In modern industrial manufacturing, plastic products are widely used in various products due to their advantages such as light weight, corrosion resistance, and low cost. Among them, plastic rulers, as an important part of measuring tools, directly affect the accuracy of measurement results. The molding process of plastic ruler scales is one of the key links that determine their size accuracy. Therefore, studying and standardizing the size tolerance range of plastic ruler scale molding is of great significance for improving product quality and ensuring measurement accuracy.

The basic principle of plastic ruler scale molding

Plastic rulers are usually manufactured by injection molding or molding. Among them, molding is a processing method that places thermoplastic materials in a mold, and shapes them into the required shape under certain temperature and pressure. For the ruler scale, it is necessary to ensure that the spacing, width, and depth of the scale lines during the molding process meet the design requirements to ensure the measurement accuracy of the ruler.

During the molding process, due to factors such as material shrinkage, mold deformation, and temperature changes, there will be certain deviations between the finished product size and the design size. This deviation is known as size tolerance. A reasonable tolerance range not only ensures the functionality of the product but also reduces production costs and improves production efficiency.

Two, The Importance of the Molding Size Tolerance of Plastic Ruler Graduations

Affecting Measurement Accuracy

The error in the spacing between the graduations of the ruler will directly lead to inaccurate measurement results. For example, if the spacing is too large or too small, the user may misread the value when using it, which may affect the measurement effect. Therefore, controlling the tolerance range of the graduation size is the key to ensuring the functionality of the ruler.

Affecting Product Uniformity

In mass production, if there are significant differences in the size of the ruler graduations between different batches or within the same batch, it will affect the uniformity and interchangeability of the products. This not only reduces user experience but may also trigger quality issues.

Affecting Subsequent Processing and Assembly

Plastic rulers are often used in conjunction with other components, such as in instruments, meters, or electronic devices. If the size tolerance of the graduations is too large, it may cause difficulties in installation or poor fit, which may affect the overall performance.

Three, Determining Factors of the Molding Size Tolerance of Plastic Ruler Graduations

Material Characteristics

Different types of plastic materials (such as polypropylene, polyethylene, ABS, etc.) have different shrinkage rates during heating and cooling, which directly affects the size stability of the final product. Therefore, choosing the appropriate material and understanding its coefficient of thermal expansion is the basis for controlling the tolerance.

Mold Design and Manufacturing Precision

The precision of the mold determines whether the size of the molded part meets the requirements. The mold cavity size, surface roughness, structural design, and other factors will affect the quality of the graduation molding. High-precision molds can effectively reduce the tolerance range.

Process Parameter Control

The reasonable setting of process parameters such as temperature, pressure, and holding time directly affects the fluidity and curing effect of the material, and thus affects the final size accuracy of the product. By optimizing process parameters, it is possible to effectively control the tolerance range.

Post-processing Technology

Some rulers need to be treated with annealing, cooling, and other processes after molding to eliminate internal stress and reduce deformation. These post-processing steps will also affect the final size accuracy.

Four, Specifications and Standards for the Molding Size Tolerance of Plastic Ruler Graduations

Currently, there are relevant standards at home and abroad that specify the size tolerance of plastic rulers. For example, the GB/T 10610 'Plastic Ruler' standard clearly stipulates the tolerance range for parameters such as graduation spacing, line width, and depth. In addition, ISO standards also provide similar reference bases.

Generally, the tolerance of the spacing between the graduations of plastic rulers is usually controlled within ±0.1mm, and the tolerance of the line width of the graduations is generally ±0.05mm. The specific values need to be adjusted according to the actual application requirements and material characteristics. In high-precision measurement situations, more stringent tolerance requirements may be needed.

Five, Conclusion

The reasonable setting of the tolerance range for the molding size of plastic rulers is an important link to ensure product quality and measurement accuracy. By comprehensively considering various factors such as materials, molds, processes, and post-treatment, it is possible to effectively control the tolerance range and improve the stability and consistency of the products. In the future, with the development of intelligent manufacturing technology, more precise tolerance control methods will emerge continuously, further promoting the plastic ruler industry towards high precision and high quality.