This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
These terms are defined by Richards, in his 'Workshop Manipulation,' in the following words: "Forging relates to shaping metal by compression or blows when it is in a heated or softened condition; as a process it is an intermediate one between casting and what may be called the cold processes. Forging also relates to welding or joining pieces together by sudden heating that melts the surface only, and then by forcing the pieces together while in this softened or semi-fused state. Forging includes, in ordinary practice, the preparation of cutting tools, and tempering them to various degrees of hardness as the nature of the work for which they are intended may require; also the construction of furnaces for heating the material, and mechanical devices for handling it when hot, with the various operations for shaping. Finishing and fitting relate to giving true and accurate dimensions to the parts of machinery that come in contact with each other and are joined together or move upon each other, and consist in cutting away the surplus material which has to be left in founding and forging because of the heated and expanded condition in which the material is treated in these last processes.
In finishing, material is operated upon at its normal temperature, in which condition it can be handled, gauged, or measured, and will retain its shape after it is fitted. Finishing comprehends all operations of cutting and abrading, such as turning, boring, planing, and grinding, also the handling of material; it is considered the leading department in shop manipulation, because it is the one where the work constructed is organized and brought together. The fitting shop is also that department to which drawings especially apply, and other preparatory operations are usually made subservient to the fitting processes. A peculiarity of forging is that it is a kind of hand process, where the judgment must continually direct the operations, one blow determining the next, and while pieces forged may be duplicates, there is a lack of uniformity in the manner of producing them. Pieces may be shaped at a white welding heat or at a low red heat, by one or two strong blows or by a dozen lighter blows, the whole being governed by the circumstances of the work as it progresses.
A smith may not throughout a whole day repeat an operation precisely in the same manner, nor can he, at the beginning of an operation, tell the length of time required to execute it, nor even the precise manner in which he will perform it. Such conditions are peculiar, and apply to forging alone."