While the parts of plastic molds are mostly prepared by machining carbon steels, after the machining work is completed, final adjustment by hand finishing will be necessary to a small or a large extent. In recent machining operations, the NC data are supplied easily by CAD or CAM, and it has become possible to carry out relatively easily the machining operations at high accuracies due to the development of CNC machines or tools. However, it is necessary to carry out the final finishing by experienced and skilled hands, and since their automation is difficult, mastering this requires considerable expertise.

The details of hand finishing work are given below.

Details of hand finishing work:

Filing
Lapping
Assembling
Scraping
Marking
Drilling
Reaming
Thread cutting
Slicing
Shaving

Measuring instruments used:

Calipers
Micrometer
Dial gauge
Block gauge
Pin gauge
Metal scale
Long metal scale
Calipers
Metallurgical microscope

In order to learn hand finishing, the most definite method is to learn by working with an experienced technician having an accurate knowledge (a person having a special technician certificate or a Grade 1 technician certificate). Although finishing can be done to some extent by looking at and copying an experienced technician, if it is not possible to work with the correct knowledge and using the correct procedure, it is difficult to carry out precision work or work that is highly paid.