Single Cavity, Multi Cavity and Family Tools
Our customers often have new projects in the pipeline but are uncertain what volumes of injection moulded parts will be needed. Sometimes it could be a few hundred, sometimes it would be 10’s of thousands.
If it runs in to 1000’s should the tool have more than one cavity? Or is it best sticking with one cavity? If there are more than one type of part could you consider producing a family tool to mould all of the parts at once?
Our prototype tooling can adopt the same techniques used by production tool makers. This means that we can produce prototype parts that will be a true representation of your production parts.
The different tooling options can sometimes be a minefield so we’ve put together a few basic positives and negatives on single cavity, multi cavity, and family tooling that will help you to make an informed decision when it’s needed.
This is the cheapest option when laying down an injection mould tool. The tool will produce one moulding at a time, at a set cycle time. They’re suited for lower volume production when cost is less prohibitive. The tool is generally easier to produce which reduces lead times and cost.
The tool can only produce one moulding at a time so if the volume increases rapidly the tool may struggle to produce enough parts to keep up with demand. Although producing one part at a time keeps the tool cost down, compared to multi cavity tooling it makes the part cost more expensive.
The benefits of having a tool that produces more than one of the same part is volume and cost. If the cycle time of running a single impression tool is 30 seconds, 120 parts will be produced per hour. If the tool had two cavities it would make twice as many parts in the same time scale.
Making two or more parts at once reduces the cost of moulding and gives greater opportunity to produce higher volumes in a set period of time.
The other side of the coin with multi cavity tools is they tend to be more expensive to produce and can push lead times out due to the work involved during manufacture. It’s a balance of high cost for the tooling, but cheaper mouldings. Where as single cavity tooling is cheaper but with higher moulding prices.
Family tooling can be used to produce several different shaped parts in the same materials, off the same mould tool. This is a very cost effective solution if you’re selling a kit of components. The tooling tends to be more expensive than a single cavity tool but you only purchase one tool to produce several different parts. Like multi cavity tooling the moulding cost is reduced by moulding more than one part from the same tool.
There are limiting factors when producing family tools. If the parts are various sizes it becomes a balancing act to get all of the cavities to fill with plastic when moulding at the same rate. If there’s a big imbalance between cavity filling this can cause quality issues with parts. Family tools produce parts using the same material which can be difficult should one of the parts be needed in a different material or colour. Finally, if one of the cavities becomes damaged then it can stop the rest of the parts in the tool being produced.
This list is far from exhaustive, there are pros and cons to all injection mould tools but we hope the above gives a little insight into the subject.