One of the means to realize low cost but reliable LCA is to reduce the number of mechanical elements (parts count) used. The mechanical element reduction can be categorized in the following two ways.
The following design thoughts and proceedings are the key.
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![[Fig.1] Example of Eliminating Unnecessary Features](http://www.misumi-techcentral.com/tt/en/lca/images/057_1.gif)
![[Fig.2] Example of Eliminating Inappropriate Designs](http://www.misumi-techcentral.com/tt/en/lca/images/057_2.gif)
In addition to the above points, it is important to acquire the following design practice points that reduce mechanical element machining costs.
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From simple jig fixtures to automated assembly machines and machine tools, all machines are based on the following three functionalities.
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Check list items during the concept/design phase for the three functionalities above are as shown below.
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In Japan where engineer's labor costs are high, "Sound Mechanisms" that require the shortest amount of time from design to completion are considered as short delivery time and low cost LCA.
When mechanisms comprised of combinations of mechanical elements are classified into 1. Tools, 2. Equipment, 3. Manual Jigs, 4. Automation Machinery, the number of comprising elements are defined as the table shown below. The Tools for instance, a hex wrench would be 1 element, a manual swaging jig would have several tens of elements (number of parts). For transportation mechanisms, an automobile = 104 order, an aircraft = 105 order, and a rocket would have 106 order of mechanical elements.
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Some mechanical elements are gathered to constitute subsystem-like mechanism elements (i.e. ball bearings), and these subsystems are gathered to make up the mechanisms.
Some mechanical elements are gathered to constitute subsystem-like mechanism elements (i.e. ball bearings), and these subsystems are gathered to make up the mechanisms.
 | 1. | Decrease the number of mechanical elements used. |
 | 2. | Utilization of Units (Units are: Standardized mechanisms made of combinations of mechanical elements. |
Machine's reliability improves with less troubles and maintenance requirements decreases with less mechanical elements used. And utilizing the standardized mechanism units reduces costs and shortens delivery times.
A representative example for this is personal computers. Discrete devices have been integrated into one LSI device, and HDDs and mother boards have been standardized where an individual can purchase the components and assemble a computer.
In LCA mechanism planning, utilization of standardized mechanism elements results in simplified structures and improves the soundness of mechanisms.
Power transmission mechanisms can be categorized into following three types.
A power transmission method where the Driver node is directly connected to the Driven node, such as Gears and Cams.
Most are the types where the Driver node is inter-coupled with the Driven node. There are following types.
| 1. | Rigid coupling - - - Connecting Rods, etc. |
| 2. | Flexible member coupling - - - Belts, Ropes, Other flexible member |
| 3. | Fluid coupling - - - Oil, Air, etc. are used |
Coupling via air gaps such as magnetic bearings.
Mechanism transmits Prime Mover's power to the Driven side to obtain intended motion to give functionality, generally. Therefore, the motion of the Driven node is different in the type, velocity, and direction from the Prime Mover node. Specific mechanism is dedicated in order to facilitate this conversion of motion. Steps to design the Driven node are as follows.
The Driven node design must vary to accommodate the characteristics of each manufactured product, but the intermediate and Prime Mover nodes should utilize general mechanisms for standardizing and simplifying.
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