HONY Fabrication & Machining of Engineering Plastics

HONY Fabrication & Machining of Engineering Plastics

HONY Fabrication & Machining of Engineering Plastics
 
Overview
Non-reinforced thermoplastics can be processed with high-speed steel: for reinforced plastics, cemented carbide steel is required. During all processing, the cutter head must maintain a certain degree of peak profit. Due to the poor thermal conductivity of plastics, it is necessary to ensure the dissipation of heat. The best way to cool is through the cutter head.
 
Dimensional stability
The prerequisite for obtaining high-precision dimensions is to use semi-finished products that have undergone internal stress treatment. The heat generated in the machining process will inevitably lead to the release of internal stress, resulting in deformation of the workpiece. If the machining volume of the part is large, an annealing treatment should be carried out after the rough machining is completed to eliminate the stress generated during the machining process. We can provide specific annealing temperature and time for various materials. For materials with high water absorption (such as nylon), it needs to be dehumidified before processing. The dimensional tolerance of plastic is larger than that of metal. At the same time, it must be considered that the coefficient of thermal expansion of plastic is much larger than that of metal.
 
Machining method
1. Turning processing
Please refer to the reference diagram for the tool structure data. If the surface requirements of the workpiece are particularly high, the cutter head should be designed as a wide head shape as shown in Figure 1. For the cutter head used to cut the profile, the shape shown in Figure 2 should be designed to avoid excessive burrs. When processing thin-walled and soft materials, it is best to use a knife-like structure as shown in Figure 3.

 
 
2. Milling
If it is plane milling, face milling is more economical than circumferential milling. For circumferential and forming milling cutters, it should not have more than two cutting edges, so that the deviation caused by the vibration of the blade can be minimized, and it can also ensure that there is enough space between the tools.
 
3. Drilling
Twist drills can be used: the spiral angle ranges from 12°-16°. In order to facilitate chip removal, the spiral groove should be smooth. When processing a hole with a large diameter, it is necessary to drill step by step or use a hollow drill or cut directly. When drilling solid materials, pay special attention to the use of sharper drill bits, otherwise the increasing pressure during the drilling process may cause the parts to crack.

 
Compared with non-reinforced materials, reinforced plastics have greater internal stress during machining, and lower impact strength, which makes them easier to crack. Therefore, if possible, heat the profile to about 120°C before drilling the reinforced material (heating time is 1 hour for every 10mm thick part). We recommend heating nylon and polyester as well.
 
4. Sawing
In the sawing process, thinner blades are usually used to cut thicker parts, and the heat generated by friction should be avoided as much as possible. It is best to use a saw blade with a serrated sharp, sharp and larger serration.
 
5. Thread Cutting
It is best to use a threaded cutter to process the threads. Using a double-toothed cutter can also avoid flash. We do not recommend using the die when tapping, because the die will be cut again when returning the knife. The machining allowance should be considered when tapping (the amount of machining allowance depends on different materials and apertures, the reference value is 0.1mm)
 
6. Safety regulations
Failure to comply with this processing guide may cause local overheating of the material and degradation of the plastic. Substances like PTFE should be treated with exhaust equipment after degradation. To prevent poisoning, smoking is strictly prohibited in the processing workshop.