Testing on intermediate goods and final goods made of plastics
The objectives of testing specimens taken from finished parts or intermediate products differ significantly from those of molding materials testing. Molding materials testing produces material data that can be compared. This data can be used to compare materials, however calculating the characteristics of a finished product is not possible in most cases.
Therefore, tests on intermediate goods and final goods are performed with two different objectives: determination of functional properties and determination of material properties of a good or product.
Measuring the notch resistance of electrically low voltage cables
- Every car has many meters of low voltage cable inside. These cables run through the entire car and when installed, make contact with very sharp edges at times. The insulation of these cables must not be damaged.
- To measure this behavior, the automobile industry developed the LV 112 test method to determine the notch resistance of cable insulation.
- The principle is simple. A cable is placed on a plate and electrically connected to a contact element. The test die has a extremely hard, high-strength wire, also electrically contacted, as the cutting tup. Using the wire, a load is applied to the cable until the electrical contact between the cutting tup and the cable's conductor is established. The force required for this is recorded by the testing machine. This offers a realistic assessment of the notch sensitivity of the cable insulation.
Determining the stack height of packaging
- Yogurt cups, beer crate, or water bottles— each type of packaging is stored for some amount of time in a warehouse and is stacked there. But how may layers of packaging can be stacked without breaking those on the bottom?
- The question can be answered very simply by a testing machine. To find out, the filled or empty packaging is compressed individually or in a stack between the compression platen of the testing machine, measuring the maximum load capacity. The value allows us to determine how many layers can be stacked on top of each other.
- But how can the packaging be improved? Typically, the mechanical characteristics should be achieved using the lowest material cost possible. To achieve this, an intelligent, constructive design is needed and the engineer must understand where the critical points of the container are. The testing machine is equipped with a video camera and the testXpert III Video Capturing Plus option, which synchronizes the film sequence with the force travel diagram. It allows the engineer to analyze the deformation behavior of the packaging under any load and can optimize points that are truly critical.
Measuring the activation force of a spray pump
- Many products are marketed in packages that must also perform a specific function.
- One example is a spray pump, which is used for expensive perfume as well as household cleaners. The window cleaner must be stored in the bottle, but must also be able to be sprayed onto the window in a forceful stream or as an atomized spray.
- The activation force must be tolerable for the user, and the dose must be high enough so that the user does not have to pump the handle too often.
- ZwickRoell’s electromechanical testing machines assist here as well, to optimize the product and assist in quality control by measuring the activation force of various pump speeds. Subjective perceptions of quality are measured in this way.
Measuring the force required to open the container
Who hasn't encountered this problem? The creamer lid needs to close tightly, but still be able to be opened without a lot of effort. In a worst case scenario, the creamer doesn't pour into the coffee cup, but rather spills onto your shirt or blouse. To prevent this from happening, high-quality manufacturers test opening forces with a testing machine. The test sequence mirrors the exact same sequence as when a human opens the package. First the die presses in the lid and breaks the seal. Then a small hook opens the lid. The forces required are recorded by the testing machine.
Measuring the corner stiffness of window frames
Synthetic windows must be able to withstand many loads and still close tightly over a long period of time. The corner stiffness of the window frame is one of the characteristics that is used as a characteristic control point. A defined support that enables frictionless movement of the leg of the test specimen ensures high reproducibility of the measured forces.
Function tests on syringes
Syringes are manufactured in large batches and must meet high quality standards. One test measures the glide force and the activation force of a filled syringe. ZwickRoell offers the right fixtures for these tests, and these fixtures can be mounted on any testing machine. The testXpert III software controls the test sequence and automatically determines the results, such as the average friction force.
Determining the pull-off strength of a backpack
- School backpacks must withstand a significant amount of wear and tear— heavy books, a snack, and whatever else children need at school. They are carried and sometimes hung by their handles and straps. So that backpacks last multiple years, the handles and straps must be firmly attached.
- This example shows a backpack being tested. A clamp from ZwickRoell's product line of tools holds the backpack in the testing machine while a hook pulls on the handle. This ensures that the seams and plastic parts withstand wear and tear for many years.
Determining the stacking strength of plastic cups
Dynamic testing of the resistance of a dog leash
Load tests on mattresses
Flexural strength and hardness of a toothbrush head
Testing of Material Properties of a Product
- During the manufacture of a finished product or a semi-finished product, the processed polymer is subject to a variety of mechanical, thermal, and chemical loadings and normally forms orientations for the polymer chains and fillers. Therefore, the mechanical properties of a polymer differ at various points of the component.
- To compare material properties of an end product produced by injection molding, extruding, or compression molding, a sampling plan for the specimen is defined. This sampling plan is based on the forming process of the end product and defines the number, form, size, and direction of sampling of the specimen.
- After appropriate conditioning, the specimens taken are tested to the test standards also used in molding materials or to specific information found in the product specification.
- Regular specimen sampling from ongoing production ensures that specific material properties remain constant in one product within predefined tolerances and over longer production periods.
- ZwickRoell supplies reliable universal testing machines and extensometers for tensile, flexure and compression tests, together with pendulum impact testers, hardness testing machines, extrusion plastometers and HDT/Vicat testers in manual and fully automated versions. Thus, the statistical scatter of your results is significantly reduced.
