How to mark non-standard screws

How to mark non-standard screws

I don't know if you have visited the screw manufacturer. If you have to go, you will find that the production drawings hanging on the machine are marked with tolerance. So the good people will wonder: what role does this play? Next, the screw manufacturer will talk with you about it:

For customers, no matter what type of screw customization is, there are requirements for the tolerance of screws. After all, without the size of the screws, they can not use them. To let suppliers replenish, or find new suppliers, for customers to increase their workload, but also increase their costs.

The reason to mark the tolerance is also to let the customer responsible for the inspection at the same time. Is not all familiar with and understand the screws, so if there is no mark tolerance on the drawings, they are measured according to the drawings, usually determine this batch of goods is unqualified, and no screw manufacturers can keep their production screw size is the same, no deviation, so mark tolerance on the drawings is very important.

When manufacturing parts, in order to make the parts have interchangeability, the size of the parts is required to be within a reasonable range, so that the limit size is specified. The actual size shall be within the specified maximum and minimum limit sizes. The variation of allowed dimensions is called dimensional tolerance analysis, or tolerance analysis.

Non-standard screw standard tolerance standard: the value of the standard tolerance marked IT is basically marked by any of the tolerance listed in the standard to confirm the size of the tolerance marked band. Standard tolerance annotation are divided into 20 grades, namely IT01, IT02, IT1 to IT18. IT represents standard tolerance annotation and numbers indicate tolerance annotation grade. IT01 tolerance has the smallest value and the highest accuracy; IT18 tolerance has the largest value and the lowest accuracy.

Basic dimensions: design the given size.

Limit size: two limit values that allow size change, which are determined based on the base size. Deviation: the algebraic difference of an actual size minus its basic size. Limit deviation: that refers to the upper deviation and the lower deviation. The algebraic difference of the maximum limit size minus its basic size is the upper deviation; the algebraic difference of the minimum limit size minus its basic size is the lower deviation.

Dimension tolerance annotation: the amount of allowable allowed. That is, the difference between the maximum limit size and the minimum limit size; it is also equal to the absolute value of the algebra difference between the upper and lower deviation.

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