High Abrasive Resistance Twin Screw Elements For Buss Twin Screw Extruder

High Abrasive Resistance Convey Screw Elements for Buss Twin Screw Extruder | CONLIN

High Abrasive Resistance Conveying Screw Elements for Buss Twin Screw Extruders

On a Buss co-kneader, the conveying elements are the first parts to fail — and the cheapest to replace.

Buss oscillating-screw compounders are specified for exactly the jobs that destroy conventional screws: highly filled compounds, glass fiber reinforcement, halogen-free flame retardant cable compounds, powder coating, mineral-filled masterbatch and abrasive recycling streams. The conveying elements in the feed and first conveying zones meet that material first, at the point where the filler is still cold, still sharp, and not yet dispersed into the melt.

That is where abrasive resistance stops being a material preference and becomes the determining factor in your maintenance interval.

Material Selection: Matching the Alloy to the Abrasive Load

For Buss conveying elements we manufacture in three wear classes. The right choice depends on the filler, the loading level and whether corrosion is present as well as abrasion.

1. High-speed tool steel — W6Mo5Cr4V2 (HRC 60-64)

The economical entry point for genuinely abrasive duty. Vacuum quenched and triple tempered, it delivers roughly double the wear life of nitrided 38CrMoAlA on glass-fiber-filled compounds, at a fraction of the cost of powder metallurgy. The right choice for medium filler loadings and for customers who want a measurable step up from nitriding without a premium material budget.

2. HIP powder metallurgy alloys — the benchmark for high abrasive resistance (HRC 58-64)

Hot isostatic pressing produces a homogeneous, segregation-free microstructure with a uniform distribution of hard carbide particles throughout the matrix — not just on the surface. This is the key difference from a surface-hardened or coated part: as a PM element wears, it exposes fresh wear-resistant material underneath. A coated element loses its protection the moment the coating is breached.

3. Carbide-reinforced surface protection — for the flight crest

Where abrasion concentrates on the flight tip, we apply tungsten carbide protection over a PM or tool steel body:

• Tungsten carbide HVOF coating — WC-Co / WC-CoCr applied at supersonic velocity, HV 1,200-1,400, coating density above 98%, adhesion beyond 10,000 psi, thickness 0.125-0.25 mm, diamond-polished afterward to Ra 0.2-0.4 µm. Full-coverage options are specified for compounds up to 65% glass fiber.
• Carbide-bearing PTA hardfacing — Colmonoy 83 class weld alloy at HRC 59-64, applied to the flight crests over a heat-treated body. Robust, economical, and straightforward to rebuild when it eventually wears.

Conveying Element Types We Manufacture for Buss Machines

Designed Around the Oscillating Shaft

A Buss screw shaft is not a plain rotating shaft. It reciprocates axially with each revolution, which places a specific set of demands on every element mounted on it:

• Mass and balance. Because the shaft assembly reciprocates, element mass and mass distribution matter more than on a rotating-only machine. We control weight per element and balance across the assembly.
• Axial location under reciprocating load. Elements must stay positively located on the shaft through millions of stroke cycles. Our elements are machined to controlled fit tolerances and are ground after heat treatment so that stack-up error does not accumulate along the shaft.
• Pin clearance is a dimensional property, not a material property. The stationary kneading pins do not collide with the flights, but the operating clearance between flight and pin is set by element geometry. Post-heat-treatment grinding holds that geometry through the whole element, which is what keeps the mixing effect repeatable.
• Self-cleaning must be preserved. The self-wiping character of the Buss principle depends on the flight and pin geometry being accurate. A worn or distorted conveying element degrades self-cleaning, which shows up as degraded product and longer cleaning cycles.

Materials & Heat Treatment

Standard for high abrasive duty (this product):

Alternative grades for less abrasive or cost-sensitive duty:

• 38CrMoAlA (SACM645) nitrided steel — ion nitriding, case depth 0.4-0.7 mm, HV 950-1100, core HRC 28-32. Suitable only for unfilled or lightly filled compounds; not recommended for glass fiber or mineral-filled Buss duty.

Corrosion-resistant grades (for halogen-free FR and chemically aggressive compounds):

• 316L / C276 stainless steel, nickel-based alloys, 17-4PH, 1.4114
• WR14 / WR45 for combined wear and corrosion resistance

Heat treatment:

• Vacuum quenching and triple tempering (standard for PM and tool steel)
• Ion nitriding / gas nitriding (for nitrided grades)
• Cryogenic treatment available for dimensional stability

Surface treatment:

• Tungsten carbide HVOF coating (WC-Co / WC-CoCr), HV 1,200-1,400
• Carbide-bearing PTA hardfacing on flight crests (Colmonoy 83 class)
• Hard chrome plating, 0.03-0.09 mm
• Sand blasting or mirror polishing, Ra ≤ 0.4 µm
• Bimetallic hardfacing for extreme local wear

Key Specifications

Compatible Buss Machine Sizes and Other Platforms

Our Buss-compatible conveying elements are manufactured to OEM-compatible geometry for:

Buss co-kneader sizes: Buss 65 · Buss 100 · Buss 140 · Buss 176 · Compeo series · MKS / MK series · PR / LR series and other Buss oscillating-screw compounders.

Our manufacturing base covers Ø15.6-430 mm segmented screw elements, which means we also supply for:

Coperion (W&P ZSK) · KraussMaffei Berstorff (ZE) · Leistritz (ZSE-MICRO) · Theysohn (TSK) · Maris (TM-W) · APV (MP65) · JSW (TEX) · Toshiba (TEM) · Clextral · Kobe · OMC · Labtech (LTE) · Useon (TDS) · Keya · Shizhou (MTE) · Lantai and other co-rotating twin screw platforms.

Applications

• Glass fiber reinforced compounds — PA-GF, PP-GF, PBT-GF, POM-GF cable and engineering parts
• Halogen-free flame retardant cable compounds — ATH / MDH filled, LSHF / LSZH formulations
• Highly filled masterbatch — mineral, talc, calcium carbonate, carbon black at high loading
• Powder coating — epoxy, polyester, hybrid powder coating compounds
• Engineering plastics compounding — PA, PBT, POM, PC, PPS, PEEK filled grades
• WPC and natural fiber — wood flour and natural fiber filled profiles
• Abrasive recycling streams — filled post-consumer and post-industrial recyclate
• Technical rubber and TPE compounding — EPDM, TPV, TPE with high filler loading
• Adhesive and sealant compounds — highly filled hot melt and sealant formulations
• Chemical and reactive compounding — where abrasive pigments or catalysts are present

Quality Control — Every Element

1. Material verification — PM and tool steel sourced from domestic or European twin-screw specialty suppliers, verified by elemental analysis and metallurgical inspection
2. In-house heat treatment — vacuum quenching, tempering and nitriding performed in our own furnaces, so the process is controlled rather than outsourced
3. Post-heat-treatment finishing — final grinding after heat treatment to eliminate deformation and achieve zero-gap assembly
4. Spline inspection — checked with spline plug gauges to guarantee interchangeability
5. Coating verification — HVOF coating thickness and hardness verified; adhesion and density controlled to specification
6. CNC machining — assures shape and tolerance consistency element to element
7. Dimensional report — supplied with each shipment
8. Stock availability — common sizes held in stock; new production typically 30-60 days

Why Buyers Choose CONLIN

• Competitive cost per unit of production — OEM-equivalent geometry and metallurgy at aftermarket pricing
• Fast turnaround for replacement and refurbishment of worn Buss elements
• Parts available from stock across a wide range of extruder makes and sizes
• Comprehensive inspection on every part prior to dispatch
• Documented quality with material certificate, hardness report and dimensional record
• Latest manufacturing techniques and metallurgy for consistent, repeatable performance
• Customized solutions — non-standard geometry, reverse engineering from sample or drawing, and full screw configuration design

Ordering Information

To quote accurately, please provide: machine brand and model (e.g. Buss 65 / Buss 140), screw diameter, element type and length, OEM part number if available, processed polymer, filler or additive type and loading percentage, whether the compound is corrosive (e.g. halogen-free FR), and quantity. If you only have the worn part, we can reverse-engineer from a sample or a dimensional drawing.