Required Dynamic Capacity (Bearing)
Calculate the dynamic load rating C a bearing needs to reach a desired life, C = P·(L10)^(1/p), from the equivalent dynamic load P (N), the desired nominal life L10 (in millions of revolutions) and the exponent p (3 for balls, 10/3 for rollers). It is the INVERSE of the life calculation, and how bearing SELECTION is done in practice: the designer knows the load the bearing will carry (P) and the life it must reach (L10, derived from required operating hours and rotation), and computes the minimum needed dynamic capacity C. Then a bearing is chosen from the maker's catalog whose tabulated C is EQUAL OR GREATER than the required — and that fits the available dimensions (shaft and housing diameter). The dynamic capacity C is, by definition, the load giving an L10 life of exactly 1 million revolutions, and it is each bearing's 'rating' in the catalog. This calculation is the heart of sizing: it translates the application requirement (load and life) into the component spec (capacity), letting you pick the right bearing — neither undersized (early failure) nor oversized (needless cost and space). Enter the equivalent load, the desired life and the exponent.
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Capacidade dinâmica requerida (rolamento)
A capacidade de carga dinâmica C que um rolamento precisa ter para atingir uma vida desejada é C = P·(L10)^(1/p), a partir da carga dinâmica equivalente P, da vida nominal desejada L10 (em milhões de revoluções) e do expoente p. É a operação inversa do cálculo de vida, e a forma como a seleção de rolamentos é feita na prática: o projetista conhece a carga que o rolamento vai suportar (P) e a vida que precisa atingir (L10, derivada das horas de operação e da rotação), e calcula a capacidade dinâmica C mínima necessária. Em seguida, escolhe no catálogo um rolamento cujo C tabelado seja igual ou maior que o requerido — e que caiba nas dimensões disponíveis (diâmetro do eixo e do alojamento). A capacidade dinâmica C é, por definição, a carga que dá uma vida L10 de exatamente 1 milhão de revoluções, e é a 'nota' de cada rolamento no catálogo. Este cálculo é o coração do dimensionamento: traduz a exigência da aplicação (carga e vida) na especificação do componente (capacidade), permitindo escolher o rolamento certo — nem subdimensionado (falha precoce) nem superdimensionado (custo e espaço desnecessários). Informe a carga equivalente, a vida desejada e o expoente.
Related Tools
L10 Life in Hours (Bearing)
Calculate a bearing's nominal L10 life in HOURS of operation, L10h = (10⁶ ÷ (60·n))·(C/P)^p, from the dynamic load rating C (N), the equivalent dynamic load P (N), the rotation n (rpm) and the exponent p (3 for ball bearings, 10/3 for roller bearings). L10 life is the core of bearing selection: the number of revolutions (or hours) that 90% of a batch of identical bearings reaches or exceeds before FATIGUE failure (spalling of races and rolling elements) — i.e., only 10% fail earlier (hence 'L10', the life with 90% reliability). The basic formula L10 = (C/P)^p gives life in MILLIONS of revolutions; dividing by the rotation (rpm × 60 min/h) converts to hours, the practical unit for machines. The result shows the huge load sensitivity: since the exponent is 3 (balls), DOUBLING the load cuts life to 1/8! So a slightly overloaded bearing lasts far less. The capacity C is tabulated in each bearing's catalog. This calculation decides whether a bearing meets the application's required life (typically 20,000-100,000 h for industrial machines) or whether a larger one is needed. Enter the dynamic capacity, the equivalent load, the rotation and the exponent.
Bearing Life L10
Compute nominal bearing life L10 in million revs: L10 = (C/P)^p with p=3 (ball) or p=10/3 (roller).
Reliability-Adjusted Life (Bearing)
Calculate a bearing's adjusted life for a reliability other than 90%, L_na = a_1·L10, from the reliability factor a_1 (dimensionless) and the nominal life L10 (in millions of revolutions). The standard L10 life corresponds to 90% reliability (10% failures). But many CRITICAL applications — where a bearing failure is unacceptable (turbines, aerospace, medical equipment, continuous-process machines) — require HIGHER reliabilities (95%, 99%, 99.9%). Since demanding higher reliability means accepting FEWER failures, the corresponding life is SHORTER: a_1 is below 1 for reliabilities above 90%. Typical values: a_1 = 1.0 for 90% (L10), 0.64 for 95% (L5), 0.21 for 99% (L1), 0.093 for 99.9% (L0.1). For example, to ensure 99% of bearings survive (instead of 90%), the design life drops to about 21% of L10. This is one of the 'modified life' corrections in the standards (ISO 281), which also include factors for material and lubricant quality and contamination (the more sophisticated a_ISO factor). Adjusting life for required reliability is essential in critical designs: simply using L10 (90%) would be too risky for a turbine, and too conservative for a household fan. Enter the reliability factor and the L10 life.
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.