Tek Tip - Data Sheet Properties vs. Specifications

  • Occasionally a specification for a particular product will come to us that is obviously written using values from a data sheet supplied by us or our suppliers. These values have little meaning as far as a guide to manufacturing the product and here’s why:

    DATA SHEET PROPERTIES

    The values for the various properties on a data sheet are considered typical properties. This means that these values are typically what can be expected of the product. They are usually average values that are based on the run history of the product and will change little if at all during the life of the product offering.

    These values do not accurately represent the range within a product is manufactured. This is why data sheet properties do not normally contain a value range or tolerance such as 8000-12000psi or 1.256 +/- 0.012 units. These values are meant to be used only for comparing to other products.

    When drafting a product specification refer to the manufacturers specification available on most products through TEKRA.

    MANUFACTURER’S SPECIFICATION

    The manufacturer’s specification is a controlled document that reports the values for certain properties within which the manufacturer feels he can make the product on a consistent basis. These values will have a range or a tolerance associated with them and can change periodically with improvements in manufacturing practices or changes in raw materials. Because of these potential changes these documents are distributed only upon request.

    PRODUCT SPECIFICATION

    A product specification should contain only those properties that are important to your application. Specifying values for properties that are not relevant only complicates and delays the specification process. If there are properties that are important to your application and are not included in the manufacturers specification contact TEKRA to negotiate a specification for those properties. These can usually be determined based on retains of previous runs or some cases may require evaluating several new runs when manufacturing changes are made.

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