Extrusion Haul-Off Speed
Calculate the haul-off speed of an extrudate by mass conservation, v = Q ÷ A, from the extruder volumetric flow Q (m³/s) and the final product cross-sectional area A (m²). After the die, the extrudate is pulled by a haul-off (belts, rollers, winder) at a speed that must be SYNCHRONIZED with the extruder flow: by mass conservation, in steady state, the volume leaving the extruder per second must equal the volume the haul-off removes per second (product area times line speed). If haul-off is too fast for the flow, the product thins below size or breaks; if too slow, material accumulates and deforms. This speed sets the line's PRODUCTIVITY (metres per minute) and, with die swell and draw-down ratio, sets the final dimensions. Controlling the extrusion-haul-off synchrony — often with dimension sensors and closed loop — is essential for dimensional uniformity of pipes, profiles, wire and sheet. This gives the theoretical line speed from flow and desired section. Enter the flow and the product section area.
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Velocidade de puxamento da extrusão
A velocidade de puxamento (haul-off) de um extrudado decorre da conservação de massa, v = Q ÷ A, a partir da vazão volumétrica da extrusora Q e da área da seção transversal do produto final A. Depois da matriz, o extrudado é tracionado por um sistema de puxamento (esteiras, roletes, bobinadeira) a uma velocidade que precisa estar sincronizada com a vazão da extrusora: pela conservação de massa, em regime permanente, o volume que sai da extrusora por segundo deve igualar o volume que o puxamento remove por segundo (a área do produto vezes a velocidade da linha). Se o puxamento for rápido demais para a vazão, o produto afina abaixo da medida ou rompe; se for lento demais, o material acumula e deforma. Essa velocidade define a produtividade da linha (metros de produto por minuto) e, junto com o inchamento da matriz e a razão de estiramento, determina as dimensões finais. Controlar a sincronia entre extrusão e puxamento — muitas vezes com sensores de dimensão e malha fechada — é essencial para a uniformidade dimensional de tubos, perfis, fios e chapas. Este cálculo dá a velocidade de linha teórica a partir da vazão e da seção desejada. Informe a vazão e a área da seção do produto.
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Calculate the drag flow of a single-screw extruder, Q_d = ½·π²·D²·N·H·sin(φ)·cos(φ), from the barrel diameter D (m), screw speed N (rev/s), metering-zone channel depth H (m) and helix angle φ (degrees). Drag flow is an extruder's main pumping mechanism: the melt is dragged forward by the relative motion between the rotating screw and the fixed barrel, like a screw pushing a nut that cannot turn. This viscous drag is proportional to screw speed and channel geometry, and would be the maximum theoretical flow with no back-pressure. In practice the net flow is the drag flow MINUS the pressure flow (the backflow from die/head resistance). The balance between drag and pressure sets the extruder's operating point on its characteristic curve. Drag flow is the basis of extrusion screw design, the process that makes pipes, profiles, films, sheets, wire and the pellets of nearly all transformed plastic. Enter the diameter, speed, channel depth and helix angle.
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Estimate an extruder's head pressure, ΔP = (Q·μ) ÷ K, from the volumetric flow Q (m³/s), the melt viscosity μ (Pa·s) and the die conductance constant K (m³, summarizing the head+die flow-resistance geometry). Head pressure is the pressure the melt reaches at the screw end, before being forced through the die that gives the product its final shape. It results from the balance between the screw's pumping capacity (drag flow) and the die's resistance: more restrictive dies (smaller orifices, longer narrower channels) need higher pressure for the same flow. Extrusion pressures are very high — typically 100-400 bar (10-40 MPa) — and measuring and controlling them is essential: pressure indicates process state (blockages, viscosity changes from temperature, screw wear), governs flow and product uniformity, and has safety limits (excessive pressure can rupture the head or trigger burst disks). The screw-die balance, shown in the extruder's characteristic curve, is the heart of process control. Enter the flow, viscosity and die constant.
Plastic Injection Flow Rate
Compute the injection flow rate by dividing the injected volume by the fill time, in cm³/s. It is the speed at which the molten plastic enters the mold — a parameter that controls the shear rate, molecular orientation, surface finish and defects such as jetting or flow marks. High flow fills fast but may degrade; low flow may solidify before filling. Enter the injected volume and the fill time.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.