FAQs

A: There are two different "types" of lens used in industrial laser machines: meniscus and plano-convex. The correct type is usually specified in the machine manufacturer's manual.
For a technical explanation about the differences between the two types please refer to the Duralens� section of our catalog.
Basically, Plano-Convex lenses are usually found in workshops which cut thicker materials and are more popular in American and Japanese machinery. European customers and machine manufacturers (OEM's) traditionally use the meniscus range.

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A: Obviously the number of lenses used per year depends on the machine workload and the type of metal it is processing. Our studies show that in average, lenses are replaced 4-5 per year while mirrors are usually replaced once a year.

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A: The higher the pressure at which the machine cuts, the thicker should the lens be.

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A: When cutting mild steel thicker than 4mm it is best to use oxygen with a maximum pressure of 3.5bar. If thickness is 15mm use gas pressure of 1bar and a small nozzle (=1mm).

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A: When cutting mild steel (thickness up to 5mm) the focal position should be about 1/3 in the workpiece. When cutting thicker steel the focal point is moved up.

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A: When cutting stainless steel use nitrogen. In this case the focal position is always under the sheet surface.

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A: When cutting thin materials (less than 2mm) you can use shop air. However, shop air could be contaminated with oil and water or other impurities requiring a high level of filtering.
When cutting Aluminum, Oxygen can be used. Note: For a quality cut proceed slowly. Nitrogen can also be used for Aluminum (cut quality improves when cutting slowly).

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A: In order to check the beam quality, check the sparks under the sheet: they should follow the input laser angle to make one line. If it is lagging the focal position needs to be adjusted.
Also, pay attention to the color of the plasma in the cutting area - it should not be blue. If the plasma is blue - stop the cut and re-adjust machine constants.

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A: 7.5" length is placed far from the workpiece so there is less chance for it to damage - for a longer lifetime. However, the laser power density reaching the workpiece decreases. When cutting thin material (5mm and less) one should use 5" focal length since the spot diameter is smaller.

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A: These lenses absorb less heat and therefore their performance (i.e. focusing efficiency and lifetime) is better.
The reduced absorption in the black-coated lenses affects lens operation as follows:

1.	Thermal Lansing is reduced, and therefore the focus position during operation with a high-power-laser is more stable.
2.	Since thermal effects also increase lens aberration, increasing the spot size, the spot size of a black-coated lens during operation in a high-power-laser is smaller than the spot size of a conventional lens.Therefore when using a black-coated lens the energy concentration is higher and enables a better and faster cut using less gas.

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A: Ophir's unique product, the Black Magic lens, was created using a revolutionary black coating technology. The Black Magic lens has achieved the lowest absorption on the market - lower than 0.15%. The Black Magic lens has achieved the lowest absorption rates on the market - lower than 0.15%. The black coating is much harder, has better ability to withstand back splatter, requires less maintenance (i.e. extended lens cleaning intervals) and is RADIOACTIVE FREE.
In most applications, the Black Magic increases the cutting speed, save up to 20% of gas consumption and lasts twice the lifetime of a standard lens.
The black magic is the best solution for cutting thicker metals in high power laser cutting machines.

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A: Ophir Optronics understands that beam alignment is crucial for a clean cut. We suggest operating the laser machine leaving the gas off and turning on the focus manually. After finding the right focus the laser machine can be used regularly.

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A: No. The machine constants need to be re-adjusted in order to ensure its best results.

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A: Clean the lens using a liquid soap and a soft tissue. Follow our cleaning instructions (found on our web site).

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A: Please perform the following steps:
Check lens mounting direction, realign the laser beam, check the focus spot size and check the color of the plasma (should be blue).
If the problem remains check for dust in the machine.
A final step is replacing mirrors (turning mirrors or resonator mirrors). Normally mirrors are replaced once a year - by a qualified person only!

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