Cutting Clearance (Punch-Die)
Calculate the per-side cutting clearance between punch and die in sheet cutting, c = (a ÷ 100)·t, from the recommended percentage clearance a (% of thickness) and the sheet thickness t (mm). Cutting clearance is the small gap between punch and die, and one of the MOST important parameters in sheet-cut quality. As the punch descends, it shears the material, but the cut is not a clean slice: the material first deforms (roll-over), then shears giving a smooth zone (burnish), and finally FRACTURES, giving a rough zone and a burr. The correct clearance makes the cracks starting from punch and die MEET, giving a clean cut with minimal burr. The ideal clearance depends on material and thickness: typically 5-10% of thickness per side for steels (less for soft materials, more for hard). Too SMALL a clearance gives a secondary cut (double burr) and tool wear and needs more force; too LARGE gives heavy burr, distortion and poor edge quality. Getting clearance right is essential for tool life, required force and cut-part quality. Enter the recommended percentage clearance and the sheet thickness.
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Folga de corte (punção-matriz)
A folga de corte por lado entre o punção e a matriz é c = (a ÷ 100)·t, a partir da folga percentual recomendada a (% da espessura) e da espessura da chapa t. A folga de corte (clearance) é o pequeno espaço entre o punção e a matriz, e é um dos parâmetros mais importantes na qualidade do corte de chapas. Quando o punção desce, ele cisalha o material, mas o corte não é uma fatia limpa: o material primeiro deforma (a 'rebarba de embutimento', ou roll-over), depois cisalha gerando uma zona lisa e brilhante (burnish), e finalmente fratura, gerando uma zona rugosa e uma rebarba (burr) na saída. A folga correta faz com que as trincas que partem da aresta do punção e da aresta da matriz se encontrem, gerando um corte limpo com mínima rebarba. A folga ideal depende do material e da espessura: tipicamente 5 a 10% da espessura por lado para aços (menos para materiais moles, mais para duros). Folga pequena demais gera corte secundário (rebarba dupla), desgaste do ferramental e exige mais força; folga grande demais gera muita rebarba, distorção e baixa qualidade de borda. Acertar a folga é essencial para a vida da ferramenta, a força necessária e a qualidade da peça cortada — e é uma das primeiras coisas que se verifica quando um ferramental começa a produzir peças com rebarba. Informe a folga percentual recomendada e a espessura da chapa.
Related Tools
Punching Force (Sheet Cutting)
Calculate the force to punch (cut) a round hole in sheet metal, F = π·D·t·τ, from the hole diameter D (mm), sheet thickness t (mm) and the material shear strength τ (N/mm²). The product π·D is the cut perimeter; times thickness gives the area to be sheared; times shear strength gives the force. Punching (and sheet cutting in general, like blanking) is one of the most common stamping operations: a punch descends against a die, with a small clearance, and shears the material, separating the part or scrap. Computing the force is essential to select the press (whose tonnage capacity must exceed the force with margin) and to size the tooling. Force can be reduced with tricks like adding a shear angle to the punch or die, making the cut progressive instead of simultaneous over the whole perimeter — reducing the peak force (but increasing stroke). Knowing the force also lets you estimate the operation's work and energy. Enter the hole diameter, thickness and shear strength.
Punching Work
Calculate the work (energy) consumed in punching or sheet cutting, W = (k·F·t) ÷ 1000, from the penetration factor k (~0.3-0.6, the fraction of thickness the punch travels shearing before fracture), the cutting force F (N) and the sheet thickness t (mm); the result is in joules. While the cutting FORCE sets the press tonnage, the WORK sets the ENERGY the press must deliver in the stroke — a distinct and equally important parameter, especially in eccentric and friction presses that store energy in a flywheel. The factor k appears because the cut does not consume maximum force over the full thickness: the punch penetrates shearing, force rises to a peak, then drops as the material FRACTURES abruptly (the fracture propagates and separates the material before the punch crosses the whole thickness). So the work is only a fraction (k) of the maximum-force × thickness product. Knowing the work is essential to size the press flywheel and motor (which must replenish the energy between strokes) and to avoid heavy cuts 'stalling' the press from lack of stored energy. Enter the penetration factor, cutting force and thickness.
Bearing Radial Clearance
Calculate the radial clearance of a journal bearing, c = (D_bore − D_shaft) ÷ 2, subtracting the shaft diameter from the bearing bore diameter and dividing by two. The result is the radial space between shaft and bearing, where the lubricant oil film forms. Clearance is a critical design parameter: too small hampers film formation and heat dissipation (seizure risk); too large reduces load capacity and increases vibration and noise. A rule of thumb uses a radial clearance of about one thousandth of the diameter. Enter the bore and shaft diameters.
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.