The tolerances (shown in the chart below) are just the beginning of what we can provide. If you are designing an aluminum investment casting and you are looking for some guidelines, you can feel comfortable relying on the following linear tolerances.
When Machining is Necessary
If casting itself does not achieve the tolerances you desire, the next step would be machining to meet the necessary specifications. For example, investment casting enables near-pinpoint precision with certain hole-size specifications, but machining is usually needed to achieve the desired precision with every hole. In order to ensure a very tight fit for parts such as mating surfaces, where one flange is mated to another— both surfaces should generally be machined.