Plate construction tolerances

Up to about 24 in. (610 mm) shells are normally constructed from standard, close tolerance, pipe above 24 in. (610 mm) they are rolled from plate. 

Where +1/32 inch (+0.8 mm) has been the standard thickness tolerance for 4 foot (1.22 meter) wide panels produced in double belt lines, the standard for the fluid film process is +0.010 inch (+0.25 mm). At times, an accuracy within +.005 inch (+.127 mm) has been achieved. Such accuracy is possible because of the precision and rigidity of the tunnel construction. The platens are reinforced weldments, stress relieved after welding and then ground and chrome plated. They are separated by precise gage blocks to form the two faces of the tunnel. Deflection is practically non-existant since the foam pressure on the platen is balanced by the fluid pressure within the platen reservoir. The fluid film is accurately controlled to maintain it at a normal working thickness of 0.005 inch (0.127 mm). 

Bonded joints are extensively employed in the construction of composite structures in aerospace applications, maritime structures, lifting equipment, wind mills as well as automotive industries [3, 4, 5], Unlike the bolt hole in mechanical fastening that causes a stress concentration in the composite joint plates, adhesively bonded joints minimize the potential for stress concentration within the joint. Besides, applications where lower structural weight, improved damage tolerance design philosophy are required, adhesively bonded joints provides a potential solution. Bonded joints are an efficent fastening solution also for hybrid structures, i.e., structures where composite parts are connected to metal parts. 

For bore holes and shafts, thermal expansion is very important and should be calculated in the course of construction. The assembly and production-oriented design of the mold should not be overlooked. In principle, it must be ensured that the shaping geometry and the entire mold structure can be designed in a way that always the most cost-effective production process can be applied. Flat parting planes should be provided, standards for plate dimensions for the construction should be used, and the diameter of the cavity should be selected so that little machining is required. Radii and aspect ratios should be chosen with care to avoid costly erosion, and tolerances should only be set at the functionally relevant dimensions. 

Withdrawal of labour does not have to be negative. For example, when a steel plate leaves the mill, it is flat within the tolerances of the British Standards. If after construction it appears warped or it is not what was sent out or what was on the drawing, whoever sees it should have some means of querying it. The pressures on people not to query things are much greater than the incentives on them to do so, and this could be reversed. 

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