OEM engineers want precision in meeting the exact specifications of the aluminum components that go into their products. There is an expectation that everything from the extruded profile through the machining, fabricating and finishing will fully meet the requirements for the intended function. However, a level of variance in dimensional or physical property control is inherent in virtually every manufacturing process. Machined components from aluminum extrusions are certainly no exception. The degree of allowable dimensional or property variance that can be accepted is critical to be understood by all parties – component manufacturers, OEMs and end users.
The term “tolerance” is very common in industry precisely because of the inherent assumption that true dimension is simply not achievable. Allowances for dimensional or property variances – tolerances – vary depending on how a product is used; it’s quality expectation, safety requirements and lifecycle among other user needs.
An extruded profile can be manufactured to various “acceptable standards” including very precise, special tolerances. “Geometrics” is a term that some engineers use when referring to precision geometric dimensioning in product or component design. It’s important to understand specific application tolerances to ensure an extruded component’s suitability for a final application. During a new profile inquiry, the preference is always to establish strict tolerance limitations and build-up using the customer’s electronic CAD file.
The Aluminum Extruders Council Extrusion Manual is a comprehensive guidebook that documents standard and precision dimensional tolerances complete with illustrated examples. A downloadable PDF is available on our Resources Page.
Perfectly Good Aluminum Parts
Manufacturing an extruded component without any variance is simply not feasible, however making it “fully suitable for the intended application” is certainly achievable in most cases. For some product applications, the economics of demand combined with present day manufacturing capabilities can determine the tolerances allowed or preferred in various product designs. Going too far in precision geometrics might put production costs out of range for certain markets while relaxing the tolerance standards too much will render unacceptable product suitability for its final application.
To arrive at the right tolerance for a precision aluminum profile or finished component, a balance may have to be struck. The single issue is to control manufacturing costs while at the same time ensure “form, fit and function.” Collaboration is the key!
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