Polycarbonate Machining Technology

 2. Applicable to machining

Optical-grade special ultra-thick clear polycarbonate solid sheet can directly carry out cold working and special hot processing including cutting, engraving, rounding, punching, polishing, chamfering, milling, turning, boring, drilling, grinding, etc. Optical-grade special ultra-thick clear polycarbonate solid sheet can be processed into industrial transparent parts such as optical large-size plates, hollow cylinders, transparent columns, transparent cylinders, transparent pipe fittings, transparent conical parts, transparent polygonal three-dimensional parts, special-shaped irregular parts, high-pressure transparent bodies, etc., suitable for different equipment requirements and terminal applications in higher industrial fields.

 3. Processing equipment

At present, CNC machining equipment (CNC lathes and machine tools) is quite common in various countries/regions, and there will be such equipment where there is industry, and even larger industrial companies generally have their own processing departments and specialized equipment. At present, most CNC processing equipment in China can achieve high accuracy and meet complex processing requirements, and can basically meet the requirements in terms of functionality and accuracy. Of course, more high-end equipment processing will be better.

 4. Processing methods

Adjustments can be made according to different workpiece requirements, processing methods (turning, milling, boring, grinding, milling, engraving, rough polishing, fine polishing, etc.), processing equipment, etc., Optical-grade special ultra-thick clear polycarbonate solid sheet itself has good CNC machinability, selecting appropriate tools and correct processing methods, can achieve high satisfactory results.

 5. Machining flow

Prepare the materials (optical-grade special ultra-thick clear polycarbonate solid sheet), formulate clear transparent workpiece requirements (drawings, shapes, requirements, etc.), conduct relevant process analysis, establish processing route schemes, do accurate microcomputer data processing programming (CAD/CAM technology is relatively mature and perfect), check data input and output, Adjust and prepare CNC machining equipment (applicable cutting tools, fixtures, measuring tools, etc.), finishing processing (supplemented by manual machining), post-processing, review inspection methods and condition testing, packaging parts, etc.

large-thickness clear solid sheet

When CNC machining, it is necessary to accurately operate the machine tool equipment, fix the optical-grade special ultra-thick clear polycarbonate solid sheet, and strictly control the vibration of the non-feed direction of the tool to maintain machining accuracy and avoid non-fault damage. And pay attention to increasing the spindle speed, reducing the workpiece feed rate and tool feed rate, and appropriately controlling the cutting amount and speed of the tool according to the actual processing. In all CNC machining processes, the cutter head must maintain a high sharpness, and pay attention to cooling by the cutter head cooling or cooling with compressed air.

Machining tools are recommended to use cemented carbide steel tools, ceramic tools, single crystal diamond tools, etc., the latter two tools can directly get better processing results. The typical technique for processing optical grade special ultra high clear polycarbonate solid sheets is the ultra precision cutting technology of single crystal diamond tools, which can directly achieve high-precision effects of mirror polishing below Ra0.2 on the machined surface. In short, using sharp machining tools and cooling during the machining process are the basic points of CNC machining.

Our materials have a processing allowance, and it is recommended to do simple trial processing first.

 6. Cutting

Optical-grade special ultra-thick clear polycarbonate solid sheet materials are generally suitable for electronic cutting machines, plate cutting machines, sawing, CNC milling, waterjet cutting and other cutting methods, among which CNC milling processing and ultra-high pressure waterjet cold cutting methods are the best recommendations.

Water knives belong to cold cutting, divided into sandless water cutting (pure water cutting) and sand-water cutting, neither of which changes the physical quality and chemical properties of the optical-grade special ultra-thick clear polycarbonate solid sheet. Because the cutting surface finish obtained by sand-free water cutting is better, it can achieve a polishing effect, according to the thickness of the optical-grade special ultra-thick clear polycarbonate solid sheet to be cut and the allowable conditions of waterjet equipment, it is recommended to use ultra-high pressure sand-free water cutting; When cutting optical-grade special ultra-thick clear polycarbonate solid sheet (when exceeding 200mm thickness), you can also use sand water cutting, that is, mixed with pomegranate, emery and other abrasives in high-pressure water to assist cutting, which can improve the cutting speed and cutting thickness of the waterjet, the smaller the abrasive particle size, the better the jet polishing effect, and the higher the cutting surface finish. At present, in China, the maximum working pressure of waterjet has exceeded 520MPa ultra-high pressure technology, and can even cut steel plates with a thickness of more than 300MM, and the technology is more advanced has reached 4-axis, 5-axis, 6-axis waterjet, which can basically meet the one-time complex cutting processing of any curve of machining transparent parts.

According to the accuracy of the cutting equipment and the thickness of the cutting material, the optimal dimensional accuracy that can be achieved by water jet cutting is less than 0.1mm; According to the diameter of the cutting nozzle (0.1-0.4MM diameter) and the size thickness of the cutting material, the current width of the water cut seam is between 0.3-1.8mm.

 7. Drilling

When using twist drilling to open holes, the range of the spiral angle is recommended to be 12~16°, in order to facilitate chip removal, the spiral groove should be kept smooth and free of sticky matter, and attention needs to be paid to the cooling of the cutting head and processing surface; When machining holes with a large inner diameter, step drilling or hollow drilling should be carried out; When drilling, special attention is paid to the use of sharper drills to avoid damage to the tool and the machining surface. When optical-grade special ultra-thick clear polycarbonate solid sheet needs to open holes in the stressed structure, it is recommended that the hole/edge distance be greater than the thickness of the sheet, and the hole/hole distance should be greater than three times the thickness of the sheet. It should be noted that when opening bolts to fix holes, considering the influence of material expansion and contraction coefficient, the diameter of the screw hole should be slightly larger than the diameter of the screw.

 8. Boring milling

When optical-grade special ultra-thick clear polycarbonate solid sheet needs to be made into thick-walled hollow cylindrical transparent parts, digging holes, semi-perforated parts, and hollow transparent parts, boring is a typical CNC transparent part internal processing method.

Starting the CNC boring machine process, combined with milling, drilling, grinding and other processing methods, the optical-grade special ultra-thick clear polycarbonate solid sheet can be bored with suitable tools. Boring can be divided into through-hole, taper hole and opaque and other processing technology, according to the material thickness specification, through the rotation of the tool or workpiece with the corresponding feed movement, can be made into any inner aperture and any wall thickness of hollow parts.

For workpieces with high precision and surface finish requirements, it is recommended to use precision boring, which generally requires a diamond boring machine and the use of diamond, cemented carbide, cubic boron nitride and other superhard materials cutting tools. It is pre-machined by rough, semi-fine and fine boring processes, leaving the thinnest and homogeneous possible machining allowance for precision boring operations. The precision boring process is generally recommended to adjust the small feed of 0.02~0.08mm/r, and the cutting depth of 0.05~0.1mm, which is higher than the cutting speed of ordinary boring. The machining accuracy using precision boring can reach IT6~5 precision level, and the surface roughness can reach Ra0.2~0.08μm micron-level polishing effect, achieving high workpiece transparency, and basically eliminating the polishing process.

 9. Polishing

It can be processed by the traditional mechanical way of normal milling, grinding, rough polishing, grinding and fine polishing, it is recommended that the rough grinding depth is 0.06-0.2mm, and the fine grinding depth is recommended to be 0.01-0.05mm, and pay attention to the speed of the abrasive and the cooling of the processing surface during the grinding process. For fine polishing treatment that requires optical-grade special ultra-thick clear polycarbonate solid sheet processing surface with high smoothness and transparency, the mechanical polishing speed is recommended to be 610-750r/min, and wool pads can also be used for polishing; When a small area needs to be polished, generally according to the manual fine polishing, the skim cotton soaked in professional fine polishing paste is pressed on the polishing surface with a force of 1kgf, and the uniform force is uniform to do the fitting movement of the polishing range. CNC equipment has the conditions, can use single crystal diamond tool ultra-precision cutting technology, the processing surface can directly reach the high-precision effect of mirror-like polishing below Ra0.2, roughness of 8rms, better than the relevant technical standards of 32rms of transparent materials of the American classification society.

The optical-grade special ultra-thick clear polycarbonate solid sheet is covered with a high-transparency protective film on both sides when leaving the factory. In order to protect the sheet surface from external force damage, it is required that the material shall not tear off the protective film before the completion of processing, ensure the cleanliness of the fixing mechanism and the workbench, and protect the clamping mechanism and the workbench as much as possible, so as not to damage the non-processing surface of the sheet, and then tear off the protective film paper of the plate after the processing is completed, and the processing process shall not be interrupted in non-emergency situations. In addition, it should be noted that the original surface of polycarbonate should be retained as an important or large main surface of the workpiece as much as possible, which can also maintain the original high optical transparency while reducing the processing workload.

Generally, our materials will retain the size margin for users, the first time to process optical-grade special ultra-thick clear polycarbonate solid sheet materials, it is recommended to use the offcuts or reserved processing allowance to do a good test, master the use of processing tools and reliable processing technology.

 10. Cooling

a. Choose sharp single crystal diamond tools or cemented carbide tools, and the diameter of the milling knife should be as small as possible.

b. Tool head cooling, pouring a large flow of neutral coolant onto the cutting tool, or blow the machining chips and tool surface of the cutting area with compressed air through the air pipe to reduce the machining temperature of the cutting area and prevent the occurrence of chips sticking to the knife.

c. Keep the cutter head sharp, and appropriately increase the front angle and back angle of the cutting tool, it is recommended that the front angle be 0~10°, the back angle is 2~5°, to reduce the machining friction heat.

d. Appropriately increase the cutting speed, it is recommended to be 200~320mm/min, the feed amount is recommended to be 0.05~0.25mm/r, and the cutting depth is recommended to be 0.05~0.25mm.

 11. Annealing

The optical-grade special ultra-thick clear polycarbonate solid sheet has undergone annealing and other process procedures before leaving the factory. When re-annealing is required for use in ultra-high-end or ultra-precision applications, generally, the annealing scheme of air as the heat medium is adopted, the optical-grade special ultra-thick clear polycarbonate solid sheet is placed in an air furnace, and the sheet is slowly heated to 100±3 °C at a uniform temperature of 1 °C/min, and the holding time is calculated according to the material thickness of 1mm/10min. After that, slowly reduce to room temperature at a uniform temperature with a maximum allowable cooling rate of 10 ℃/h, and complete the annealing program.

 12. Special needs

optical-grade special ultra-thick clear polycarbonate solid sheet is an ultra-high molecular amorphous polymer material, which can support hot processing methods in theory and practice, but in view of the particularity of the material (high strength and toughness special transparent material, and large thickness), the non-versatility of hot processing equipment (generally need to engrave one-to-one molds for the needs of user workpieces), hot processing technology (high general technical requirements, Requires special thermal processing equipment), so thermal processing operations are not recommended.

If CNC and other cold processing methods cannot meet user needs, such as the need for large irregular transparent parts, transparent polygonal shaped parts, transparent cavity hemispherical parts, transparent solid hemispherical parts, transparent spherical parts, large transparent bored parts, large transparent curved parts, etc., it is recommended to contact us for customized production (provided that the demand is in large quantities and can withstand high cost budgets). Pasmo specialty polycarbonate materials are committed to providing professional multi-type solutions for high-end industrial users to solve users' practical problems.

 13. Installation and fixation

Easy installation and operation: Thanks to the excellent mechanical properties of polycarbonate material (high strength and high toughness coexist), it can be directly drilled and fixed with bolts, rivets, flanges, frames, etc. It is firmly combined with the installation body, simple, convenient, and easy to seal; When used in the field of pressure resistance, it can effectively increase the component effect of radial tensile stress and axial shear stress of the material on the compressive stress of the medium, improve the safety factor, and achieve a better pressure-resistant use effect; It should be noted that considering the influence of the thermal expansion and contraction coefficient of the material, the diameter of the screw hole should be slightly larger than the diameter of the screw. Select large head bolts to avoid excessive concentration of locking force, and supplemented by sealing gaskets, sealed with neutral glue.

 14. Bonding method

When optical-grade special ultra-thick clear polycarbonate solid sheet is used in pressure-resistant equipment or stressed structures, the highest bonding strength is chloroform molten adhesive, this adhesive is very common, its highest bonding strength shear stress can reach 18 to 23Mpa MPa, can be used as structural adhesive. It should be noted that the bonding surface can not have moisture, dust, oil, it is best to evenly apply glue on both sides, do not move after the bonding surface is combined to prevent gas from entering, and the strongest adhesion can be achieved 48 hours after fixation. It should also be noted that chloroform molten adhesives are corrosive, and other positions except for the bonding surface should not be stained with glue. When used for non-pressure-resistant or non-stressed structure bonding, it is generally sealed and bonded with ordinary neutral glue glue.

 15. Note

Please make the most suitable adjustment in time according to different processing equipment, use of tools, processing methods, processing requirements, etc., the above is for reference. In addition, we are a typical material production supplier, we only provide special optical-grade ultra-thick clear polycarbonate solid sheets [30-450mm thickness], and technical consulting of related solutions. Because our production is very busy, and the machining of polycarbonate materials is simple and common, we do not do any processing to foreign users.