Screws and barrels melt and homogenize polymers in moulding and extrusion. Wear‑resistant steels and specialized screw designs ensure stable melt quality for PE, PP, ABS, PA and filled materials, supporting applications from injection moulding to pipe, film, and sheet extrusion.
Screws and barrels in plastifier units are core components in injection moulding and extrusion, responsible for melting, homogenizing, and conveying thermoplastic materials. The process begins as polymer pellets enter the feed zone, where the screw transports them forward, generating frictional and heating. In the compression zone, the channel depth decreases, increasing pressure and completing melting. The metering zone ensures consistent melt quality before injection or extrusion. Typical materials processed include PE, PP, ABS, PA, PC, PVC, and filled compounds such as glass‑fiber‑reinforced polymers. Screws are designed as standard three‑zone types or specialized barrier, mixing, and venting screws to improve melt uniformity and are typically manufactured from nitrided steels, bimetallic alloys, or tool steels including advanced powder metallurgical tool steels to ensure wear and corrosion resistance. Barrels are produced from nitrided or bimetallic materials featuring iron‑, nickel‑, or cobalt‑based liners to withstand abrasive fillers like glass fibers and corrosive polymers such as PVC or flame‑retarded compounds. Tooling considerations include heater bands, cooling channels, check valves, and wear sleeves. Applications span injection moulding, pipe extrusion, film and sheet production, recycling systems, and compounding lines, where consistent melt preparation is critical for product quality.
BÖHLER K294 MICROCLEAN is a cold work tool steel manufactured using powder metallurgy and belongs to the group of 10% vanadium steels. The high content of vanadium carbides makes this steel highly resistant to wear. The toughness is at the same level as conventional 12% chromium steels. BÖHLER K294 MICROCLEAN is used in situations where wear resistance is the decisive factor and toughness is of secondary importance.
Read MoreBÖHLER K340 ISODUR belongs to the group of 8% chromium steels. This tool steel is produced using the electro-slag remelting (ESR) process developed by BÖHLER. This re-melting technology ensures the lowest micro and macro segregation as well as excellent purity and uniformity of the material. Compared to conventional 12% chromium steels, BÖHLER K340 ISODUR offers significantly better toughness, hardening response and higher resistance to adhesive wear. This material is therefore used in virtually all cold work applications in situations where tool steels like 1.2379 are insufficient in terms of adhesive wear resistance and toughness. K340 ISODUR also features better machinability and reduces the risk of stress cracking during electrical discharge machining.
Read MoreBÖHLER K360 ISODUR belongs to the group of 8% chromium steels. This tool steel is produced using the electro-slag remelting (ESR) process developed by BÖHLER. This re-melting technology ensures the lowest micro and macro segregation as well as excellent purity and uniformity of the material. The alloy composition with higher molybdenum and vanadium content makes BÖHLER K360 ISODUR even more wear resistant than BÖHLER K340 ISODUR. Compared to tool steels like 1.2379 (D2), this combination of better toughness and wear resistance offers significant advantages for punching and cutting tools.
Read MoreBÖHLER K390 MICROCLEAN is a high-alloyed, high-performance cold work tool steel manufactured using powder metallurgy. This material has the highest alloy content in the group of cold work tool steels with high vanadium content. The high alloy content gives this material outstanding wear resistance. At the same time, the powder metallurgical manufacturing process creates a uniform matrix with finely distributed primary carbides. Among other things, this leads to good material toughness. BÖHLER K390 MICROCLEAN is a problem solver for applications requiring extremely high wear resistance and compressive strength.
Read MoreBÖHLER M310 ISOPLAST is a corrosion-resistant, martensitic chromium steel which, through electroslag remelting and optimization of the chemical composition, has a good homogeneity and a balanced hardness-toughness-corrosion resistance ratio.
Read MoreBÖHLER M390 MICROCLEAN is a corrosion-resistant, martensitic chromium steel produced by powder metallurgy. Due to its alloy design, this steel has very high wear resistance and good corrosion resistance. In addition, BÖHLER M390 MICROCLEAN is approved for food and beverage contact.
Read MoreBÖHLER N695 is a corrosion-resistant, martensitic chromium steel with a high carbon content and added molybdenum.
Read MoreUddeholm Tyrax ESR combines best in class toughness, corrosion and wear resistance. This grade was developed for molding of high performance plastics often filled with glass fiber reinforcements and additives like flame retardants. This matrix- based microstructure is designed to achieve a high-gloss surface by only a few polishing steps, dramatically reducing the tool lead time and enabling production of top quality plastic parts. Uddeholm Tyrax ESR can achieve a high hardness (up to 58 HRC) and is a suitable upgrade from AISI 420 ESR, AISI S7 and AISI 440C. Benefits good dimensional stability at heat treatment and in service even microstructure and small grain size good hardenability Uddeholm Tyrax is also available for Additive Manufacturing, powder for processing Laser Powder Bed Fusion (LPBF) and Laser Metal Deposition (LMD).
Read MoreUddeholm Vanadis 8 SuperClean sets a new standard for Powder Metallurgical Tool Steel. The technological advancements makes this cold work tool steel superior to its predecessors. The unprecedented combination of extremely high wear and chipping resistance paired with improved machining properties raises production rates and reduces costs. Benefits Lower price per produced part Longer tool life Predictable Production Standard specification AISI D2 / AFNOR de type Z230VCD8.5.4
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