Some plastic injection molded products for medical use are made of a combination of multiple parts, and these parts may be assembled by fitting each other. If there is no gap between the mating parts that acts as a “Nozoki” (invitation) to some extent, the work efficiency of the assembly work will deteriorate. For products used for medical purposes, cleaning and autoclave are frequently performed because they need to be kept clean. However, if there is no gap between the fittings, it will take time and effort to disassemble.

If it is designed as the fitting force can be adjusted at the design stage of plastic injection molding, the efficiency of assembly work will increase, and costs will be reduced by reducing man-hours. For example, a taper is used, and the beginning of the fitting is used as a “Nozoki” with “loose fitting” so that the fitting can be firmly fitted as the parts are inserted deeper. Also, products that are frequently cleaned and autoclaved, such as plastic injection molded products for medical equipment, can be easily removed.