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 K110 is a 12% ledeburitic chromium steel and corresponds to material number 1.2379 (X153CrMoV12, D2). This tool steel combines the advantages of conventional 12% ledeburitic chromium steels with those of advanced tool steels. In the group of 12% ledeburitic chromium steels, BÖHLER K110 offers the best combination of wear resistance, compressive strength and toughness, for which reason it is used in virtually all cold work applications. Its advantageous tempering behavior with a pronounced secondary hardness maximum also enables the use of advanced coatings. This also makes BÖHLER K110 suitable for complex tools requiring a high degree of dimensional stability and shape stability.
Read MoreBÖHLER K340 ECOSTAR belongs to the group of conventionally produced 8% chromium steels. Compared to conventional 12% chromium steels, this conventionally smelted tool steel has better toughness, hardening response and higher adhesive wear resistance. This combination of high adhesive wear resistance and toughness also offers advantages for industrial knives subject to high stress. This grade is also used for stamping and cutting tools.
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 W302 ISOBLOC is a 5% chromium steel and corresponds to material number 1.2344 (X40CrMoV5-1). Produced via the electroslag remelting process (ESR), this tool steel has very high hot toughness as well as very high hot hardness and a very good resistance against heat-checkings. The combination of these properties makes it a top performer in closed- and open-die forging as well as in high- and low-pressure die casting. In addition, this material has very good polishability and is therefore also often used as a molding material for plastic injection molds.
Read MoreBÖHLER W360 ISOBLOC is a material produced by the electroslag remelting process (ESR), which has been specially adapted for use at high tool hardnesses in the range of 51-57 HRC. Although the steel can be classified as a 5% chromium steel, the increased carbon and molybdenum content coupled with state-of-the-art manufacturing technology ensures that BÖHLER W360 ISOBLOC still shows a very good toughness and an exceptionally good thermal resistance, even at high hardness levels. These properties make the steel the perfect choice for smaller components in the die casting sector (e.g., mold inserts, cores, core pins, ejector pins, etc.). The material also is frequently the preferred choice for closed-die and open-die forging tools due to its high wear resistance. Because of this excellent wear resistance and the high toughness, BÖHLER W360 ISOBLOC is also frequently used for cold work applications and as a molding material for plastic injection molds. The Steel also is available as powder material for metal-3D-printing under the brand name BÖHLER W360 AMPO.
Read MoreUddeholm Mirrax ESR is a through hardening corrosion resistant steel with very good polishability. Mainly intended for medium to large cross sections. It has a unique combination of toughness, corrosion resistance and through hardening properties. Benefits Low mould maintenance costs: The surface of cavity impressions retain their original finish over extended running periods. Moulds stored or operated in humid conditions require less protection. Low production costs: Water cooling channels are less affected by corrosion Heat transfer characteristics, and therefore cooling efficiency, are constant throughout the mould life, ensuring consistent cycle times. Safe mould use because of good toughness also in big dimensions
Read MoreUddeholm Orvar Supreme can be regarded as an “all-round” steel used in several application areas. Except for hot work application areas the steel is also used in moulds for plastics and as a material in high stressed axles. The high degree of purity and the very fine structure shows improvement in dies and components where high mechanical and thermal stresses are involved. Uddeholm Orvar Supreme is produced using the Electro-Slag-Refining (ESR) technique. The ESR process gives Uddeholm Orvar Supreme a high level of homogeneity and cleanliness which results in a high performance hot work tool steel of the highest quality. Benefits Improved tooling performance Uddeholm Orvar Supreme meets the North American Die Casting Association (NADCA) #207 requirements for Superior high quality H-13 die steel. Standard specification W.nr 1.2344 / AISI H13 / AFNOR Z38 CDV 5.1
Read MoreUddeholm Sleipner is a general purpose steel for cold work tooling. It has a mixed-abrasive wear profile and a good resistance to chipping. Furthermore a high hardness (>60 HRC) can be obtained after high temperature tempering. This means that surface treatments such as nitriding or PVD can be made on a high strength substrate. Also, it means that complicated shapes with hardness levels >60 HRC can be wire EDM’d from blocks with relatively thick cross-sections with a much reduced risk of cracking. Uddeholm Sleipner is recommended for medium run tooling applications where a resistance to mixed or abrasive wear and a good resistance to chipping are required. Benefits Very broad property profile Very good steel for all types of surface treatments Extremely versatile conventional tool steel for medium run cold work tooling Suitable upgrade where added chipping or wear resistance is needed over traditional AISI A2 or AISI D2 In East/South East Asian countries served by ASSAB, Uddeholm Sleipner is sold as ASSAB 88.
Read MoreUddeholm Stavax ESR is a premium stainless mould steel for small and medium inserts and cores. Uddeholm Stavax ESR combines corrosion and wear resistance with excellent polishability, good machinability and stability in hardening. Mould maintenance requirement is reduced by assuring that core and cavity surfaces retain their original finish over extended operating periods. When compared with non stainless mould steel, Uddeholm Stavax ESR offers lower production costs by maintaining rust free cooling channels, assuring consistent cooling and cycle time. This classic stainless tool steel is the right choice when rust in production is unacceptable and where requirements for good hygiene are high, as within the medical industry, optical industry and for other high quality transparent parts. Uddeholm Stavax ESR is a part of the Uddeholm Stainless Concept. Benefits Low mould maintenance because of corrosion resistance: Surfaces retain their original finish Less production during storing and operation in humid condition Lower production costs: Since water-cooling channels are unaffected by corrosion Heat transfer characteristics, and therefore cooling efficiency, are constant throughout the mould life, ensuring consistent cycle times. Long life mould Standard specification W.nr 1.2083 / AISI 420 / AFNOR Z40 CV 14 (RSL)
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 4 Extra SuperClean is the most versatile pm tool steel on the market today, combining high wear resistance with very good ductility and resistance to chipping of edges. Excellent machinability in both soft and hard condition ensures advantages in both tool making and tool maintenance. Uddeholm Vanadis 4 Extra SuperClean is also available as powder for processing by electron beam melting technology (EBM). This powder has the same chemical composition as the PM material. Benefits Reliable production with low risk of edge chipping Best combination of high hardness, wear resistance and chipping resistance High compressive strength Best stock standard program of all PM grades Standard specification AISI D2 / AFNOR de type Z136 CDV 5.4
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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