How to choose plastic injection mold cavity?

Plastic injection mold cavity decides product output. 
Especially for small products, and mass consumption products, multi-cavity mould is required. Choose mold cavity is also an important step. 
Usually the mold cavity is choosing according to required output and molding cycle time. 
In some conditions, other elements need to be considered. 

First condition:
It’s a big plastic company. It wants to start a new project. The output requirement is large. 
It already has some injection molding machines. And plan to use the machines to produce the products. 
For example, the product is thin wall container. 2 cavity cycle time is about 4s, 4 cavity cycle time is about 6s, 8 cavity is about 8s(cycle time also related to injection machine). If customer required output is 3000 pcs an hour, we will suggest 8 cavity. But 8 cavity mould needs larger high speed injection machine. The buyer already has 2 smaller high speed injection machine, then he could buy 2 2-cavity molds. He needs not buy another large machine, and 2-cavity mold is easier to maintain. 

Second condition: 
It’s the first time customer start a plant, he has no molds and no machines. He has no formal experience. 
For example, he wants to produce a whole set of disposable tableware. Spoon, fork, bowl, knife, plate. The required output is not large, 1000 sets per hour. The spoon, fork and knife is similar, the bowl is much slower. The bowl mould should have 4 cavities. The spoon, fork and knife should have 3 cavities each. Then we can make the spoon, fork and knife in the same mold, according to product property, make it reasonable cavity number. In this way, customer only need to buy 2 injection machines. 

This case is not a very typical one. But for new starters, this kind of suggestion is good, it saves first time investment. 

Welcome further communication on your project.