Blow-Up Ratio (Blown Film)
Calculate the blow-up ratio (BUR) in blown-film tubular extrusion, BUR = D_bubble ÷ D_die, from the film bubble diameter D_bubble and the annular die diameter D_die. Blown-film extrusion makes most of the world's plastic films (bags, packaging, sacks, sheeting): the melt is extruded through an annular die forming a tube, which is then INFLATED with compressed air like an elongated balloon and pulled upward at once, stretching the film in two directions to its final thickness (a few micrometres). The blow-up ratio is how much the tube is inflated relative to the die diameter — typically 1.5:1 to 4:1. It controls molecular orientation in the TRANSVERSE (circumferential) direction: a higher BUR stretches the film more in width, balancing its properties in both directions (transverse by blowing and longitudinal by pulling). The balance between blow-up and draw (pulling) sets the biaxial orientation, which determines the film's strength, stiffness, clarity and tear behavior. Adjusting BUR is a main control variable in making blown films with the desired properties. Enter the bubble diameter and the die diameter.
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Relação de sopro (filme soprado)
A relação de sopro (blow-up ratio, BUR) na extrusão de filme tubular soprado é BUR = D_balão ÷ D_matriz, a razão entre o diâmetro do balão (bolha) de filme e o diâmetro do anel da matriz. A extrusão de filme soprado produz a maior parte dos filmes plásticos do mundo (sacolas, embalagens, sacos, lonas): o polímero fundido é extrudado por uma matriz anular formando um tubo, que é então inflado com ar comprimido como um balão alongado e, ao mesmo tempo, puxado para cima — esticando o filme em duas direções até a espessura final (poucos micrômetros). A relação de sopro mede quanto o tubo é inflado em relação ao diâmetro da matriz, tipicamente entre 1,5:1 e 4:1. Ela controla a orientação molecular transversal (circunferencial) do filme: um BUR maior estica mais o filme na largura, equilibrando as propriedades nas duas direções (a transversal pelo sopro e a longitudinal pelo puxamento). O equilíbrio entre a relação de sopro e a razão de estiramento define a orientação biaxial, que determina a resistência, a rigidez, a transparência e o comportamento de rasgo do filme. Ajustar o BUR é uma das principais variáveis de controle na produção de filmes soprados. Informe o diâmetro do balão e o diâmetro da matriz.
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Extruder Head Pressure
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.
Extrusion Specific Energy (SEC)
Calculate the extrusion specific energy consumption (SEC), SEC = power ÷ mass throughput, from the screw motor power (kW) and the mass throughput (kg/h). The result, in kWh/kg, is the energy to process each kilogram of polymer, and the main ENERGY-EFFICIENCY indicator of an extruder. Since extrusion melts and pumps plastic largely by VISCOUS heating (screw mechanical energy converted to heat by shear), specific consumption directly reflects how well the screw is doing its job. Typical values are 0.1-0.4 kWh/kg, varying with polymer (each has a melting enthalpy), screw geometry, speed and temperature. An abnormally HIGH SEC signals problems — wrong screw, excessive shear (which can degrade the material), poor temperature setting — and energy waste (the largest part of an extruder's operating cost). A very low SEC may indicate incomplete melting. Monitoring SEC is central to efficiency, quality and cutting cost and emissions in plastics processing. Enter the power consumed and the mass throughput.
Draw-Down Ratio
Calculate an extrudate's draw-down ratio (DDR), DDR = (D_die ÷ D_product)², from the die orifice diameter D_die and the final product diameter D_product, as the ratio of cross-sectional areas. After leaving the die, the extrudate (a wire, tube, filament) is often PULLED and stretched by a haul-off at a speed higher than the exit speed, reducing its cross-section to the final size. The draw-down ratio is how much the section area is reduced. Drawing not only sets the final size but ORIENTS the molecular chains in the pull direction, which can greatly increase the product's mechanical strength in that direction (used in oriented fibers, tapes and films, far stronger than unoriented material). The draw-down ratio, combined with die swell, sets the relation between orifice size and final product. There are limits: excessive drawing can break the extrudate or cause defects. It is a key parameter in making fibers, monofilaments, small-diameter tubes and wire coating. Enter the die diameter and the final product diameter.
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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.