. Annealing of plastics
Stress relieving and annealing is one of the most crucial aspects of the process of plastic machining. Annealing in plastics is used to release off the stress buildup in the parts when they are being manufactured. By doing so, it can be assured that the plastics would not lose its integrity while being used as a component in something. Cracking of the plastics under load and strain is also greatly reduced with industrial grade annealing.
Polishing is one of the most commonly used post-processing methods on plastics. Polishing is inclusive of different techniques which includes flame polishing, mechanical buffing and vapour polishing. Each of this polishing method is distinct to the configuration and the type of plastic used.
As the name suggests, this method uses a flame to polish the outer surface. Flame polishing is known to create the clearest surface finish, especially on the acrylics. This method is usually used on the parts that are flat and are less complex.
This method uses chemical vapour to polish out the plastic parts. Under this process, the chemical attacks the plastic which causes it to flow. The best plastics to be polished using this process are Polysulfone, Ultem ® and Polycarbonate. Acyclic are not advised to be polished using this technique
It is one of the most basic and commonly practised polishing methods. However, mechanical polishing leaves very small scratches on the surface and are not recommended for the optical work. Buffering also is not recommended to do vapour or flame polishing has already been done on the plastic.
Why Machining Plastics?
Machining plastics is an important industrial manufacturing technique. It is a cheaper alternative to a vast number of different materials that are either hard to manufacture or have bad physical and chemical properties. The following are some of the main advantages and the disadvantages of machining plastics
A) Advantages of Machining Plastics
There are several advantages of machining plastics. Some of them are listed below;
- Plastics are usually machine dried
- No extra moulds are needed for this process
- Thicker plastic wall sections can be accommodated easily
- It has the ability to manufacture low batches of material easily
- The forces required to machine the plastics are usually low as compared with other materials
B) Disadvantages of machining plastics
Though there are several benefits of machining plastics, there are several disadvantages as well which are stated as follows;
- The plastic block is relatively expensive
- Plastics do not self-conduct the heat while manufacturing
- Prone to contamination by dust or small metal parts
- There can be high scrap during the manufacturing process
- The high volume of plastic production requires robust fixtures and jigs