The mould material used by the MM casting process is applied as a slurry and is easily removed by water jets. This enables fine through holes to be cast. Length to diameter ratios can vary upwards from 4:1 dependent on diameter.
Blind holes can be cast provided the depth to diameter ratios do not exceed 3:1. Holes of under 0.5 mm (0.020") diameter are often cast.
Elongated holes can easily be cast allowing the take up of tolerances within an assembly.
Threads are best not cast but provision of a hexagonal cavity around a bolt hole allows the use of a captive nut or bolt, removing the need to tap a hole.
Also holes can be cast which are suitable for self tapping screws.
To reduce cost and improve accuracy a cast counter bore can be used in through hole applications where a tight tolerance is rarely needed over the full length.
Drill starts can be incorporated to aid drilling in cases where blind holes may be too long to cast.
Where a component is to be clamped to a shaft, a clamping slot can be cast, rather than machined. To make reaming of a through hole easier and more accurate a removable support bridge should be included.
