With so many different force test stands available, choosing one that suits your needs may seem a difficult task. However, this decision can be made easier by clarifying some confusion in the differences between specifications for travel distance, clearance, and throat depth.
Clearance (also known as daylight) is defined as the maximum possible distance between the force gauge's loading shaft and the base of the test stand. This specification is useful in determining if the sample's dimensions fit into the constraints of the test stand. Clearance does not take grips, fixtures, or other attachments into account. That is, if such accessories are used to help secure the sample during a test, these will cut into clearance, since one such accessory is normally mounted to the force gauge, and the other to the test stand's base. It is, therefore, important to note the overall length of these accessories and factor them into your calculations. If it is determined that the clearance is insufficient, most Mark-10 test stands' columns can be extended.
Throat depth is also a distance specification, only this refers to the maximum possible distance between the centerline of the force gauge's loading shaft and the column. In determining whether a sample will fit within the constraints of the stand, throat depth should be doubled to calculate the maximum possible sample diameter.
Travel distance (also known as stroke) is often confused with clearance, but the two are quite different. Travel distance is defined as the maximum travel the force gauge is able to move vertically along the length of the column. Many applications require relatively little travel, such as Belleville washer testing. However, in testing elastic materials such as rubber, plastics, elastomers, and others, longer travel is required.
With these specifications clearly defined, choosing an appropriate test stand should not be too daunting a task after all. We provide a comparison chart that compares stands on these, and other, specifications, and can be seen here: http://www.mark-10.com/instruments/stands/stand%20comparison.html.
Happy testing!
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