Elevator doors have two major types, manual and automatic. Manual doors are normally opened and closed manually by hand, and automatic doors are the standard type of doors found in modern days elevators, usually powered by a door operator.
Non-automatic/manual doors
Automatic doors
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These doors are normally opened or closed manually using hands, although some of them close automatically. Most older and small European elevators from the 1950's to 1970's are using manual hinged door (similar to normal room doors), while the inside has a manual sliding scissor gate or often there is no door at all. For manual doors, sometimes the door can be spring loaded so the gate can't be left open, or the gate can automatically close when you press the button, and partly/completely close when the elevator gets to a floor. The inside door can also be a tubular gate, which is a gate that in many cases folds around the side of the cab when it is open (often called a barred gate by elevator enthusiasts, though this is likely not the actual term), and which can be automatic or manual.
These type of door is still used today, normally for smaller wheelchair lifts or home elevators. Some older freight elevators may have a horizontal or vertical manual doors. In some Asian countries, one may find an old freight elevators with manual accordion or scissor gate. Some old elevators may have a semi-manual doors a configuration of manual door outside and an automatic door inside.
Automatic doors are the standard type of doors found in modern days elevators which was introduced in 1887. Almost all the automatic doors are usually powered by a door operator installed on the elevator car. Those except manual door with automatic door opening/closing device and all the incline elevators with every independent door operator belongs with every single shaft doors and car doors.
Polycarbonate (PC) is a versatile thermoplastic that can be processed using various techniques, including injection molding, extrusion, blow molding, thermoforming, printing, bonding, coating, and machining. Among these, injection molding is the most widely used due to its efficiency and ability to produce complex shapes with high precision.
Before processing, it's essential to pre-dry polycarbonate to ensure moisture content remains below 0.02%. Even small amounts of moisture can cause issues during high-temperature processing, such as discoloration, silver streaks, or bubbles in the final product. At room temperature, PC exhibits significant elastic deformation capability, making it suitable for cold forming processes like cold drawing, rolling, and stamping.
For extrusion applications, the molecular weight of PC should exceed 30,000, and a graded compression screw is recommended. A length-to-diameter ratio of 18:1 to 24:1, along with a compression ratio of 2.5:1, helps achieve better flow and quality. High-quality, transparent bottles can be produced through extrusion blow molding, injection-blowing, or injection-pull-blowing methods.
PC can also form alloys or blends with other polymers to enhance its properties. These combinations improve processability, reduce stress cracking, and offer better performance in different applications. Common PC-based alloys include PC/ABS, PC/ASA, PC/PBT, PC/PET, PC/PET/elastomer blends, PC/MBS, PC/PTFE, and PC/PA. Each blend offers unique advantages—such as improved impact resistance, heat stability, or aesthetics.
For example, the PC/ABS alloy combines the high heat resistance, toughness, and strength of PC with the good flowability and surface finish of ABS. This combination not only enhances the material’s overall performance but also reduces production costs and improves design flexibility. By blending materials, manufacturers can tailor the properties of polycarbonate to suit specific industry needs, from automotive and electronics to consumer goods and medical devices.