Xiamen Defenghang PC/ABS H906（C） is a compounded polycarbonate/acrylonitrile-butadiene-styrene alloy. The H906 designation places the grade within a flame-retardant, medium-flow injection-molding family; the parenthetical (C) suffix conventionally denotes a color variant or a customer-specific additive package. Because the manufacturer’s public documentation does not provide a complete certificate of analysis for this exact suffix, the numerical bands below are reference values from comparable industrial PC/ABS formulations and are not lot-specific certification. Lot confirmity must be verified against the shipment certificate and, where required, against the supplier’s REACH and RoHS declarations.

What property inputs are required for filling a 1.2 mm wall with a 4000 kN clamp?

Initial mold-filling simulation for H906（C） requires density, melt-flow, specific heat, thermal conductivity, and shear-viscosity data. A representative density of 1.15 g/cm³ to 1.19 g/cm³ is determined according to ISO 1183-1:2019; the melt volume-flow rate is typically 14 cm³/10 min to 22 cm³/10 min at 260 °C/5 kg under ISO 1133-1:2022. The corresponding shear viscosity at 1000 s−1 falls from 120 Pa·s to 180 Pa·s, and at 10 000 s−1 the viscosity falls to 35 Pa·s to 55 Pa·s, depending on pigment dispersion and moisture state. A melt temperature of 250 °C to 270 °C and a mold temperature of 70 °C to 85 °C are used with a screw forward speed of 30 mm/s to 60 mm/s. For a 1.2 mm nominal wall with a 4000 kN hydraulic clamp, hold pressure is set at 60 MPa to 80 MPa and switch-over position is adjusted to leave a cushion of 3 mm to 5 mm.

Drying is the first critical step, not a preliminary convenience. In a desiccant-bed dryer with a dew point below −30 °C, H906（C） pellets are dried at 100 °C to 110 °C for 3 h to 4 h when initial moisture exceeds 0.10 wt%. The target residual moisture before plastication is less than 0.02 wt% according to ISO 15512:2019. If residual moisture reaches 0.05 wt%, the polycarbonate phase undergoes hydrolysis at barrel temperatures above 260 °C; the visible result is splay or silver streaks radiating from the gate, and the mechanical result can be a weld-line strength reduction of 10% to 25% compared with the same part molded at 0.02 wt% moisture. The dryer hopper should be insulated, return air temperature should remain below 70 °C, and desiccant regeneration is set to 180 °C for not less than 4 h to restore the molecular sieve. Only neutral pH purge compounds are used; alkaline purges can accelerate polycarbonate hydrolysis.

Thermal residence time and barrel cleanliness are also constrained. At 260 °C, total melt residence time should not exceed 10 min. Shutdowns longer than 15 min require barrel cooling to 180 °C or purging with a neutral polycarbonate cleaning compound. H906（C） is not to be processed in a barrel contaminated with polyoxymethylene or polyvinyl chloride residues, because trace acid gases from those polymers degrade polycarbonate and shift the melt-flow rate upward.

Thermal and rheological boundary conditions for regrind reuse

The regrind fraction is limited by three process-coupled effects: flame-retardant additive depletion, polycarbonate molecular-weight loss, and batch-to-batch melt-flow variation. On a three-zone screw with an L/D ratio of 22:1, a compression ratio of 2.0:1 to 2.5:1, and a non-return valve, back pressure is maintained at 0.8 MPa to 1.2 MPa to avoid shear overheating. Recycled sprues and runners from H906（C） may be introduced at up to 15 wt% if part tolerance is not tighter than ±0.05 mm. At regrind fractions above 30 wt%, the probability of UL 94 vertical burn shifting from V-0 at 1.5 mm to V-1 or V-2 increases because the flame-retardant package is partially decomposed during the previous heat history. The exact threshold for a given production lot cannot be established without retained-lot burn data. In addition, recycled material can increase the melt-flow rate by 2 cm³/10 min to 6 cm³/10 min after three heat histories under ISO 1133-1:2022, requiring a corresponding reduction in injection velocity to maintain the same filling pattern.

On 400 kN to 1000 kN molding machines, H906(C) should not be processed with screw decompression exceeding 2 mm after plastication. Larger decompression draws air into the melt stream and creates gas burns at the end of fill. The nozzle temperature is held 5 °C to 10 °C below the front barrel zone to prevent drool, and the hot-runner manifold is set at 240 °C to 260 °C when the part has a 1.0 mm to 1.5 mm wall. If the mold has a cold runner, runner diameter should not be less than 4 mm for a shot weight below 200 g; below 3 mm, premature freeze-off can occur at the runner-to-gate junction when mold temperature falls below 60 °C.

When a thin-wall electrical enclosure specification makes H906(C) preferable to unfilled ABS

Unfilled ABS has a heat deflection temperature of 75 °C to 85 °C under 1.8 MPa per ISO 75-2:2013. A thin-wall electrical enclosure of 1.2 mm wall thickness subjected to a 70 °C local hot-spot adjacent to a transformer can show distortion during cooling. H906(C), within the reference PC/ABS band, has a heat deflection temperature of 85 °C to 100 °C and a Vicat B50 value of 100 °C to 115 °C under ISO 306:2014, which moves the thermal failure threshold upward. However, the higher melt viscosity of PC/ABS increases screw recovery time by approximately 10% to 20% against unfilled ABS. The molding machine is set with barrel temperatures of 240 °C to 270 °C and hold pressure of 60 MPa to 80 MPa to prevent sink marks at bosses and snap-fit features. For UL 94 V-0 compliance at 1.5 mm, the actual housing geometry must be tested because flame-retardant performance is a function of wall thickness, rib geometry, and gate location; passing a 2.0 mm plaque test does not automatically establish V-0 for a 1.2 mm wall.

Regulatory compliance for H906(C) is documented through the supplier’s RoHS directive 2011/65/EU with delegated directive 2015/863 and REACH candidate list declaration. The (C) suffix can affect the colorant package; pigments containing cadmium or lead are prohibited in the European Union, so the certificate must identify the exact pigment chemistry. For applications with skin contact or indirect food contact, migration testing under EU 10/2011 or US FDA 21 CFR 177.1580 may be required. Published data for H906(C) in food-contact configurations is limited, and migration testing must be performed on the final part geometry.

Automotive interior trim with snap-fits or living-hinge features is another application class where H906(C) is considered. When a door trim or instrument panel carrier is molded with a 2500 kN clamp and a multi-cavity hot runner, gate freeze time must be checked because the PC/ABS melt does not tolerate excessive shear at the hot tip. Gate diameters of 1.0 mm to 1.2 mm are used to generate sufficient shear thinning; a gate below 0.8 mm can produce degraded material deposits on the hot tip after 500 cycles. Mold release agents based on amine-free, neutral formulations are required. If the part is subsequently painted, the molded surface must be free of wax or silicone contamination; adhesion tests are performed under ISO 2409:2020 cross-cut before production qualification. Exposure to certain aromatic hydrocarbons, ketones, or esters can induce environmental stress cracking; chemical compatibility must be evaluated with the specific cleaner or plasticizer under ISO 22088-2:2006 before part release.