How to judge the qualified rubber products?

1. Abnormal quality performance of rubber products that are prone to occur frequently during the vulcanization process: lack of material, damage, deformation, air bubbles, dirty mold (bonding), bulge, missulfide, undersulfur, oversulfur, frost spray, mold bite , mechanical scratches, secondary vulcanization and other phenomena.

2. For various abnormal quality performance, analyze the cause of the problem, as follows:

2.1 Lack of materials:

2.1.1 Causes:

a. The material (film) does not reach the rated consumption, that is, the material is insufficient; (inaccurate weighing, artificial reduction, loss of transportation after weighing and before loading)

b. The material (film) is not placed properly during the rubber mold loading process, resulting in part not being squeezed into the mold cavity; (improper placement, causing the rubber material to be squeezed out of the mold cavity)

c. Insufficient pressure, resulting in the rubber material not fully filling the mold cavity; (rubber press pressure drop, pressure is not set properly, mold seam gap is too large)

d. The specific gravity of the rubber is too large; (the density of the rubber is too large, and the volume is relatively reduced under the same mass, and the cavity cannot be filled)

e. The clinker of the previous mold product was not cleaned or not cleaned up; (due to clinker clogging, the glue injection is not smooth)

2.2 Damage phenomenon:

2.2.1 Causes:

a. Excessive force and excessive force in the demoulding process;

b. The product seam gap is too large or there are different degrees of cracks in other positions. During the demolding process, it is torn from the crack; (the gap is too large because of the mold; other positions may be lack of materials to cause cracks; the mold has sharpened puncture and cause product scratches)

c. The edge cleaning process is cut or cut by scissors; (cause of operation and processing errors)

d. The rubber compound has not reached positive vulcanization; (under-sulfur, over-sulfur is easy to break)

e. Severely dirty mold; (the product is damaged after serious bonding)

2.3 Deformation phenomenon:

2.3.1 Causes:

a. The positive vulcanization condition has not been reached; (generally, the lack of sulfur can easily lead to deformation)

b. The product is caused by mechanical force during the ejection process; (the product is not completely in line with the top plate during ejection, resulting in ejection deviation; after the mold is opened,

The upper template falls back and squeezes and deforms)

c. Use the wrong skeleton or mold; (the overall deformation does not match the required state; the installation holes are different; there is a serious shortage of materials)

2.4 Bubble phenomenon:

2.4.1 Causes:

a. The production process is not exhausted or effectively exhausted; (the number of exhausts has not been reached; the timing of exhaust is inaccurate and irregular)

b. The vulcanization process conditions are inconsistent with the performance of the rubber compound; (the vulcanized product is easy to foam at high temperature and relatively short time)

c. The mold cavity and structure design are not reasonable and suitable; (different products have different requirements for mold design)

d. The rubber material is not parked according to the cycle or compounded before use; (the rubber material does not meet the requirements for use)

e. Too much water in the rubber compound itself or sticky water stains during transportation; (water content in the formula material and external water)

f. Seasonal humidity is caused; (ambient air humidity is high)

g. The placement of rubber materials is not reasonable; (different products and molds have different placement requirements)

2.5 Dirty mold (bonding) phenomenon:

2.5.1 Causes:

a. Lightly and severely dirty molds have the phenomenon of bonding rubber on the mold to varying degrees; (bonding is a serious manifestation of dirty molds)

b. The rubber mold has been used for a long time without effective maintenance, causing the interface to corrode and gradually contaminate the mold;

c. The electroplating layer on the surface of the mold is rubbed or damaged by rough objects, resulting in a decrease in smoothness and easy to contaminate the mold;

d. The rubber compound has not reached the specified vulcanization conditions (that is, the mold temperature, pressure, and time have not been met), and it has been over-sulfured or under-sulfurized;

e. There is too much moisture in the rubber compound; (the moisture of the raw material needs to be tested)

f. The design of the mold structure is not reasonable enough to cause it to be difficult to exhaust;

2.6 Bumpy phenomenon:

2.6.1 Causes:

a. The hardness of the material is too large and the fluidity is poor; (the glue material cannot be effectively welded in the mold cavity)

b. Some clinker edges are not cleaned thoroughly, resulting in mixing with the secondary mold compound, and forming obvious bulges on the surface;

2.7 The phenomenon of wrong sulfur:

2.7.1 Causes:

a. Wrong use of rubber material or skeleton; (cannot be used and operated effectively and accurately; can not be effectively distinguished and judged; wrong hair, wrong use)

b. Insufficient basic knowledge of the product, unable to effectively determine whether the product is correct or not; (the degree of understanding of the product)

c. Guidance is wrong, resulting in product error; (cannot be effectively determined and effectively stopped, resulting in wrong production)

d. Failure to receive raw materials or operations in accordance with the operation instructions, resulting in missed work; (resolutely carry out the whole process operation and first-piece self-inspection in accordance with the process documents or temporary requirements)

e. Insufficient personal knowledge, lack of consultation and coordination ability; (lack of due quality awareness)

2.8 Under-sulfur phenomenon:

2.8.1. Causes:

a. The vulcanization conditions required by the process have not been met; (should follow the process requirements)

b. Illegal operation, early demoulding, resulting in partial or overall lack of sulfur; (consciously improve quality awareness, improve self-inspection and control ability)

c. Inaccurate temperature control of molds and equipment; (should be monitored at any time according to product quality performance, and equipment abnormalities should be found)

d. The practical performance of the material itself is inconsistent with the vulcanization process conditions, resulting in insufficient sulfur; (the formula has not changed, and the performance of raw materials is unstable;)

e. Formula adjustment or change; (manually adjust formula parameters or weighing error is too large)

2.9 Over-sulfur phenomenon:

2.9.1 Causes:

a. Inaccurate temperature control of molds and equipment

b. Caused by human operation: (intentionally increase the vulcanization temperature, or delay the product release time)

c. The practical performance of the material itself is inconsistent with the vulcanization process conditions, resulting in excessive sulfur; (the formula has not changed, and the performance of raw materials is unstable;)

d. Formula adjustment or change; (manually adjust formula parameters or weighing error is too large)

3. 0 Frosting phenomenon:

3.0.1 Cause:

a. The formula design is not reasonable enough, and the corresponding process parameters are inaccurate and reasonable; (the various raw and auxiliary materials in the formula are improperly matched, resulting in excess ejection; the process parameters do not match the actual production and processing of the formula materials)

b. The operator shortened or changed the process parameters without authorization, resulting in insufficient sulfur; (leading to unstable process parameters and inconsistent with the actual processing performance of the formula material)

c. Inaccurate temperature control, pressure and time control of production equipment, resulting in insufficient sulfur; (leading to unstable process parameters and inconsistent with the actual processing performance of formula materials)

d. The humidity in the storage environment of the finished product is too high;

3.1 Die gnawing phenomenon:

3.1.1 Causes:

a. The skeleton is not placed in place, resulting in crushing; (caused by operating errors)

b. The mold is dislocated, causing crushing; (improper mold installation, poor self-limiting)

c. The frame size does not meet the requirements; (irregular, has exceeded the size requirements or is deformed by force)

3.2 Mechanical scratches:

3.2.1 Causes:

a. Mold damage; (sharp corners and sharp edges in use)

b. Instrument damage during edge cleaning; (inadvertently cut, blade scratched)

c. The matching gap is too small, after the product is formed, the frame and the mold are scratched and scratched during the demoulding process; (or the frame is deformed, the size is not standard), there is no detailed content, and it needs to be improved and supplemented; I hope to give more valuable opinions!

     After fully learning and understanding various abnormal quality phenomena of vulcanized rubber products, it can significantly improve the ability and efficiency of employees to judge and distinguish unqualified products, improve quality awareness, improve labor production efficiency, and reduce the frequency of unqualified products. Reduce unnecessary losses and waste.