Source / Subject: http://en.wikipedia.org/wiki/Interchangeable_parts
-A - Opening paragraph, 7th sentence "Today machine tools are typically powered other than by human muscle (e.g., electrically, hydraulically, or via line shaft), used to make manufactured parts (components) in various ways that include cutting or certain other kinds of deformation.
- B - Opening paragraph, 8th sentence "With their inherent precision, machine tools enabled the economical production of INTERCHANGEABLE PARTS."
* ONE *
Sentence -A- laboriously provides 2 pieces of information in a rather disjointed fashion: - Historically, machine tools were historically powered by human muscle [& guided by the human] [these = 'hand tools'] - Machine tools cut and/or deform items (subtractive) to produce manufactured identical parts (components)
A "tool" is a physical item used to achieve some goal. A "machine" is technically a tool that transforms the direction or magnitude of a force applied to it into some specific action. The source of the force used by a tool may be mechanical, chemical, thermal or electrical. A "hand tool" is a simple machine powered and guided solely by a human [technically: chemical/electrical & mechanical]. A "motor" converts energy into mechanical action. A "power tool" is a motorized machine powered ("power accentuated") primarily by some source other than by a human, but directed only by a human. An electronic machine that converts energy into some action, with no moving components, is still technically a power tool.
An ACTUATOR is a motor (converts energy into mechanical action).
This motor moves &/or controls a mechanism &/or system
An actuator is a type of motor that is responsible for moving or controlling a mechanism or system. eg. wooden screws to crush grapes: .
It is operated by a source of energy, typically electric current, hydraulic fluid pressure, or pneumatic pressure, and converts that energy into motion. An actuator is the mechanism by which a control system acts upon an environment. The control system can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or any other input.
MECHANISM (plural mechanisms: Within a machine or machinery; any mechanical means for the conversion or control of motion, or the transmission or control of power. ny combination of cams, gears, links, belts, chains and logical mechanical elements.
MACHINING is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process. The many processes that have this common theme, controlled material removal, are today collectively known as subtractive manufacturing, in distinction from processes of controlled material addition, which are known as additive manufacturing. Exactly what the "controlled" part of the definition implies can vary, but it almost always implies the use of machine tools (in addition to just power tools and hand tools).
* TWO *
Sentence - B - "With their inherent precision, machine tools enabled the economical production of INTERCHANGEABLE PARTS."
- The precise meaning of the NOUN/SUBJECT that is 'economically produced' is unclear **
The subjects of sentence -B- are: - 'machine tools' and - 'interchangeable parts', which are components of some entity or assembly.
While the author may have purposely omitted adding a subject to which the 'interchangeable parts' belong, I believe this omission may lead the reader to conclude that these 'parts' apply to the first subject: that is, that the interchangeable parts are components of the 'machine tools' itself.
In the previous sentence -A-, 'manufactured parts' are followed by the bracketed term 'components'. While this definition could have clarified the meaning of the subsequent sentence -B-, the term "component" is used in conjunction with 'manufactured', not 'interchangeable' parts. As it currently reads, it is not obvious that the manufactured and interchangeable parts are one and the same.
2 proposed solutions to TWO:
First ... Given that the "parts" referred to in both sentence -A- and -B- are the same, I suggest INCLUDING A COMMON TERM in both sentences to make this fact clear to the reader: add the word 'interchangeable' (used in sentence -B-) to -A-, so that sentence -A- reads "manufactured interchangeable parts (components)".
Second ... The bracketed term 'component' clarifies the meaning of 'parts' in sentence -A-. Embed a LIVE LINK to the Wiktionary DEFINITION of 'COMPONENT' (http://en.wiktionary.org/wiki/component#Noun). The Wiktionary definition reads: A smaller, self-contained part of a larger entity. Often refers to a manufactured object that is part of a larger device.