With the continuous development of the automotive industry, people's demand for ride comfort is also increasing. Seats, as an important component of the car interior, directly affect the comfort and health experience of drivers and passengers. Among these factors, the hardness of seat foam is a key indicator, directly impacting the seat's support, elasticity, and overall riding experience.
This article will delve into the concept of seat foam hardness, introduce the testing principles and methods, and discuss the impact of different hardness levels on drivers and passengers. Furthermore, we will focus on the challenges faced by the automotive manufacturing industry in seat design and production, and how hardness testing can address these challenges to improve seat quality and comfort.
I. Test Content
1. Indentation Hardness
Under specified laboratory conditions, equipment, and testing procedures, indentation hardness is the force required to cause a foam sample to undergo a certain deformation, measured in Newtons (N), hereinafter referred to as "hardness".
2. Curing
During the production process, after demolding, foam products are placed in a natural workshop environment for 24 hours to allow their physical properties to stabilize, making them suitable for seat production and related testing. This placement process is called curing.
II. Testing Principle
Under specified test conditions, the hardness test of passenger car seat foam involves applying force to the foam within a specified distance using testing equipment and measuring the required feedback force to define the foam's hardness value.
III. Relevant Testing Standards
The test is conducted in accordance with standard Q-JLY J7111077B-2019.
IV. Testing Instruments
1. Customized Dual-Column Tensile Testing Machine
Note: The force measurement accuracy of the testing machine is ±1%, or ±1N.
2. Customized Pressure Plate and Indenter
The pressure plate surface is smooth but does not require polishing. It is assembled using spherical connectors to prevent vertical movement, or other suitable connection methods. The pressure plate diameter is 200+30mm, and the bottom edge chamfer radius is 1.0+0.50mm.
3. Test Bracket
During the testing of foam products, the bracket's profile must completely conform to side B of the foam product, ensuring that the test plane is essentially parallel to the pressure plate surface.
Bracket Material Requirements: Resin, wood, or other rigid materials are required. The surface must have a porous arrangement of 6mm diameter holes spaced 20mm apart to allow gas to escape during testing.
4. Test Conditions
(1)Test products should be placed in the workshop under natural conditions for 24 hours after production until fully cured. Cured test products should then be stored in a test chamber for at least 12 hours for conditioning, ensuring they are not deformed or damaged by external pressure.
(2)Temperature: (23±2)℃, Relative Humidity: (50±5)%
V. Test Procedure
(I) Test Location
1. Seat Cushion Foam Test Location
The test area for the seat cushion foam is located in the center of the Y-direction of the central block. The X-direction test is defined according to the specific product. A 200mm diameter pressure plate is used for testing the central test area, and a 25% indentation test value is recorded.
The test area for the side wings is located at the highest and thickest part of the side wings, as shown in the figure.
2. Backrest Foam Testing Location
The testing area for the backrest foam is located in the center of the middle block in the Y direction. The Z direction testing area is based on the specific definitions of each product. A 200mm diameter pressure plate is used for the center testing area, and a 25% indentation test value is recorded.
The testing area for the side wing is located at the highest point of the side wing, and specific measurements are based on the specific definitions of each product.
3. Rear Seat Foam Testing Location
The testing area for the rear seat cushion foam is located in the center of the middle block in the Y direction. The X direction testing area is based on the specific definitions of each product. A 200mm diameter pressure plate is used for the center testing area, and a 25% indentation test value is recorded.
The testing area for the side wing is located at the highest point of the side wing, and specific measurements are based on the specific definitions of each product. The variation range of the side hardness value in each area should be within 10%.
4. Rear Backrest Foam Testing Location
The testing area for the rear center armrest foam is located in the center of the rear seat in the Y direction. The X direction testing area is based on the specific definitions of the product. A 50mm diameter pressure plate was used for testing, and a 25mm indentation test value was recorded.
(II) Test Method
1. Center Hardness of the Seat Cushion Backrest Block
Step 1. Foam Product Preparation
a. Place the foam on the testing fixture, ensuring the 200mm pressure plate is aligned with the test area.
b. Pre-compress with 4.5N and measure the thickness of the test area, recording the position.
c. Remove the foam, measure the thickness at the same location on the fixture surface, and calculate the product thickness.
Step 2. Compression Test
a. Perform three pre-compressions at a speed of 100mm/min, holding for 10 seconds each time.
b. Compress to 70%-75% indentation at 100mm/min, holding for 10 seconds, repeating three times.
c. Compress to 25% at 100mm/min, holding for 10 seconds, and record the value.
Step 3. Data Reading
a. Read the data during the compression test, ensuring a 10-second pause at each compression stage.
b. Record the value when the required indentation is reached.
Step 4. Result Analysis
a. Analyze the compression test data, including the indentation and corresponding compression force.
b. Check if the product meets the hardness standards and other specified requirements.
Step 5. Report Compilation
a. Summarize the test results and analysis, and compile a test report.
b. Include the test conditions, test process, test results, and conclusions in the report.
The above is the information shared by the editor regarding the hardness testing of passenger car seat foam. We hope it can be helpful to you! If you would like to know more about passenger car seat headrest hardness testing, foam hardness testing standards and methods, universal testing machine models and specifications, and verification procedures, please feel free to send a private message or leave a comment. The Standard Group technical team will answer your questions free of charge!
