Raw Material

Our Engine Valve Cover Gasket compound from world class suppliers or domestic rubber supplier and customized pantone code is available, hardness from 30 to 90 Shore A.

Size

Standard size with our current mold or customized according to your sample or drawing( 2D, 3D drawing , format STP, DWG, PDF , etc)

Quality and Certificate

We execute ISO9001 quality system and our Engine Valve Cover Gasket With Hole has passed ROHS/Reach/WARS certificate.

Mold and tooling

In house tool making and free of tooling charge for standard rubber gasket, the mould parting line will be sent to customer confirmation.

Management and quality tracking: Strict material traceability under ERP system.

Engine Valve Cover Gasket process flow

PO confirm---Develop mold according to drawing or sample---Develop chemical formula according to specifications---Mix the raw material as per formula---Prepare and Install the mold on the machine---Preform the rubber compound---Put the compound into mold and vulcanization with certain temperature and pressure---After a while, remove the goods from the mold---Trimming the flash---Inspection---Packing---Shipping

Small MOQ: there’re variety Engine Valve Cover Gasket in stock, so mini MOQ is acceptable.

Function: seal, sealing

Payment: T/T, L/C, Credit card. USD, RMB ,Euro and so on other currency is available.

Trade Term: EXW, FOB, CIF etc

Package: poly bag and carton(40*32*25CM). If you need pack by pallet or other customized package, it’s also ok.

Shipping method: By air, by sea, by express, multi-modal transport

Shrinkage rate of rubber products: in the process of pressing and heating vulcanization, deformation and crosslinking occur inside the rubber, resulting in thermal expansion force, vulcanization in the process of cooling, the stress tends to be eliminated. The linear size of the compound is scaled down. Therefore, in the mold design, the size of the forming part needs to be increased accordingly. The shrinkage ratio is generally expressed as a percentage.

General law of shrinkage of rubber products

① Factors affecting the shrinkage rate of rubber: the higher the curing temperature (beyond the positive curing temperature), the greater the shrinkage rate. In general, the shrinkage rate increases by 0.1% ~ 0.2% for every 10°C increase in temperature.

(2) the shrinkage rate of the compound in the rolling direction and the flow direction in the mold is greater than that in the vertical direction; The longer the flow distance, the greater the shrinkage.

(3) The higher the amount of semi-finished rubber material, the higher the density of finished products, and the smaller the shrinkage rate.

(4) the larger the plasticity of the compound, the smaller the shrinkage; The higher the hardness of the compound, the smaller the shrinkage. (With the exception of high hardness, according to the experimental measurement, the hardness of rubber material exceeds 90 degrees Shaw, its shrinkage rate has a rising trend)

⑤ The larger the amount of filler, the smaller the shrinkage rate; The higher the gum content, the higher the shrinkage.

⑥ In the multi-cavity mold, the shrinkage rate of the middle cavity pressure products is slightly smaller than that of the edge cavity products.

⑦ the shrinkage rate of injection products is smaller than that of molding products.

⑧ The shrinkage rate of thin products (section thickness less than 3mm) is 0.2% ~ 0.6% larger than that of thick products (more than 10mm).

⑨ The shrinkage rate of general products decreases with the increase of inner and outer diameter and cross section of products. The shrinkage rate of different types of rubber is fluorine rubber, silicone rubber, EPDM, natural rubber, butaneyl rubber, neoprene rubber. (The above rubber type is based on the type of rubber, not on the type of rubber formula).

⑩ The shrinkage rate of commonly used rubber products

The shrinkage rate is generally 0 ~ 0.4% for laminated cloth products made of cotton cloth and rubber after coating;

Polyester wire products, the shrinkage rate is generally 0.4 ~ 1.5%;

Sandwich nylon silk, nylon cloth products, the shrinkage rate is generally 0.8 ~ 1.8%;

The more interlayer fabric, the less shrinkage.

The shrinkage rate of rubber products lined with metal inserts is small, and the shrinkage rate is generally 0 ~ 0.4% toward the metal direction;

The shrinkage rate of unidirectional adhesive products is generally 0.4 ~ 1.0%; (for example, the shrinkage rate of the embedded adhesive part of the skeleton oil seal structure is generally 0 ~ 0.4%; The shrinkage rate of the lip part (pure glue part) is in the form of ladder. The closer it is to the end of the insert, the smaller the shrinkage rate is, and the larger the shrinkage rate is.

Hard rubber (Shore hardness greater than 90 degrees), glue content of about 20%, the product shrinkage rate is generally 1.5%;

The shrinkage rate of rubber and plastic products is generally 1.1% ~ 1.6%; About 0.1% ~ 0.3% smaller than similar rubber products;

For square products with slots, the shrinkage of B direction is 0.2% ~ 0.4% larger than that of A direction due to the extrusion direction of rubber pressing.

Calculation method of shrinkage of rubber products

The shrinkage of rubber material varies with different factors such as rubber type, mould and technological conditions. There is no accurate, perfect and practical formula for calculating the shrinkage. Experienced designers often rely on empirical data to estimate and accumulate actual measurement data for reference.

The commonly used formula for calculating rubber shrinkage is as follows:

1. Rubber products and mold cavity corresponding size calculation formula:

C= (L2 - L1)/L1 X 100%

C - shrinkage rate of rubber products:

L1 -- dimensions of rubber products measured at room temperature;

L2 -- Mold cavity size measured at room temperature.

2. The empirical formula for calculating the shrinkage rate of rubber compound based on Shaw hardness is:

C= (2.8-- --0.02K) X 100%

K - Shore hardness of rubber.

3. The general formula for calculating the shrinkage rate of rubber compound by vulcanizing temperature of rubber is:

C= (α-β) δT? R X 100%

α-linear expansion coefficient of rubber;