Bending strength or flexural strength is the stress in a given material just before it bends. In an object made of a single material, the stress level differs at different points. The bending strength is a key indicator in determining the stability of a material. Determining the bending strength is critical in a range of functions and industries, from buying parts of a machinery to manufacturing dental material. The bending strength is a reliable measurement of the strength of an object in resisting pressure or in ascertaining the point at which it can deform.
This why a bending strength testing machine is so important in manufacturing. The tests are done to determine the bend strength, ductility, fracture strength and the extent of resistance to fracture. In short, it tells us how a material will behave under pressure. It is especially important in testing construction material, from concrete slabs to body implants.
Apart from judging the strength of a given material, it is also useful in testing the strength of wends. The sleds or joints are where a construction is often the weakest. If the weld holds under a bending strength test, it is deemed an acceptable weld. This is especially important in construction industry. The bending strength of concrete and concrete joints in the construction of a bridge, for instance, gives us an accurate picture of the overall strength of the bridge.
The two most common type of bend tests are:
3-point bend: The three-point bending test gives us the elasticity in bending, flexural/bending stress, flexural/bending strain, and the flexural/bending stress–strain. This is an easy test to carry out. However, the specimen, strain rate and loading geometry is very specific.
4-point bend: The four-point bending test gives us elasticity in bending, flexural/bending stress, flexural/bending strain, and the flexural/bending stress–strain. The only difference from a three-point test is the addition of a fourth bearing, giving us a larger portion for testing.
How to select a bending strength testing machine:
Load: The material to be tested can be of a varied weight — from a lightweight dental implant to concrete. The machine to measure this will not be the same, since every machine will have some kind of weight range. Anything heavier can cause damage to the machine, while anything lighter than its lower limit will simply not register. So, determine the weight of the object to be loaded.
Type of object: Bending test is carried out on a whole of objects that include anything from concrete slabs to small chips. Although though science behind the test may be similar, the machine to carry these out will be very different. For instance, a micro test machine is designed to test miniature items only. Some machines are better equipped to test delicate objects like a plastic pipette tip than others which are designed to test heavier and bulkier objects like a wooden slab.
Keep the calculations ready: A bedding test is ultimately done according to a specific formula. It must account for the axial load, width, length and thickness of the material. The calculation, especially those pertaining to the material must be ready before we start looking for the machine. The force exerted will depend on the product specifications. SO, keeping it ready will save you from making mistakes later on.
Decide the speed: The speed of the testing could be important for those working at an industrial scale. Some machines are configured to work fast in a conveyer belt fashion. You may need to specify particulars like motor, actuator and drive. Today we can have automated machines that work fast and cut down on labour and time. But the question is whether, we need to make that expense.
Accreditation: It is critical that the machine meets the right ISO standards. These international standards are set to ensure that there is a standardization of machines and procedures. Without the standardization, we cannot impose a certain regulation in an industry. Also, keep in mind that the accreditation of the machines will also effect the accreditation of your own products.
Budget: As with every business decision, bending strength testing machines will also be decided according to the budget at hand. There is quite a wide range here — from international companies to local testing instrument firms. Going for the most expensive is not necessary. However, check if the firm has a reputation for reliability and carries all required accreditations.