Paper Tensile Index
Compute the paper tensile index, index = tensile strength (N/m) / grammage (g/m²), in N·m/g, normalizing the strength by the grammage to allow comparing papers of different weights. It is one of the most important mechanical properties, linked to fiber strength, inter-fiber bonding and refining. Packaging and sack papers require a high tensile index. Enter the tensile strength and the grammage.
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Índice de tração do papel
Como comparar a 'força' de um papel fino de seda com a de um cartão grosso? Não pela resistência absoluta (o cartão sempre ganharia por ser mais pesado), mas pelo índice de tração = resistência à tração (N/m) / gramatura (g/m²), em N·m/g, que normaliza a força pelo peso da folha. Assim se compara a qualidade intrínseca das fibras e de suas ligações, independentemente da espessura. O índice de tração depende de três fatores: a resistência das próprias fibras (tipo de madeira, processo), a ligação entre elas (as fibras de celulose colam umas nas outras por pontes de hidrogênio quando a água sai — quanto mais área de contato, mais forte) e o refino (o tratamento mecânico que fibrila e flexibiliza as fibras, aumentando o contato — daí mais refino aumenta a tração, embora reduza o rasgo e a drenagem). Papéis para sacos de cimento, embalagens e fitas adesivas exigem alto índice de tração; papéis higiênicos, ao contrário, são propositalmente fracos e macios. É a propriedade mecânica número um na ficha técnica de um papel. Informe a resistência à tração e a gramatura.
Related Tools
Paper Tear Index
Compute the paper tear index, index = tear force (mN) / grammage (g/m²), in mN·m²/g, normalizing the tear resistance by the grammage. Tearing depends greatly on fiber length (long fibers resist more) — which is why packaging papers use long softwood fibers. It is a property that often competes with tensile (more refining raises tensile but lowers tear). Enter the tear force and the grammage.
Paper Breaking Length
Compute the breaking length (self-rupture) of paper, L = tensile index / 9.80665, in km — the length of a paper strip that, hung from one end, would break under its own weight. It is an intuitive, classic way to express tensile strength, independent of grammage. Common papers break around 3–8 km; high-strength papers, more. Enter the tensile index (N·m/g).
Belt Installation Tension
Calculate a belt's installation (static) tension, T_i = (T₁ + T₂) ÷ 2, from the tight-side T₁ and slack-side T₂ tensions (N). The installation tension is the INITIAL tension applied to the belt when mounting it (with the machine stopped), tensioning it between pulleys — it is the average of the tensions that will exist on both sides during operation. Setting this initial tension correctly is one of the most important and most neglected maintenance tasks in belt drives: a SLACK belt (low tension) slips under load — losing power, generating heat, wearing fast and even burning; an OVER-TIGHT belt (high tension) overloads the bearings and shafts (drastically shortening bearing life), stretches and fatigues the belt, and wastes energy. The correct installation tension is the one that, under operating load, keeps the slack side with enough tension not to slip, without overdoing the tight side. In practice, the installation tension is measured by belt deflection under a standard force, or by the span natural frequency (sonic meter). Tension 'settles' in the first hours (a new belt stretches), so re-tensioning after the run-in period is recommended. Enter the tight- and slack-side tensions.
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.