Basic Engineering Drawing Pdf
Millard Winnin
As already said, such a technical drawing has all the information for manufacturing a part or welding and building an assembly. The info includes dimensions, part names and numbers, etc. So once a manufacturing engineer gets the drawing, he can start the production process without a second thought.
First, we have to pause for a second and address our own customers here to avoid confusion. The drawings you submit for instant pricing and manufacturing in our system do not need any of this. The same applies to 3D models. CAD files and drawings made according to our design tips include all the necessary information for making your product. The only time we ask for a drawing is if you want to specify tolerances.
A few decades ago, you would have had to sit down at a drawing board covered with papers of different size, rulers, callipers, etc. Today, all these instruments are still good for manual drafting but no contemporary manufacturer really wants such drawings.
Why? Because most of the machinery uses CNC systems that can read the information straight from the files and produce a cutting program accordingly. Drawings done by hand would just add a lot of manual work for manufacturing engineers.
You can, of course, use CAD for making drawings from scratch. But the easier option is to first make a 3D model and create the drawings from that, as the programs generate the views with only a few clicks. All you need to do is add the dimensions. Having models also makes updating the drawings for revisions simple.
Hidden lines can show something that would not be otherwise visible on the drawings. For example, hidden lines may show the length of an internal step in a turned part without using a section or a cutout view (we explain both later).
Break lines indicate that a view has been broken. If you have a part that is 3000 mm long and 10 mm wide with symmetric properties, using a break-out makes gives all the info without using as much space.
While a good way for giving information to people, CNC machines need full views in order to cut the parts. Otherwise, the manufacturing engineer has to reconstruct the whole part from the measurements.
The lines that are vertical and parallel are in their true length. This means you can use a ruler and the scaling of the drawing to easily measure the length straight from a paper drawing, for example. The same does not apply to angled lines.
It is important to distinguish the isometric view from a perspective view. A perspective view is an artistic one that represents an object as it seems to the eye. Engineers stay true to the dimensions rather than optical illusions.
If you are making a folded sheet metal part, do not forget to add a flat pattern view. The cutting job comes before bending. When it comes to our customers, the easiest way is just to upload a STEP file without any accompanying drawings.
If you are using the standard part environment, the same option is not available. Still, many CAD programs can convert a standard part into sheet metal if the part properties correspond to sheet metal (e.g. uniform thickness, inside radius, etc.).
A section view can easily display some of the part features that are not evident when looking just from the outset. Cross section is the preferred option compared to hidden lines as it brings more clarity. The cross hatching feature is an indicator for cross sectional views.
The detail view gives us a close-up of a selected section of a larger view. This can be especially useful if an otherwise large part includes many important dimensions in a small area. Using the detail view improves the readability of these measurements.
The keyword here is necessary. Avoid using the auto-dimensioning feature that a lot of CAD programs offer because they tend to show everything they can find. For a beginner, it may seem like adding it all ensures that no mistakes can be made.
Actually, it can result in a confusing web of measurements that is left for the manufacturing engineer to untangle. Also, adding all dimensions you can find makes it hard to pinpoint which ones are the most important.
The image above shows a shaft with all the measurements. In reality, it creates a closed system whereby the manufacturer cannot guarantee all these dimensions 100%. Therefore, you have to determine the most important ones. In our case, we chose the end steps to be more important than the length of the central part. Thus, we should delete the 120 mm dimension.
One crucial bit of information that is missing from CAD models is geometric dimensioning and tolerancing (GD & T). For example, when looking to produce a shaft for a bearing system, limits and fits are of high importance. The right dimensions can guarantee a longer life with less maintenance.
We at Fractory are trying to save this time by automating the reading of 3D models for production, be it for different cutting and bending operations or CNC machining. This leaves engineers with the task of producing assembly and GD&T drawings only. The purpose is to keep the focus on engineering better products.
The engineering community is seeing this movement as a new trend. But as we all know, taking the whole industry up to a new standard takes a lot of time. Thus, if you still outsource your production to manufacturing companies that need drawings, you must know the basics at the very least.
Engineering drawing is critical for effectively expressing your requirements to the manufacturer and ensuring the final product matches your expectations. This article aims to walk you through the engineering drawing basics and 8 crucial tips for creating better engineering drawings.
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Engineering drawings, also known as mechanical drawings, manufacturing blueprints, drawings, etc., are technical drawings that show the shape, structure, dimensions, tolerances, accuracy, and other requirements of a part in the form of a plan. It helps to define the requirements of an engineering part and conveys the design concept.
An engineering drawing can be used as a starting point for the creation of more comprehensive manufacturing drawings, manufacturing blueprints, mechanical drawings, dimensional prints, and more. Detailed information about the drawing, such as who drew it and who approved it, is contained in a title block or information box.
The engineering drawing of a single part provides a visual representation of the structure, dimensions, tolerances, and other requirements of a part. In the manufacturing industry, a single-part drawing is often used as the unit of processing.
An engineer can make use of an assembly drawing to show a machine/equipment that is assembled from several parts to achieve a certain function. Assembly drawings are often used to verify that the actual production of individual parts meets the assembly requirements.
Drawing boards, paper, rulers, calipers, and round gauges are essential tools for manual drawing. Suitable for university courses, they play an important role in developing the spatial imagination and conceptual skills that underpin creative thinking in university students.
Computer drawing, commonly used in CAD software, is more suitable for the contemporary manufacturing industry. CNC machining centers equipped with CNC systems can read data and information directly from digital files and generate machining programs accordingly, saving time and effort. At the same time, computerized drawing facilitates the modification of drawings, on the one hand allowing different versions of the design to be retained, and on the other hand eliminating the tedious process of manual drawing.
The 3D model can also be used in machining centers but requires engineering drawings to communicate important information such as materials, tolerances, special requirements, etc. We usually recommend the use of a 3D model in conjunction with engineering drawings.
In addition, it includes technical details such as the measurement units, the angle of projection, the surface polish criteria, the scale, and the material of construction. Title blocks are used for a better understanding of all the parts of the technical drawing.
Lines that are not visible to the naked eye can reveal information that would otherwise be obscured by the designs. The length of an interior step in a turned part can be shown using hidden lines instead of a section or cutout view.
Parts with holes and symmetrical features can be shown by using center lines. Symmetry can reduce the number of dimensions in a drawing and make it more visually appealing, making it easier for the reader to comprehend.
When a view is broken, break lines appear. In the case of a part that is 3000 mm long and 10 mm wide and has the same geometric qualities, a break-out provides all the information without taking up too much space.
A Dimension is a numerical value that expresses the size, position, orientation, form, or any other geometric properties of a part in the relevant units of measurement. Dimensioning, thus, is the process of depicting on a drawing the size of an object, as well as any other data critical to its design and operation, by means of lines, numerals, symbols, notes, etc.
In addition, when parts are machined, it is often difficult to guarantee that a 10mm length can be 100% 10mm, and the final product may be 9.9mm or 10.2mm. This can be done by defining tolerances to limit the upper and lower limit deviations and helping suppliers understand important dimensions.
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