With restriction
With restriction
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With restriction refers to an assembly process in which obstructions may occur due to poor visibility or insufficient space.
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Explanation
With restriction sight:
Restriction due to visibility means that the field of vision required to perform the assembly job is obstructed. The positioning location is obscured or cannot be fully seen. Thus, the positioning process is performed "blind" or requires a sense of touch.
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With restriction space:
Restriction due to space means that the space available for the assembly process is restricted. Accessibility is limited, either at the positioning location itself or in its surroundings. This requires additional auxiliary or corrective motions.
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There are three application rules:
Rule M-B1:
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In the case of restriction due to space or visibility, a frequency of 1 is entered in the corresponding column.
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Rule M-B2:
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In the case of restriction due to space and visibility, both types of restriction are evaluated with a frequency of 1.
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Rule M-B3:
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If when positioning a component, the positioning locations are hidden by the component itself, restriction due to visibility is analyzed.
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Without positioning aids
Without positioning aids
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"Without positioning aids" refers to an assembly process where neither the component nor the positioning location is equipped with positioning aids, such as stops, guides, etc.
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Explanation
Without positioning aids:
Missing positioning aids inevitably result in assembly interferences.
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Without positioning aid
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with positioning aid
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With fixing of position
With fixing of position
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With fixing of position refers to an assembly process in which a component or sub-assembly is not in a stable (final) position after initial positioning.
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Explanation
With fixing of position:
Fixing of position comprises all measures necessary to keep a part in a specific position until it has reached a stable position through a subsequent assembly process.
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The component is fixed only by the subsequent positioning of screws.
Example: Assemble bolt with lock washer and washer
Assembly steps:
1. Place base plate in stable position
2. Lay washer on base plate and fix of position
3. Place lock washer on washer and fix of position
4. Position bolt through washer and lock washer into thread and fix of position
5. Engage thread with screw driver
6. Turn on and tighten bolt
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Fault assembly position possible
Fault assembly
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"Fault assembly position possible" refers to an assembly process where it is possible to fit a component or assembly in more than one way. One or more of the possible positions may be wrong (poka-yoke).
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Explanation
The design of the component or assembly allows for fitting in more than one way. This may make it necessary to rework individual components or assemblies, or it may represent a risk of improper functioning. To avoid this, components or assemblies should be designed in such a way that wrong assembly positions are impossible (see schematic diagram or, e.g., tabs on a plug with defined polarity).
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A design that allows for several assembly positions simplifies the assembly process.
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