Importances of CO2 Laser Tubes and Laser Engravers

Purchasing of a laser engraving machine should be careful and conscious. Failed investment in wrong equipment may adversely affect the successful development of your business.

GCC is glad to share this article written by our Belarus distributor to help customers know more about laser engravers. 

In this article, we will provide a brief overview of the Chinese laser cutting machines’ main technical characteristics and make a comparative analysis with GCC LaserPro laser engravers.

In general, we set goals as below:

• To raise the customers’ level of knowledge and requirements of choosing the laser equipment.
• To reveal the design features of Chinese laser machines, which are mostly withheld by sellers.
• To increase general level of laser culture among laser machines users.

Mechanics of the laser engraving:

Most of the Chinese laser equipment manufacturers install the stepper motors in their machines. Installation of the stepper motors can reduce the cost of laser machine but the functional efficiency is significantly declined. The laser machine with stepper motors can not provide high accuracy and ease of operation, compared to the laser engraver which is equipped with high-precision servo motors.

Usually the laser machines with stepper motors have no feedback. It means that a machine does not receive any information about the real position of the carriage, but only sends commands. Due to the lack of feedback the stepper motors may lose the coordinates in the process by moving the carriage. The loss of stepper motor’s coordinates can cause a huge number of defects, which occur during laser engraving and cutting. Pressing the pause button in the process of laser engraving, the user of laser machine with stepper motors will not be able to continue the operations, and will be forced to discard the product.

The laser machines with stepper motors form the stair-stepping when cutting organic glass and cannot provide a smooth and clean cut. The stepper motors can cause blank spots or gaps in cutting, as well as blurred edges of images and objects in laser engraving. The only advantage of the laser machines with stepper motors is their low cost.

For reference GCC LaserPro laser engravers series S180II, Spirit, Spirit LS, Spirit GLS and T500 provide high quality laser engraving and cutting along with high speed. The laser engravers series Spirit LS and Spirit GLS have high-precision servo motors made by Japanese company Tamagawa Seiki. The cost of servo motors significantly exceeds the cost of stepper motors.

The servo motors are equipped with encoders that constantly transmit the real-time information about the position of laser carriage and eliminate the loss of coordinates. Due to feedback the servo motors can achieve high accuracy and high speed of laser engraving without blurring the edge of images. In addition, high-precision servo motors can achieve clean and mirror cut of the organic glass without stair-stepping.

 

CO2 laser tube:

As a rule, the Chinese manufacturers of laser machines install CO2 glass laser tube in their equipment as on the figure below. CO2 glass laser tube has its own advantages and disadvantages, which we describe below.

Most of the Chinese CO2 laser tubes manufacturers are using manual or outdated production technologies. The average lifetime of a glass laser tube does not exceed 2 000 - 3000 hours of operation. Reci Laser is the only company in China, who uses high-tech equipment and the latest advanced technologies in the production of CO2 laser tubes. The average lifetime of Reci laser tube is about 8000 hours of under the proper operating conditions.

If you bought the Chinese laser machine with Reci laser tube, we believe that you are very lucky. At the same time, we do not exclude the fact that it might be imitative Reci laser tube because the Chinese manufacturers actively forge everything that is in demand. Reci Laser is aggressively working on the protection against counterfeiting its products by using the QR code, which must appear on the laser tube’s label.

 

The main advantages of CO2 glass laser tubes:

The low price of laser tube can reduce the overall cost of laser machine. Up to 150W high power laser tube enables to cut thick and thin materials.

 

The main disadvantages of CO2 glass laser tubes:

• The glass laser tube requires a water cooling device or chiller.
• The glass laser tube does not support the photo engraving mode with color intensity of 256 shades of gray and automatic change of output power in accordance with the gray level.
  The glass laser tube does not support the manufacturing conditions of seals and stamps.
  The glass laser tube is not suitable for the applications which require high-quality engraving and marking.
• The glass laser tube has unstable power output parameters. Unstable operation of the tube may cause its transition from single-mode to multi-mode and defocusing of laser into several laser beams. As a result, you get vague, reduced and changeable output power of the laser tube.
• The glass laser tube cannot be repaired. Compared to the American laser tubes, which can be fixed and gas refilled, the glass laser tube has to be discarded after damaging. 
• The glass laser tube may fail within 5-6 months even without being used because glass cannot keep gas for long period of time. Buying a new laser tube it is unclear if its operational life has not expired yet.
• The glass laser tube is unsafe for the laser machine user because of high voltage up to 30 kV applied to its contacts.
• The glass laser tube is not resistant to the mechanical, thermal and heavy influencing factors of the production environment.
• The glass laser tube is not protected by metal housing and looks like a piece of glass that easily cracks during the transportation, repair and maintenance of the machine.
  Condensation is exposed inside the glass laser tube due to room temperature extremes which may cause its rapid failure. 

The Chinese glass laser tube has low quality of laser beam (multi-mode etc.). In practice, the high power of laser tube and poor oscillating mode of laser beam (multi-mode TEM01) significantly slow down the speed of materials cutting process. It is inefficient to invest in such machine.

The Chinese glass laser tube cannot generate the accurate laser beam with high density focused power. As a result you get low quality laser engraving and cutting combined with low speed. The high quality laser tube operates in single-mode (TEMoo) that enables to reach full space coherent which allows generating focused laser beam of high power and high density into smallest achievable spot size.  

For example, the laser engraver Spirit LS 30W with American laser tube Synrad generates high quality and high density laser beam in single mode (TEMoo) that enables to cut 3mm thick organic glass 30% faster than the Chinese laser engraver with 60W laser tube. The higher power of laser tube the faster the cutting materials process, it is not always true. Quality rather than quantity is important.

For comparison, GCC laser engraver C180II, Spirit LS, Spirit GLS and T500 are equipped with the reliable laser tubes produced by Synrad. The American laser tubes are sealed in metal housing. The cost of Synrad laser tube exceeds in large excess over the cost of Chinese glass laser tube.

 

The main advantages of Synrad CO2 laser tube (USA):

• Long operational life of the laser tube: near 45 000 hours or 5-7 years of the constant running.
• The sealed metal housing enables the laser tube resistance to mechanical, thermal and heavy influencing factors of the production environment.
• Air cooling of the laser tube
• High quality of the laser beam (parameter M2 < 1.2)
• Stable parameters of the laser’s output power +- 2-5%
• High pulse frequency of laser up to 20kHz increases laser engraving speed up to 200 cm per second.
• The laser tube supports the photo engraving mode with color intensity of 256 shades of gray and automatic change of output power in accordance with the gray level.
• The laser tune supports the seals and stamps production mode.
• High quality of laser engraving and cutting

 

Cooling system of the laser tube:

The steady operation of the laser machine is largely dependent on the cooling system of the glass laser tube. Any problems with the cooling system may cause the laser tube failure. Therefore the laser machine has to be equipped with a water-cooling unit or chiller to cool the laser tube. The chiller keeps the water temperature at the given level.

Freon gas which does not destroy the ozone layer is used as the refrigerant. The chiller provides the steady operation of the laser tube. If you buy a laser machine with the cooling system which consists of a plastic tank and an aquarium compressor, we think that the supplier has disrespected you.

The chiller must properly fit the laser machine and conform to power of the installed laser tube. Sometimes the Chinese manufacturers deliberately install the chiller which does not meet the requirements for cooling the laser tube.

The cooling circuit of laser machine must be equipped with the water flow sensor as the additional protection of the water cooled laser tube. In case if the sensor detects the lack of flow or poor water circulation, the laser machine will power off the laser tube automatically thus protect it from damages and save your money and nerves.

GCC laser engravers with water cooled laser tube operate like this. The user may figure out about availability of the water flow sensor in the Chinese laser machine by oneself.  

If you are tired of constant replacements of the glass laser tube due to chiller’s failure, we recommend to purchase GCC laser engraver which is equipped with the American laser tube. All laser engraves with the laser tube up to 100W are air cooled. The laser tube is cooled by the fans that are built in the laser tube and laser engraver housing. It makes the laser engraver convenient in operations and saves your nerves.

The lack of protection for the laser optical path against dirt and dust contamination in the laser tube.

There is no built-in laser tube protection against dirt and dust contamination at the outlet of laser tube in the Chinese laser machines that causes fast failure of laser tube and decreases laser power during operation. 

For comparison, the GCC LaserPro laser engravers’ optical path is totally protected against dirt and dust contamination in the laser tube area.

 

Mirrors and focus lenses of the optical system:

The laser engraving and cutting quality mainly depends on the quality of the built in the laser optical path mirrors and focus lenses as well as the type of coating laid on the optical elements. As a general the laser optical path consists of 3 or 4 mirrors which sequentially transmit the laser beam at an angle of 90 degree from the laser tube to working area and a focus lens built in the laser carriage to converge the laser beam at the spot on the working area.

The special coating laid on the mirrors of optical system enhances the laser beam reflection rate. Economy class mirrors are installed in the Chinese laser machines. The coating laid on this mirror burns and fails quickly. The rate of laser power loss is high from the economy class mirror. As a result of such economy the laser beam loses significant amount of laser power before to converge at the working area. The percentage of laser power loss in the optical path reaches 20-50%.

The focus lens is the major part of laser optical system. Focus lenses are made of zinc selenide which has highest transmission ratio of laser beam. The special coating or plating on the focus lens minimizes the laser beam refraction coefficient on the lens surface and increases the capacity of laser beam through a lens. The installation of economy class focus lens in the Chinese laser machines causes distortion of laser beam, large loss of laser power in the working area and as a result poor quality of laser engraving and cutting.

The optical path of GCC laser engravers are completed with the high quality mirrors covered by gold plating from II-VI Infrared Company (Taiwan). Gold has the highest reflection ratio of laser beam. Mirrors with gold plating provide high quality transmission of laser beam from laser tube to the working area without any loss of power. The focus lens mounted at the carriage of laser engraver in the outlet of optical path converges the laser beam at the spot on working surface without any distortion and with high laser power density.

On default, 2” focus lens is set in the optical path of laser engravers. You can purchase the additional 1.5”, 2.5” and 4” focus lenses as well. Each lens has different focal depth, the spot size and focal distance. The choice of lens size depends on the applications. 

1.5”-Focus lens with small spot size 0.073 mm. The lens is best suitable for small lettering, very fine details laser engraving applications, small circular shapes and drawing thin lines as well as for manufacturing seals and stamps with microscript and guilloche grid.

2”-the most commonly used focus lens with spot size 0.099 mm. The lens is best suitable for cutting thin and thick materials as well as for normal laser  engraving.

2.5”-Focus lens for laser engraving and cutting. The spot size is 0.121 mm. The lens is used for cutting thin and thick materials as well as for normal engraving.

4”-Focus lens with the largest focal distance and depth. The lens is used for cutting 10 mm and above materials. The big spot size of 0.198 mm provides effective processing on the materials that require laser engraving of layout with big dies and fillings. 

 

Component parts for laser machines:

Most of the Chinese manufacturers assemble rather than produce the laser machines based on the standard component parts and units that they do not develop by themselves but outsource it from others. Laser machines differ in assemble quality, design body, mechanics and component parts.

Buying the laser machine in China, the manufacture can make the machine at any target price. For example, if the laser machine was quoted at $ 4000 and you were able to reduce the price up to $3500, it doesn’t mean that you purchase $4000 machine at $ 3500. They will make machine equivalent to $3500 cost replacing boards, motors, component parts and units by low cost counterparts.

Two similar laser machines with standard specifications from different manufacturers, or even from the same manufacturer turn out to be assembled from different components (motors, boards, steering units, power supplies, etc.) and, accordingly, will operate in different ways.

Buyer of the Chinese laser machine never knows what is inside in the delivered machine. Believe us, we have an experience working with the Chinese equipment manufacturers and do not indulge in illusions.

Buying GCC LaserPro laser engraver, a buyer is always sure that will receive high quality equipment assembled from the standard component parts and with the same specification as declared on the website. Even if the buyer gets a vendor’s discount on hardware then no one will change the engines into cheaper counterparts.
 

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Design features and optional items of laser machines:

Most of the Chinese laser machine manufacturers are not willing to share the information so it makes certain difficulties to do the correct comparative analysis of the laser machine design features from different manufacturers.

Therefore, below is just brief overview of the main design features of GCC laser engravers that buyer will be able to define the certain design features in the Chinese machines based on this example.

• The closed system of carriage motion along X-axis in Spirit LS and Spirit GLS laser engravers protects the guide rails against contamination during laser engraving and cutting.
• The reinforced belts made of highly durable and wear-resistant material Kevlar are installed on X- and Y- axis of Spirit LS and Spirit GLS laser engravers motion system to improve its accuracy and increase reliability.
• All GCC laser engravers support automatic table motion on Z-axis (except T500, X500).
• All laser engravers are equipped with automatic focus setting sensor - Autofocus.
• Illumination of the working area in the GCC laser engravers makes operations convenient.
• All GCC laser engravers have red LED indicator which facilitates positioning of laser beam on the product surface in the beginning of the operation.
• GCC laser engravers are equipped with air supply system in laser engraving and cutting area.  
• Automatic turning power on and off of the compressor to supply air in the working area through a driver of Spirit LS and Spirit GLS laser engravers.
• All GCC laser engravers can be equipped with a device for laser engraving on the cylindrical objects.
• Convenient back and front doors that are easily open in GCC laser engravers enable laser engraving and cutting on the large size objects.

For the details refer to the Spirt GLS laser engraver specifications and technical features.

 

Warranty, maintenance service and operating costs:

The Chinese equipment manufactures provide warranty only for a laser machine. The glass laser tube is expandable material and not covered by warranty. Buying the Chinese laser machine a buyer becomes return and desirable customer for repairs and replacement of laser tube to the company who sold this equipment.

We would like to attract your attention to high operating costs of laser machines equipped with CO2 glass tube. Due to the lack of certified service center and spare parts warehouses of the Chinese laser machines in Belarus, the owner of Chinese equipment have to purchase a new laser tube and high voltage power supply in Russia or Ukraine. As a result, during the years the final operating costs of cheap Chinese laser machine can exceed the cost of buying a high-quality GCC laser engraver.

 

Overestimation of the laser machine specifications and misleading the customers:

Buyers should be careful with the sellers of laser equipment who try to overrate the Chinese laser machines specifications, or misinform buyers that the Chinese laser machine is able to perform high-quality laser engraving on any materials and provide high precision cutting of material with fine details, which required to keep object’s geometry and dimensions without distortion.

Below are the standard ways that Chinese laser machine sellers are using to mislead the customers:

• Improper positioning of the laser target segment
• Overestimating cutting speeds up to 36 000 mm \ min.
• Overestimating engraving speeds up to 64 000 mm \ min.
• Overestimating engraving resolution up to 4000 dpi.

If the laser engraving and cutting speed is specified in mm/h, the figures are even larger and make a great impression on customers. None of the European and American laser engravers supports 4000 dpi resolution. We advise customers to request the seller of Chinese laser machine to demonstrate the opportunity of laser engraving and cutting at highest declared parameters and provide the suggested engraving specifications for different materials to compare it with the specifications declared in brochures.

Ask the seller to show the quality of laser engraving on anodized aluminum and double-layer industrial film from 3M and Tesa as well as on IPI or Rowmark double-layer plastic at 1000mm/s. For comparison, GCC Spirit LS and Spirit GLS laser engravers are able to engrave on double-layer plastic at max. 2000mm/s.

We recommend buyers to negotiate with a seller about cost of the Chinese laser machine with installed Synrad laser tube high-precision servomotors.

 

Laser machines' safety and declaration of compliance with the Customs Union technical regulations:

All laser machines and engravers have to be in compliance with three technical regulations of the Customs Union:

• 2004/108/EC(EMC) "Electromagnetic compatibility of technical means"
• 2006/95/EC(LVD) "About safety of low voltage equipment"
• 2006/42/EC "About safety of machines and equipment"

You can see the GCC Spirit LS \ GLS laser engravers declaration following the link. CE Declaration
Declaration of laser equipment of compliance with the technical regulations ensures its safety operation. At the same time, the declaration of laser equipment in compliance with technical regulations 010 "About safety of machines and equipment" is rather time-consuming and expensive procedure. To do this, the supplier is required to provide many important documents from laser machines manufacturer.

 

Technical Construction File:

Test report for determination of compliance with the standard of laser safety EN 60825-1: 2007.
Test report for determination of compliance with the standards EN 60204-1: 2010 and EN ISO 12100: 2010 (Safety of machinery and risk assessment). Test report for determination of compliance with the different standards: insulation breakdown, noise level etc.

The laser machines suppliers are aware that to get the full set of documents from the Chinese manufacturer is impossible and, therefore, deliberately do not declare machines for compliance with the technical regulations 010 "About safety of machines and equipment." Some suppliers even prefer to buy illicit certificate or declaration in order not to spend time on declaring products in compliance with 010 technical regulations. As a result, a buyer takes the risk of purchasing the laser machine which is not entirely safe for his health.

Take notice that to get a certificate or declaration for a period of 5 years is required the laser machine manufacturer to provide much more documents as the certificate of quality management, ISO 9001 certificate, etc. In addition, the employees of the certification agency have to inspect the production line.

We do not exclude the fact that many suppliers of laser machines work hard and spend a lot of money to legally conduct the necessary tests and certify the Chinese equipment in the territory of the Customs Union. A buyer always has a right to know whether the laser machine is safe for health and compliant with the technical regulations of the Customs Union.

 

Laser safety and your health:

Information in this section may save someone's life or preserve the health.

The laser machines are equipped with a sealed carbon-dioxide (CO2) laser that emits intense and invisible laser radiation with a wavelength of 10.6 microns (10600nm) in the infrared spectrum. Laser radiation is invisible for human eyes because of the applicable wavelength.

The Infrared (invisible) laser radiation is especially dangerous for human eyes because its effect enhanced by crystalline lens focuses on the retina of eyeball. The high intensity of radiation on the retina leads to powerful localized heating and burns its tissue which causes reduction or loss of vision. Therefore working closed to the laser beam (during maintenance, positioning of optical system, repair) always protect eyes.

The laser equipment kit includes the goggles for working with materials that can reflect the laser beam. The user must wear the goggles to operate the machine. The goggles do not protect the eyes from direct laser beam, but only from reflection and within a few seconds.

Avoid the laser and red beam to enter the eyes directly. The reflection of the laser beam may cause blinding glare during continuous visual observance. Never look directly at the reflected beam on the speculum metal. Never look directly or at an angle at the laser and red beam’s aperture.

The user is responsible for compliance with health and safety while operating the laser machine.

The direct, reflected and scattered laser radiation is dangerous while operating the machine. Prevent hands and body from contacts with the laser beam working area. The scattered laser radiation can burn the skin on hands. The damage degree depends on the duration of laser beam exposure. It is obliged to wear appropriate protective clothing for skin protection.

Smoke, toxic gases and particles emitted during the laser operating process can significantly damage your health and cause death. Carefully check the material safety datasheet (MSDS) and the material composition for emission of harmful substances. Provide high-quality air extraction system in the working area of laser engraver. The smoke and gassed emitted during laser engraving and cutting can contaminate and damage the optical lenses and mirrors.

The laser machine focus lens is made of zinc selenide (ZnSe). The focus lens is safe for health under normal operating conditions, but it requires regular inspection and cleaning. In case of damage (cracks, split, scratches, abrasion, overheating and etc.) the focus lens has to be replaced by new. Using the damaged optics can cause the emission of toxic gases and harm your health.

The toxic vapor of zinc oxide and selenium oxide is emitting while working with the damaged focus lens. Zinc selenide is toxic if inhaled or swallowed. Dust may cause irritation of eyes and respiratory system. If you find the optic is damaged, you must thoroughly ventilate the room and carefully clean the laser equipment from dirt formed due to emission of toxic vapor on the damaged optics. Contact your supplier to get more details about laser safety.