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Ask Dr. ADF
If you have any questions about our products, please send us an email through our "Contact Us" page.
Q1. What is ADF?
A: ADF stands for Auto Darkening Filter, which consists of an optical band pass filterer, one or two LCD’s (Liquid Crystal Display), protective lens, and an electronic circuit unit.
Q2. What's the function of LCD?
A: LCD reduces visible light intensity entering the eyes by an electronic circuit, which is energized by sensors. LCD response speed and circuit design will determine ADF reaction speed. The faster the reaction speed, the better.
Q3. What's the function of the band pass filter?
A: The welding arc consists of a wide-spectrum range of lighting. Some lighting is harmful to human eyes, like UV, FUV, NUV, NIR and IR. An optical band pass can stop UV (Ultra-Violet, including near UV and deep UV) and IR (Infra-Red, including near IR and far IR) light from entering human eyes when the welding arc is generated.
Q4. Why is a high-quality optical band pass so important?
A: UV (especially deep UV) and IR (especially near IR) can damage the retina of human eyes if exposed for a certain period of time. According to DIN standards, the “UV component of welding arc light shall not surpass 0.000012% max of general UV range, and IR component shall not surpass 0.015% max of general IR range.”
LCD CAN NOT STOP UV and IR by itself ! Actually LCD is complet transparency to all IR range.
An optical band pass is composed of many multi-layer optical films, and each layer's thickness is strictly controlled within a quarter of the visible wavelength, around 100 nm. All these layers work together to create optical interference for visible light band pass, which means that visible light can pass through, while UV and IR are stopped by the band pass. The optical layer is deposited by an evaporation process in a vacuum oven. Each layer's thickness is different from the others. If any layer fails to be the right thickness, the whole band pass transmittance vs. wavelength curve will be influenced dramatically. Some UV or IR segments will arise and more UV/IR light will enter the welder’s eyes.
Q5. What happens if a poor-quality band pass is used?
A: If a poor-quality band pass is used, the user’s eyes will be exposed to harmful UV or IR during each use. In the short-term, it will cause sore, burning eyes, and eye-sight will decrease considerably or it may even cause temporary blindness. In the long-term, it can cause cataracts, iris aging, glaucoma, floaters, retinal detachment, and permanent blindness.
Q6. How do we know if a poor-quality band pass is being used?
A: Naked human eyes can’t tell if a band pass curve is good or bad since UV/IR rays are mostly invisible. But judgment can be made using the following criteria:
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Band pass transmission color: A high quality band pass looks more colorful (from blue to red), and more comfortable to human eyes than a poor quality band pass. Since a manual or semi-manual production process can’t control the optical layer precisely, it’s hard to widen the visible light wavelength range while keeping UV/IR as low as required. Besides optical layer thickness control problem, a manual or semi-manual production process can not have many optical interference layers which means higher colorful transmission, because of production costs.
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How a band pass is made: Usually the quality of a band pass made by fully automatic evaporation equipment is much higher, more consistent, and more reliable than that made by manual or semi-manual evaporation equipment, because of different tolerances and process controls. An automatic production process usaully is capable of having more optical interference layers easily, compared to a manual or semi-manual process. The hard-coating process (in which anti-erosion optical material is used) can withstand atmospheric environments longer than the soft-coating process, which is usually combined with manual or semi-manual evaporation equipment. The shelf life of a hard-coating band pass (around 6 months) is much longer than that of a soft-coating band pass (less than a month) during production.
Q7. What's the function of the protect lens?
A: Since the polarized outside of an LCD is a type of plastic film, it’s easily scratched and difficult to clean. By using a glass protective lens, we're able to make an anti-scratch and anti-smear ADF lens, which is crucial in rugged environments.
Q8. How are the band pass, LCD, and protective lens layers put together?
A: There are three processes to combine the Band Pass, LCD and Protective Lens. The first is the non-laminated process. Just simply put the Band Pass, LCD, and lens together, and put glue at the edges. There are two (or three) air gaps between the Band Pass/ LCD/Protective lens. The second is the glass-to-plastic lamination process: laminating hard plastic film on outside of LCD. But there is still an air gap between the Band pass/LCD or Lens/LCD, and it is not entirely anti-scratch. The third is the glass-to-glass lamination technology. Glue the band pass with the LCD and the Protective Lens at one time, so there are no air gaps between the Band Pass/LCD and Lens/LCD.
Q9. What is glass-to-glass lamination, and what are its advantages?
A: Glass-to-glass lamination is achieved by gluing the band pass, LCD and protective lens together at one time without any air bubbles, contamination or debris. The advantages of glass-to-glass lamination are:
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The band pass is protected from atmospheric erosion, and acidic environment, which can corrode the band pass.
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Reduces haze on ADF: By reducing internal light reflection between band pass/LCD/protective lens, we improve the image contrast considerably.
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Relieves dizziness problems: Reduction of haze reduces dizziness, so users will be more comfortable when using a CrystalClear ADF.
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Avoids eyesight damage: If welder looks through non-glass-to-glass-laminated ADF, it's like wearing dirty, foggy glasses which can damage eyesight over long periods.
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Increased product life and reliability. By gluing all parts together, we increase the strength of the ADF.
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Anti-scratch and anti-smear lens: Since the outside of glass-to-glass laminated ADF is glass, rather than plastic, it makes the ADF much less likely to scratch or smear.
Q10. What is shade?
Shade is a measurement unit of visible light transmittance for special welding and very dark measurement application. If the shade number is higher, the transmittance is lower, and the arc is larger.
ADF Application Recommendation Table
Table 1. Recommended Guide for Shade Numbers (Adapted from ANSI Z49.1-2005)
|
Process |
Electrode Diameter
inch. (mm) |
Arc Current
(Amperes) |
Minimum Protective
Shade |
Suggested Shade No.
(Comfort) |
|
Shielded Metal Arc Welding(SMAW) |
< 3/32 (2.4) |
< 60 |
7 |
– |
|
|
3/32 – 5/32 (2.4 – 4.0) |
60 – 160 |
8 |
10 |
|
|
5/32 – ¼ (4.0 – 6.4) |
160 – 250 |
10 |
12 |
|
|
> ¼ (6.4) |
250 – 550 |
11 |
14 |
|
|
|
Gas Metal Arc Welding GMAW) & Flux Cored Arc Welding (FCAW) |
|
< 60 |
7 |
– |
|
|
|
60 – 160 |
10 |
11 |
|
|
|
160 – 250 |
10 |
12 |
|
|
|
250 – 00 |
10 |
14 |
|
|
|
Gas Tungsten Arc Welding (GTAW) |
|
< 50 |
8 |
10 |
|
|
|
50 – 150 |
8 |
12 |
|
|
|
150 – 500 |
10 |
14 |
|
|
|
Air Carbon Arc Cutting(CAC-A) |
(Light) |
< 500 |
10 |
12 |
|
|
(Heavy) |
500–1000 |
11 |
14 |
|
|
|
Plasma Arc Welding (PAW) |
|
< 20 |
6 |
6 – 8 |
|
|
|
20 –100 |
8 |
10 |
|
|
|
100 – 400 |
10 |
12 |
|
|
|
400 – 800 |
11 |
14 |
|
|
|
Plasma Arc Cutting (PAC) |
|
< 20 |
4 |
4 |
|
|
|
20 – 40 |
5 |
5 |
|
|
|
40 – 60 |
6 |
6 |
|
|
|
60 – 80 |
8 |
8 |
|
|
|
80 – 300 |
8 |
9 |
|
|
|
300 – 400 |
9 |
12 |
|
|
|
400 – 800 |
10 |
14 |
|
|
|
Torch Brazing (TB) |
3 – 4 |
|
|
|
Torch Soldering (TS) |
2 |
|
|
|
Carbon Arc Welding(CAW) |
14 |
|
|
|
Plate Thickness |
Suggested Shade No.
(Comfort) |
|
|
Inch |
mm |
|
|
Oxyfuel Gas Welding (OFW) |
|
Light |
< 1/8 |
< 3 |
|
4 or 5 |
|
Medium |
1/8 – ½ |
3 – 13 |
|
5 or 6 |
|
Heavy |
> ½ |
> 13 |
|
6–8 |
|
Oxygen Cutting (OC) |
|
Light |
< 1 |
< 25 |
|
3 or 4 |
|
Medium |
1 – 6 |
25 – 150 |
|
4 or 5 |
|
Heavy |
> 6 |
> 150 |
|
5 or 6 |
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