A working drawing is a drawing that includes all the information required to successfully and accurately execute a job. A detail drawing is essentially a working drawing that incorporates much more specific information including the size and shape of the project, the materials to be used, finishing information, and degree of accuracy needed. An assembly drawing, on the other hand, may incorporate very little detail (Figure 7.10). The purpose of this type of technical drawing is mainly to show how the machine is to be assembled.
There are several types of detail drawings used in various industrial settings. They convey the information and instructions for manufacturing the part, including the object's shape, size, and specifications. The detail drawing should provide all the information needed to produce the particular part (Figure 7.11). In addition to the part production, the detail drawing can be used when bidding a job or as a master drawing from which other drawings are produced. The information on a detail drawing is specific to the part to be produced, typically drawn one part per page or sheet. Included in the information should be the pertinent shape, size, specifications, and notes. The notes and/or title-block information would normally include the scale, tolerances, surface texture, and specified material. Other data may be required that stipulate finish specification, moisture contents, color code, and other specifications requested by the customer.
Figure 7.10 Two categories of industrial drawings are detail drawings and assembly drawings.
A casting drawing details the size and location of separation lines, called parting lines. When the mold separates, the parting line is left on the casting. The other information typically found on a casting detail drawing may be a pattern number, sand requirements, part numbers, customer name, draft, shrinkage, finish, ribs and other support webbing, and the material used in the casting/mold.
Wood patterns, made by patternmakers in the general male or female shape of the finished part are configured into the sand mold and removed, leaving an impression to be filled with molten metal. When cooled, this metal casting is removed and the process is continued. These castings are then machined into items such as engine blocks, cast-iron tools, or other metal castings we use every day. Bearing blocks, machinery bases and parts, and many household items have castings produced in this manner.
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