Correcting the axis and diameter of holes can be done manually or with specialised machines called boring machines. This operation not only corrects hole dimensions, but can also enlarge the diameter to the exact size required.
What the boring process involves
Boring is carried out on CNC machines operated by highly specialised staff. Working with boring machines is a task of extreme precision: the goal is to bring the hole to the correct size with practically infinitesimal margins of error.
Boring is suitable for a wide range of materials, including alloy steels, aluminium and its alloys, copper, brass, bronze and plastics such as Teflon, PVC and nylon. For through holes, which go from one side of the metal to the other, the tool must pass out of the opposite side, while for blind holes the depth is predefined. Boring can also be carried out on angled or inclined surfaces, but the entry angle must be kept very low.
It should be noted that boring is not recommended for correcting errors in the position or straightness of an existing hole, so it is essential that the first hole is made with maximum precision.
During boring, lubricating oils are used to ease and improve machining. As the hole size increases, more lubricant is used to extend tool life and ensure effective chip evacuation.
When holes with special shapes are needed, such as square, rectangular or angled holes, specific tools called broaches are used, in a process known as broaching.