Random Tumble Pilling Tester and Testing Method

What are Pilling and Pill?

Pilling is the formation of small balls of entangled fibers on the surface of the fabric. A pill is therefore a cluster or entanglement (bundle) of fibers in the form of a ball, attached to the fabric surface by one or more anchor fibers, sometimes incorporating lint or foreign matter. Such surface deterioration is generally unacceptable to the consumer. The amount of pilling that develops is governed by the rate of fiber entanglement, the rate of surface fiber development and the rate of fiber and pills wear-off. These pilling rates depend on the fiber, yarn and fabric properties. Many pilling tests now include assessment of fabric fuzzing, which can be a precursor to pill formation.

Pilling, when it occurs, represents a serious quality problem, particularly in apparel and upholstery fabrics, and can be one of the reasons why a product becomes ‘unsightly’ and no longer acceptable for further use. Although pilling is an unacceptable fabric fault or weakness, it is often a necessary tradeoff when a high degree of softness is required, which frequently comes associated with increased pilling propensity. Furthermore, when easy-care is required, strong synthetic fibers with a long flex life are often blended with weaker natural fibers, such as wool and cotton, with the synthetic fiber anchoring pills to the fabric and preventing them from wearing off.

To evaluate the pilling tendency of fabrics in a controlled laboratory setting, various testing instruments are used. Among them, the Random Tumble Pilling Tester is a widely recognized and reliable device, especially for knitted, woven, and nonwoven fabrics. In this article I will explore about pilling, pill formation technique, measurement of pilling and Random Tumble Pilling Tester (RTPT).

How Pills are Formed?

Broadly speaking, there are three different stages involved in pilling – fuzz formation, pill formation and pill wear-off – and the rate at which each occurs depends on fiber, yarn and fabric properties and their interactions. In order for pills to form, a sufficient density and length of fiber ends (hairs) is required on the fabric surface, so that they can entangle during mechanical action such as rubbing the fabric surface. Therefore, pilling cannot occur where the fabric contains continuous filament yarns, unless the fabric is subjected to a treatment that breaks the filaments on its surface. Mechanical action applied to the fabric surface, for example, the rubbing action during wear or cleaning, or even during dyeing and finishing, can cause surface fibers to break and become entangled into clusters or balls (i.e. pills). The mechanical action can also cause fibers to migrate to the fabric surface (i.e. to be pulled out from the body of the fabric) and to extend further from the fabric surface until the density and length of surface fibers (fuzz or hairs) are such that further mechanical action and frictional forces cause them to become entangled into pills that remain attached to the fabric by one or more fibers, the latter often being the stronger fibers in a blend. Loose fibers, or even contaminants, on the fabric surface often form an integral part of the pill-formation process and pill.

Continued mechanical action can cause the pills to wear off. Generally, pills are removed during wear as a result of the anchoring fibers being pulled out of the fabric or breaking; flex life is a critical factor in the latter case, and fiber length and binding in the former.

There are many factors that affect the degree of pilling that occurs during use, including the following:

• End use
• Wear conditions
• Washing and dry-cleaning conditions
• Fiber properties
• Yarn properties
• Fabric properties
• Fabric finishing
• Relative humidity

Measurement of Pilling

A large number of pilling test instruments and associated methods (ISO EN BS12495) have been developed, and these have been covered in detail elsewhere. In brief, pilling testers utilize either a generally flat rubbing/abrading action or a tumbling action to develop pills.

Examples of the former include:

• Martindale Abrasion and Pilling Tester
• Stoll Quartermaster universal wear tester (using an elastomeric friction pad)
• Brush and sponge pilling tester

Examples of pilling testers based upon a tumbling action are:

• Random tumble pilling tester
• ICI pilling box

Traditionally, the pilling induced on the fabric sample during laboratory testing has been assessed (i.e. quantified) subjectively by a rating system, often with the aid of photographic standards, and additional objective and sophisticated techniques have been developed in recent years.

Generally, tumbling pilling testers are used mostly for knitted fabrics, and abrasion pilling testers for woven fabrics. Correlations vary greatly when comparing the results of different pill testers, pill testers with actual wear, and corresponding rankings of fabrics, and depend upon the fabric type and construction, as well as the testing and wear conditions involved.

Random Tumble Pilling Tester

Random Tumble Pilling Tester (RTPT) also named Textile Random Tumble Pilling Machine which is used to determine the pilling and fuzzing characteristics of textile fabrics. The main purpose of this tester is to test the pilling resistance of textile, suitable for all kinds of clothing fabric. Random Tumble Pilling Tester complies with ASTM D3512, ISO 12945-3 etc.

Testing Standards

The Random Tumble Pilling Tester is commonly used as per the following standards:

1. ASTM D3512 — Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Random Tumble Pilling Tester
2. ISO 12945-3 — Determination of Fabric Propensity to Surface Fuzzing and to Pilling

Principle of the Random Tumble Pilling Test

Fabric specimens are placed inside a rotating cylindrical chamber lined with cork. The chamber rotates at a specified speed while air is injected to create a random tumbling effect. This combined action of mechanical tumbling and air turbulence simulates the natural formation of pills on the fabric surface.

After a specific period, the specimens are removed, and the degree of pilling is assessed visually against a standard photographic rating scale.

Materials and Equipment Required

1. Random Tumble Pilling Tester
2. Fabric specimens (usually 105 mm diameter circles)
3. Cork-lined rotating drum
4. Compressed air source
5. Photographic pilling rating standards
6. Scissors and templates
7. Specimen holders
8. Digital timer

Technical Specifications of Random Tumble Pilling Tester

Testing Procedure

1. Sample Preparation

• Cut four fabric specimens of 105 mm diameter using a standard template.
• Condition the specimens in a standard atmosphere (20 ± 2°C temperature and 65 ± 4% relative humidity) for at least 4 hours.

2. Mounting the Specimens

• Place each specimen inside the cork-lined drum.
• Ensure the drum is clean and free from debris from previous tests.

3. Testing Process

• Set the rotating drum to a speed of 1200 ± 10 RPM.
• Start the airflow to create random tumbling.
• Run the machine for the desired time period (commonly 30 minutes or as per standard requirement).

4. Assessment

• After tumbling, remove the specimens carefully.
• Assess the pilling by comparing the fabric surface against standard photographic pilling rating standards (usually graded 5 to 1, where 5 = no pilling and 1 = severe pilling).

Advantages of Random Tumble Pilling Tester

1. Simulates actual wearing conditions effectively.
2. Provides quick, reproducible results.
3. Suitable for all types of fabrics.
4. Can test multiple specimens simultaneously.
5. Standardized, globally recognized testing method.

Limitations of Random Tumble Pilling Tester

1. Requires subjective visual assessment, which may vary among operators.
2. Cork lining needs periodic replacement for consistent results.
3. Airflow and drum speed must be precisely maintained for accuracy.

Conclusion

Random Tumble Pilling Tester is a critical instrument in textile quality control for evaluating the pilling behavior of fabrics under simulated wear conditions. This tester provides a reliable, standardized assessment of fabric durability against pilling. By combining mechanical action with controlled environmental factors, it offers textile manufacturers critical data for quality improvement. By adhering to standardized testing methods like ASTM D3512, industries can ensure consistent fabric performance and customer satisfaction.

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