Application of the hottest mechanical thickness ga

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Application of mechanical thickness gauge in packaging materials II

3. Design difficulties and solutions of mechanical thickness gauge through the analysis of standards, we can see the performance and requirements of the machine according to the requirements of flexible packaging film. Mechanical thickness gauge has two design difficulties: first, the control of the pressure of the measuring head; The second is how to realize the high parallelism of the upper and lower measuring surfaces

3.1 control of the pressure of the measuring head

the compression deformation of the soft packaging material can not be ignored when it is under pressure. Therefore, the requirements of the standard on the contact area and pressure of the sample must be strictly observed during the test. Different standards have different requirements for the test area and the pressure applied. For example, the thickness of the paper is also tested. The pressure applied is required to be 50kPa in ASTM d645, but the pressure of lookpa is preferred in ISO 534. Therefore, when comparing the test results, we must pay attention to the test standards and test conditions

the mechanical thickness gauge with the same principle produces different test results when testing the same sample. The main reason is that the pressure applied to the sample in the measurement process is different, because the development of the equipment is carried out in accordance with the standard. The commonly used simple thickness gauge is the screw micrometer, but the pressure it exerts on the sample is not easy to quantify, and the force applied when measuring film and paper is the same, which obviously does not meet the requirements of relevant test standards. Therefore, it is unilateral to compare the test results without including the test conditions imposed by the thickness gauge

3.2 requirements for the parallelism of the measuring head and the measuring base

there are two basic requirements for the measuring head and the measuring base: the two measuring surfaces of the measuring head and the measuring base are parallel to each other, and the moving direction of the measuring head should be perpendicular to the measuring picture of the measuring base. The relevant description in ASTM D 645 is as follows: the surface of the presser foot shall be parallel to the surface of the anvjl towithin 0.00lmm. The presser footmovement shall be on an axis that is perpetual to the anvilsurface. (the surface of the measuring head shall be parallel to the surface of the cutting board, and the difference shall be kept within 0.oolmm. The measuring head shall move in an axial direction perpendicular to the surface of the cutting board.) In fact, ensuring that the movement direction of the measuring head is perpendicular to the measuring surface of the measuring base is also to ensure that the upper and lower measuring surfaces are parallel in the measurement process and ensure the test accuracy of the equipment

there are two common measuring heads for measuring film thickness: planar measuring head and spherical measuring head. The former can make the tested area of the sample under uniform stress, while the latter is easy to realize that the upper measurement point is parallel to the lower measurement surface, but the measurement area and pressure cannot be controlled and quantified. Most mechanical thickness gauges choose planar measuring heads, so the test data are more representative

for the parallel processing between the measuring head and the base, labthinkchy-c1 adopts a set of automatic "leveling" structure. Once the calibration is completed, the user does not have to move again. Of course, it is necessary to ensure that the two measuring surfaces are parallel, not only to ensure that the two measuring surfaces are clean and free of dirt, but also to avoid touching the measuring head as much as possible. If the test device is disassembled without permission, the accuracy of the equipment will be completely lost

4. Outlook

due to the compressibility of its structure, which is expected to reduce the plastic part of the vehicle and feed back the out of tolerance signal to adjust the traction or screw speed by 20%, the application of various non-contact thickness measuring equipment is limited, and more and more composite materials are used to replace metal materials. Mechanical thickness gauge has always been the first choice for thickness measurement of various soft packaging materials. Of course, the thickness values of the same soft packaging material under different pressures are generally different. It is a major feature of soft packaging material thickness measurement to detect under the specified standard test pressure according to the material of soft packaging material

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