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    • CommentAuthorqzz10011
    • CommentTime17 11 2017
     

    Two times the processing method of turning machining method actually belongs to plastic, Teflon PTFE sintered products due to low hardness, and good toughness, therefore, processed into teflon film by metal cutting method. Turning generally requires special lathes, metal processing lathes and woodworking lathes.

    The cutting blanks of TPFE Teflon bar sintering molding. This bar is a sintering process, the internal organization and the plasticizing degree is not very uniform, sometimes with some raw materials, and the bar with the change of the environment, easy to deformation, these are not permitted by the film production. Therefore, PTFE embryo material needs pretreatment.

    The pretreatment can be carried out in the sintering furnace, the general treatment temperature is 360~380, after reaching the temperature, holding for a certain period of time, and then slowly cooling to room temperature. For large embryo material, it can be stored at 327 2H for minutes at first, then dropped below 250 degrees Celsius, and then wrapped to room temperature. The treated embryo material can be processed by turning after 3~5 days.

    Most of the same PTFE Teflon plastic, the compressive strength is higher than the tensile strength, generally 2~3 times, the plastic compressive fracture force constant is greater than the tensile force. Therefore, in the turning process of PTFE, the shape of cutting tools and the choice of turning conditions should be well designed so as to avoid tensile fracture.

    The tool used in turning is made of carbon steel quenching tool. The cutting edge is sharp and the rake angle is bigger. From the mechanical point of view, it is more conducive to tensile fracture and can reduce the turning force accordingly. Therefore, the rake angle of the tool should be above 20~30 degree.

    If conditions permit, turning PTFE Teflon should be carried out in a constant temperature environment, because PTFE changes with temperature, the size change is relatively large. Generally, the processing temperature is always at 22~25, and the temperature changes little, which can ensure the uniformity of the film. At the same time, the heat generated by turning process is easy to change the temperature. Therefore, when the film precision is high, the spray cooling should be carried out during cutting. Liquid fluorides are commonly used in cooling media.

    The turning speed should be properly chosen to prevent overheating and cooling. At the same time, the cutting speed also affects the performance of the film, such as finish. Turning speed in general PTFE Teflon is 90~225m/min.

    Turning process of the film thickness up to about 0.04mm. The film has good mechanical properties, without any substance in the process, low impurity content, non-toxic, and can be used in medicine.


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