Depending on the application industry and requirements, vacuum suction cups are available in different compounds and materials.
So how to choose compounds and how and when use them?
First you have to choose considering the hardness of the material to be handled. The hardness determines the ability of a vacuum cup to seal itself on the surface of the product.
The second choice concerns the temperature resistance of the compound. Most pick-and-place applications, in fact, occur at room temperature, but sometimes, as in plastic moulding, the parts have high temperatures. If we then consider the handling of cold products, such as refrigerated or frozen food packaging, for example, knowing the temperature of the product is crucial to the success of the process.
In addition, one should consider the service life of the suction cup when it comes into contact with the load and its wear rate.
The most commonly used compounds are: nitrile rubber, silicone and polyurethane.
Nitrile rubber is used in many industrial applications: in the handling of steel, plastic, wood, cardboard and any other application where the cup must resist to oils and chemicals. It has excellent wear resistance.
Silicone is a very popular material and offers the advantage of extreme temperature resistance, both cold and hot. It is ideal, for example, for handling frozen packaged food and hot plastic moulded parts. It is softer than nitrile rubber, allowing it to adapt better to shaped or rough surfaces such as cardboard sheets, corrugated plastic and plastic food packaging. Silicone can also be supplied according to food and pharmaceutical industry compliance. Some specifications also ensure that the dyes do not spread, contaminating the process. However, the wear resistance of silicone is lower than nitrile rubber wear resistance. Silicone should also never be used on surfaces to be painted, such as car body panels, as the paint does not adhere properly to the area touched by the silicone suction cup. (Do you understand how important it is to consider the individual case?)
Finally, polyurethane suction cups are used in high wear applications. Polyurethane has a very high wear resistance compared to both silicone and rubber, but it is generally more expensive, so it is not advisable to use it except in specific situations.
This is only a general guide for the choice of compounds; it is always useful to assess specific needs, so if you have any doubts about the most suitable compound for your application, do not hesitate to contact Vuototecnica designers.