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カラー・トレランスは、製品の外観の許容限度を設定するもので、カラーに関する品質保証および品質管理プロセスの不可欠な部分です。公差を設定することで、製品が限界内に収まっているかどうかを効率的に判断することができます。許容範囲内であれば、その製品は合格です。不合格品は公差の範囲外であるため、望ましい外観を作り出すために工程の調整が必要な場合があります。 

食品、プラスチック、化学などの多くの業界は、正確な外観に依存しています。公差は、標準を確立し、どの程度の変動を許容するかを決定することを可能にし、一貫した色の結果をもたらします。 

カラー・トレランスとは何か？

色彩の許容範囲とは、製品の色彩が許容範囲内で変化し得るパラメータのことである。通常、許容できる色の範囲を定義する最初のステップは目視による評価です。その後、分光光度計が客観的かつ科学的に許容範囲を数値化し、管理します。

許容値を設定する前に、観察者を決め、ハンターL,a,bのようなカラースケールを選択し、D 65やイルミナントAのような比較のための照度を選択する必要があります。何を測定するかによって、選択するスケールは、世界的な測定基準を設定する国際照明委員会(CIE)のものであったり、別の団体のものであったりします。 

比較基準ができれば、製品を集めて色を測定し、許容誤差と呼ばれるばらつきを判断することができる。 

このプロセスでは、まず製品に関連する標準を選択し、次に、外観に目に見える違いが生じる前に、この標準がどの程度変化しうるかを判断します。このテストは、今後の製造の境界線を設定するのに役立ち、製品が元の標準に十分に近いかどうかを客観的に判断し、品質への期待に適合させることができます。

色の違いを検出する

公差は2段階の差に基づいて設定できる：

• 最小許容差： 目視による比較では、標準試料と試料との間に、ちょうど認識できる程度の差があることを示す。 
• 最大許容差（Maximum acceptable difference）：標準とサンプルの間の最大許容差を表すレベル。 

最大許容差に焦点を当てることは、より広い許容値の範囲を意味し、一方、最小知覚差のみに依存することは、高い不合格率と材料の浪費につながる可能性がある。その結果、正しいアプローチを選択することは、一般的に業界主導となる。例えば、食品業界は最大許容差を頻繁に使用しますが、製薬メーカーは通常、最小知覚差を選択します。

許容範囲の定義

許容範囲は、確立された色標準に関連する許容可能な変動レベルです。 CIE L*a*b*のような測定モデルを使用してこの標準を確立します：

• L*:明るさ、ゼロの暗さから100の明るさまで。
• a*:赤緑軸上の位置で、正の数が赤、負の数が緑を示す。
• b*:黄色をプラス、青色をマイナスとする。

標準を確立したら、各寸法の許容誤差を決めることができる。以下は、サンプルと基準間の差（∆）を求める公式です：

∆L* = L*sample - L*reference

∆a* = a*sample - a*reference

∆b* = b*sample - b*reference

また、3つの値間の色の差の合計を1つの式で計算することもでき、その結果はΔE* (∆E*)で表されます。以下は∆E*を求める式です：

∆E* = √((△L*)2+(△a*)2+(△b*)2)

E*値は有用ですが、この方法は慎重に使用してください。差が3つの次元にまたがっている場合、許容できるように見える値が得られるかもしれないが、赤と緑など、1つの測定で大きなばらつきがある。 

このばらつきは顕著な視覚的差異を生じますが、他の寸法が標準に近ければデルタE*値には影響しないかもしれません。差の値を別々に計算すれば、それぞれをより注意深く監視して、標準から大きく外れているものがないことを確認することができます。

Color tolerances set acceptable limits for the appearance of a product and are an essential part of quality assurance and quality control processes for color. You can efficiently determine whether a product falls within the limits by establishing tolerances. If it does, the product passes. Failed goods fall outside the tolerances, meaning process adjustments may be necessary to create the desired appearance. 

Many industries, such as food, plastics, and chemicals, rely on accurate appearance. Tolerances enable you to establish a standard and decide how much variation to allow, giving you consistent color outcomes. 

What Is Color Tolerance?

Color tolerances are the parameters within which a product's color can vary yet remain acceptable. Typically, visual assessment is the initial step to define the acceptable color range. Spectrophotometry then objectively and scientifically quantifies and manages those tolerances.

Before establishing tolerance values, you must decide on the observer, choose a color scale, such as Hunter L,a,b, and then select illuminants for comparison, like D 65 and Illuminant A. Depending on what you're measuring, the scale you choose might come from the International Commission on Illumination (CIE), which sets global measurement standards, or from another entity. 

Once you have a comparison standard, you can gather products and measure their color to determine acceptable variations called tolerance values. 

In this process, you start by selecting a relevant standard for your product, then determine how much this standard can vary before it creates visible differences in appearance. This test helps you set boundaries for future production to objectively decide whether products fall close enough to the original standard to conform to quality expectations.

Detecting Color Differences

You can establish tolerances based on two levels of difference:

• Minimum perceptible difference: A visual comparison shows a just-noticeable difference between the standard and the sample. 
• Maximum acceptable difference: The level represents the largest acceptable difference between a standard and a sample. 

Focusing on the maximum acceptable difference means a broader range of acceptable values, while relying solely on minimum perceptible difference can lead to high rejection and material waste. As a result, choosing the right approach is typically industry-driven. For example, the food industry frequently uses the maximum acceptable difference, but pharmaceutical manufacturers usually opt for the minimum perceptible difference.

Range of Tolerance Definition

The range of tolerance is the acceptable level of variation related to an established color standard. You will establish this standard using a measurement model like CIE L*a*b*, which results in three values measuring:

• L*: Lightness, from dark at zero to light at 100.
• a*: Position on the red–green axis, with the positive number indicating red and the negative indicating green.
• b*: Position on the yellow–blue axis, with yellow represented as the positive and blue as the negative.

Once you establish a standard, you can decide on each dimension's tolerance. Here are the formulas for determining the difference (∆) between a sample and a reference:

∆L* = L*sample - L*reference

∆a* = a*sample - a*reference

∆b* = b*sample - b*reference

You can also calculate the total color difference across the three values in a single formula, with the results represented by delta E* (∆E*). Here's the formula to determine ∆E*:

∆E* = √((∆L*)2+(∆a*)2+(∆b*)2)

While ∆E* values can be helpful, use this method carefully. When the difference is spread over three dimensions, you may get a value that looks acceptable but has significant variation in one measurement, such as red vs. green. 

This variation will create a noticeable visual difference but may not impact the delta E* value if the other dimensions are close to the standard. If you calculate the difference values separately, you can more closely monitor each one to verify that none stray too far from the standard.

Color tolerances set acceptable limits for the appearance of a product and are an essential part of quality assurance and quality control processes for color. You can efficiently determine whether a product falls within the limits by establishing tolerances. If it does, the product passes. Failed goods fall outside the tolerances, meaning process adjustments may be necessary to create the desired appearance. 

Many industries, such as food, plastics, and chemicals, rely on accurate appearance. Tolerances enable you to establish a standard and decide how much variation to allow, giving you consistent color outcomes. 

What Is Color Tolerance?

Color tolerances are the parameters within which a product's color can vary yet remain acceptable. Typically, visual assessment is the initial step to define the acceptable color range. Spectrophotometry then objectively and scientifically quantifies and manages those tolerances.

Before establishing tolerance values, you must decide on the observer, choose a color scale, such as Hunter L,a,b, and then select illuminants for comparison, like D 65 and Illuminant A. Depending on what you're measuring, the scale you choose might come from the International Commission on Illumination (CIE), which sets global measurement standards, or from another entity. 

Once you have a comparison standard, you can gather products and measure their color to determine acceptable variations called tolerance values. 

In this process, you start by selecting a relevant standard for your product, then determine how much this standard can vary before it creates visible differences in appearance. This test helps you set boundaries for future production to objectively decide whether products fall close enough to the original standard to conform to quality expectations.

Detecting Color Differences

You can establish tolerances based on two levels of difference:

• Minimum perceptible difference: A visual comparison shows a just-noticeable difference between the standard and the sample. 
• Maximum acceptable difference: The level represents the largest acceptable difference between a standard and a sample. 

Focusing on the maximum acceptable difference means a broader range of acceptable values, while relying solely on minimum perceptible difference can lead to high rejection and material waste. As a result, choosing the right approach is typically industry-driven. For example, the food industry frequently uses the maximum acceptable difference, but pharmaceutical manufacturers usually opt for the minimum perceptible difference.

Range of Tolerance Definition

The range of tolerance is the acceptable level of variation related to an established color standard. You will establish this standard using a measurement model like CIE L*a*b*, which results in three values measuring:

• L*: Lightness, from dark at zero to light at 100.
• a*: Position on the red–green axis, with the positive number indicating red and the negative indicating green.
• b*: Position on the yellow–blue axis, with yellow represented as the positive and blue as the negative.

Once you establish a standard, you can decide on each dimension's tolerance. Here are the formulas for determining the difference (∆) between a sample and a reference:

∆L* = L*sample - L*reference

∆a* = a*sample - a*reference

∆b* = b*sample - b*reference

You can also calculate the total color difference across the three values in a single formula, with the results represented by delta E* (∆E*). Here's the formula to determine ∆E*:

∆E* = √((∆L*)2+(∆a*)2+(∆b*)2)

While ∆E* values can be helpful, use this method carefully. When the difference is spread over three dimensions, you may get a value that looks acceptable but has significant variation in one measurement, such as red vs. green. 

This variation will create a noticeable visual difference but may not impact the delta E* value if the other dimensions are close to the standard. If you calculate the difference values separately, you can more closely monitor each one to verify that none stray too far from the standard.

Color tolerances set acceptable limits for the appearance of a product and are an essential part of quality assurance and quality control processes for color. You can efficiently determine whether a product falls within the limits by establishing tolerances. If it does, the product passes. Failed goods fall outside the tolerances, meaning process adjustments may be necessary to create the desired appearance. 

Many industries, such as food, plastics, and chemicals, rely on accurate appearance. Tolerances enable you to establish a standard and decide how much variation to allow, giving you consistent color outcomes. 

What Is Color Tolerance?

Color tolerances are the parameters within which a product's color can vary yet remain acceptable. Typically, visual assessment is the initial step to define the acceptable color range. Spectrophotometry then objectively and scientifically quantifies and manages those tolerances.

Before establishing tolerance values, you must decide on the observer, choose a color scale, such as Hunter L,a,b, and then select illuminants for comparison, like D 65 and Illuminant A. Depending on what you're measuring, the scale you choose might come from the International Commission on Illumination (CIE), which sets global measurement standards, or from another entity. 

Once you have a comparison standard, you can gather products and measure their color to determine acceptable variations called tolerance values. 

In this process, you start by selecting a relevant standard for your product, then determine how much this standard can vary before it creates visible differences in appearance. This test helps you set boundaries for future production to objectively decide whether products fall close enough to the original standard to conform to quality expectations.

Detecting Color Differences

You can establish tolerances based on two levels of difference:

• Minimum perceptible difference: A visual comparison shows a just-noticeable difference between the standard and the sample. 
• Maximum acceptable difference: The level represents the largest acceptable difference between a standard and a sample. 

Focusing on the maximum acceptable difference means a broader range of acceptable values, while relying solely on minimum perceptible difference can lead to high rejection and material waste. As a result, choosing the right approach is typically industry-driven. For example, the food industry frequently uses the maximum acceptable difference, but pharmaceutical manufacturers usually opt for the minimum perceptible difference.

Range of Tolerance Definition

The range of tolerance is the acceptable level of variation related to an established color standard. You will establish this standard using a measurement model like CIE L*a*b*, which results in three values measuring:

• L*: Lightness, from dark at zero to light at 100.
• a*: Position on the red–green axis, with the positive number indicating red and the negative indicating green.
• b*: Position on the yellow–blue axis, with yellow represented as the positive and blue as the negative.

Once you establish a standard, you can decide on each dimension's tolerance. Here are the formulas for determining the difference (∆) between a sample and a reference:

∆L* = L*sample - L*reference

∆a* = a*sample - a*reference

∆b* = b*sample - b*reference

You can also calculate the total color difference across the three values in a single formula, with the results represented by delta E* (∆E*). Here's the formula to determine ∆E*:

∆E* = √((∆L*)2+(∆a*)2+(∆b*)2)

While ∆E* values can be helpful, use this method carefully. When the difference is spread over three dimensions, you may get a value that looks acceptable but has significant variation in one measurement, such as red vs. green. 

This variation will create a noticeable visual difference but may not impact the delta E* value if the other dimensions are close to the standard. If you calculate the difference values separately, you can more closely monitor each one to verify that none stray too far from the standard.

Las tolerancias de color establecen límites aceptables para el aspecto de un producto y son una parte esencial de los procesos de garantía y control de calidad del color. Se puede determinar de manera eficiente si un producto se encuentra dentro de los límites estableciendo tolerancias. Si es así, el producto pasa la prueba. Los productos defectuosos se encuentran fuera de las tolerancias, lo que significa que puede ser necesario realizar ajustes en el proceso para crear el aspecto deseado. 

Muchas industrias, como la alimentaria, la del plástico y la química, dependen de una apariencia precisa. Las tolerancias le permiten establecer un estándar y decidir cuánta variación permitir, lo que le proporciona resultados de color consistentes. 

¿Qué es la tolerancia al color?

Las tolerancias de color son los parámetros dentro de los cuales el color de un producto puede variar y seguir siendo aceptable. Por lo general, la evaluación visual es el primer paso para definir el rango de color aceptable. A continuación, la espectrofotometría cuantifica y gestiona esas tolerancias de forma objetiva y científica.

Antes de establecer los valores de tolerancia, debe decidir el observador, elegir una escala de colores, como Hunter L,a,b, y luego seleccionar iluminantes para la comparación, como D 65 e iluminante A. Dependiendo de lo que esté midiendo, la escala que elija puede provenir de la Comisión Internacional de Iluminación (CIE), que establece estándares de medición globales, o de otra entidad. 

Una vez que se dispone de un estándar de comparación, se pueden reunir los productos y medir su color para determinar las variaciones aceptables, denominadas valores de tolerancia. 

En este proceso, se comienza seleccionando una norma relevante para el producto y, a continuación, se determina cuánto puede variar dicha norma antes de que se produzcan diferencias visibles en la apariencia. Esta prueba ayuda a establecer límites para la producción futura, con el fin de decidir de forma objetiva si los productos se ajustan lo suficiente a la norma original como para cumplir con las expectativas de calidad.

Detección de diferencias de color

Puede establecer tolerancias basadas en dos niveles de diferencia:

• Diferencia mínima perceptible: Una comparación visual muestra una diferencia apenas perceptible entre el estándar y la muestra. 
• Diferencia máxima aceptable: El nivel representa la mayor diferencia aceptable entre una norma y una muestra. 

Centrarse en la diferencia máxima aceptable significa un rango más amplio de valores aceptables, mientras que basarse únicamente en la diferencia mínima perceptible puede dar lugar a un alto índice de rechazo y al desperdicio de material. Por lo tanto, la elección del enfoque adecuado suele estar determinada por la industria. Por ejemplo, la industria alimentaria suele utilizar la diferencia máxima aceptable, pero los fabricantes de productos farmacéuticos suelen optar por la diferencia mínima perceptible.

Rango de tolerancia Definición

El rango de tolerancia es el nivel aceptable de variación en relación con un estándar de color establecido. Este estándar se establece utilizando un modelo de medición como CIE L*a*b*, que da como resultado tres valores de medición:

• L*: Luminosidad, desde oscuro en cero hasta claro en 100.
• a*: Posición en el eje rojo-verde, donde el número positivo indica el rojo y el negativo indica el verde.
• b*: Posición en el eje amarillo-azul, donde el amarillo representa el positivo y el azul el negativo.

Una vez establecido un estándar, se puede decidir la tolerancia de cada dimensión. A continuación se muestran las fórmulas para determinar la diferencia (∆) entre una muestra y una referencia:

∆L* = L*muestra - L*referencia

∆a* = a*muestra - a*referencia

∆b* = b*muestra - b*referencia

También se puede calcular la diferencia total de color entre los tres valores en una sola fórmula, con los resultados representados por delta E* (∆E*). Esta es la fórmula para determinar ∆E*:

∆E* = √((∆L*)2+(∆a*)2+(∆b*)2)

Aunque los valores ∆E* pueden resultar útiles, utilice este método con precaución. Cuando la diferencia se distribuye en tres dimensiones, es posible que obtenga un valor que parezca aceptable, pero que presente una variación significativa en una medición, como el rojo frente al verde. 

Esta variación creará una diferencia visual notable, pero puede que no afecte al valor delta E* si las demás dimensiones se acercan al estándar. Si calcula los valores de diferencia por separado, podrá supervisar más de cerca cada uno de ellos para verificar que ninguno se aleje demasiado del estándar.

Color tolerances set acceptable limits for the appearance of a product and are an essential part of quality assurance and quality control processes for color. You can efficiently determine whether a product falls within the limits by establishing tolerances. If it does, the product passes. Failed goods fall outside the tolerances, meaning process adjustments may be necessary to create the desired appearance. 

Many industries, such as food, plastics, and chemicals, rely on accurate appearance. Tolerances enable you to establish a standard and decide how much variation to allow, giving you consistent color outcomes. 

What Is Color Tolerance?

Color tolerances are the parameters within which a product's color can vary yet remain acceptable. Typically, visual assessment is the initial step to define the acceptable color range. Spectrophotometry then objectively and scientifically quantifies and manages those tolerances.

Before establishing tolerance values, you must decide on the observer, choose a color scale, such as Hunter L,a,b, and then select illuminants for comparison, like D 65 and Illuminant A. Depending on what you're measuring, the scale you choose might come from the International Commission on Illumination (CIE), which sets global measurement standards, or from another entity. 

Once you have a comparison standard, you can gather products and measure their color to determine acceptable variations called tolerance values. 

In this process, you start by selecting a relevant standard for your product, then determine how much this standard can vary before it creates visible differences in appearance. This test helps you set boundaries for future production to objectively decide whether products fall close enough to the original standard to conform to quality expectations.

Detecting Color Differences

You can establish tolerances based on two levels of difference:

• Minimum perceptible difference: A visual comparison shows a just-noticeable difference between the standard and the sample. 
• Maximum acceptable difference: The level represents the largest acceptable difference between a standard and a sample. 

Focusing on the maximum acceptable difference means a broader range of acceptable values, while relying solely on minimum perceptible difference can lead to high rejection and material waste. As a result, choosing the right approach is typically industry-driven. For example, the food industry frequently uses the maximum acceptable difference, but pharmaceutical manufacturers usually opt for the minimum perceptible difference.

Range of Tolerance Definition

The range of tolerance is the acceptable level of variation related to an established color standard. You will establish this standard using a measurement model like CIE L*a*b*, which results in three values measuring:

• L*: Lightness, from dark at zero to light at 100.
• a*: Position on the red–green axis, with the positive number indicating red and the negative indicating green.
• b*: Position on the yellow–blue axis, with yellow represented as the positive and blue as the negative.

Once you establish a standard, you can decide on each dimension's tolerance. Here are the formulas for determining the difference (∆) between a sample and a reference:

∆L* = L*sample - L*reference

∆a* = a*sample - a*reference

∆b* = b*sample - b*reference

You can also calculate the total color difference across the three values in a single formula, with the results represented by delta E* (∆E*). Here's the formula to determine ∆E*:

∆E* = √((∆L*)2+(∆a*)2+(∆b*)2)

While ∆E* values can be helpful, use this method carefully. When the difference is spread over three dimensions, you may get a value that looks acceptable but has significant variation in one measurement, such as red vs. green. 

This variation will create a noticeable visual difference but may not impact the delta E* value if the other dimensions are close to the standard. If you calculate the difference values separately, you can more closely monitor each one to verify that none stray too far from the standard.

Using a spectrophotometer is the best way to measure the color of plastic pellets. These technological devices deliver reliable and accurate measurements that help you ensure the color remains consistent with each batch while adhering to industry standards.

Measure the Color of Plastic Pellets Using the Right Equipment

Plastic pellets vary in transparency and opacity, so you should use the appropriate measurement equipment and accessories for accurate results. Plastic pellets should be measured with a reflectance spectrophotometer. Opaque plastic pellets require only a sample cup, while transparent plastic pellets may require the use of an opaque cover. 

Keep Industry Standards in Mind

An effective color measurement system follows industry standards. As a part of quality and process control, it's important to measure the color of plastic pellets according to the testing standards set by ASTM. Plus, following the standards ensures you measure the pellets more accurately for consistent results.

Spectrophotometers can help you adhere to industry standards by offering a straightforward way to meet the outlined specifications.

Assess the Degree of Yellowness

Achieving clear and consistent colors is critical in plastic production. However, plastic resin can turn yellow when subjected to oxidation. Yellowness directly impacts the value and perceived quality of plastic products. To prevent the yellowish appearance, optical brighteners are used to make the plastics look more clear or white. 

Optical brighteners are also often used to enhance the appearance of recycled plastics. As a result, it's essential to assess the degree of yellowness in plastic resin to determine the appropriate concentration of optical brighteners needed to counteract the yellowing effect of plastics throughout the supply chain.

As the plastic production industry moves toward using recycled plastics, you'll need a robust spectrophotometer that can measure the color and fluorescence quality of virgin and recycled plastic resin and a combination of the two. By doing so, the spectrophotometer can help mitigate yellowness and ensure the optical brighteners are adjusted for at every stage of the production process.