Dimensional Tolerance

Definition and Overview

Dimensional tolerance defines how much difference from the standard dimensions listed in the specification sheet, such as garment length, body width, and sleeve length, is still considered acceptable. It refers not to the standard dimensions themselves, but to the allowable range set around them.

Apparel is made through multiple processes such as cutting, sewing, pressing, and washing. Because it is also affected by fabric stretch and shrinkage, thickness, and sewing method, it is not realistic to make every product exactly the same size.

Position in Product Development

Dimensional tolerance is set at the planning stage together with the pattern and specification sheet, and is used as a common judgment standard from sample approval through mass production and final inspection. It is important for the client and sewing factory to agree on it in advance.

Before mass production, the revised sample is checked for measuring points, measuring method, and finished condition. For products that undergo washing or garment dyeing, dimensions and tolerance must be checked based on the post-processing condition.

• Record the standard dimensions and tolerance in the specification sheet.
• Clarify the starting and ending points of the measuring locations, and the condition in which the product is placed.
• Check the dimensions after grading for each size.
• Continue sampling measurements during mass production to identify trends early.

Practical Considerations for Setting and Implementation

Tolerance is set according to the item, area, material, design, and whether processing is involved. For knitted fabrics with high stretch, areas with gathers or tucks, and products that change after washing, the numerical value can vary depending on the measuring conditions when laid flat, so it is especially necessary to standardize the measuring method.

Be careful not to set an unnecessarily wide tolerance for areas that strongly affect wearing comfort or appearance. On the other hand, overly strict tolerance that does not account for manufacturing variation can lead to more alterations and waste, so it should be considered based on sample results.

Points to Note in Ordering and Quality Control

When placing an order, do not communicate only the tolerance; compile the measurement drawing, measuring procedure, and how to handle cases that exceed the allowable range in the specification sheet. Also clearly state conditions that are likely to be interpreted differently, such as left-right differences, front-back differences, and whether measurements are taken without stretching.

During inspection, use the same table, the same measuring tool, and the same procedure to reduce errors caused by differences in the measurer or how the product is placed. Even if dimensions are within tolerance, if there is a problem with overall balance or left-right symmetry, judge it separately as an appearance quality issue.

Differences from Similar Terms

Standard dimensions are the target dimensions for the product. Dimensional tolerance is the range of allowable difference from those standard dimensions. Shrinkage rate is a term that indicates the rate of dimensional change due to washing, processing, or the passage of time, and its role differs from dimensional tolerance, which indicates the acceptable range for a finished product.

AQL is a concept used to determine whether a lot passes in sampling inspection. Dimensional tolerance is the allowable range for individual measured values, while AQL is treated as a standard for inspection operations, including inspection quantity and number of defects.

Frequently Asked Questions