With restriction
Definition: |
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With restriction refers to an assembly process in which obstructions may occur due to poor visibility or insufficient space. |
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:
Definition: |
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In the case of restriction due to space or visibility, a frequency of 1 is entered in the corresponding column. |
Rule M-B2:
Definition: |
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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. |
Rule M-B3:
Definition: |
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If when positioning a component, the positioning locations are hidden by the component itself, restriction due to visibility is analyzed. |
Without positioning aids
Definition: |
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Without positioning aids refers to an assembly process in which neither the component or sub-assembly, nor the positioning location, is equipped with positioning aids, such as stops, guides, etc. |
Explanation:
Without positioning aids: Missing positioning aids inevitably result in assembly interferences. |
 w/o positioning aid |
 with positioning aid |
With fixing of position
Definition: |
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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. |
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: |
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Assemble bolt with lock washer and washer  Assembly steps: 1.Place base plate in stable position 2.Lay washer on base plate and hold it in place 3.Place the spring washer on the washer and hold it in place 4.Position bolt through washer and lock washer into thread and hold it in place 5.Engage thread 6.Turn on and tighten bolt |
Fault assembly position possible
Definition: |
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Fault assembly position possible refers to an assembly process in which it is possible to assemble a component or sub-assembly in more than one way. One or more of the possible positions may be wrong (Poka Yoke). |
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 provides for several assembly positions simplifies the assembly process.