Pull-out Strength
Pull-out strength is the force required to pull a component vertically away from fabric with press fasteners or eyelets attached.
Contents6 sections
Definition and Overview
Pull-out strength is a test that checks the strength by applying tensile load to installed press fasteners, eyelets, or cap and close posts until the component pulls out from the fabric or breaks. It represents not only the strength of the accessory itself, but also performance including the fabric and the installed condition.
It is distinguished from the engagement force required to open and close a button. Engagement force is the force when the male and female sides separate, whereas pull-out strength is an indicator of how difficult it is for the entire component to come off the fabric.
Component Structure and Size Considerations
Press fasteners are generally used by combining multiple matching parts such as the outer cap, spring or female side, stud or male side, and the backing washer. Eyelets also use a combination of the eyelet body and washer, so it is important to choose a combination that matches the same specification.
Component size is checked by the outer diameter of the cap, the length of the post, and the compatible fabric thickness. Even if the outer diameter is large, if the post length or washer shape does not suit the fabric, proper setting will not be achieved and pull-out strength will not be stable.
- For thin fabrics, consider using interfacing or a pressing cloth to reinforce the fabric.
- For thick fabrics, select a component whose post is not too short for the fabric thickness.
- Avoid combinations in which the component diameters or specifications differ between the front and back sides.
Installation Method and Its Effect on Strength
Use a setting tool, anvil, hand press, foot press, or air press, and install each part with the specified tool. If the shape of the tool does not match, it can cause scratches on the head, deformation, insufficient setting, or excessive crimping, affecting both appearance and strength.
Press settings are adjusted according to fabric thickness, hardness, weave structure, number of layers, and whether interfacing is used. After a test setting, check the front and back setting shape, component tilt, rotation, looseness, and opening and closing performance, and perform a pull-out test if necessary.
Main Applications and Points of Attention
Pull-out strength is important in areas subject to repeated force, such as the front opening of garments, pockets, cuffs, waist areas, and bags. Especially for products for infants and children, management standards should be established in advance according to the intended use so that small parts do not come off.
In thin, loosely woven fabrics, highly stretchable knits, pile fabrics, and coated or laminated fabrics, the holding force and setting performance of the component change. It is important to make samples with the same material composition as the product and also check conditions after washing or under assumed use conditions.
Metal accessories may rust, discolor, or form verdigris due to humidity, sweat, detergents, or storage conditions. For products that require consideration of nickel-related effects, confirm nickel-free specifications, and if there is a needle detection process, also confirm whether they are needle detector compatible as part of the accessory specifications.
Differences from Similar Terms
Side pull strength is the resistance when force is applied in a direction close to parallel with the fabric surface against the attached component. Whereas pull-out strength targets the force that removes the component vertically from the fabric, the force direction and assumed failure state are different.
Tensile strength, tear strength, and bursting strength are terms mainly used to evaluate the strength of the fabric itself. Pull-out strength, on the other hand, evaluates the performance of the attachment area, including the type of accessory, combination of parts, setting conditions, and the reinforcement condition of the fabric.
Frequently Asked Questions
What are the main causes when pull-out strength is insufficient?
The main causes are an incorrect post length for the fabric, a mismatch between the component and the setting tool specification, insufficient or excessive press pressure, and improper washer selection. Thin, stretchy, or loosely woven fabrics also tend to have reduced holding power, so confirm these points including reinforcement methods.
Is a high engagement force enough for the pull-out strength of a press fastener?
Not necessarily. Even if the engagement force is high, if the fastening of the component is insufficient, the component may come off the fabric during opening operations. It is necessary to evaluate engagement force, pull-out strength, appearance, and the condition after repeated opening and closing separately.
Is it enough to check pull-out strength only before mass production?
In addition to prototype confirmation before mass production, it is desirable to check during mass production as well, taking into account variations in setting conditions and wear of the setting tool. If the fabric lot, interfacing, components, or process conditions change, rechecking even with the same specification helps quality control.
