Cixi Guozhiguang PC/ABS 3070 is supplied as a compounded polycarbonate/acrylonitrile-butadiene-styrene alloy in pellet form. The 3070 suffix is treated as a manufacturer grade identifier within the unfilled alloy portfolio, not as a direct declaration of melt-flow ratio or filler content. Published datasheet values for this exact configuration are limited; numerical data in this document are therefore presented as a representative 70/30 unfilled PC/ABS engineering envelope and must be confirmed against lot-specific certificates of analysis before die design, process qualification, or regulatory submission.

In industrial practice, the material is evaluated for injection-moulded electronic enclosures, appliance control panels, power adapter shells, and interior structural brackets. Processing is typically performed on reciprocating-screw injection moulding machines with clamping force between 800 kN and 4,000 kN, where the polycarbonate phase contributes thermal stability and notched impact resistance while the ABS phase reduces melt viscosity and improves flow into thin-wall sections. The alloy is not suitable for transparent glazing because the ABS phase produces opacity, and it is not inherently flame-retardant unless a specific FR formulation is designated by the manufacturer.

This table is not a manufacturer certification. It is a screening envelope assembled from general unfilled 70/30 PC/ABS grade data and specimen preparation practice according to ISO 294-1:2017. Lot-specific values for 3070 may differ.

How Should the 3070 Grade Be Dried Before Melt Processing?

Hydrolytic degradation of the polycarbonate phase is governed by residual moisture content and barrel residence time. Pre-drying in a desiccant-bed or rotary-wheel dryer capable of maintaining dew point below -30°C is specified. A drying temperature of 80°C to 95°C for 3 h to 4 h is typical for unfilled PC/ABS; material exposed to warehouse humidity above 60% RH or stored in opened gaylords may require extension to 6 h. Target moisture content by Karl Fischer titration should be below 0.02% by weight, with ISO 15512:2019 used for water content verification. Regrind fractions above 25% by weight may increase water uptake variability because of increased surface area, requiring hopper-magnet and screen-pack inspection before re-introduction.

On the production floor, the practical failure mode observed on reciprocating-screw injection moulding machines is splay or silver streaking at the gate, accompanied by a measured reduction in melt viscosity due to chain scission. If splay cannot be eliminated by drying alone, barrel temperature should be profiled downward, with rear-zone temperature not exceeding 230°C, and screw backpressure limited to 5–10 bar to reduce frictional heating. Dried-air conveying from the dryer to the feed throat is required in ambient relative humidity above 60%, since re-moisturisation of pellet surfaces can occur within 15 min to 30 min in unsealed transfer lines.

For injection moulding, the unfilled alloy is processed with nozzle melt temperature between 245°C and 270°C, measured by an inserted thermocouple during purge rather than by controller setpoint alone. Mould wall temperature is controlled between 60°C and 90°C through pressurised water or oil thermolators. Fill time for 1.5 mm to 2.5 mm wall stock is generally held at 0.5 s to 1.5 s, with injection velocity profiled so that the flow front remains continuous; short shots induced by hesitation at ribs can be corrected by local gas vents or by reducing rib thickness to 50% of adjacent wall. Packing pressure is profiled in two stages: an initial packing stage of 40–60 MPa hydraulic pressure for 0.5 s to 2 s per millimetre of wall thickness, followed by a hold stage at 20–30 MPa until the gate freezes. These process settings are assembled from general PC/ABS production guides and are not a substitute for simulation using lot-specific melt viscosity data.

Melt Rheology, Filler Sensitivity, and Gate Design Constraints

Capillary rheometry per ISO 11443:2021 on unfilled 70/30 PC/ABS at 260°C shows shear thinning from approximately 300 Pa·s at 100 s⁻¹ to 80 Pa·s at 5,000 s⁻¹. The power-law index in the processing shear-rate region is approximately 0.6 to 0.8, indicating pronounced pseudoplasticity. This shear-rate dependence means that apparent viscosity is significantly lower in thin-wall gates and runners than in low-shear regions such as thick bosses; when gate land length is too short, jetting can occur before the flow front becomes stable.

Residence time in the barrel should not exceed 5 min at 260°C, and higher temperatures above 270°C accelerate polycarbonate chain scission and ABS phase oxidation. Degradation is monitored by comparing melt volume-flow rate after moulding with the incoming pellet value; a shift greater than 20% or a yellowness index increase beyond 2.0 units on a 3 mm plaque tested per ASTM E313-20 is treated as evidence of thermal damage. In production, screw recovery should be set so that cycle time does not exceed thermal stabiliser capacity; if cycle interruptions exceed 10 min, the barrel should be purged with an unfilled PC or general-purpose PC/ABS purge compound before production resumes.

Gate and runner sizing for cold-runner tools is based on flow-length-to-thickness ratios below 150:1. For a nominal wall of 1.5 mm, the maximum practical flow length from gate to cavity end without sequential valve gating is approximately 225 mm when melt temperature is at the upper end of the process window. Sub-gate lands are typically 0.5 mm to 1.0 mm long, and vent depths are limited to 0.02 mm to 0.03 mm because the unfilled alloy has lower melt viscosity than glass-filled or high-viscosity polycarbonate grades. Hot-runner valve-gate systems are used when multiple drops feed a large fascia; valve-pin sequencing is required when flow-front convergence occurs at visible surfaces, otherwise hesitation lines and weld-line notch sensitivity cannot be corrected by packing pressure alone.

Painting adhesion on moulded surfaces is influenced by mould release residues and polycarbonate-rich skin orientation. After demoulding, parts are cleaned with an alkaline detergent, rinsed to conductivity below 30 µS/cm, and dried. Surface energy testing per ISO 8296:2003 should show a wetting tension above 38 mN/m before two-component polyurethane topcoat application. Adhesion is scored by cross-cut test according to ISO 2409:2020, with acceptance criteria commonly at class 0 or 1. For electroless plating, the ABS content enables etching in a chromic-sulphuric bath, but etch time should be controlled below 8 min at 60°C because overetching creates microcrazing at the polycarbonate/ABS interface and reduces peel strength measured by ASTM B533-85. Laser marking with a 1064 nm ytterbium fibre laser at 20 W to 30 W output and marking speed of 1,500–3,000 mm/s is used for serialized labels, but contrast depends on pigment package and lot-specific plateout behaviour.

When Flame-Retardant or High-Stiffness Specifications Control Grade Selection

If the end-use specification requires UL 94 V-0 at 1.5 mm, a flame-retardant PC/ABS compound should be selected in place of unfilled 3070 unless the manufacturer qualifies this exact grade under a Yellow Card. Phosphate-based FR packages commonly raise density by 0.03–0.08 g/cm³, reduce notched Charpy impact by 20% to 40%, and reduce tensile stress at yield by 5% to 15% relative to non-FR unfilled PC/ABS. The comparison is made using ISO 179-1/1eA and ISO 527-2 on specimens conditioned per ISO 291:2008 at 23°C/50% RH.

Glass-fibre grades are substituted when flexural modulus above 3,500 MPa or mould shrinkage below 0.4% is required. Fibre reinforcement at 10–20 wt% reduces linear mould shrinkage from 0.5–0.7% to 0.2–0.4%, measured according to ISO 294-4:2018, but introduces anisotropic warpage and increases abrasion on tooling. The selection of 3070 over mineral-filled PC/ABS is therefore appropriate only when the part design tolerates higher mould shrinkage and lower modulus while requiring better surface appearance and ductility.

Regulatory classification requires supplier documentation, not generic grade assignment. RoHS screening is performed by XRF according to IEC 62321-3-1:2013 and wet chemistry per IEC 62321-5:2013 for cadmium and lead. REACH SVHC content above 0.1% w/w in an article triggers communication under Article 33 of Regulation (EC) No 1907/2006. Food-contact status under EU 10/2011 or FDA 21 CFR 177.1580 is not self-declared for this grade; migration testing must be performed on the finished article. Medical cytotoxicity per ISO 10993-5:2009 is not presumed from polymer class and requires change-control documentation for raw materials. UL 94 classification of the 3070 grade should be verified against the manufacturer’s published UL Yellow Card; in its absence, end-product certification cannot rely on a Recognized Component rating.

The grade is not a direct replacement for polycarbonate homopolymer in sterilisation-heavy applications.

Steam autoclave exposure at 121°C for 15 min per cycle is a hydrolytic stress condition. Unfilled PC/ABS without a hydrolysis stabiliser can exhibit molecular-weight loss, surface crazing, and a reduction in Charpy notched impact after repeated cycles; the ABS butadiene phase also undergoes oxidative embrittlement at elevated temperature. Published data for Cixi Guozhiguang 3070 under steam autoclave or gamma sterilisation at 25 kGy to 50 kGy are limited. Therefore, no sterilisation resistance, bioburden, or endotoxin compatibility claim should be transferred from polycarbonate homopolymer or from general PC/ABS literature to this grade.

In material replacement projects, the first comparison is melt-flow ratio. If the incumbent material is a high-flow PC/ABS with melt volume-flow rate above 20 cm³/10 min at 260°C/5 kg, unfilled 3070 may not replicate filling at the same hydraulic pressure unless gate and runner diameters are enlarged. If the incumbent material is a low-flow, high-impact PC/ABS with Charpy notched impact above 60 kJ/m² at 23°C, the 3070 medium-flow envelope may show lower low-temperature ductility. Instrumented puncture testing according to ISO 6603-2 at -30°C, 0°C, and 23°C is preferred over single-point tensile and Charpy data when snap-fit retention and drop-impact performance are critical.

For thin-wall electronic enclosures with nominal wall thickness between 1.0 mm and 1.6 mm, moulders commonly pilot the unfilled 70/30 alloy with a flow length to thickness ratio below 150:1, sequential valve gating for visible convergence points, and post-mould cooling fixtures held at 60°C to 80°C for 20 s to 40 s to control flatness. In appliance fascia panels, the material is paired with two-shot gaskets or laser-etched legends, but chemical wipe-down qualification under the final disinfectant remains mandatory because the ABS phase is susceptible to solvent-induced stress cracking in the presence of ketones, esters, and certain aromatic hydrocarbons.