The product designation Yuyao Xinde High School ABS DGK-KJD678R-BZ identifies an acrylonitrile-butadiene-styrene material or compounded grade intended for melt processing. Public technical datasheets for this exact SKU are limited in English-language literature; no lot-specific melt flow rate, tensile stress at yield, notched Izod impact value, or ISO 11469:2016 marking code has been published for the DGK-KJD678R-BZ suffix. The designation carries an entity field that appears to contain an educational-institution term, but no formal corporate registration is confirmed without supplier verification. Consequently, the processing and performance statements below separate confirmed grade identification from generic unfilled ABS reference data. Generic reference data are drawn from standard test methods and typical ABS processing windows and must not be interpreted as guaranteed values for this grade.

What Drying and Melt Temperature Constraints Apply to This ABS Code?

Residual moisture in unfilled ABS generally reaches 0.2 % to 0.45 % after exposure at 23 °C and 50 % relative humidity. Because the exact moisture uptake of DGK-KJD678R-BZ is unpublished, desiccant drying rather than hot-air drying is required. Initial drying should be set at 80 °C for 2 h to 4 h, with supply air dew point at or below −20 °C. At ambient relative humidity above 60 %, the drying time should be extended to the upper limit of 4 h and the hopper should be blanketed with dry air. Residual moisture above 0.05 % can produce silver streaking, splay, weld-line porosity, and dimensional instability in thick sections. Thermal degradation of unstabilised ABS becomes measurable at melt temperatures above 260 °C, and discoloration accelerates above 280 °C. The melt temperature window for general-purpose ABS is 200 °C to 250 °C; for this grade the supplier lot certificate should confirm whether the upper limit should be reduced to 240 °C because the stabilizer system is unknown. After a shutdown longer than 30 min at barrel temperatures above 240 °C, the barrel should be purged with a non-ABS polymer or purging compound to remove stagnated material.

On a production-scale injection moulding line, first-trial barrel settings for an unfilled ABS with unknown melt flow rate are set at 200 °C, 220 °C, 230 °C, and 235 °C nozzle. Mould temperature is held at 40 °C to 60 °C for standard gloss grades; if low-gloss surface is suspected from the -BZ suffix, mould temperatures above 70 °C may be needed to reproduce surface texture but will extend cooling time. The screw should be a general-purpose ABS or polyolefin screw with an L/D ratio of 20:1 to 24:1 and compression ratio of 2.0:1 to 2.5:1. Back pressure is maintained at 5 bar to 10 bar, and screw speed is limited to 40 min⁻¹ to 80 min⁻¹ to avoid excessive shear heating. Hold pressure is set at 50 % to 70 % of injection pressure, with cushion remaining at 3 mm to 6 mm. Injection pressure is adjusted to achieve filling within 95 % to 98 % of full part volume before transfer to hold. Clamp force per unit projected area for ABS is commonly estimated at 0.5 tonne/cm² to 0.8 tonne/cm², corresponding to cavity pressure of 30 MPa to 50 MPa. If weld-line strength is critical, injection speed should be increased and mould temperature raised toward 70 °C; this may reduce weld-line visibility but can increase cycle time.

Capillary rheometry data for unfilled ABS generally show shear-thinning behaviour; apparent viscosity at 240 °C and 1000 s⁻¹ is typically between 50 Pa·s and 200 Pa·s. The pressure drop through a hot runner manifold of 6 mm diameter should be kept below 30 MPa to limit shear heating. Gate freezing time for unfilled ABS is commonly estimated from part wall thickness using the empirical relation t = 0.2 × wall thickness squared in mm²/s, but this estimate is not specific to DGK-KJD678R-BZ. Melt temperature should be measured at the nozzle with an immersible probe; an infrared probe is unreliable for carbon-containing ABS. If nozzle melt temperature varies by more than ±10 °C across cycles, barrel heater bands and screw recovery settings must be revalidated. Short shots below 90 % filled volume indicate flow-front hesitation due to gate size or venting; increasing injection speed without addressing venting can cause burns at the end of fill. Gate design for unfilled ABS should use round or trapezoidal gates with land lengths of 0.5 mm to 1.0 mm. Gate diameters below 0.8 mm can restrict flow and require higher melt temperatures, which may push material near the 240 °C to 250 °C upper limit. Vent channels should be 0.02 mm to 0.03 mm deep and 3 mm wide to allow air escape without flash. Mould shrinkage should be determined per ISO 294-4:2018 on a plaque of 60 mm × 60 mm × 2 mm or equivalent; for unfilled ABS it generally lies between 0.4 % and 0.7 % along flow and 0.5 % and 0.7 % transverse, depending on packing pressure.

When DGK-KJD678R-BZ Is Evaluated Against General-Purpose and High-Impact ABS Grades

Substitution of DGK-KJD678R-BZ for an incumbent ABS grade requires a head-to-head property comparison using specimens moulded on the same machine and conditioned per ISO 291:2008. Without a published datasheet, no property value can be assigned to this specific grade; however, the grade family likely falls within one of the unfilled ABS categories shown in Table 1. The suffix -BZ may indicate a low-gloss or matte package, but no surface gloss value per ISO 2813:2014 is publicly available. High-impact ABS grades typically exhibit higher notched Izod values but lower tensile yield stress and lower modulus than general-purpose ABS. Heat-resistant ABS grades shift heat deflection temperature upward but often require higher barrel temperatures and exhibit lower flow. If the DGK-KJD678R-BZ lot has a melt flow rate below 5 g/10 min at 220 °C and 10.00 kg load per ISO 1133-1:2022, higher packing pressure and longer hold time are required. If the melt flow rate exceeds 20 g/10 min, thin-wall fill is improved but weld-line strength and impact retention may decline. A melt flow rate difference greater than 20 % relative to the incumbent grade should trigger barrel profile adjustment and screw speed revalidation. Compared with polycarbonate/ABS blends, unfilled ABS has lower impact energy absorption and lower heat deflection temperature but lower melt viscosity. Compared with polystyrene, ABS shows higher notched Izod impact and better resistance to brittle failure under cold-temperature loading.

These reference windows are not DGK-KJD678R-BZ lot values. They are supplied solely to establish whether an incoming lot behaves closer to a general-purpose, high-impact, or heat-resistant ABS grade. The processor must obtain a certificate of analysis from the supplier before approving the material for production.

Screw Plastication and Barrel Residence-Time Boundaries

Machine selection for ABS compounds is constrained by residence time distribution and shear input. A screw with L/D ratio of 20:1 to 24:1 and compression ratio of 2.0:1 to 2.5:1 is acceptable for unfilled ABS. The barrel capacity should be matched so that shot weight represents 30 % to 70 % of maximum shot capacity; residence times below 30 s can produce unmelted granules, while residence times above 8 min accelerate thermal degradation. Vented barrels are not recommended for unfilled ABS because volatiles are minimal and vent draw can cause feedstock blockage; if a vented barrel is used, vacuum should not exceed 0.08 MPa absolute pressure because excessive vacuum may pull low-molecular-weight additives. Check-ring wear must be monitored: clearances above 0.15 mm can reduce packing consistency and increase part mass variation beyond 0.3 % of mean part mass. Nozzle temperature is commonly set 5 °C to 10 °C below front-zone temperature to minimize drool. A shut-off nozzle is required if cycle time exceeds 60 s to prevent stringing. Screw recovery time should be shorter than cooling time; if recovery consumes more than 80 % of cooling time, screw speed or barrel zone set points must be adjusted. Melt pressure at the nozzle should remain below 150 MPa to avoid excessive shear heating, and a pressure transducer should be installed to monitor shot-to-shot consistency.

Differences from plated, low-gloss, and flame-retardant ABS subgrades are significant. Electroplating-grade ABS requires a butadiene particle size distribution that supports chromic acid etching and adhesion of electroless nickel or copper layers; no such qualification is publicly available for DGK-KJD678R-BZ. Low-gloss ABS grades achieve specific surface gloss units below 60 GU at 60 ° angle per ISO 2813:2014; if the -BZ suffix denotes such a surface, the supplier must provide a gloss certificate from a calibrated glossmeter. Flame-retardant ABS compounds typically contain halogenated or halogen-free FR packages and are tested per UL 94, ASTM D635-22, or ISO 1210; no such classification is available for this grade. Anti-static and UV-stabilized ABS grades also differ in surface resistivity and accelerated weathering stability, respectively; these properties cannot be inferred from base resin behaviour.

Compliance documentation for ABS DGK-KJD678R-BZ must be obtained from the supplier. Table 2 lists the minimum verification matrix. ABS is susceptible to environmental stress cracking when exposed to ketones, esters, aldehydes, chlorinated hydrocarbons, and aromatic hydrocarbon fluids at service temperatures above 40 °C. Storage should avoid direct ultraviolet exposure and relative humidity above 60 %. The material should be stored in sealed containers at 5 °C to 35 °C and pre-dried before moulding if opened for more than 24 h. No food-contact, medical-grade, or flame-retardant classification is established for this SKU unless a supplier-issued certificate of compliance explicitly references the relevant regulation. If the material is supplied under a Chinese domestic standard, the supplier may issue test data per GB/T 12672-2009, which covers melt flow rate, tensile, impact, and thermal properties for ABS resin. US-origin datasheets may cite ASTM D638-14 for tensile properties; values from ASTM D638-14 are not directly interchangeable with ISO 527-2:2012 because specimen geometry and test speed differ.