Polycarbonate is one of major resin which SEASKYTOOLING are using for plastic injection molding to produce instrument plastic accessories,plastic accessories, medical device accessories electric plastic accessories and plastic accessories etc. On this article, we will guide you for polycarbonate molding for plastic part manufacturing, also include how to choose steel and why you need polycarbonate molding.
Typical Applications for polycarbonate molding parts
Electronic and business equipment (computer parts, connectors, etc.), Home appliances (food processors, refrigerator drawers, plastic cup etc.), transportation (head lights, tail lights, instrument panels, etc.), Instruments( Instrument lenses, instrument gauge, instrument housing, instrument enclosures, etc.),
Polycarbonate molding parts can be transparent color, it is very common to use lenses or where need to use transparent color cover. Compare to PMMA transparent molding parts, Polycarbonate molding parts have high impact performance.
Polycarbonate Injection Molding Processing Conditions
|Poly carbonate Drying Before molding||PC resins are hygroscopic and pre-drying is important. Recommended drying conditions are 100 – 120 C (212 – 248 F) for 3 to 4 hours. Moisture content must be less than 0.02% prior to processing.|
|Polycarbonate Molding Melt Temperature||260 – 340 C (500 – 644 F); higher range for low MFR resins and vice-versa|
|Mold Temperature For Polycarbonate Molding||70 – 120 C (158 – 248 F); higher range for low MFR resins and vice-versa, On the PC molding process, we should prepare hot oil supplies or hot water supplies for temperature control.|
|Fill Pressure||As high as possible for rapid molding|
|Injection Speed||Slow injection speeds when small or edge gates are used; high speeds for other types of gates|
Compare to PMMA and ABS resin, polycarbonate flowability is worse, then on the injection mold design, we optimize design on location and gate type, normally we did not suggest to use sub-gate for PC molding, but we should consider to automatic production by using sub-gate, we should consider in details such as mold flow analysis and DFM analysis. Also we can consider valve gate hot system to prevent the gate mark issue with automatic production.
Chemical and Physical Properties Of Polycarbonate
Polycarbonate is a polyester of carbonic acid. All general-purpose polycarbonates are based on bisphenol A. The bisphenol A component of the molecule contributes to the high glass transition temperature (150 C / 302 F). The rotational mobility of the carbonyl group within the molecule contributes to the high ductility and toughness of the resin.
PC is an amorphous engineering resin with exceptionally good impact strength, heat resistance, clarity, sterilizability, flame retardancy, and stain resistance. The notched Izod impact strength of PC is very high and mold shrinkage is low and consistent (.1 -.2 mm/mm).
High molecular weight PCs (which translate to low melt flow rate) have higher mechanical properties, but processibility of such resins becomes difficult. The type of PC chosen for a particular application should be based on the desired criteria (for high impact properties, use a low-MFR PC; conversely, for optimal processibility, use a high-MFR PC).
The melt viscosities are typically Newtonian up to shear rates of 1000 1/s and decrease beyond that. The Heat Deflection Temperature Under Load is typically between 130 -140 C (266 – 284 F) and the Vicat Softening Point is typically around 155 C (311 F).
Polycarbonate Major Manufacturers
Dow Chemical (Caliber), GE Plastics (Lexan), Bayer (Apec, Macrolon), DSM (Xantar), LNP (Lurbricomp, Thermocomp), Mitsubushi Engineering Plastics (Novarex), Teijin Chemical (Panlite).
Polycarbonate Molding color,
Polycarbonate Molding parts can be various color, it can be transparent color and semi-transparent color.
Polycarbonate molding parts secondary process,
It is easy have printing and painting on polycarbonate molding parts. On electroplating, polycarbonate molding is worse than ABS molding parts, you had better to choose vacuum plate for polycarbonate injection parts.
What kind of steel are most common for core and cavity?
Polycarbonate molding parts is transparent color,
If so, you should choose stainless steel for mold making, in US, you can choose Finkl 420 steel. In Europe, you can choose ASSAB S136 steel. If you purchase the mold in China, and theis lower or equal to SPI A3, you can consider the 420 steel, you can also import this LKM 420 steel mold to US or Europe. Also if you produce low volume transparent plastic parts in China, you China mold manufactuer can choose lots of local stainless steel from local manufacturer.
Please noted that there is prehard and though hard stainless, generally the prehard steel with H on the end of steel type of number. For example LKM 420H, it is prehard steel, some of guys call it soft steel, anyhow it is the steel which the steel manufacturer already have heat treatment.
For large volume trasparent plastic parts manufacturing, I suggest to choose the through hard steel, then you have longer mold life.
Polycarbonate molding parts is not transparent color,
You can choose lots of steel for your mold such as P20, H13, H11, 2344 and 2343etc. On this suitation, the steel is depends on the mold life (It is like that how many parts you need to produce from this mold).
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