Fastener testing allows you to determine the mechanical properties of externally and internally threaded fasteners, washers, direct tension indicators, and rivets. Testing may consist of a machined specimen or a full-size product. The type of fastener testing that will be described below applies to a full-size product testing. Fastener testing is not applicable to all. The head design, shank thickness, and product length can determine if the testing is required of the product.
A proof load test consists of stressing the product with a specified load that the product must withstand without measurable permanent set (Method 1 - Length Measurement). The load that is used to stress the fastener is specific to the size, and grade/property class.
A tensile test yields a tensile load, which is then calculated to an ultimate tensile strength, or UTS. UTS is the maximum tensile stress a material can sustain without fracture. For fastener testing there are two types of tensile testing we perform, axial and wedge.
An Axial tensile test is a method for determining behavior of materials under axial tensile loading. The tests are conducted by fixturing the fastener into the test apparatus and then applying a force to the fastener by separating the testing machine crossheads.
A Wedge tensile test is an axial test, except that a wedge is placed under the head during the testing. This wedge tensile test is typically done on hex or square head fastener and socket head cap screws. This test is to see if the head of the fastener is capable of sustaining the added stress of the wedge.
Test Method/Material and Property Requirements
- ISO 898-1
- ISO 898-2
- SAE J429
- SAE J995
- SAE J1199