Everything You Need to Know About Computer Aided Design (CAD)


Making the use of a computer to assist in the creation, modification, analysis, or optimization of a design is called Computer-aided design (CAD). A specified software is used in design creation of the part and this software helps to enhance the designer’s productivity, improve the quality of design, improve communications through documentation, and to create a database for manufacturing.

In the past, creating a design was not so easy as we can easily do using computer software now. Before the development of this technology, the designs used to create drawings include using drawing boards, papers, rulers, calipers, and other hand drawing instruments. These old instruments and techniques for manual drawings are still available now. But in order to get benefits from these advanced machining technologies, we need to use computer aided designs.

This is because the modern CNC systems can read the information right from the files. It helps them to bring out a suitable cutting program as per the requirements of the manufacturing. But using manual drawings would make the process inefficient and unmanageable.

The technological advancement brings CAD software that has made the design creation very easy and it proves to be a blessing for the designers. These software offer numerous merits over manual drawings. You can easily create a part drawing in just a few simple steps.

If you are looking to know what is necessary about computer aided designs then read till the end. We hope that you will be able to learn a lot of valuable things ahead in this article. We will discuss about CAD designs, their advantages, top techniques to improve your CAD design, and some important practically implemented tips.

Benefits of Using Computer Aided Design

Some benefits of creating your part design using CAD over traditional drafting and 3-D model making are discussed below

  • Using a CAD provides you with the benefits of creating a simple and precise automation and process modeling (known as mechanical design automation). Conventionally, if you were required to create a mechanical design automation for a part then you first needed to make its physical prototype. And you had to assemble it to check whether it fulfills the purpose or not. But CAD provides an exceptional facility to digitally model and automate a prototype before generating a physical model. Therefore, using a computer aided design provides extensive manufacturing efficiency and cost-effectiveness.
  • Using a CAD provides with the benefits of converting your CAD design file into a programming code called a CAM code (computer aided manufacturing). Which then dictates the CNC machine and different tools to produce your product.
  • CAD takes into account material properties and interactivity characteristics between different materials.
  • CAD makes the use of vector graphic technology that empowers it to perform a highly accurate dimensional analysis and mathematical scalability.
  • CAD helps to increase productivity as it enables designers to work faster and smarter that in the end leads to swift part manufacturing.
  • Using a CAD provides highly precise part tolerances.
  • CAD designs can be easily reused for manufacturing and making design changes is also quite easier.

Top Techniques to Improve Your CAD Design

In the manufacturing industry, quality drawings are considered as the backbone of your overall CNC process. No matter what your engineers and technicians are capable of. If your designer can not create such drawings that cannot tell the shop floor exactly how each part, structure or assembly will be manufactured. Then don’t worry, we are going to elaborate various important techniques that will help you to improve your CAD designs.

The following drafting techniques will assist you to learn something valuable or refine your CAD designs. That will surely enhance the manufacturability of your drawings, improve the clarity, precision and accuracy and it will help to optimize your templets.

  • You Must Avoid Designing Unnecessarily Thin Walls

While designing your part drawings, you must avoid designing unnecessary thin walls. Otherwise, you may face workpiece stiffness issues that will cause decreasing machining accuracy. Since, the wall thickness of the workpiece is directly proportional to the stiffness of its material. So, if you use excessively thin walls, it will result in unavoidable vibrations during the machining process. Thus, your machining accuracy will be affected. For metals, the standard minimum wall thickness is 0.794 mm. Whereas for plastics, it is 1.5 mm.

In some cases, if it is a necessary requirement to design thin walls then it is highly recommended to use other manufacturing techniques for better final output and cost efficiency like sheet metal fabrication. Typically, manufacturing drone parts or whistles require thin walls.

  • You Must Avoid Designing Such Features That Can Not Be Manufactured

            One this is for sure, even after the inclusion of Artificial Intelligence in the CNC machining, it still has its own limitations. We cannot manufacture every design using CNC technology. So, before you start your drawing, it is very advantageous to know in advance that the particular design feature you want to include weather CNC can machine it or not.

             For example, if you want to create a curved hole using CNC mills, lathes or drills. Then, you will not succeed because manufacturing curved holes are beyond the machining capabilities of the CNC technology. For such design, you can use electrical discharge machining. So, it is highly advisable to avoid the inclusion of any such feature to your drawing that cannot be machined using CNC.

  • You Must Avoid Using Immoderate Tolerances

            As a designer, you must avoid using immoderate tolerances because excessive tolerancing will result in project delay and increased manufacturing cost. You are anticipated,

as a designer, to tolerance dimensions where necessary and must maintain homogeneous

tolerancing to lower machining time. Tight tolerances should only be specified in case if necessary. If your dimensions have no tolerancing then the machine will use its standard tolerance for such dimensions. Because every CNC machine has its individual tolerance standards.

            Sometimes, designers introduce such features to enhance the aesthetic of the drawing just to look smart or to impress his/her senior. But while doing so, they must keep one thing in mind, introducing unnecessary features may result in project delay and can affect processing efficiency. So as a designer, you must consider that the design which you are creating weather it can be machined or not. What processes will be executed to successfully accomplish it. You can create an excellent drawing if you pay more attention on the design creation rather on its looks. Aesthetics can be achieved by applying many processes after the completion of the part such as deburring, polishing etc.

  • You Must Design Cavities with Perfect Depth-to-Width Ratios

             If you want to create a good CNC design then you must design the cavities perfectly. To do so, just take care of the depth-to-width ratio of cavities while designing them. As a thumb rule, the cavities higher than six times the tool diameter are considered to be deep, and should have a maximum depth of four times the width of the cavity. For example, a 10 mm wide cavity should not have a depth of 40 mm (i.e., four times of the width of the cavity). The problems that too deep cavities can cause include tool deflection, tool hanging, and tool fracture.

             You should not design unnecessary longer thread lengths. Generally speaking, strong thread connections take place in the first few threads. That’s why designing extra-long threads are not recommended at all. Keep in mind that a thread longer than 3 times the hole diameter is unnecessary.

  • You Should Not Design Too Small Features

             It is advisable to avoid designing too small features that will become impossible to machine then. Generally, most of the CNC machines have a minimum tool diameter of 2.5mm. So, when you design too small features that has a diameter less than 2.5 mm, it must be avoided. Reason being, it will be very hard to machine it because it would require a special tool resulting in cost and time increase.

  • You Must Design Standard Size Thread Holes

To save machine time and cost, it is recommended that you must design standard sized thread holes. Because standard sized holes are milled using standard drill bits. But if you do not design standard sized holes then you will have to use an end mill tool to make them standard. In case of non-standard holes, you must apply the same rule as we discussed above for depth of cavity i.e., the depth must be four times the diameter of the cavity.

If you are looking to design your part’s drawing then you are at the right place. We have a seasoned team of CAD designers. They have years of experience working in CNC machining industry. Our designers are the best at what they do. They have designed hundreds of CNC drawings. The above- mentioned techniques that we discussed with you, are written in the light of their expertise and directions. Contact us and then leave the rest on our designers.

Cora Feng
Cora Feng

Project Manager working on CNC Machining since 2010

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