Milk powder is a reconstituted food obtained by using fresh milk or goat milk as raw materials, using freezing or heating methods to remove almost all of the water in the milk, and then adding appropriate amounts of vitamins, minerals and other ingredients after drying.
Milk powder is mostly packaged in metal cans because the latter has high barrier properties and good sealing properties. Between the two processes of milk powder filling and canning, the milk powder tank must be vacuumed and filled with nitrogen to ensure that the residual oxygen rate in the milk powder tank is less than 3%. If the tightness of the milk powder tank is not good, the nitrogen in the tank will be lost, and the oxygen and moisture in the air will enter the tank. Since milk powder contains a large amount of high-nutrient substances such as protein and fat, it is prone to slow oxidative deterioration, agglomeration, abnormal color and taste and other quality problems after long-term contact with oxygen. Therefore, the importance of the sealing performance of the milk powder can is evident.
If the sealing of the milk powder tank is not good, the milk powder is prone to slow oxidation deterioration, agglomeration, abnormal color and taste and other quality problems.
Milk powder cans are mostly tinplate three-piece cans. The name of the “three-piece can” comes from the fact that it is composed of three parts: the can body, the bottom and the top. Among them, the can body is generally welded by a resistance seam welding machine. The top of the can is usually an easy-to-tear lid made of tinplate and aluminum foil, and the bottom of the can is often a tinplate flat-bottomed lid.
In order to ensure the tightness of the milk powder cans, the canning equipment factory and the milk powder factory need to strictly control and cooperate with each other in their respective production processes. The former needs to control the quality of the can body welding seam, involving flexibility, tail length, overlap amount, solder joint spacing, burrs and other indicators; easy-to-tear lid aluminum foil adhesion; and the quality of the can top and can body roll seal. The latter should control the quality of the can bottom and can body roll seal. It can be seen that most of the control points of the tightness of the milk powder tank fall on the process of the canning equipment, so the quality of each process should be checked regularly. In addition, online leak detection for each empty can of finished milk powder is also essential.
