The Technical Guide to the Nickerson PMS Screw & Barrel Range

In modern injection moulding and extrusion, the plasticising unit, comprising of the feedscrew, barrel, non-return valve, and heating assemblies, is the critical heart of the processing system. As moulding requirements advance with complex engineered resins, high percentage filler loads, and ever- reducing cycle times, selecting the ideal screw geometry and wear-resistant metallurgy is essential for maintaining process stability and product quality.

Nickerson PMS offers a leading portfolio of custom-engineered feedscrews and barrels designed to meet or exceed OEM tolerances. This technical guide explores the OEM compatibility, screw design profiles, high- performance steels, protective coatings, and resin-specific configurations available in the Nickerson PMS range.

1. Major OEM Compatibility

Nickerson PMS designs and refurbishes screws, barrels, and screw tips engineered as direct drop-in replacements for machinery from major global OEMs. Drive shank profiles, overall length (OAL), flight pitch, keyways, nozzle threads, and heater band locations strictly match original machine specifications, ensuring rapid changeover without requiring mechanical modification.

Supported OEMs include but are not limited to: Arburg, Engel, KraussMaffei, Netstal, Battenfeld, Nissei, JSW, Sumitomo, Fanuc, Haitian, Yizumi, Milacron, Cincinnati, Boy and Husky.

2. Advanced Screw Designs & Geometries

Optimising screw design balances melt homogeneity, recovery time, back-pressure control, and shear input. Nickerson PMS produces several key profiles engineered for targeted processing demands:

General Purpose (GP) Screws

Profile: Classic three-zone layout featuring a deep feed section, a gradual compression transition section, and a shallow metering section.
Best Applications: Unfilled commodity resins (GPPS, ABS, HDPE, PP) with standard additive loading.
Benefits: Cost-effective, highly versatile, and easy to purge during frequent color changes.

Barrier Screws

Profile: Features a secondary (barrier) flight in the transition zone, creating separate channels for solid resin pellets and molten liquid polymer.
Best Applications: Polyolefins (PE, PP), crystalline polymers, and high-throughput packaging moulding.
Benefits: Higher melting rates, lower melt temperatures, reduced cycle times, and complete elimination of un-melts.

Mixing Screws

Profile: Integrates high-shear or high-distributive mixing elements into the metering zone.
Dispersive Mixers (e.g., Egan, Maddock): Force the polymer through narrow radial gaps to break down masterbatch agglomerates and gel particles.
Distributive Mixers (e.g., Pin Mixers, Diamond, Saxton): Split and recombine melt streams continuously to blend pigments without generating excessive frictional heat.
Best Applications: High-cosmetic parts, masterbatch blending, and direct liquid colorant dosing.

Vented / Degassing Screws

Profile: Two-stage screw design separated by a low-pressure decompression zone aligned with a barrel vent port.
Best Applications: Processing hygroscopic materials (such as PMMA, ABS, PC, or PA) without pre-drying, or removing volatile organic compounds (VOCs) and entrapped gases.
Benefits: Prevents splay, moisture marks, and void formation directly within the plasticising unit.

3. High-Performance Steels & Metallurgy

Selecting the correct base metal ensures the screw withstands heavy mechanical torque, thermal shock, corrosion, and continuous abrasion.

Through-Hardened Tool Steels

D2 Tool Steel (1.2379): High-carbon, high-chromium tool steel offering outstanding resistance to abrasive wear. Ideal for standard to moderately demanding moulding.
H13 Tool Steel (1.2344): Exceptional toughness and thermal fatigue resistance, making it suitable for large-diameter screws subjected to high torsional loads.
CPM 9V / 10V (Powder Metallurgy): Particle metallurgy steels with high vanadium carbidecontent, holding precision tolerances far longer than traditional tool steels under severe abrasion.

Stainless Steels

440C Stainless Steel (1.4125): High-carbon martensitic stainless steel delivering high surface hardness (58–60 HRC) alongside robust corrosion protection.
CPM M4 / Powdered Stainless Alloys: Engineered for highly corrosive environments combined with heavy filler loads, such as flame-retardant glass-filled resins.

4. Wear Coatings, Liners & Surface Treatments

To extend component lifespan in demanding moulding environments, Nickerson PMS provides advanced surface engineering that far outlasts standard nitrided components.

Bimetallic Barrels: Cast using centrifugal force to fuse an interior alloy lining to a steel backing tube. Options range from iron-base alloys for standard wear to nickel/cobalt-base alloys containing tungsten carbide particles for aggressive corrosive and abrasive applications.
Flight Hard-Facing (Colmonoy / Stellite): High-hardness alloys (such as Colmonoy 56/83 or Stellite) welded directly onto the flight tips to stop metal-to-metal contact against the barrel wall.
HVOF Thermal Spraying: High-Velocity Oxygen Fuel technology applies dense, ultra-low-porosity tungsten carbide coatings across the screw root and flight flanks.
Hard Chrome Plating: Provides a smooth, low-friction barrier that prevents sticky resins (like PVC or TPE) from adhering to the screw, while protecting against mild chemical attack.

5. Polymer Specialisation

Matching the screw geometry and metallurgical composition to the specific polymer structure ensures consistent processing and prevents thermal or shear degradation:

Amorphous Polymers (e.g., PC, PMMA, PS, ABS)

Processing Characteristics: Soften gradually across a broad temperature band; sensitive to shear degradation.
Design Strategy: Deeper flight depths, gentle compression ratios (2.0:1 to 2.5:1), and highly polished surfaces to avoid shear-induced discoloration.

Semi-Crystalline Polymers (e.g., PA66, PBT, POM, PEEK)

Processing Characteristics: Sharp, distinct melting points requiring rapid latent heat input; sudden drop in viscosity upon melting.
Design Strategy: Steeper transition zones, higher compression ratios (2.8:1 to 3.5:1), and precise zone heating to guarantee complete plasticisation.

Corrosive &Heat-Sensitive Materials (e.g., PVC, Fluoropolymers)

Processing Characteristics: Release corrosive acidic byproducts (e.g., hydrochloric acid, hydrofluoric acid) if overheated or allowed to stagnate.
Design Strategy: Highly streamlined three-piece or ball-check tip assemblies, solid stainless steel or chrome-plated construction, and smooth radii with zero dead spots.

6. Solutions for Abrasive & Agressive Resins

Processing modified, reinforced, or flame-retardant polymers drastically increases mechanical wear. Nickerson PMS manufactures tailored material solutions according to filler type:

Glass-Filled Resins (15% – 50%+ Glass Fibre)

Wear Mechanism: Glass fibres act as miniature blades, gouging flight flanks and eroding barrel walls.
Solution: Bimetallic barrels with tungsten carbide linings matched with CPM 9V powder metallurgy screws featuring Colmonoy 83 hard-faced flight lands.

Mineral-Loaded Resins (Talc, Calcium Carbonate, Barium Sulphate)

Wear Mechanism: Fine particulate minerals coat metal surfaces, causing micro-abrasion and polishing wear that degrades flight clearances.
Solution: HVOF tungsten carbide thermal spray coatings applied over the screw roots and flight flanks to maintain tight radial tolerances.

Halogenated & Flame-Retardant Plastics (FR-ABS, FR-PA, PBT+FR)

Wear Mechanism: Flame-retardant additives break down under elevated heat, forming acidic compounds that pit nitrided steels.
Solution: Premium nickel-based bimetallic barrels coupled with 440C stainless steel or powder metallurgy stainless screws.

Engineering Best Practice

Proper matching of screw geometry, core metallurgy, surface treatment, and non-return valve design can extend plasticising unit operating life by up to 300% to 500% under high-wear conditions, while significantly improving melt quality and reducing cycle times.