When designing a silicone rubber keypad for production, the geometry and dimensions of the product being produced is critical. Designs communicate exact engineering tolerances and dimensions. With the use of computer models and engineering drawing, we can explicitly describe nominal geometry and the allowable variation.

With experience and knowledge in part design, SiTECH can ensure the interpretation of drawings to improve quality and to reduce costs. An engineering drawing communicates the geometry of the part, critical functional relationships, tolerances, part number and drawing revision number. Dimensions are defined as numerical values expressed in appropriate units of measurement and are used to define the size, location, orientation, form and other geometric characteristics of a part. Tolerance is the total amount of a specific dimension that is permitted to vary from the specified dimension. The tolerance is the distance between the minimum and maximum values allowed.

In silicone production, this standard for drawings helps to ensure the highest quality and functionality of the component being produced, with repeatable results. There are many fundamental rules defined in and applied to drawings to adhere to the standards of silicone rubber injection molding.

First and foremost is that all dimensions must have a tolerance. Every feature of all manufactured parts is subject to some variation. In turn, the limits of those allowable variations need to be specified. Plus and minus tolerances need to be applied directly to dimensions or applied from a general tolerance note. The dimensions should be applied to all the features and arranged in such a way as to represent the functions of each feature. All the dimensions and tolerances should be applied in such a way for maximum readability and should be applied to visible lines and true profiles.

The drawings define a part without specifying a manufacturing process. A 90-degree angle applies where centerlines and lines depicting features are shown on a drawing at right angles and no dimension is shown. A 90-degree basic angle applies where centerlines of features in a pattern or surfaces shown at right angles on a drawing are located and defined by basic dimensions and no angle is specified. Unless otherwise specified, all dimensions are applicable at 68 degrees F and all geometric tolerances apply to the full depth, length and width of the feature. Silicone can grow or shrink, depending on ambient temperature.

Drawing and interpretational errors can become very costly in terms of money, time, material and the inevitable delay in production. Using a standard and well-recognized method for drawing out exact dimensions and tolerances can help avoid problems and delays. Drawings using this standard help avoid issues in silicone rubber manufacturing, including drawing misinterpretations, understanding the designer’s intent and communicating complex drawing requirements. Silicone rubber injection molding is an excellent option when tight tolerances are required. With the latest technology, it is an extremely accurate production method with high quality and repeatable results for the life of your product. For all your custom silicone rubber manufacturing needs, you can trust the expertise in design interpretation and implementation SiTech can offer.