A number of plastics are used for food containers. PET bottles, food cups, and food packaging are mostly made of plastics.
Quality control of food containers is necessary to ensure that they are hygienic and that they do not have any flash that can hurt fingers or lips so that people can feel safe about consuming food from the containers.
In addition, even quality defects such as holes or cracks are not allowed because bacteria can penetrate through them and cause the food to rot.
Some typical food containers are the following.
– Margarine container: PP
– Ice cream container: HIPS, HDPE
– Lactobacillus beverage (fermented milk drink) container: HIPS
– Pudding container: PS, PP
– Snacks container: HIPS, PP, HDPE
– Soft drinks bottle: PET
Depending on the usage of the food item, the container will have to have heat resistance (for foods that are heated and consumed), low temperature resistance (for foods consumed after refrigerating or freezing), or gas barrier ability (for food items that are to be stored so that they do not come into contact with oxygen).
Since the sales of food containers is influenced greatly by the design (treatment for beautiful appearance) of the molded item, three dimensional curved shapes and designs are given importance. Therefore, three dimensional solid data becomes important in the design of the molded item and in the mold design.
In addition, since there is the risk of flash being generated at the parting surface of the mold, it is necessary to give sufficient considerations to the parting surface.
Similarly, even the position and method of providing gates are also important.
It is necessary that the cavity and the core are made of a steel material having very good corrosion resistance. Also, since it is desirable that the mold is not coated with grease or oil for promoting sliding, the recommended mold structure is one which can operate safely without any lubrication.
Electrical motor driven type injection molding machine is preferable, and it is still better that the molding and machining is done in a clean room.
Valve gates and hot runners can be used. If large volume production is expected to grow, the effect of eliminating scrap and high cycle speeds are extremely advantageous.
