How can silicone seal without burrs?
In all the silicone products, in addition to the tire, the most common, the another is O ring, which has damping, sealing, wear-resisting, features, according to different materials, it can also be oil resistance, chemical resistance and other properties, and it is often used in excavator, automotive, instrumentation, engineering machinery and other fields, and the most basic requirements to confirm whether O ring is good or bad is flash (trimming), only zero burrs to ensure the good sealing of O ring.
The generation of burrs often occurs when the mold is pressed to vulcanize, at this time the rubber material will fill the hole cavity of the mold, and because the filled rubber material should have sufficient amount, so at this time the excess rubber material will flow out along the parting surface, resulting in inner diameter and outer diameter of different thickness of the edge, such edge is called "burrs".
There are two common trimming methods: manual trimming and mechanical trimming:
A. Manual trimming: this way is the most primitive and traditional, the manual use of knives to remove the inner and outer edges of the ring, this way of trimming quality depends on the experience of workers, low efficiency, and high scrap rate, so it is only suitable for small batch zero trimming O ring processing.
B. there are two kinds of mechanical edging: grinding wheel edging, low temperature frozen edging:
1. The grinding wheel edge grinding, grinding wheel sandpaper edge grinding compared to artificial trimming, have more promotion in the efficiency and quality, the specific way is to cure the o ring set in its inner diameter size of sand bar or nylon rods, motor drive the high-speed rotation, again by sand paper or cylindrical grinding wheel friction O ring, in order to achieve the trimming, but accuracy is not high, grinding surface roughness etc are the disadvantages.
2. Cryogenic edge removal: this method is originated from Japan, is also a kind of mechanical edge repair, the difference is working in the frozen environment, through: vibration, swing or jitter, drum, brush grinding and shot blasting, five different forms to achieve zero burr O ring.
Specific working principle is: in the low temperature freezing environment, type O thin ring of burrs for frozen from elastic state to a glassy state (harden brittle), but the product itself is still have certain elasticity, and then with the vibration of the operation (or other forms of five), collision between products and products, products with abrasive abrasive, and blasting impact, then thin flash will be broken, and then fall off, and finally achieve the purpose of trimming, and the product will restore its original performance at room temperature, this way of high production efficiency, but the inner ring edge effect is poor.