There are many kinds of standard and custom plastic and rubber parts which are used in different industries that have wide variety of applications. While selecting or designing these plastic & rubber parts requires certain important consideration like kind of material, physical & mechanical properties, durability and flexibility. For rubber & plastic parts, its hardness is very crucial property which can decide how it can handle pressure in different conditions. That’s why these components to work optimally, it is essential to know & select right hardness for these parts.
To measure this hardness, a device called a Durometer Gauge is used. Let’s understand what it is and how it is used.
What is a Durometer?
A durometer or also known as shore durometer is a standardized way to measure the hardness of non-metallic materials like rubber and plastic. It measures the hardness of the materials like …
- Rubber Tubing, Strips & Hose
- Gasket & O Rings
- Molded Rubber Parts
- Thermoplastic Parts
The durometer measures the hardness of the material by testing its resistance against penetration and permanent indentation. The test is carried out with the help of a standardized pressure footer. The depth of the indentation depends on factors like
- The hardness of the material
- Viscoelasticity of the material
- The shape of the pressure footer
- Duration of the test
It is important to select the appropriate scale while testing the hardness of a particular plastic or rubber material. 12 different kind of scales are used to measure the hardness. However, the most commonly used scales are Shore A and Shore D scale. Scale A is used to measure the hardness of soft & flexible rubber and scale D is used for hard rubber, semi rigid plastics and hard plastic or rubber.
There are a few points that you need to remember about these scales.
- The range of scale is 0-100.
- If you get a reading of more than 90 on scale A, use scale D.
- If you get a reading of less than 10 on scale D, then use scale A.
How and Where is it Used?
Before starting the test, you need to keep a note of the following things-
- Both the A and D scales demand that the measurement is taken at least 12 mm from the material’s edge.
- You should apply the pressure for 15 seconds.
- The thickness of the material must be at least 6.4 mm. If the material is thinner than this, you can reach this minimum thickness by layering more of the same material.
After considering the above points, you can start the test.
- Step 1: Place the sample to be tested on a hard and horizontal surface.
- Step 2: Hold the durometer gauge in such a way that the indenter touches the surface of the sample.
- Step 3: Press the presser footer down till it makes contact with the sample.
- Step 4: Note the reading.
Durometer is used in those industries that make extensive use of rubber and plastic. Some of these industries are
- Food & Beverage Processing Equipment
- Medical Device
- Aerospace and Defence
- Electric & Electronics
What Does This Mean for You?
Knowing the hardness of rubber or plastic is very important, especially in those industries where it will be used for high pressure or extreme temperature applications. For example, it is important to know the durometer value of high-temperature silicone rubber if it to be used in sealing and gasketing for high or low temperature environment. General rule is that a gasket if you have uneven surface or larger gap than it should be softer which makes it easy to fill the gap between tow surfaces. However, if it requires lots of load then it should be hard enough so it can resist the lateral forces acting upon. A gasket material that compresses easily accommodates variation in the gap between two surfaces without needing more closing force
About Accurate Rubber Corp
Accurate Rubber Corporation is an ISO 9001:2015 certified custom rubber and silicone parts manufacturer and supplier. They aim to provide high-quality rubber parts to OEM, industrial suppliers and industrial end-users. Their products range from silicone tubing, silicone rubber gaskets & extruded silicone seals to silicone rubber cord and silicone rubber strips. They can provide a customized rubber part using different durometer rubber material at a competitive price and on time. They have served numerous industries with their high-quality products and excellent customer service.
It’s important to grasp the importance of a durometer and why it is necessary to test material for its hardness. So, next time you have requirement to use a rubber or a plastic, make sure you use an appropriate hardness rubber material which can serve your purpose.