Press Fastener

Definition and Overview

A press fastener is a fastening device that is fastened by pressing the male and female parts together and opened by pulling them apart. Because it does not require making a buttonhole in sewing and is relatively easy to operate with one hand, it is used for front openings and pocket openings in apparel.

In general, it refers to a type that is crimped onto the textile, but sometimes even sew-on snaps are included under the term snap button. In specifications, indicating whether it is the hammered type or the sew-on type helps prevent misunderstandings.

Materials and Structure

A hammered-type press fastener is often made by combining the front head, the female spring or socket, the male stud, and the cap and close post that secures it on the back side. Part names and configurations vary depending on the shape and manufacturer, so select components within the same series.

Metal types include brass, iron, and stainless steel, and there are also resin types. Metal surfaces may be plated, and not only appearance but also corrosion resistance and resistance to color transfer onto apparel are subject to specification checks.

• Spring type: a structure in which the female spring holds the male part.
• Jumper type: the female-side structure differs, giving it distinct opening and closing feel and holding power.
• Resin type: lightweight, and sometimes used for products where compatibility with metal detection is considered.

Size Indication and Selection

Size is generally indicated in millimeters based on the diameter of the head or outer circumference. However, because the basis for the indicated dimensions and the compatible textile thickness differ by product, it is important not to judge compatibility by diameter alone.

When selecting, check the size of the visible head, the force required to fasten and unfasten, the length of the part legs, and the thickness of the textile together. For stretch textile, lightweight fabric, and fuzzy fabric, verify with prototypes, including the use of interlining or reinforcement fabric.

How to Attach and Main Applications

Use a dedicated setter and a hand press or pressing machine to crimp each part perpendicular to the textile. Use a setter that matches the shape and size of the part, and avoid mixing different product numbers or series.

It is used for shirts and blouses, outerwear, workwear, baby and kids' apparel, bag openings, and pockets. Depending on the application, consider the frequency of opening and closing, direction of pulling, and whether it will be washed or used outdoors, and choose the necessary holding power.

• Before mass production, perform trial fastening on actual textile.
• Check for bad fastening, deformation, or weak holding.
• Perform tensile tests, including whether the textile tears or parts fall off after opening and closing.

Points of Caution and Differences from Similar Terms

Using a part with long legs on thin textile may cause insufficient crimping or looseness in the part. Conversely, using short legs on thick fabric may prevent sufficient crimping and lead to detachment. In addition to textile thickness, weave density, stretch, and whether interlining is used also affect performance.

For applications exposed to sweat, moisture, detergent, and the like, check for metal rust, plating discoloration, and effects on surrounding textile. For products intended to address nickel metal allergies, confirm the nickel-free scope and test conditions individually.

Press fastener often refers to a hammered-type snap, while sew-on snaps are a different specification attached with thread. Also, tack buttons are fixed buttons mainly used on denim and the like, and differ from press fasteners that have an opening and closing structure.

• For products that require needle detection, confirm whether the parts to be used are needle detector compatible.
• For products for infants and toddlers, verify strength to prevent detachment.
• Evaluate under assumed use conditions such as washing, dry cleaning, and salt-containing environments.

Frequently Asked Questions

How should I choose the size of a press fastener?

Choose by checking not only the visible head diameter needed for appearance, but also the textile thickness, part leg length, required holding power, and the setter to be used. Because parts may have different configurations even with the same indicated diameter, it is important to perform trial fastening on actual textile and check opening, closing, and tensile strength.

What is the difference between a press fastener and a sew-on snap?

A press fastener is generally attached by crimping the parts with a dedicated setter and press. A sew-on snap is fixed with thread through holes or sewn sections. The processing method on the textile, required equipment, ease of repair, and appearance differ.

Does nickel-free mean metal allergy considerations are sufficient?

Nickel-free indicates a specification that takes nickel use and elution into consideration, but it does not guarantee that allergic reactions will not occur for all people. Depending on the intended application, confirm the material composition, surface treatment, and test conditions.