Liquid silicone rubber testing is a critical element in the production process, it is the best way to assure key functionality requirement of final LSR parts. In LSR materials testing, we should analyze and verify the key properties of LSR raw materials. There are a wide range of LSR testing methods available to ensure quality and consistency.
Why LSR Testing is Important?
In LSR testing, both LSR material testing and LSR part testing are important. These testing serve many essential purposes as the following:
LSR Materials testing can observe and verify key properties of LSR materials.
LSR parts testing can detect potential issues in manufacturing process.
Testing methods for high concern substances is critical for LSR products with strict substances limiting regulations.
All the data in testing process will inspire new concepts, this will enhance performance in mold design and LSR injection molding process.
Liquid Silicone Rubber Testing Methods
There are various professional methods for LSR materials and LSR parts testing, we will introduce these methods in the following sections:
Infrared Spectroscopy (IR)
Infrared spectroscopy is an effective method for early detection of fluctuations in LSR materials. The IR testing analyzes the wavelengths absorbed by LSR materials once exposed to electromagnetic impulses. The test data is a useful reference for different LSR materials comparison and out-of-spec properties identification.
There are some benefit of IR testing method on LSR materials:
- LSR materials test results provide valuable evidence for adjustment in LSR injection molding process.
- Results on out-of-spec findings provide substantiation for material inspection before processing.
- Demonstrate the correlation between the chemical and mechanical data. Exhibit a comprehensive view of all LSR materials curing properties. Provide insight into the chemical element behind the reactions.
Rheology
Rheology is the analysis method of cross-linking reaction in LSR materials. In LSR analysis process, we measure the shearing resistance after mixing two LSR compounds (A&B) at a defined temperature, such as 110℃. With the variation data in shearing resistance, we can optimize the injection molds and the molding process parameters, in order to enhance process quality.
Furthermore, rheology measurements are also effective to analyze thermoplastic materials, we can observe thermoplastic polymer behaviors after melting. From these analytic data of thermoplastics degradation in injection molding process, it is a useful way to compare the raw materials with the finished components.
The benefits of rheology analysis in LSR materials testing are as following:
- In liquid silicone rubber (LSR) materials rheology testing, the observation of crosslinking behaviors provides an excellent overall view. In addition, LSR viscosity measurement is the best method of materials insight.
- Crosslinking behaviors of LSR materials provide critical data in the curing process, such as duration, speed, and other viscosity data.
- Detail information of LSR materials behaviors will assist us to optimize LSR injection molding parameters. Such as injection pressure, holding pressure, cooling time, and cycle time.
- Observation and comparison data in different batches provide valuable information about crosslinking behaviors in inspection process.
Mechanical Testing
Mechanical Testing can provide detail information of materials’ mechanical characterization. It is the standard method for material properties’ verification in the material certificates. Therefore, we apply this method as the longtime standard in incoming material inspection and quality releases. The most common mechanical testing methods for liquid silicone rubber are hardness, tensile elongation, tear strength, and compression set. For example, we normally apply hardness measurement of Shore A for LSR materials.
Furthermore, mechanical testing is also an efficient way to observe the influence on liquid silicone rubber mechanical properties in injection molding process. This testing can detect and prevent non-conforming LSR parts from production releasing.
The benefits of mechanical testing including:
- Mechanical testing can reduce risk of material batch changes in processing.
- The mechanical performance testing can detect the potential issues, which will affect the quality of final LSR parts.
- The mechanical test data provide detail information to understand the effect in molding process.
- It is valuable to get the cause-and-effect knowledge in LSR molding simulations and new LSR products designs. This will improve the design insight and suitability for intended applications.
Adhesion Testing
Adhesion testing is critical to confirm the bonding between liquid silicon rubber and thermoplastic in 2-shot molding, or liquid silicone rubber and metal substrates in over-molding. This method normally measure the maximum force of pull-off on a standard test specimen. Such as, the mechanical adhesion testing detects the peeling properties, we can apply these data information to prevent potential adhesion-related failures of LSR materials.
Miwo has different types of substrate for adhesion-testing with LSR materials, this will assist our customer to determine the best LSR 2-shot molding or LSR over-molding solutions. Furthermore, our engineering team also can develop new apparatus or fixture for specific functionality testing, try to simulate LSR parts behavior as closely as possible.
Additional Testing Methods
There are other testing methods for LSR materials and parts inspection, all these findings will assist our engineers to optimize LSR materials selection, LSR parts design.
Rubber-filler Test: it will reveal the interaction between LSR polymer and various rubber-filler substances, and discover potential effect of LSR materials.
Dynamic Scanning Calorimetry (DSC): DSC testing analyzes the behavior of LSR materials or parts as heat increase. It is effective to observe the melting and crystallization of vulcanized or unvulcanized LSR elastomer.
RAMAN Spectroscopy: this equipment can analyze and identify the chemical structure and chemical compound in LSR products.
Thermogravimetric Analysis (TGA): this method can measure the stability of LSR materials by analyzing the mass change of specimen as temperature increase.
EN 12868: We normally apply this method to analyze the release of nitrosamines from LSR materials, this testing method is suitable for products like baby pacifiers and bottle nipples.
EN 14350-2: this test can detect volatile organic substance in LSR products, typically for children cups and other drinking products.
The Karl Fischer Method: Also known as ISO 760, this method analyze the reaction between LSR material water content and iodine, sulfur dioxide, pyridine, and methanol solution.
LSR Material Testing for Innovation
LSR products must satisfy customers’ requirements to add value for further development. Exploring and adopting new technologies and knowledge from teat will result in advance in LSR molding process. Our internal and external testing methods can ensure LSR solutions with high quality and customer satisfaction. As LSR parts size become smaller, we need to face the challenges of part geometries and performance requirements by new innovation.
Miwo has wide testing capabilities to ensure our LSR process and product quality. LSR materials testing can analyze and verify the key properties, these data assist us to optimize LSR molding and address issues in process. Furthermore, functional testing of LSR products is critical to verify specific properties of parts’ function.
Miwo is a professional liquid silicone molding company. We are constantly searching for the best LSR manufacturing way to improve quality and productivity.
Contact our engineering team for more detail information of liquid silicone rubber testing.
