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Tolerance Stacks | ||
Tolerance Stacks also known as Stack-ups, Stacks, or Tolerance Analysis is the process in mechanical engineering of calculating the effects of dimensions and tolerances. Arithmetic stacks use the maximum and minimum values of dimensions and tolerances to calculate the maximum and minimum distance (clearance or interference) between two features or parts. Statistical stacks evaluate the maximum and minimum values based on the absolute arithmetic calculation combined with some method for establishing likelihood of obtaining the maximum and minimum values such as Root Sum Squared (RSS). While no official engineering standard covers the process of tolerance stacks the practice of tolerance stacks is essential to good product design. Tolerance stacks are practiced in every corner of industry where mechanical engineers are employed. The practices associated with conducting a tolerance analyisis are derived from the engineering standard used on the drawing such as ASME Y14.5 or ASME Y14.41. Understanding the tolerances, concepts, and boundaries created by these standards is vital to performing accurate calculations. Tolerance stacks serve engineers by... * helping engineers and designers study dimensional relationships within an assembly * giving designers a means of calculating part tolerances * helping engineers compare design proposals * helping designers produce complete drawings DocumentationAn important aspect of performing tolerance stacks is the documentation. The calculations need to be available for multiple engineers, designers and suppliers in industrial applications. Therefore good documentation practices are vital to using a stack calculation. A stack form, stack matrix (or other database) and a stack layout are frequently used documentation practices. If a stack is not properly documented the calculation will be useless to other users. Concerns with Stack-upsA safety factor is often included in designs because of concerns about: * Operational temperature of the parts or assembly * Wear * Deflection of components after assembly * The possibility or probability that the parts are slightly out of specification (but passed inspection) * The sensitivity or importance of the stack (what happens if the design conditions are not met) Copyright 2008 - France BtoB from Wikipédia
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• Richard Hall Gower
• SMED : Formal Method • History of Lean manufacturing • Definition of availability • Automation • Types of innovation • System Lean : Types of waste | |
