All about Mold Repair by laser welding

Laser welding by high powered pulses is a high quality and precise process that can repair metal molds to as-new condition, or build up small features so they can relocated slightly.  Focused infrared laser radition (basically light, but invisible) is used to melt fine welding wires, usually held by hand.  Laser can be used for welding up any tool material.  The laser path is guided by a joystick or buttons, while the process is observed on a CCD display or binocular microscope with a shutter timed to block out the laser pulses.

Touchscreen for pulsed mold repair laser
User interface with main laser pulse welding parameters

What are the advantages of laser welding for  Mold Repair?

Laser welding molds has several advantages over TIG:

  • Laser welding’s parameters are pre-set and remove most of the operator variability associated with TIG.
  • Laser welding doesn’t require pre-heating of molds.  
  • Welding can be performed faster than TIG welding.
  • Less heat input means less stress and distortion.

What are the different types for Mold Repair?

There are 3 types for laser welding small items:
a.  Our kiloWatt lasers are fibre lasers (solid state, very reliable) which are normally continuous wave. You adjust the power level and move the beam around (including wobbling/weaving) to get the penetration and weld width required.
b.  The best way:  Our fibre lasers can also be configured/built for pulsing, which is a modern, reliable way of getting a pulsed laser (type c below).  By pulsing a powerful 1.5kW laser we can get a higher pulse energy than flash tube types with good consistency and reliability.  Because the laser is turned off most of the time via PWM (pulsing), the kW power level drops to hundreds of Watts.
c.  The normal way of getting a pulsed laser is to use an old school YAG xenon arc flash tube.  This is cheaper than a fibre laser but not as reliable, the pulse power can drop off, and it requires maintenance.  The pulse energy (penetration into the metal) is generally less with these than we can get from b.  Typically the pulse energy is between 40 and 90 Joules.

Laser welding head movement system
Welding head with XY electronic movement
System with welding XYZ table and main laser host machine
Mold repair laser welder

What is the best laser welder for mold repair? 

We believe Laser Welder Company sells the best mold repair laser welder, all things considered.  Just to explain this assertion:

Mold repair laser welders are made by LaserStar, Sisma, Hans and Laser Welder Company, among others.

Many on the market such as Hans are YAG flash tube based, which are cheaper but less consistent and reliable, and require more maintenance.  They are also extremely inefficient, using very high current.  In our opininon these should not be on your list.  Fibre laser is superior, although more costly.

Sisma and Laser Star welders are good but several times the cost of ours.  The performance is similar, so the extra cost is difficult to justify.  As with all our laser welders, our mold repair laser welders are the best value.  Our laser source has been proven reliable and efficient in Australia in our high volume laser welders.

What are the main laser welding parameters? 

 
Laser welder camera display showing pulsed welds
Test piece laser welded by first time user

Correct focusing is a key parameter for obtaining maximum power density.  De-focusing allows you to change the spot size and soften the pulse if required. Our user manual that comes with every laser welder explains the focus control.

Other key parameters are:

  • Pulse power, expressed as a percentage of maximum power
  • Pulse width in milliseconds
  • Pulse frequency
  • Travel speed
  • Wire thickness.  Wire thickness is a huge variable. Doubling wire thickness gives four times as much wire volume.

The pre-sets on our touchscreen control system allow the operator to store the optimal settings for a job, and use them whenever required.

What new developments are planned for Mold Repair welding?

Some molds are made from aluminium.  If you look at a chart of absorption against wavelength, known as the absorption spectrum, aluminum absorbs much more blue light than infrared. For this reason blue lasers are being developed. At present they are very expensive but in future blue light lasers could provide another solution for laser welding aluminium molds

Upload Image...