What is Spectrophotometer? MiniScan EZ by HunterLab

1          Abstract:

Every industry needs different types of equipment and instruments to analyze its performance and to compare actual results with standard results. Every company wants to produce best products according to standards for its reputation in market and gain maximum profit. Similarly, some industries where color is a big factor like Textiles, Plastics, Paints, Glass, Paper, etc. need some equipment to measure the color of products and standardize it. Spectrophotometers are best for this purpose. In this draft, we explained working and application of spectrophotometer. A spectrophotometer named MiniScan EZ by HunterLab is studied for detailed elaboration.

2          What is Spectrophotometer?

Instrument used to measure the intensity of wavelengths in a spectrum of light compared with the intensity of light from a standard source is called spectrophotometer.

According to Beer's law, the amount of light absorbed by a medium is proportional to the concentration of the absorbing material or solute present. Thus the concentration of a colored solute in a solution may be determined in the lab by measuring the absorbency of light at a given wavelength. Wavelength is measured in nm.

3          How it Works?

The spectrophotometer technique is to measures light intensity as a function of wavelength. 

It does this by:

•  diffracting the light beam into a spectrum of wavelengths
•  direct it to an object
• receiving the light reflected or returned from the object
•  detecting the intensities with a charge-coupled device
•  displaying the results as a graph on the detector and then the display device

Figure 1: Principle of Spectrophotometer

4          What are its Applications?

Spectrophotometers have wide application area. Some major applications are;

• Measure the concentration of the solution.
•  Identify organic compounds by determining the absorption maximum.
•  Used for color determination within the spectral range.
• Detection of Impurities (UV absorption spectroscopy is one of the best methods for determination of impurities in organic molecules).
•  Chemical Kinetics (The UV radiation is passed through the reaction cell and the absorbance changes can be observed).
•  Molecular weight determination.

5          What is HunterLab?

Richard Hunter, developed the measurement scale of L,a,b values, in 1942, that are the basis for every color measurement technique and scale used today by all involved in the business of color.

Utilizing their industry-leading, innovative technology, and backed by over 60 years of experience, HunterLab provide products that measure color the way human eye sees it.

HunterLab's spectrophotometer systems are industry-leading color measurement systems. The only color measurement company in the world offering a complete line of 45º/0º geometry instrumentation; portable, laboratory bench-top, and production in-line.

6          MiniScan EZ by HunterLab:

If one need to measure color outside the laboratory, take the MiniScan EZ. The MiniScan EZ spectrophotometer gives the best of two worlds; laboratory performance in a light-weight, take-anywhere design. Sophisticated dual-beam technology, normally found only in bench-top sensors, ensures accuracy. The durable ergonomic design promotes one-hand, one-touch operation so sample measurements are taken in seconds.

6.1         Measuring Principle:

Measuring principle of MiniScan EZ is dual-beam spectrophotometer. It works as;

Figure 3: MiniScan EZ Principle

6.2         System Geometry:

System geometry defines how the sample is illuminated and the angle at which the reflected light is measured. To best fit measurement requirements, MiniScan EZ is available with 45°/0° or diffuse/8° measurement geometry.

6.2.1        45°/0° Geometry:

If one wants to measure how the sample appears to customer, the 45°/0° system is best. This system illuminates the sample at a 45° angle and measures it at 0° which is perpendicular to the sample. The 45°/0° MiniScan EZ ignores the glare from the sample (specular excluded) and sees both the effect sample coloration the effect of its gloss or texture. This is how your customer visually sees it.

6.2.2        Diffuse/8° Geometry:

If you want to know only the sample’s coloration, ignoring the effect of its gloss or texture, then the d/8° system is best. The diffuse/8° MiniScan EZ illuminates the sample diffusely and measures it at an 8° angle to the surface.  This geometry includes the sample glare (specular included) and will only see the effect of coloration, ignoring its surface characteristics.

6.3         Pulsed Xenon Lamp:

Pulses Xenon Lamp is used as light source in MiniScan EZ. Pulsed Light can deliver peak energies 100,000 times higher than the sun's intensity on the earth's surface. Pulsed Light is high-energy light delivered in incredibly short periods of time. It’s a simple concept with profound ramifications, because it means we can produce extremely large amounts of energy, up to 1 megawatt, while generating very little heat.

6.3.1        The Benefits of Pulsed Light:

• Deeper penetration for complete cures with full and consistent results. Pulsed Light penetrates thick and semi-opaque substrates more effectively than continuous light.
• Uses far less power for lower cost of ownership. Light is only produced for a small portion of the typical duty cycle, saving up to 80% on energy use compared to continuous light.
• Process flexibility. Engineers can tailor key parameters including peak power, pulse repetition rate, pulse sequencing, cure duration, and output spectrum, to achieve the optimal balance of energy, heat, and processing times.
• Reduced cure time for much higher throughput. Pulsed Light keeps temperatures low even while it delivers high energy, allowing higher throughput for volume manufacturing.

6.4         Specifications:

Major specifications of MiniScan EZ are;

Table 1: Specifications of MiniScan EZ

Measurement
Measurement Principle	Dual-beam spectrophotometer
Geometries	Diffuse/8° (specular component included) OR Dirrectional annular 45° illumination/0° viewing (specular component excluded)
Spectrophotometer	256 element diode array and high resolution, concave holographic grating
Sphere Diameter	63.5mm
Spectral Component	Excluded on 45°/0° models, Included on Diffuse/8° models
Spectral Range	400nm – 700nm
Spectral Resolution	<3nm
Effective Bandwidth	10nm equivalent triangle
Reporting Interval	10nm
Photometric Range	0 – 150%
Light Source	Pulsed Xenon Lamp
Flashes per Measurement	1
Lamp Life	> 1million flashes
Measurement Time	< 1 second from button push to measurement 2 seconds from button push to data display
Firmware
Data View	Color Data, Color Difference Data, Tristimulus Color Plot, Spectral Data, Spectral, Difference Data, Spectral Plot, Spectral Difference Plot
USB Flash Drive Features	Backup of Setups and Data, Setup Transfer to Multiple Units, Data Export to Excel
Other Features	Pass/Fail, Average Multiple Readings, Search for Closest Standard
Illuminants	A, C, D50, D55, D65, D75, F2, F7, F11
Observers	2° and 10°
Color Scales	CIE L*a*b*, Hunter Lab, CIE L*C*h, CIE Yxy, CIE XYZ
Color Difference Scales	∆L*a*b*, ∆Lab, ∆L*C*H, ∆Yxy, ∆XYZ
Physical/Electrical
Dimensions	Height: 13.9 cm (5.5 in.) Width: 10.9 cm (4.3 in.) Depth: 26.7 cm (10.5 in.) Weight: 1 kg (2.2 lbs) with batteries
Display	5.8 cm x 5.8 cm (2.3 in. x 2.3 in.) backlit LCD, blue monochrome
Interface	USB 2.0
Power	Six AA-size alkaline batteries or nickel metal-hydride rechargeable batteries
Operating Environment	10° to 40°C (50° to 104° F), 10 % to 90 % RH, noncondensing

6.5         Special Features:

Some distinct features of MiniScan EZ are;

6.5.1        Easy to use:

• Ergonomic and flexible design and ease of use, reducing user fatigue and preventing reading errors.
• In-hand controls provide easy one-handed operation with thumb-tip navigation of all functions.
• Easy pass/fail determination based on user-entered tolerances or automatic tolerances.
•  Large   easy-to-read, LCD graphical display  with screen four rotation options: 0°, 90°, 180°and 270°.
• Lightweight construction, weighing only 1kg (2.25lbs) including batteries.

6.5.2        Accurate:

• Available in 45°/0° and diffuse/8° geometry systems, each with large area or small area view options. Wavelength calibration check filter provided.
• Displays color data, color difference data, color plot, spectral data, spectral data difference, spectral plot, and spectral difference plot.
• Measures the visible spectrum from 400 nm to 700 nm with 10 nm resolution.

6.5.3        The HunterLab Advantage:

• EZ is backed by over 60 years of quality innovation and experience from HunterLab, the world’s most trusted color quality experts.
• With an unmatched reputation for delivering the right solution for any challenge, HunterLab tailors products and technologies for every color measurement need and budget offering the broadest range of color measurement solutions in the industry.

Figure 6: Special Features of MiniScan EZ

6.6         Application Area of MiniScan EZ:

MiniScan EZ is designed for color measurements in following areas;

Table 2: Application Areas of MiniScan EZ

Applications of MiniScan EZ
Sr. No.	Area of Application	Sr. No.	Area of Application
1	Paint Chips	2	Metals
3	Extruded Plastic Pieces	4	Meat
5	Patties	6	Carpet
7	Pallets	8	Yarn
9	Siding	10	Tiles
11	Steaks	12	Fiber Packages
13	Decking Materials	14	Translucent Solids
15	Paper	16	Plastic Parts
17	Opaque Solids	18	Threads
19	Glass	20	Plastic Plaques
21	Fabric	22	Packaging Materials
23	Fillets

7          Conclusion:

After all explanation, it is concluded that spectrophotometers have wide application area and have acquired a very important place in industries. HunterLab is one of the most reputed manufacturers of spectrophotometers and they ensure accuracy and consistency in their instruments. MiniScan EZ by HunterLab is one of the finest instruments produced by them and the biggest advantage is that it is portable along with accurate measurements.

What is Yarn Conditioning and How it works???

1        Abstract:

Moisture in atmosphere has a great impact on the physical and mechanical properties of textile fibers and yarns. Relative humidity and temperature decide the amount of moisture in the atmosphere. High speed spinning machines generate high friction and provide additional heat to the yarn, as a result moisture content of yarn is decreased due to evaporation of its moisture content by additional heat. Increasing the speeds in spinning result in decreased yarn quality for other processes because dry yarn has the worse properties and if it is sold then result in monetary loss.

Conditioning is to provide an economical device for supplying the necessary moisture to yarn to achieve its natural moisture content. In this assignment yarn conditioning mechanism, process parameters of conditioning, applications of yarn conditioning, advantages and disadvantages of yarn conditioning are discussed and explained.

2        Introduction:

Yarn physical and mechanical properties are directly affected by its moisture content and due to heat of high production machines, it evaporates and deteriorate the yarn properties. Moreover now a high production level is achieved in weaving and knitting machines due to which yarn quality required to run on these machines should be very good. To satisfy these demands without changing the raw material, it is possible to use inherent properties of cotton fibers in short staple spinning. Cotton fiber is hygroscopic material and has the ability to absorb water in the form of steam. Hygroscopic property of cotton Fibers is directly related with relative humidity. The higher the humidity and more will be the moisture absorption. An increase in relative humidity of atmosphere increase the moisture content of cotton fiber.

The fiber strength and elasticity increase with the increase in moisture content. If the water content of the cotton fiber is increased, the fiber swells and result in an increased fiber to fiber friction in the twisted yarn structure due to which strength and elasticity of yarn are increased. So, to increase moisture conditioning processes are used to increase humidity in yarn surroundings to increase its moisture content.

3        What is yarn conditioning?

“Yarn conditioning is a process in which yarn is conditioned for better performance (such as strength, serviceability, luster, handle etc.) by increasing relative humidity in its surroundings or by providing moisture in steam or any suitable form.”

4        Why conditioning is required?

Today modern weaving and knitting machines have high production rates at high speed operations. To run on these machines, yarn should have best mechanical properties and also its physical properties should not disturb. Yarn properties especially cotton yarn properties have direct relation with moisture content of cotton fibers. Moisture content is directly related with temperature and humidity of atmosphere. Moisture content of cotton is 8.5% naturally but cotton fibers have to pass through different spinning operations (opening, cleaning, carding, drawing, combing, roving formation, ring spinning & winding). In these processes, it is impossible to maintain 8.5% moisture due to heat produced by high speed machines which continuously evaporate the moisture from fibers. As a result a dry yarn or a yarn with low moisture content than natural is formed, which has worst properties (strength, elasticity, luster, handle etc.) to run on subsequent weaving and knitting properties.

In addition to subsequent processes problems, monetary loss for a spinner is increased because the evaporation of moisture results in weight loss of final yarn package. To overcome all these problems, the best way is to maintain the natural moisture content or to provide enough humidity at the end for moisture regain of fibers. The first condition is impossible to achieve but the second way is applicable and is used. So conditioning is must for a spinner to optimize monetary losses and for a weaver and knitter for smooth (low breakage) running of operations.

5        Types of conditioning:

Yarn conditioning at the end of spinning processes is mostly done by using steam. But another option of conditioning is available which is mostly used in different spinning processes to control humidity and temperature is to use humidifiers. Humidifiers are very less used for yarn conditioning at the end of spinning. So, conditioning has two types:

1.  Conditioning by steam
2. Conditioning by humidifiers

5.1    Conditioning by steam:

Saturated steam is used to provide enough humid atmosphere to yarn packages for natural moisture regain of fibers. Steam could be produced by a separate boiler or by a machine which provides moisture to yarn packages. Steam conditioning has two methods of application:

1. Conventional conditioning
2. Vacuum / Mechanical conditioning

5.1.1   Conventional conditioning:

In this process saturated steam of 100^OC is produced by a boiler and supplied to yarn conditioning room where yarn packages are placed. Yarn packages are kept in conditioning room for 24 hours for moisture absorption. Cotton fibers absorb moisture to 8.5% in conditioning room and regain their moisture that was evaporated in spinning operations. Water jets could also be used instead of steam.

5.1.1.1    Advantages:

•  It is very efficient in twist setting of yarn that will reduce snarling effect in subsequent processes.
• Simple process and don’t need any special monitoring or operating skills.

5.1.1.2    Disadvantages:

•  It is a time consuming process.
• Top layers of yarn package got a high moisture and inner layers gain a very low moisture or may remain dry that produce variations in subsequent processes.
• A large space (conditioning room) is required.
• It prevents optimum flow of goods.
• Due to large space yarn packages have tendency to re-adjust moisture content to ambient conditions.
• The steam used for conditioning could have moisture droplets in it.

5.1.2   Mechanical conditioning:

Xorella introduced CONTEXXOR process of yarn conditioning. In this method a capsule shaped space is used by machine and steam is produced within the machine and no separate boiler is required. Low temperature (40-60OC) saturated steam is produced in which 100% moisture is converted to gaseous state.

In process, yarn packages enter in capsule and vacuum is created in it to eliminate air pockets in between yarn structure. Then 100% gaseous steam is supplied and due to vacuum moisture is evenly distributed from outer layer to inner layer of the package in 40-45 minutes.

5.1.2.1    Advantages:

•  Due to vacuum even distribution of moisture is ensured.
•  Less space required to machine as compare to a room in conventional.
• 100% dry moisture ensures that no droplets are deposited to package.
• Process is short and time efficient. Only 40-45 minutes are required.
•  Low energy consumption.
• Low installation and maintenance cost.

5.1.2.2    Disadvantages:

• Operating and monitoring skills are required.

5.2    Conditioning by humidifiers:

Humidifiers are the devices used to add moisture to any area where humid atmosphere is required. Humidifiers are only used for conventional conditioning and add moisture to the room where packages are placed for 24 hours.

Different types of humidifiers are available:

1.  Spray type air washers
2. Pan evaporative humidifiers
3. Electrically operated humidifiers
4. Air operated humidifiers

5.2.1   Spray type air washers:

Air washers consist of a row of spray nozzles inside a chamber or casing. A tank at the bottom of the chamber provides collection of water as it falls through the air and comes into contact with the wet surface of the chamber baffles. The principal functions of the air washers are to cool the air passed through the spray chamber and to control humidity.

5.2.2   Pan evaporative humidifiers:

The evaporative type humidifier is fully automatic, the water level being controlled by means of a float control. In operation, when the relative humidity drops below the humidity-control setting, the humidifier fan blows air over the surface of the heated water in the tank. The air picks up moisture. The air is blown to the space to be humidified. When the humidity control is satisfied, the humidifier fan stops.

5.2.3   Electrically operated humidifiers:

Dry-steam electrically operated humidifiers operate by means of a solenoid valve, which is energized by a humidistat. When the relative humidity drops slightly below the desired level set by the humidistat a solenoid valve actuated by the humidistat, admits steam from the separating chamber to the re-evaporating chamber. The fan (which is energized when the solenoid valve opens) assists in dispersing the steam into the area to be humidified.

5.2.4   Air operated humidifiers:

These utilize a pneumatic hygrostat as a humidity controller and an air operator to open or close the steam valve. A decrease in relative humidity increases the air pressure under a spring loaded diaphragm to open the steam valve wider. An increase in relative humidity reduces the pressure under the diaphragm and allows the valve to restrict the steam flow.

5.2.5   Advantages of humidifiers:

Ø Simply add moisture to the conventional conditioning room and automatically operated.

Ø Spray type air washers don’t need fuel to convert water to steam.

5.2.6   Disadvantages of humidifiers:

• Steam or moisturized air provided by humidifiers could have water droplets in it.
• Tendency of moisture absorption of cotton is good for steam but not absorb much moisture from moisturized or humid air.
• Due to low moisture absorption from humid air these are very less used for conditioning but used to control humidity in back processes of spinning.

6        Pros and cons of yarn conditioning:

Everything in this world has both positive and negative aspects. Similarly yarn conditioning has some advantages and disadvantages, described below:

6.1    Pros:

Yarn conditioning improves yarn performance such as strength, serviceability, luster, handle, etc. of yarn. It also effects performance of subsequent processes such as weaving and knitting.

6.1.1   Weaving:

• Yarn breakage frequency at weaving is reduced.
• Fly is reduced.
• Due to conditioning yarn take-up of sizing material is increased.
• Aesthetic properties of fabric such as feel and comfort are improved.

6.1.2   Knitting:

• Wax sets well and don’t melt from waxed yarn used in knitting.
• Efficiency of knitting machines is increased by 20%
• Needle breaks are reduced at knitting machines.
• Moisture content is uniformly distributed due to which variations in resultant fabric are reduced.
• Stitch formation is more regular because of reduced breaks.
• Chances of size change in final fabric are reduced.
• Electrostatic charges are eliminated due to moisture regain.
• Fly is reduced.

6.1.3   Twisting:

• Conditioning and fixing of the twist at the same time in a single process.

6.1.4   Dyeing:

• No stripes in dyed fabric.
• Better dye ability.

6.2    Cons:

• Uneven moisture absorption in conventional method produce variations in yarn properties.
• If moisture environment is not controlled to optimum values then yarn properties are deteriorated. More moisture than standard cause cotton fibers to swell and produce mass variations.
• If moisture in conditioning goes too high, it may deteriorate the paper cones.
• Uncontrolled conditioning cause deposition of water droplets on packages.

7        Conditioning process for various yarns:

1. 100% Polyester yarn: Yarn is loaded in the form of cones wound on plastic cones, in to a beam dyeing machine. Steam is pushed in and temperature is raised to 100°C at gradual increase of 3°C per minute. Steam is given for 15 minutes at 100°C followed by 15 minutes cooling completes 1 cycle. Cycle is repeated 4 times.
2. 100% Nylon: Yarn is loaded in the form of cones wound on plastic cones, in to a beam dyeing machine. Steam is introduced and temperature is raised to 100°C at increase of 3°C per minute. Steam is given for 15 minutes at 100°C followed by 15 minutes cooling to a temperature of 50°C completes 1 cycle. Cycle is repeated for 4 times.
3. Silk yarn: Yarn is loaded in the form of cones wound on plastic cones, in to a beam dyeing machine. Steam enters and temperature is raised to 70°C at gradual increase of 3°C per minute. Steaming for 15 minutes at 70°C followed by 15 minutes cooling to a temperature of 30°C complete 1 cycle. Cycle is repeated for 4 times.
4. Cotton/Lycra (40's Lycra) or Viscose/Lycra (60's): These are conditioned at parameters same as silk yarn.

8        Conclusion:

After all above explanation, it is concluded that optimum yarn conditioning should be done for smooth and efficient running of yarn in weaving and knitting. Yarn conditioning is a great technique to improve physical properties of yarn and mechanical performance of yarn especially cotton yarn. Disadvantages are also present but using optimum parameters eliminate the negative aspects. Different types and methods are available and used according to requirement and budget by an industry. Mechanical method by Xorella is widely used and is much efficient as compare to others.

9         References:

• Research paper titled “Effects of yarn conditioning in short staple spinning” by Fracis & Taylor.
• Research paper titled “Yarn conditioning: An overview” by N. Muthukumar & Dr. P. Kandavadivu