Dow HDPE NG7000 is an injection-molding grade of high-density polyethylene supplied as free-flowing pellets. The product is identified by a nominal density of 0.955 g/cm³ under ISO 1183-1:2019 and a nominal melt mass-flow rate of 20 g/10 min at 190 °C and 2.16 kg under ISO 1133-1:2022. These values place NG7000 in the high-flow segment of HDPE injection resins, where short fill time, low locked-in orientation, and dimensional repeatability are the primary design drivers. Typical component classes include thin-wall tubs, disposable cutlery, closures, overcaps, and housewares with nominal wall thickness between 0.4 mm and 2.5 mm. The grade is not intended for blown film, sheet thermoforming, pipe extrusion, or continuous blow molding of large containers. Compared with fractional-melt HDPE blow-molding grades, the melt viscosity is substantially lower under injection shear rates, which alters both hot-runner pressure drop and gate sealing time.

How Should Melt Temperature and Residence Time Be Controlled on Multi-Cavity Tools?

Processing guidance for high-flow HDPE of this density is constrained at the lower end by short-shot risk and at the upper end by stabilizer consumption. The recommended melt temperature range is 190–240 °C. At melt temperatures below 190 °C, thin sections with flow-length-to-wall-thickness ratios above 150:1 may freeze before complete packing. Above 240 °C, residence time becomes the dominant variable because the antioxidant package is consumed more rapidly and the melt can shift toward yellowing. Barrel profiles on 22:1 to 25:1 L/D general-purpose screws are typically set from 180 °C in the feed zone to 220 °C at the nozzle; a reverse or flat profile is used only when the screw speed is high enough to generate excess shear heating. Mold temperature is usually controlled between 10 °C and 40 °C. Lower mold temperatures reduce cycle time but increase molecular orientation and may reduce hinge toughness in closures. Back pressure is typically held below 0.8 MPa; higher back pressure can increase melt temperature by 5–10 °C and destabilize shot weight on machines with long screw recovery. In accumulator-capable packaging lines, injection time below 0.35 s is common for 0.4 mm wall lids; conventional hydraulic machines may need the melt temperature at 230–240 °C to achieve equivalent fill. Residence time at 220 °C should not exceed 5 min, and at 240 °C the same limit is shortened to 3 min; purge with a fractional-melt polyethylene or commercial HDPE purge compound before shutdown. In hot-runner valve-gated systems with 8 or more cavities, melt temperature variation should be held within ±5 °C to keep part mass variation below ±0.05 g on a 4 g container when measured with a 0.01 g resolution balance.

Published data for the exact barrel-temperature profile of NG7000 in a given hot-runner system is limited; the values above are standard process guidelines for high-flow HDPE and should be verified on the actual machine.

When high-flow injection HDPE is compared with fractional-melt blow-molding HDPE of similar density, the operational distinctions are not limited to melt flow. A blow-molding grade with MFR 0.3 g/10 min and density 0.954 g/cm³ typically requires accumulator-head extrusion or continuous shuttle blow molding, with melt temperatures above 200 °C, because its higher molecular weight and melt strength are necessary to maintain parison geometry. NG7000 at 20 g/10 min has lower melt strength and is therefore unsuitable for those processes. In injection molding, however, the high MFR reduces pressure drop through sprue, runner, and valve gate. The difference is most visible in thin-wall flow: at filling shear rates between 1000 s⁻¹ and 5000 s⁻¹, the apparent viscosity of a 20 g/10 min HDPE at 220 °C is generally in the range 80–150 Pa·s, whereas a 0.3 g/10 min HDPE can exceed 400 Pa·s under the same conditions. This viscosity difference permits shorter hold times and lower packing pressures but also reduces the molecular chain entanglement that contributes to stress-crack resistance and impact strength. As a result, NG7000 is not the correct selection for containers requiring ESCR above 100 h under ASTM D1693-21 condition A or for long-term hydrostatic pipe service.

Mechanical Property Data Anchored to ISO and ASTM Designations

The tabulated values are representative and not specification limits. The combination of 1400 MPa flexural modulus and 25 J/m notched Izod impact indicates that the grade provides high bending stiffness with moderate impact toughness. Compared with a 0.3 g/10 min HDPE blow-molding grade, the notched impact value is lower because the lower molecular weight reduces chain entanglement density. For applications such as thin-wall cups, the limiting mechanical response is usually top-load rigidity rather than impact; top-load can be improved by sidewall ribs, stacked rim geometry, or increased wall thickness without changing resin. Notched impact performance may also decline if the mold temperature is kept below 10 °C or if regrind content exceeds 20 wt%.

Food-contact status is represented by the supplier as compliant with 21 CFR 177.1520 for olefin polymers when the article is used under the applicable conditions of use and food types. EU compliance is evaluated under Regulation (EU) No 10/2011, with the overall migration limit of 10 mg/dm² and specific migration limits for additives listed in the positive list. A compliance checklist is provided below. The product is not intended for implantable medical devices or for applications requiring USP Class VI testing unless the final article is separately validated. Users should confirm that the antioxidant and processing aid package is acceptable for the specific food type and sterilization method. Ethylene oxide sterilization, gamma irradiation, or autoclaving of the final article can change extracted-polymer properties and should be tested separately because the resin data sheet does not cover sterilized-article performance.

When Dimensional Stability in Thin-Wall Lids Becomes the Limiting Factor

Warpage in thin-wall HDPE parts is controlled less by melt temperature than by gate location, packing pressure, and mold cooling. For a 0.4 mm wall lid, packing pressure is generally held between 50 MPa and 70 MPa, with hold time of 0.8–1.2 s; insufficient hold time produces sink and ovality, while excessive hold time can block gate freeze and enlarge cycle time. Mold cooling water should be turbulent, not laminar, with supply temperature between 8 °C and 15 °C. A core-to-cavity temperature difference of 5–10 °C, commonly caused by inadequate baffle spacing or low flow in the cavity plate, is sufficient to produce visible warp in rectangular or non-round lids. Pin gates near the center of the part or multiple hot drops produce more balanced in-flow and cross-flow shrinkage than single-edge gates. Post-mold shrinkage after 48 h at 23 °C for high-flow HDPE of this density class is typically 1.5–2.0 %; published data for NG7000 in specific lid geometries is limited. If dimensional checking is performed before 24 h, additional shrinkage of 0.1–0.3 % may occur and cause false acceptance of out-of-spec parts.

Mold steels with high thermal conductivity, such as aluminum alloys or copper-beryllium inserts, can reduce cycle time but may require higher injection speeds to avoid premature freezing in thin ribs. Gate blush occurs when the melt temperature is too high or when the gate land is too short; reducing melt temperature by 5–10 °C and increasing gate land length by 0.1–0.2 mm is often sufficient to eliminate surface defects without sacrificing fill.

Pellets are supplied with moisture below 0.05 wt% in sealed packaging. Drying is normally not required if the hopper is closed and condensation is prevented. If sacks are opened for more than 24 h at relative humidity above 60 %, surface moisture can cause splay and should be removed by a desiccant dryer at 80 °C for 1–2 h. Regrind can be introduced up to 20 wt% in non-food applications without major loss of flow, but for food-contact articles the regrind fraction should be kept below 15 wt% and must be generated from the same resin to maintain organoleptic and migration limits. Contamination by polypropylene, nucleated HDPE, or incompatible color concentrates can cause delamination, inconsistent crystallization, and pressure spikes during filling. Store the pellets away from direct sunlight, oxidizing agents, and sources of fine dust. If the machine barrel contains PVC or acetal residue, a purge with low-MFR polyethylene is required before loading NG7000 because degradation products from those polymers can produce black specks and odor.

What Distinguishes NG7000 from General-Purpose 20-MFR HDPE Grades?

Several HDPE products list a melt flow rate of 20 g/10 min and density near 0.955 g/cm³, but NG7000 is differentiated by the combination of molecular weight distribution width, stabilizer package, and lot-to-lot control for injection molding. General-purpose 20-MFR grades may be produced with broader molecular weight distributions, which can increase die swell and produce larger shot-to-shot variation in hot-runner tools. In thin-wall packaging, part mass variation is a direct quality index; a variation of ±0.05 g on a 4 g cup measured with a 0.01 g resolution balance is a typical control limit, and density drift outside ±0.002 g/cm³ can alter top load by more than 3 % because top-load scales with wall thickness and modulus. The narrow density tolerance and controlled MFR of NG7000 reduce the frequency of process adjustments across production campaigns. The product is also distinguishable from fractional-melt HDPE and from 20-MFR rotomolding grades, which have different particle size distributions and additive packages not suited to injection screw feeding. Users should not substitute a general-purpose 20-MFR HDPE for NG7000 without first matching the certificate of analysis for density, MFR, ash, and stabilizer content, because additive packages affect color, odor, and food-contact compliance.