Screw thread

Engineering drawingIn engineering drawings, ANSI Y14.6 defines standards for indicating threaded parts. Parts are indicated by their nominal diameter (the nominal outside diameter of the screw threads), number of threads per inch, and the class of the thread. For example, “.750-10UNC-2A” is male (A) with a nominal outside diameter of 0.750″, and 10 threads per inch; “.500-20UNC-1B” would be female (B) with a 0.500″ nominal diameter (i.e., the hole will be drilled less than that) and 20 threads per inch. An arrow points from this designation to the surface in question.

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Screw

Tensile strengthScrews and bolts are usually in tension when properly fitted. In most applications they are not designed to bear large shear forces. For example, when two overlapping metal bars joined by a bolt are likely to be pulled apart longitudinally, the bolt must be tight enough so that the friction between the two bars can overcome the longitudinal force. If the bars slip, then the bolt may be sheared in half, or friction between the bolt and slipping bars may erode and weaken the bolt (called fretting). For this type of application, high-strength steel bolts are used and these should be tightened with a torque wrench.Rusty hexagonal bolt headsEnlargeRusty hexagonal bolt headsHigh-strength bolts usually have a hexagonal head with an ISO strength rating (called property class) stamped on the head. The property classes most often used are 8.8 and 10.9. The number before the point is the tensile ultimate strength in MPa divided by 100. The number after the point is 10 times the ratio of tensile yield strength to tensile ultimate strength. For example, a property class 5.8 bolt has a nominal (minimum) tensile ultimate strength of 500 MPa, and a tensile yield strength of 0.8 times tensile ultimate strength or 0.8(500) = 400 MPa.Tensile ultimate strength is the stress at which the bolt fails (breaks in half). Tensile yield strength is M10, property class 8.8 bolt can very safely hold a static tensile load of about 15 kN.

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The "Expander," a key piece of fabrication equipment at the Dillingen plant, is based on technology exclusively used by BSH. The Expander is used in the formation of the dishwasher body.



This testing area at the Dillingen, Germany factory is used after all of the dishwasher's internal components parts have been added. The area contains a testing carousel where electrical connections, water inlet, and pumps, and other functional components are tested.