Side Pull Strength

Definition and Overview

Side pull strength is a perspective for checking retention when force is applied to attached press fasteners and similar parts from a direction nearly parallel to the fabric surface. It examines whether the part is unlikely to come off, the fabric to tear, or the attachment area to deform when the part is pulled sideways during opening and closing or while worn.

It differs from strength against force pulling upward and out in the direction of the force applied and the way damage occurs. Side pull strength is not determined by the part alone; it is evaluated as a product that includes the fabric, reinforcement, and attachment condition.

Part Structure and Factors Affecting Strength

Press fasteners are generally used by combining the front and back hardware with the part that engages to open and close. An eyelet is a part that reinforces the area around a hole with hardware, and some structures also use a washer. If the combined parts do not match, it becomes difficult to obtain sufficient retention.

During side pulling, factors include how the leg portions or claws grip the fabric, the shape of the hardware, and the fabric density at the attachment position. Even if the hardware is strong, if the fabric is thin, coarse, or easily stretched, the hole may widen or the fabric may tear.

• Type, thickness, fabric weight, and stretchability of the fabric
• Whether reinforcement such as interlining or pressing cloth is used
• Combination of parts and compatible fabric thickness
• Compatibility of the setting tool, press pressure, and setting condition
• Expected pulling direction and frequency during use

Checking Size and Specifications

Side pull strength itself is not a size designation that indicates the part diameter or number. When selecting press fasteners or eyelets, check the dimensional specifications such as finished outside diameter, hole diameter, leg length, and compatible fabric thickness separately from the required retention.

Even with the same-looking size, resistance to sideways force varies depending on the part shape, material, combination, and attachment conditions. In a specification sheet, clearly stating the part configuration, attachment location, fabric and reinforcement details, and, if needed, the inspection method makes it easier to reduce variation in mass production.

Attachment and Main Applications

For attachment, use a setting tool suited to the target part and a hand press or foot press machine. If the setting tool does not match or the pressure is inappropriate, it may cause deformation of the part, insufficient crimping, or excessive biting into the fabric, which can reduce side pull strength.

For areas subject to repeated opening, closing, or pulling, such as front openings, pocket openings, cuffs, tabs, and bags, consideration of side pull is important. In particular, actual product attachment checks are necessary at positions close to edges, positions receiving diagonal force, and overlapped seam allowance areas where thickness changes.

Points to Note When Selecting

On thin or highly stretchable fabrics, even if only the part is made larger or driven in more strongly, the fabric itself may be damaged first. If necessary, distribute the load with pressing cloth or interlining, and check after washing and after repeated opening and closing as well. On thick fabrics, if the leg is too short for the compatible fabric thickness, it may not be crimped sufficiently.

For metal parts, also pay attention to rust and discoloration caused by moisture, sweat, detergents, and similar factors. For applications that touch the skin, confirm the presence or absence of nickel, and for products that require needle detection, confirm whether they are needle detector compatible as part of the part specifications. These are management items separate from side pull strength.

Frequently Asked Questions